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linux/drivers/virtio/virtio_mem.c
David Hildenbrand 61082ad6a6 virtio-mem: support VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE 
The initial virtio-mem spec states that while unplugged memory should not
be read, the device still has to allow for reading unplugged memory inside
the usable region. The primary motivation for this default handling was
to simplify bringup of virtio-mem, because there were corner cases where
Linux might have accidentially read unplugged memory inside added Linux
memory blocks.

In the meantime, we:
1. Removed /dev/kmem in commit bbcd53c960 ("drivers/char: remove
   /dev/kmem for good")
2. Disallowed access to virtio-mem device memory via /dev/mem in
   commit 2128f4e21a ("virtio-mem: disallow mapping virtio-mem memory via
   /dev/mem")
3. Sanitized access to virtio-mem device memory via /proc/kcore in
   commit 0daa322b8f ("fs/proc/kcore: don't read offline sections,
   logically offline pages and hwpoisoned pages")
4. Sanitized access to virtio-mem device memory via /proc/vmcore in
   commit ce2814622e ("virtio-mem: kdump mode to sanitize /proc/vmcore
   access")

"Accidential" access to unplugged memory is no longer possible; we can
support the new VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE feature that will be
required by some hypervisors implementing virtio-mem in the near future.

Acked-by: Michael S. Tsirkin <mst@redhat.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Marek Kedzierski <mkedzier@redhat.com>
Cc: Hui Zhu <teawater@gmail.com>
Cc: Sebastien Boeuf <sebastien.boeuf@intel.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Wei Yang <richard.weiyang@linux.alibaba.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
2021-11-10 15:32:38 +01:00

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Virtio-mem device driver.
*
* Copyright Red Hat, Inc. 2020
*
* Author(s): David Hildenbrand <david@redhat.com>
*/
#include <linux/virtio.h>
#include <linux/virtio_mem.h>
#include <linux/workqueue.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/memory_hotplug.h>
#include <linux/memory.h>
#include <linux/hrtimer.h>
#include <linux/crash_dump.h>
#include <linux/mutex.h>
#include <linux/bitmap.h>
#include <linux/lockdep.h>
#include <acpi/acpi_numa.h>
static bool unplug_online = true;
module_param(unplug_online, bool, 0644);
MODULE_PARM_DESC(unplug_online, "Try to unplug online memory");
static bool force_bbm;
module_param(force_bbm, bool, 0444);
MODULE_PARM_DESC(force_bbm,
"Force Big Block Mode. Default is 0 (auto-selection)");
static unsigned long bbm_block_size;
module_param(bbm_block_size, ulong, 0444);
MODULE_PARM_DESC(bbm_block_size,
"Big Block size in bytes. Default is 0 (auto-detection).");
static bool bbm_safe_unplug = true;
module_param(bbm_safe_unplug, bool, 0444);
MODULE_PARM_DESC(bbm_safe_unplug,
"Use a safe unplug mechanism in BBM, avoiding long/endless loops");
/*
* virtio-mem currently supports the following modes of operation:
*
* * Sub Block Mode (SBM): A Linux memory block spans 2..X subblocks (SB). The
* size of a Sub Block (SB) is determined based on the device block size, the
* pageblock size, and the maximum allocation granularity of the buddy.
* Subblocks within a Linux memory block might either be plugged or unplugged.
* Memory is added/removed to Linux MM in Linux memory block granularity.
*
* * Big Block Mode (BBM): A Big Block (BB) spans 1..X Linux memory blocks.
* Memory is added/removed to Linux MM in Big Block granularity.
*
* The mode is determined automatically based on the Linux memory block size
* and the device block size.
*
* User space / core MM (auto onlining) is responsible for onlining added
* Linux memory blocks - and for selecting a zone. Linux Memory Blocks are
* always onlined separately, and all memory within a Linux memory block is
* onlined to the same zone - virtio-mem relies on this behavior.
*/
/*
* State of a Linux memory block in SBM.
*/
enum virtio_mem_sbm_mb_state {
/* Unplugged, not added to Linux. Can be reused later. */
VIRTIO_MEM_SBM_MB_UNUSED = 0,
/* (Partially) plugged, not added to Linux. Error on add_memory(). */
VIRTIO_MEM_SBM_MB_PLUGGED,
/* Fully plugged, fully added to Linux, offline. */
VIRTIO_MEM_SBM_MB_OFFLINE,
/* Partially plugged, fully added to Linux, offline. */
VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL,
/* Fully plugged, fully added to Linux, onlined to a kernel zone. */
VIRTIO_MEM_SBM_MB_KERNEL,
/* Partially plugged, fully added to Linux, online to a kernel zone */
VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL,
/* Fully plugged, fully added to Linux, onlined to ZONE_MOVABLE. */
VIRTIO_MEM_SBM_MB_MOVABLE,
/* Partially plugged, fully added to Linux, onlined to ZONE_MOVABLE. */
VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL,
VIRTIO_MEM_SBM_MB_COUNT
};
/*
* State of a Big Block (BB) in BBM, covering 1..X Linux memory blocks.
*/
enum virtio_mem_bbm_bb_state {
/* Unplugged, not added to Linux. Can be reused later. */
VIRTIO_MEM_BBM_BB_UNUSED = 0,
/* Plugged, not added to Linux. Error on add_memory(). */
VIRTIO_MEM_BBM_BB_PLUGGED,
/* Plugged and added to Linux. */
VIRTIO_MEM_BBM_BB_ADDED,
/* All online parts are fake-offline, ready to remove. */
VIRTIO_MEM_BBM_BB_FAKE_OFFLINE,
VIRTIO_MEM_BBM_BB_COUNT
};
struct virtio_mem {
struct virtio_device *vdev;
/* We might first have to unplug all memory when starting up. */
bool unplug_all_required;
/* Workqueue that processes the plug/unplug requests. */
struct work_struct wq;
atomic_t wq_active;
atomic_t config_changed;
/* Virtqueue for guest->host requests. */
struct virtqueue *vq;
/* Wait for a host response to a guest request. */
wait_queue_head_t host_resp;
/* Space for one guest request and the host response. */
struct virtio_mem_req req;
struct virtio_mem_resp resp;
/* The current size of the device. */
uint64_t plugged_size;
/* The requested size of the device. */
uint64_t requested_size;
/* The device block size (for communicating with the device). */
uint64_t device_block_size;
/* The determined node id for all memory of the device. */
int nid;
/* Physical start address of the memory region. */
uint64_t addr;
/* Maximum region size in bytes. */
uint64_t region_size;
/* The parent resource for all memory added via this device. */
struct resource *parent_resource;
/*
* Copy of "System RAM (virtio_mem)" to be used for
* add_memory_driver_managed().
*/
const char *resource_name;
/* Memory group identification. */
int mgid;
/*
* We don't want to add too much memory if it's not getting onlined,
* to avoid running OOM. Besides this threshold, we allow to have at
* least two offline blocks at a time (whatever is bigger).
*/
#define VIRTIO_MEM_DEFAULT_OFFLINE_THRESHOLD (1024 * 1024 * 1024)
atomic64_t offline_size;
uint64_t offline_threshold;
/* If set, the driver is in SBM, otherwise in BBM. */
bool in_sbm;
union {
struct {
/* Id of the first memory block of this device. */
unsigned long first_mb_id;
/* Id of the last usable memory block of this device. */
unsigned long last_usable_mb_id;
/* Id of the next memory bock to prepare when needed. */
unsigned long next_mb_id;
/* The subblock size. */
uint64_t sb_size;
/* The number of subblocks per Linux memory block. */
uint32_t sbs_per_mb;
/* Summary of all memory block states. */
unsigned long mb_count[VIRTIO_MEM_SBM_MB_COUNT];
/*
* One byte state per memory block. Allocated via
* vmalloc(). Resized (alloc+copy+free) on demand.
*
* With 128 MiB memory blocks, we have states for 512
* GiB of memory in one 4 KiB page.
*/
uint8_t *mb_states;
/*
* Bitmap: one bit per subblock. Allocated similar to
* sbm.mb_states.
*
* A set bit means the corresponding subblock is
* plugged, otherwise it's unblocked.
*
* With 4 MiB subblocks, we manage 128 GiB of memory
* in one 4 KiB page.
*/
unsigned long *sb_states;
} sbm;
struct {
/* Id of the first big block of this device. */
unsigned long first_bb_id;
/* Id of the last usable big block of this device. */
unsigned long last_usable_bb_id;
/* Id of the next device bock to prepare when needed. */
unsigned long next_bb_id;
/* Summary of all big block states. */
unsigned long bb_count[VIRTIO_MEM_BBM_BB_COUNT];
/* One byte state per big block. See sbm.mb_states. */
uint8_t *bb_states;
/* The block size used for plugging/adding/removing. */
uint64_t bb_size;
} bbm;
};
/*
* Mutex that protects the sbm.mb_count, sbm.mb_states,
* sbm.sb_states, bbm.bb_count, and bbm.bb_states
*
* When this lock is held the pointers can't change, ONLINE and
* OFFLINE blocks can't change the state and no subblocks will get
* plugged/unplugged.
*
* In kdump mode, used to serialize requests, last_block_addr and
* last_block_plugged.
*/
struct mutex hotplug_mutex;
bool hotplug_active;
/* An error occurred we cannot handle - stop processing requests. */
bool broken;
/* Cached valued of is_kdump_kernel() when the device was probed. */
bool in_kdump;
/* The driver is being removed. */
spinlock_t removal_lock;
bool removing;
/* Timer for retrying to plug/unplug memory. */
struct hrtimer retry_timer;
unsigned int retry_timer_ms;
#define VIRTIO_MEM_RETRY_TIMER_MIN_MS 50000
#define VIRTIO_MEM_RETRY_TIMER_MAX_MS 300000
/* Memory notifier (online/offline events). */
struct notifier_block memory_notifier;
#ifdef CONFIG_PROC_VMCORE
/* vmcore callback for /proc/vmcore handling in kdump mode */
struct vmcore_cb vmcore_cb;
uint64_t last_block_addr;
bool last_block_plugged;
#endif /* CONFIG_PROC_VMCORE */
/* Next device in the list of virtio-mem devices. */
struct list_head next;
};
/*
* We have to share a single online_page callback among all virtio-mem
* devices. We use RCU to iterate the list in the callback.
*/
static DEFINE_MUTEX(virtio_mem_mutex);
static LIST_HEAD(virtio_mem_devices);
static void virtio_mem_online_page_cb(struct page *page, unsigned int order);
static void virtio_mem_fake_offline_going_offline(unsigned long pfn,
unsigned long nr_pages);
static void virtio_mem_fake_offline_cancel_offline(unsigned long pfn,
unsigned long nr_pages);
static void virtio_mem_retry(struct virtio_mem *vm);
static int virtio_mem_create_resource(struct virtio_mem *vm);
static void virtio_mem_delete_resource(struct virtio_mem *vm);
/*
* Register a virtio-mem device so it will be considered for the online_page
* callback.
*/
static int register_virtio_mem_device(struct virtio_mem *vm)
{
int rc = 0;
/* First device registers the callback. */
mutex_lock(&virtio_mem_mutex);
if (list_empty(&virtio_mem_devices))
rc = set_online_page_callback(&virtio_mem_online_page_cb);
if (!rc)
list_add_rcu(&vm->next, &virtio_mem_devices);
mutex_unlock(&virtio_mem_mutex);
return rc;
}
/*
* Unregister a virtio-mem device so it will no longer be considered for the
* online_page callback.
*/
static void unregister_virtio_mem_device(struct virtio_mem *vm)
{
/* Last device unregisters the callback. */
mutex_lock(&virtio_mem_mutex);
list_del_rcu(&vm->next);
if (list_empty(&virtio_mem_devices))
restore_online_page_callback(&virtio_mem_online_page_cb);
mutex_unlock(&virtio_mem_mutex);
synchronize_rcu();
}
/*
* Calculate the memory block id of a given address.
*/
static unsigned long virtio_mem_phys_to_mb_id(unsigned long addr)
{
return addr / memory_block_size_bytes();
}
/*
* Calculate the physical start address of a given memory block id.
*/
static unsigned long virtio_mem_mb_id_to_phys(unsigned long mb_id)
{
return mb_id * memory_block_size_bytes();
}
/*
* Calculate the big block id of a given address.
*/
static unsigned long virtio_mem_phys_to_bb_id(struct virtio_mem *vm,
uint64_t addr)
{
return addr / vm->bbm.bb_size;
}
/*
* Calculate the physical start address of a given big block id.
*/
static uint64_t virtio_mem_bb_id_to_phys(struct virtio_mem *vm,
unsigned long bb_id)
{
return bb_id * vm->bbm.bb_size;
}
/*
* Calculate the subblock id of a given address.
*/
static unsigned long virtio_mem_phys_to_sb_id(struct virtio_mem *vm,
unsigned long addr)
{
const unsigned long mb_id = virtio_mem_phys_to_mb_id(addr);
const unsigned long mb_addr = virtio_mem_mb_id_to_phys(mb_id);
return (addr - mb_addr) / vm->sbm.sb_size;
}
/*
* Set the state of a big block, taking care of the state counter.
*/
static void virtio_mem_bbm_set_bb_state(struct virtio_mem *vm,
unsigned long bb_id,
enum virtio_mem_bbm_bb_state state)
{
const unsigned long idx = bb_id - vm->bbm.first_bb_id;
enum virtio_mem_bbm_bb_state old_state;
old_state = vm->bbm.bb_states[idx];
vm->bbm.bb_states[idx] = state;
BUG_ON(vm->bbm.bb_count[old_state] == 0);
vm->bbm.bb_count[old_state]--;
vm->bbm.bb_count[state]++;
}
/*
* Get the state of a big block.
*/
static enum virtio_mem_bbm_bb_state virtio_mem_bbm_get_bb_state(struct virtio_mem *vm,
unsigned long bb_id)
{
return vm->bbm.bb_states[bb_id - vm->bbm.first_bb_id];
}
/*
* Prepare the big block state array for the next big block.
*/
static int virtio_mem_bbm_bb_states_prepare_next_bb(struct virtio_mem *vm)
{
unsigned long old_bytes = vm->bbm.next_bb_id - vm->bbm.first_bb_id;
unsigned long new_bytes = old_bytes + 1;
int old_pages = PFN_UP(old_bytes);
int new_pages = PFN_UP(new_bytes);
uint8_t *new_array;
if (vm->bbm.bb_states && old_pages == new_pages)
return 0;
new_array = vzalloc(new_pages * PAGE_SIZE);
if (!new_array)
return -ENOMEM;
mutex_lock(&vm->hotplug_mutex);
if (vm->bbm.bb_states)
memcpy(new_array, vm->bbm.bb_states, old_pages * PAGE_SIZE);
vfree(vm->bbm.bb_states);
vm->bbm.bb_states = new_array;
mutex_unlock(&vm->hotplug_mutex);
return 0;
}
#define virtio_mem_bbm_for_each_bb(_vm, _bb_id, _state) \
for (_bb_id = vm->bbm.first_bb_id; \
_bb_id < vm->bbm.next_bb_id && _vm->bbm.bb_count[_state]; \
_bb_id++) \
if (virtio_mem_bbm_get_bb_state(_vm, _bb_id) == _state)
#define virtio_mem_bbm_for_each_bb_rev(_vm, _bb_id, _state) \
for (_bb_id = vm->bbm.next_bb_id - 1; \
_bb_id >= vm->bbm.first_bb_id && _vm->bbm.bb_count[_state]; \
_bb_id--) \
if (virtio_mem_bbm_get_bb_state(_vm, _bb_id) == _state)
/*
* Set the state of a memory block, taking care of the state counter.
*/
static void virtio_mem_sbm_set_mb_state(struct virtio_mem *vm,
unsigned long mb_id, uint8_t state)
{
const unsigned long idx = mb_id - vm->sbm.first_mb_id;
uint8_t old_state;
old_state = vm->sbm.mb_states[idx];
vm->sbm.mb_states[idx] = state;
BUG_ON(vm->sbm.mb_count[old_state] == 0);
vm->sbm.mb_count[old_state]--;
vm->sbm.mb_count[state]++;
}
/*
* Get the state of a memory block.
*/
static uint8_t virtio_mem_sbm_get_mb_state(struct virtio_mem *vm,
unsigned long mb_id)
{
const unsigned long idx = mb_id - vm->sbm.first_mb_id;
return vm->sbm.mb_states[idx];
}
/*
* Prepare the state array for the next memory block.
*/
static int virtio_mem_sbm_mb_states_prepare_next_mb(struct virtio_mem *vm)
{
int old_pages = PFN_UP(vm->sbm.next_mb_id - vm->sbm.first_mb_id);
int new_pages = PFN_UP(vm->sbm.next_mb_id - vm->sbm.first_mb_id + 1);
uint8_t *new_array;
if (vm->sbm.mb_states && old_pages == new_pages)
return 0;
new_array = vzalloc(new_pages * PAGE_SIZE);
if (!new_array)
return -ENOMEM;
mutex_lock(&vm->hotplug_mutex);
if (vm->sbm.mb_states)
memcpy(new_array, vm->sbm.mb_states, old_pages * PAGE_SIZE);
vfree(vm->sbm.mb_states);
vm->sbm.mb_states = new_array;
mutex_unlock(&vm->hotplug_mutex);
return 0;
}
#define virtio_mem_sbm_for_each_mb(_vm, _mb_id, _state) \
for (_mb_id = _vm->sbm.first_mb_id; \
_mb_id < _vm->sbm.next_mb_id && _vm->sbm.mb_count[_state]; \
_mb_id++) \
if (virtio_mem_sbm_get_mb_state(_vm, _mb_id) == _state)
#define virtio_mem_sbm_for_each_mb_rev(_vm, _mb_id, _state) \
for (_mb_id = _vm->sbm.next_mb_id - 1; \
_mb_id >= _vm->sbm.first_mb_id && _vm->sbm.mb_count[_state]; \
_mb_id--) \
if (virtio_mem_sbm_get_mb_state(_vm, _mb_id) == _state)
/*
* Calculate the bit number in the subblock bitmap for the given subblock
* inside the given memory block.
*/
static int virtio_mem_sbm_sb_state_bit_nr(struct virtio_mem *vm,
unsigned long mb_id, int sb_id)
{
return (mb_id - vm->sbm.first_mb_id) * vm->sbm.sbs_per_mb + sb_id;
}
/*
* Mark all selected subblocks plugged.
*
* Will not modify the state of the memory block.
*/
static void virtio_mem_sbm_set_sb_plugged(struct virtio_mem *vm,
unsigned long mb_id, int sb_id,
int count)
{
const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id);
__bitmap_set(vm->sbm.sb_states, bit, count);
}
/*
* Mark all selected subblocks unplugged.
*
* Will not modify the state of the memory block.
*/
static void virtio_mem_sbm_set_sb_unplugged(struct virtio_mem *vm,
unsigned long mb_id, int sb_id,
int count)
{
const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id);
__bitmap_clear(vm->sbm.sb_states, bit, count);
}
/*
* Test if all selected subblocks are plugged.
*/
static bool virtio_mem_sbm_test_sb_plugged(struct virtio_mem *vm,
unsigned long mb_id, int sb_id,
int count)
{
const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id);
if (count == 1)
return test_bit(bit, vm->sbm.sb_states);
/* TODO: Helper similar to bitmap_set() */
return find_next_zero_bit(vm->sbm.sb_states, bit + count, bit) >=
bit + count;
}
/*
* Test if all selected subblocks are unplugged.
*/
static bool virtio_mem_sbm_test_sb_unplugged(struct virtio_mem *vm,
unsigned long mb_id, int sb_id,
int count)
{
const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, sb_id);
/* TODO: Helper similar to bitmap_set() */
return find_next_bit(vm->sbm.sb_states, bit + count, bit) >=
bit + count;
}
/*
* Find the first unplugged subblock. Returns vm->sbm.sbs_per_mb in case there is
* none.
*/
static int virtio_mem_sbm_first_unplugged_sb(struct virtio_mem *vm,
unsigned long mb_id)
{
const int bit = virtio_mem_sbm_sb_state_bit_nr(vm, mb_id, 0);
return find_next_zero_bit(vm->sbm.sb_states,
bit + vm->sbm.sbs_per_mb, bit) - bit;
}
/*
* Prepare the subblock bitmap for the next memory block.
*/
static int virtio_mem_sbm_sb_states_prepare_next_mb(struct virtio_mem *vm)
{
const unsigned long old_nb_mb = vm->sbm.next_mb_id - vm->sbm.first_mb_id;
const unsigned long old_nb_bits = old_nb_mb * vm->sbm.sbs_per_mb;
const unsigned long new_nb_bits = (old_nb_mb + 1) * vm->sbm.sbs_per_mb;
int old_pages = PFN_UP(BITS_TO_LONGS(old_nb_bits) * sizeof(long));
int new_pages = PFN_UP(BITS_TO_LONGS(new_nb_bits) * sizeof(long));
unsigned long *new_bitmap, *old_bitmap;
if (vm->sbm.sb_states && old_pages == new_pages)
return 0;
new_bitmap = vzalloc(new_pages * PAGE_SIZE);
if (!new_bitmap)
return -ENOMEM;
mutex_lock(&vm->hotplug_mutex);
if (new_bitmap)
memcpy(new_bitmap, vm->sbm.sb_states, old_pages * PAGE_SIZE);
old_bitmap = vm->sbm.sb_states;
vm->sbm.sb_states = new_bitmap;
mutex_unlock(&vm->hotplug_mutex);
vfree(old_bitmap);
return 0;
}
/*
* Test if we could add memory without creating too much offline memory -
* to avoid running OOM if memory is getting onlined deferred.
*/
static bool virtio_mem_could_add_memory(struct virtio_mem *vm, uint64_t size)
{
if (WARN_ON_ONCE(size > vm->offline_threshold))
return false;
return atomic64_read(&vm->offline_size) + size <= vm->offline_threshold;
}
/*
* Try adding memory to Linux. Will usually only fail if out of memory.
*
* Must not be called with the vm->hotplug_mutex held (possible deadlock with
* onlining code).
*
* Will not modify the state of memory blocks in virtio-mem.
*/
static int virtio_mem_add_memory(struct virtio_mem *vm, uint64_t addr,
uint64_t size)
{
int rc;
/*
* When force-unloading the driver and we still have memory added to
* Linux, the resource name has to stay.
*/
if (!vm->resource_name) {
vm->resource_name = kstrdup_const("System RAM (virtio_mem)",
GFP_KERNEL);
if (!vm->resource_name)
return -ENOMEM;
}
dev_dbg(&vm->vdev->dev, "adding memory: 0x%llx - 0x%llx\n", addr,
addr + size - 1);
/* Memory might get onlined immediately. */
atomic64_add(size, &vm->offline_size);
rc = add_memory_driver_managed(vm->mgid, addr, size, vm->resource_name,
MHP_MERGE_RESOURCE | MHP_NID_IS_MGID);
if (rc) {
atomic64_sub(size, &vm->offline_size);
dev_warn(&vm->vdev->dev, "adding memory failed: %d\n", rc);
/*
* TODO: Linux MM does not properly clean up yet in all cases
* where adding of memory failed - especially on -ENOMEM.
*/
}
return rc;
}
/*
* See virtio_mem_add_memory(): Try adding a single Linux memory block.
*/
static int virtio_mem_sbm_add_mb(struct virtio_mem *vm, unsigned long mb_id)
{
const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
const uint64_t size = memory_block_size_bytes();
return virtio_mem_add_memory(vm, addr, size);
}
/*
* See virtio_mem_add_memory(): Try adding a big block.
*/
static int virtio_mem_bbm_add_bb(struct virtio_mem *vm, unsigned long bb_id)
{
const uint64_t addr = virtio_mem_bb_id_to_phys(vm, bb_id);
const uint64_t size = vm->bbm.bb_size;
return virtio_mem_add_memory(vm, addr, size);
}
/*
* Try removing memory from Linux. Will only fail if memory blocks aren't
* offline.
*
* Must not be called with the vm->hotplug_mutex held (possible deadlock with
* onlining code).
*
* Will not modify the state of memory blocks in virtio-mem.
*/
static int virtio_mem_remove_memory(struct virtio_mem *vm, uint64_t addr,
uint64_t size)
{
int rc;
dev_dbg(&vm->vdev->dev, "removing memory: 0x%llx - 0x%llx\n", addr,
addr + size - 1);
rc = remove_memory(addr, size);
if (!rc) {
atomic64_sub(size, &vm->offline_size);
/*
* We might have freed up memory we can now unplug, retry
* immediately instead of waiting.
*/
virtio_mem_retry(vm);
} else {
dev_dbg(&vm->vdev->dev, "removing memory failed: %d\n", rc);
}
return rc;
}
/*
* See virtio_mem_remove_memory(): Try removing a single Linux memory block.
*/
static int virtio_mem_sbm_remove_mb(struct virtio_mem *vm, unsigned long mb_id)
{
const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
const uint64_t size = memory_block_size_bytes();
return virtio_mem_remove_memory(vm, addr, size);
}
/*
* Try offlining and removing memory from Linux.
*
* Must not be called with the vm->hotplug_mutex held (possible deadlock with
* onlining code).
*
* Will not modify the state of memory blocks in virtio-mem.
*/
static int virtio_mem_offline_and_remove_memory(struct virtio_mem *vm,
uint64_t addr,
uint64_t size)
{
int rc;
dev_dbg(&vm->vdev->dev,
"offlining and removing memory: 0x%llx - 0x%llx\n", addr,
addr + size - 1);
rc = offline_and_remove_memory(addr, size);
if (!rc) {
atomic64_sub(size, &vm->offline_size);
/*
* We might have freed up memory we can now unplug, retry
* immediately instead of waiting.
*/
virtio_mem_retry(vm);
} else {
dev_dbg(&vm->vdev->dev,
"offlining and removing memory failed: %d\n", rc);
}
return rc;
}
/*
* See virtio_mem_offline_and_remove_memory(): Try offlining and removing
* a single Linux memory block.
*/
static int virtio_mem_sbm_offline_and_remove_mb(struct virtio_mem *vm,
unsigned long mb_id)
{
const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
const uint64_t size = memory_block_size_bytes();
return virtio_mem_offline_and_remove_memory(vm, addr, size);
}
/*
* See virtio_mem_offline_and_remove_memory(): Try to offline and remove a
* all Linux memory blocks covered by the big block.
*/
static int virtio_mem_bbm_offline_and_remove_bb(struct virtio_mem *vm,
unsigned long bb_id)
{
const uint64_t addr = virtio_mem_bb_id_to_phys(vm, bb_id);
const uint64_t size = vm->bbm.bb_size;
return virtio_mem_offline_and_remove_memory(vm, addr, size);
}
/*
* Trigger the workqueue so the device can perform its magic.
*/
static void virtio_mem_retry(struct virtio_mem *vm)
{
unsigned long flags;
spin_lock_irqsave(&vm->removal_lock, flags);
if (!vm->removing)
queue_work(system_freezable_wq, &vm->wq);
spin_unlock_irqrestore(&vm->removal_lock, flags);
}
static int virtio_mem_translate_node_id(struct virtio_mem *vm, uint16_t node_id)
{
int node = NUMA_NO_NODE;
#if defined(CONFIG_ACPI_NUMA)
if (virtio_has_feature(vm->vdev, VIRTIO_MEM_F_ACPI_PXM))
node = pxm_to_node(node_id);
#endif
return node;
}
/*
* Test if a virtio-mem device overlaps with the given range. Can be called
* from (notifier) callbacks lockless.
*/
static bool virtio_mem_overlaps_range(struct virtio_mem *vm, uint64_t start,
uint64_t size)
{
return start < vm->addr + vm->region_size && vm->addr < start + size;
}
/*
* Test if a virtio-mem device contains a given range. Can be called from
* (notifier) callbacks lockless.
*/
static bool virtio_mem_contains_range(struct virtio_mem *vm, uint64_t start,
uint64_t size)
{
return start >= vm->addr && start + size <= vm->addr + vm->region_size;
}
static int virtio_mem_sbm_notify_going_online(struct virtio_mem *vm,
unsigned long mb_id)
{
switch (virtio_mem_sbm_get_mb_state(vm, mb_id)) {
case VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL:
case VIRTIO_MEM_SBM_MB_OFFLINE:
return NOTIFY_OK;
default:
break;
}
dev_warn_ratelimited(&vm->vdev->dev,
"memory block onlining denied\n");
return NOTIFY_BAD;
}
static void virtio_mem_sbm_notify_offline(struct virtio_mem *vm,
unsigned long mb_id)
{
switch (virtio_mem_sbm_get_mb_state(vm, mb_id)) {
case VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL:
case VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL:
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL);
break;
case VIRTIO_MEM_SBM_MB_KERNEL:
case VIRTIO_MEM_SBM_MB_MOVABLE:
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_OFFLINE);
break;
default:
BUG();
break;
}
}
static void virtio_mem_sbm_notify_online(struct virtio_mem *vm,
unsigned long mb_id,
unsigned long start_pfn)
{
const bool is_movable = page_zonenum(pfn_to_page(start_pfn)) ==
ZONE_MOVABLE;
int new_state;
switch (virtio_mem_sbm_get_mb_state(vm, mb_id)) {
case VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL:
new_state = VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL;
if (is_movable)
new_state = VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL;
break;
case VIRTIO_MEM_SBM_MB_OFFLINE:
new_state = VIRTIO_MEM_SBM_MB_KERNEL;
if (is_movable)
new_state = VIRTIO_MEM_SBM_MB_MOVABLE;
break;
default:
BUG();
break;
}
virtio_mem_sbm_set_mb_state(vm, mb_id, new_state);
}
static void virtio_mem_sbm_notify_going_offline(struct virtio_mem *vm,
unsigned long mb_id)
{
const unsigned long nr_pages = PFN_DOWN(vm->sbm.sb_size);
unsigned long pfn;
int sb_id;
for (sb_id = 0; sb_id < vm->sbm.sbs_per_mb; sb_id++) {
if (virtio_mem_sbm_test_sb_plugged(vm, mb_id, sb_id, 1))
continue;
pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
sb_id * vm->sbm.sb_size);
virtio_mem_fake_offline_going_offline(pfn, nr_pages);
}
}
static void virtio_mem_sbm_notify_cancel_offline(struct virtio_mem *vm,
unsigned long mb_id)
{
const unsigned long nr_pages = PFN_DOWN(vm->sbm.sb_size);
unsigned long pfn;
int sb_id;
for (sb_id = 0; sb_id < vm->sbm.sbs_per_mb; sb_id++) {
if (virtio_mem_sbm_test_sb_plugged(vm, mb_id, sb_id, 1))
continue;
pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
sb_id * vm->sbm.sb_size);
virtio_mem_fake_offline_cancel_offline(pfn, nr_pages);
}
}
static void virtio_mem_bbm_notify_going_offline(struct virtio_mem *vm,
unsigned long bb_id,
unsigned long pfn,
unsigned long nr_pages)
{
/*
* When marked as "fake-offline", all online memory of this device block
* is allocated by us. Otherwise, we don't have any memory allocated.
*/
if (virtio_mem_bbm_get_bb_state(vm, bb_id) !=
VIRTIO_MEM_BBM_BB_FAKE_OFFLINE)
return;
virtio_mem_fake_offline_going_offline(pfn, nr_pages);
}
static void virtio_mem_bbm_notify_cancel_offline(struct virtio_mem *vm,
unsigned long bb_id,
unsigned long pfn,
unsigned long nr_pages)
{
if (virtio_mem_bbm_get_bb_state(vm, bb_id) !=
VIRTIO_MEM_BBM_BB_FAKE_OFFLINE)
return;
virtio_mem_fake_offline_cancel_offline(pfn, nr_pages);
}
/*
* This callback will either be called synchronously from add_memory() or
* asynchronously (e.g., triggered via user space). We have to be careful
* with locking when calling add_memory().
*/
static int virtio_mem_memory_notifier_cb(struct notifier_block *nb,
unsigned long action, void *arg)
{
struct virtio_mem *vm = container_of(nb, struct virtio_mem,
memory_notifier);
struct memory_notify *mhp = arg;
const unsigned long start = PFN_PHYS(mhp->start_pfn);
const unsigned long size = PFN_PHYS(mhp->nr_pages);
int rc = NOTIFY_OK;
unsigned long id;
if (!virtio_mem_overlaps_range(vm, start, size))
return NOTIFY_DONE;
if (vm->in_sbm) {
id = virtio_mem_phys_to_mb_id(start);
/*
* In SBM, we add memory in separate memory blocks - we expect
* it to be onlined/offlined in the same granularity. Bail out
* if this ever changes.
*/
if (WARN_ON_ONCE(size != memory_block_size_bytes() ||
!IS_ALIGNED(start, memory_block_size_bytes())))
return NOTIFY_BAD;
} else {
id = virtio_mem_phys_to_bb_id(vm, start);
/*
* In BBM, we only care about onlining/offlining happening
* within a single big block, we don't care about the
* actual granularity as we don't track individual Linux
* memory blocks.
*/
if (WARN_ON_ONCE(id != virtio_mem_phys_to_bb_id(vm, start + size - 1)))
return NOTIFY_BAD;
}
/*
* Avoid circular locking lockdep warnings. We lock the mutex
* e.g., in MEM_GOING_ONLINE and unlock it in MEM_ONLINE. The
* blocking_notifier_call_chain() has it's own lock, which gets unlocked
* between both notifier calls and will bail out. False positive.
*/
lockdep_off();
switch (action) {
case MEM_GOING_OFFLINE:
mutex_lock(&vm->hotplug_mutex);
if (vm->removing) {
rc = notifier_from_errno(-EBUSY);
mutex_unlock(&vm->hotplug_mutex);
break;
}
vm->hotplug_active = true;
if (vm->in_sbm)
virtio_mem_sbm_notify_going_offline(vm, id);
else
virtio_mem_bbm_notify_going_offline(vm, id,
mhp->start_pfn,
mhp->nr_pages);
break;
case MEM_GOING_ONLINE:
mutex_lock(&vm->hotplug_mutex);
if (vm->removing) {
rc = notifier_from_errno(-EBUSY);
mutex_unlock(&vm->hotplug_mutex);
break;
}
vm->hotplug_active = true;
if (vm->in_sbm)
rc = virtio_mem_sbm_notify_going_online(vm, id);
break;
case MEM_OFFLINE:
if (vm->in_sbm)
virtio_mem_sbm_notify_offline(vm, id);
atomic64_add(size, &vm->offline_size);
/*
* Trigger the workqueue. Now that we have some offline memory,
* maybe we can handle pending unplug requests.
*/
if (!unplug_online)
virtio_mem_retry(vm);
vm->hotplug_active = false;
mutex_unlock(&vm->hotplug_mutex);
break;
case MEM_ONLINE:
if (vm->in_sbm)
virtio_mem_sbm_notify_online(vm, id, mhp->start_pfn);
atomic64_sub(size, &vm->offline_size);
/*
* Start adding more memory once we onlined half of our
* threshold. Don't trigger if it's possibly due to our actipn
* (e.g., us adding memory which gets onlined immediately from
* the core).
*/
if (!atomic_read(&vm->wq_active) &&
virtio_mem_could_add_memory(vm, vm->offline_threshold / 2))
virtio_mem_retry(vm);
vm->hotplug_active = false;
mutex_unlock(&vm->hotplug_mutex);
break;
case MEM_CANCEL_OFFLINE:
if (!vm->hotplug_active)
break;
if (vm->in_sbm)
virtio_mem_sbm_notify_cancel_offline(vm, id);
else
virtio_mem_bbm_notify_cancel_offline(vm, id,
mhp->start_pfn,
mhp->nr_pages);
vm->hotplug_active = false;
mutex_unlock(&vm->hotplug_mutex);
break;
case MEM_CANCEL_ONLINE:
if (!vm->hotplug_active)
break;
vm->hotplug_active = false;
mutex_unlock(&vm->hotplug_mutex);
break;
default:
break;
}
lockdep_on();
return rc;
}
/*
* Set a range of pages PG_offline. Remember pages that were never onlined
* (via generic_online_page()) using PageDirty().
*/
static void virtio_mem_set_fake_offline(unsigned long pfn,
unsigned long nr_pages, bool onlined)
{
page_offline_begin();
for (; nr_pages--; pfn++) {
struct page *page = pfn_to_page(pfn);
__SetPageOffline(page);
if (!onlined) {
SetPageDirty(page);
/* FIXME: remove after cleanups */
ClearPageReserved(page);
}
}
page_offline_end();
}
/*
* Clear PG_offline from a range of pages. If the pages were never onlined,
* (via generic_online_page()), clear PageDirty().
*/
static void virtio_mem_clear_fake_offline(unsigned long pfn,
unsigned long nr_pages, bool onlined)
{
for (; nr_pages--; pfn++) {
struct page *page = pfn_to_page(pfn);
__ClearPageOffline(page);
if (!onlined)
ClearPageDirty(page);
}
}
/*
* Release a range of fake-offline pages to the buddy, effectively
* fake-onlining them.
*/
static void virtio_mem_fake_online(unsigned long pfn, unsigned long nr_pages)
{
const unsigned long max_nr_pages = MAX_ORDER_NR_PAGES;
unsigned long i;
/*
* We are always called at least with MAX_ORDER_NR_PAGES
* granularity/alignment (e.g., the way subblocks work). All pages
* inside such a block are alike.
*/
for (i = 0; i < nr_pages; i += max_nr_pages) {
struct page *page = pfn_to_page(pfn + i);
/*
* If the page is PageDirty(), it was kept fake-offline when
* onlining the memory block. Otherwise, it was allocated
* using alloc_contig_range(). All pages in a subblock are
* alike.
*/
if (PageDirty(page)) {
virtio_mem_clear_fake_offline(pfn + i, max_nr_pages,
false);
generic_online_page(page, MAX_ORDER - 1);
} else {
virtio_mem_clear_fake_offline(pfn + i, max_nr_pages,
true);
free_contig_range(pfn + i, max_nr_pages);
adjust_managed_page_count(page, max_nr_pages);
}
}
}
/*
* Try to allocate a range, marking pages fake-offline, effectively
* fake-offlining them.
*/
static int virtio_mem_fake_offline(unsigned long pfn, unsigned long nr_pages)
{
const bool is_movable = page_zonenum(pfn_to_page(pfn)) ==
ZONE_MOVABLE;
int rc, retry_count;
/*
* TODO: We want an alloc_contig_range() mode that tries to allocate
* harder (e.g., dealing with temporarily pinned pages, PCP), especially
* with ZONE_MOVABLE. So for now, retry a couple of times with
* ZONE_MOVABLE before giving up - because that zone is supposed to give
* some guarantees.
*/
for (retry_count = 0; retry_count < 5; retry_count++) {
rc = alloc_contig_range(pfn, pfn + nr_pages, MIGRATE_MOVABLE,
GFP_KERNEL);
if (rc == -ENOMEM)
/* whoops, out of memory */
return rc;
else if (rc && !is_movable)
break;
else if (rc)
continue;
virtio_mem_set_fake_offline(pfn, nr_pages, true);
adjust_managed_page_count(pfn_to_page(pfn), -nr_pages);
return 0;
}
return -EBUSY;
}
/*
* Handle fake-offline pages when memory is going offline - such that the
* pages can be skipped by mm-core when offlining.
*/
static void virtio_mem_fake_offline_going_offline(unsigned long pfn,
unsigned long nr_pages)
{
struct page *page;
unsigned long i;
/*
* Drop our reference to the pages so the memory can get offlined
* and add the unplugged pages to the managed page counters (so
* offlining code can correctly subtract them again).
*/
adjust_managed_page_count(pfn_to_page(pfn), nr_pages);
/* Drop our reference to the pages so the memory can get offlined. */
for (i = 0; i < nr_pages; i++) {
page = pfn_to_page(pfn + i);
if (WARN_ON(!page_ref_dec_and_test(page)))
dump_page(page, "fake-offline page referenced");
}
}
/*
* Handle fake-offline pages when memory offlining is canceled - to undo
* what we did in virtio_mem_fake_offline_going_offline().
*/
static void virtio_mem_fake_offline_cancel_offline(unsigned long pfn,
unsigned long nr_pages)
{
unsigned long i;
/*
* Get the reference we dropped when going offline and subtract the
* unplugged pages from the managed page counters.
*/
adjust_managed_page_count(pfn_to_page(pfn), -nr_pages);
for (i = 0; i < nr_pages; i++)
page_ref_inc(pfn_to_page(pfn + i));
}
static void virtio_mem_online_page_cb(struct page *page, unsigned int order)
{
const unsigned long addr = page_to_phys(page);
unsigned long id, sb_id;
struct virtio_mem *vm;
bool do_online;
rcu_read_lock();
list_for_each_entry_rcu(vm, &virtio_mem_devices, next) {
if (!virtio_mem_contains_range(vm, addr, PFN_PHYS(1 << order)))
continue;
if (vm->in_sbm) {
/*
* We exploit here that subblocks have at least
* MAX_ORDER_NR_PAGES size/alignment - so we cannot
* cross subblocks within one call.
*/
id = virtio_mem_phys_to_mb_id(addr);
sb_id = virtio_mem_phys_to_sb_id(vm, addr);
do_online = virtio_mem_sbm_test_sb_plugged(vm, id,
sb_id, 1);
} else {
/*
* If the whole block is marked fake offline, keep
* everything that way.
*/
id = virtio_mem_phys_to_bb_id(vm, addr);
do_online = virtio_mem_bbm_get_bb_state(vm, id) !=
VIRTIO_MEM_BBM_BB_FAKE_OFFLINE;
}
/*
* virtio_mem_set_fake_offline() might sleep, we don't need
* the device anymore. See virtio_mem_remove() how races
* between memory onlining and device removal are handled.
*/
rcu_read_unlock();
if (do_online)
generic_online_page(page, order);
else
virtio_mem_set_fake_offline(PFN_DOWN(addr), 1 << order,
false);
return;
}
rcu_read_unlock();
/* not virtio-mem memory, but e.g., a DIMM. online it */
generic_online_page(page, order);
}
static uint64_t virtio_mem_send_request(struct virtio_mem *vm,
const struct virtio_mem_req *req)
{
struct scatterlist *sgs[2], sg_req, sg_resp;
unsigned int len;
int rc;
/* don't use the request residing on the stack (vaddr) */
vm->req = *req;
/* out: buffer for request */
sg_init_one(&sg_req, &vm->req, sizeof(vm->req));
sgs[0] = &sg_req;
/* in: buffer for response */
sg_init_one(&sg_resp, &vm->resp, sizeof(vm->resp));
sgs[1] = &sg_resp;
rc = virtqueue_add_sgs(vm->vq, sgs, 1, 1, vm, GFP_KERNEL);
if (rc < 0)
return rc;
virtqueue_kick(vm->vq);
/* wait for a response */
wait_event(vm->host_resp, virtqueue_get_buf(vm->vq, &len));
return virtio16_to_cpu(vm->vdev, vm->resp.type);
}
static int virtio_mem_send_plug_request(struct virtio_mem *vm, uint64_t addr,
uint64_t size)
{
const uint64_t nb_vm_blocks = size / vm->device_block_size;
const struct virtio_mem_req req = {
.type = cpu_to_virtio16(vm->vdev, VIRTIO_MEM_REQ_PLUG),
.u.plug.addr = cpu_to_virtio64(vm->vdev, addr),
.u.plug.nb_blocks = cpu_to_virtio16(vm->vdev, nb_vm_blocks),
};
int rc = -ENOMEM;
if (atomic_read(&vm->config_changed))
return -EAGAIN;
dev_dbg(&vm->vdev->dev, "plugging memory: 0x%llx - 0x%llx\n", addr,
addr + size - 1);
switch (virtio_mem_send_request(vm, &req)) {
case VIRTIO_MEM_RESP_ACK:
vm->plugged_size += size;
return 0;
case VIRTIO_MEM_RESP_NACK:
rc = -EAGAIN;
break;
case VIRTIO_MEM_RESP_BUSY:
rc = -ETXTBSY;
break;
case VIRTIO_MEM_RESP_ERROR:
rc = -EINVAL;
break;
default:
break;
}
dev_dbg(&vm->vdev->dev, "plugging memory failed: %d\n", rc);
return rc;
}
static int virtio_mem_send_unplug_request(struct virtio_mem *vm, uint64_t addr,
uint64_t size)
{
const uint64_t nb_vm_blocks = size / vm->device_block_size;
const struct virtio_mem_req req = {
.type = cpu_to_virtio16(vm->vdev, VIRTIO_MEM_REQ_UNPLUG),
.u.unplug.addr = cpu_to_virtio64(vm->vdev, addr),
.u.unplug.nb_blocks = cpu_to_virtio16(vm->vdev, nb_vm_blocks),
};
int rc = -ENOMEM;
if (atomic_read(&vm->config_changed))
return -EAGAIN;
dev_dbg(&vm->vdev->dev, "unplugging memory: 0x%llx - 0x%llx\n", addr,
addr + size - 1);
switch (virtio_mem_send_request(vm, &req)) {
case VIRTIO_MEM_RESP_ACK:
vm->plugged_size -= size;
return 0;
case VIRTIO_MEM_RESP_BUSY:
rc = -ETXTBSY;
break;
case VIRTIO_MEM_RESP_ERROR:
rc = -EINVAL;
break;
default:
break;
}
dev_dbg(&vm->vdev->dev, "unplugging memory failed: %d\n", rc);
return rc;
}
static int virtio_mem_send_unplug_all_request(struct virtio_mem *vm)
{
const struct virtio_mem_req req = {
.type = cpu_to_virtio16(vm->vdev, VIRTIO_MEM_REQ_UNPLUG_ALL),
};
int rc = -ENOMEM;
dev_dbg(&vm->vdev->dev, "unplugging all memory");
switch (virtio_mem_send_request(vm, &req)) {
case VIRTIO_MEM_RESP_ACK:
vm->unplug_all_required = false;
vm->plugged_size = 0;
/* usable region might have shrunk */
atomic_set(&vm->config_changed, 1);
return 0;
case VIRTIO_MEM_RESP_BUSY:
rc = -ETXTBSY;
break;
default:
break;
}
dev_dbg(&vm->vdev->dev, "unplugging all memory failed: %d\n", rc);
return rc;
}
/*
* Plug selected subblocks. Updates the plugged state, but not the state
* of the memory block.
*/
static int virtio_mem_sbm_plug_sb(struct virtio_mem *vm, unsigned long mb_id,
int sb_id, int count)
{
const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id) +
sb_id * vm->sbm.sb_size;
const uint64_t size = count * vm->sbm.sb_size;
int rc;
rc = virtio_mem_send_plug_request(vm, addr, size);
if (!rc)
virtio_mem_sbm_set_sb_plugged(vm, mb_id, sb_id, count);
return rc;
}
/*
* Unplug selected subblocks. Updates the plugged state, but not the state
* of the memory block.
*/
static int virtio_mem_sbm_unplug_sb(struct virtio_mem *vm, unsigned long mb_id,
int sb_id, int count)
{
const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id) +
sb_id * vm->sbm.sb_size;
const uint64_t size = count * vm->sbm.sb_size;
int rc;
rc = virtio_mem_send_unplug_request(vm, addr, size);
if (!rc)
virtio_mem_sbm_set_sb_unplugged(vm, mb_id, sb_id, count);
return rc;
}
/*
* Request to unplug a big block.
*
* Will not modify the state of the big block.
*/
static int virtio_mem_bbm_unplug_bb(struct virtio_mem *vm, unsigned long bb_id)
{
const uint64_t addr = virtio_mem_bb_id_to_phys(vm, bb_id);
const uint64_t size = vm->bbm.bb_size;
return virtio_mem_send_unplug_request(vm, addr, size);
}
/*
* Request to plug a big block.
*
* Will not modify the state of the big block.
*/
static int virtio_mem_bbm_plug_bb(struct virtio_mem *vm, unsigned long bb_id)
{
const uint64_t addr = virtio_mem_bb_id_to_phys(vm, bb_id);
const uint64_t size = vm->bbm.bb_size;
return virtio_mem_send_plug_request(vm, addr, size);
}
/*
* Unplug the desired number of plugged subblocks of a offline or not-added
* memory block. Will fail if any subblock cannot get unplugged (instead of
* skipping it).
*
* Will not modify the state of the memory block.
*
* Note: can fail after some subblocks were unplugged.
*/
static int virtio_mem_sbm_unplug_any_sb_raw(struct virtio_mem *vm,
unsigned long mb_id, uint64_t *nb_sb)
{
int sb_id, count;
int rc;
sb_id = vm->sbm.sbs_per_mb - 1;
while (*nb_sb) {
/* Find the next candidate subblock */
while (sb_id >= 0 &&
virtio_mem_sbm_test_sb_unplugged(vm, mb_id, sb_id, 1))
sb_id--;
if (sb_id < 0)
break;
/* Try to unplug multiple subblocks at a time */
count = 1;
while (count < *nb_sb && sb_id > 0 &&
virtio_mem_sbm_test_sb_plugged(vm, mb_id, sb_id - 1, 1)) {
count++;
sb_id--;
}
rc = virtio_mem_sbm_unplug_sb(vm, mb_id, sb_id, count);
if (rc)
return rc;
*nb_sb -= count;
sb_id--;
}
return 0;
}
/*
* Unplug all plugged subblocks of an offline or not-added memory block.
*
* Will not modify the state of the memory block.
*
* Note: can fail after some subblocks were unplugged.
*/
static int virtio_mem_sbm_unplug_mb(struct virtio_mem *vm, unsigned long mb_id)
{
uint64_t nb_sb = vm->sbm.sbs_per_mb;
return virtio_mem_sbm_unplug_any_sb_raw(vm, mb_id, &nb_sb);
}
/*
* Prepare tracking data for the next memory block.
*/
static int virtio_mem_sbm_prepare_next_mb(struct virtio_mem *vm,
unsigned long *mb_id)
{
int rc;
if (vm->sbm.next_mb_id > vm->sbm.last_usable_mb_id)
return -ENOSPC;
/* Resize the state array if required. */
rc = virtio_mem_sbm_mb_states_prepare_next_mb(vm);
if (rc)
return rc;
/* Resize the subblock bitmap if required. */
rc = virtio_mem_sbm_sb_states_prepare_next_mb(vm);
if (rc)
return rc;
vm->sbm.mb_count[VIRTIO_MEM_SBM_MB_UNUSED]++;
*mb_id = vm->sbm.next_mb_id++;
return 0;
}
/*
* Try to plug the desired number of subblocks and add the memory block
* to Linux.
*
* Will modify the state of the memory block.
*/
static int virtio_mem_sbm_plug_and_add_mb(struct virtio_mem *vm,
unsigned long mb_id, uint64_t *nb_sb)
{
const int count = min_t(int, *nb_sb, vm->sbm.sbs_per_mb);
int rc;
if (WARN_ON_ONCE(!count))
return -EINVAL;
/*
* Plug the requested number of subblocks before adding it to linux,
* so that onlining will directly online all plugged subblocks.
*/
rc = virtio_mem_sbm_plug_sb(vm, mb_id, 0, count);
if (rc)
return rc;
/*
* Mark the block properly offline before adding it to Linux,
* so the memory notifiers will find the block in the right state.
*/
if (count == vm->sbm.sbs_per_mb)
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_OFFLINE);
else
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL);
/* Add the memory block to linux - if that fails, try to unplug. */
rc = virtio_mem_sbm_add_mb(vm, mb_id);
if (rc) {
int new_state = VIRTIO_MEM_SBM_MB_UNUSED;
if (virtio_mem_sbm_unplug_sb(vm, mb_id, 0, count))
new_state = VIRTIO_MEM_SBM_MB_PLUGGED;
virtio_mem_sbm_set_mb_state(vm, mb_id, new_state);
return rc;
}
*nb_sb -= count;
return 0;
}
/*
* Try to plug the desired number of subblocks of a memory block that
* is already added to Linux.
*
* Will modify the state of the memory block.
*
* Note: Can fail after some subblocks were successfully plugged.
*/
static int virtio_mem_sbm_plug_any_sb(struct virtio_mem *vm,
unsigned long mb_id, uint64_t *nb_sb)
{
const int old_state = virtio_mem_sbm_get_mb_state(vm, mb_id);
unsigned long pfn, nr_pages;
int sb_id, count;
int rc;
if (WARN_ON_ONCE(!*nb_sb))
return -EINVAL;
while (*nb_sb) {
sb_id = virtio_mem_sbm_first_unplugged_sb(vm, mb_id);
if (sb_id >= vm->sbm.sbs_per_mb)
break;
count = 1;
while (count < *nb_sb &&
sb_id + count < vm->sbm.sbs_per_mb &&
!virtio_mem_sbm_test_sb_plugged(vm, mb_id, sb_id + count, 1))
count++;
rc = virtio_mem_sbm_plug_sb(vm, mb_id, sb_id, count);
if (rc)
return rc;
*nb_sb -= count;
if (old_state == VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL)
continue;
/* fake-online the pages if the memory block is online */
pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
sb_id * vm->sbm.sb_size);
nr_pages = PFN_DOWN(count * vm->sbm.sb_size);
virtio_mem_fake_online(pfn, nr_pages);
}
if (virtio_mem_sbm_test_sb_plugged(vm, mb_id, 0, vm->sbm.sbs_per_mb))
virtio_mem_sbm_set_mb_state(vm, mb_id, old_state - 1);
return 0;
}
static int virtio_mem_sbm_plug_request(struct virtio_mem *vm, uint64_t diff)
{
const int mb_states[] = {
VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL,
VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL,
VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL,
};
uint64_t nb_sb = diff / vm->sbm.sb_size;
unsigned long mb_id;
int rc, i;
if (!nb_sb)
return 0;
/* Don't race with onlining/offlining */
mutex_lock(&vm->hotplug_mutex);
for (i = 0; i < ARRAY_SIZE(mb_states); i++) {
virtio_mem_sbm_for_each_mb(vm, mb_id, mb_states[i]) {
rc = virtio_mem_sbm_plug_any_sb(vm, mb_id, &nb_sb);
if (rc || !nb_sb)
goto out_unlock;
cond_resched();
}
}
/*
* We won't be working on online/offline memory blocks from this point,
* so we can't race with memory onlining/offlining. Drop the mutex.
*/
mutex_unlock(&vm->hotplug_mutex);
/* Try to plug and add unused blocks */
virtio_mem_sbm_for_each_mb(vm, mb_id, VIRTIO_MEM_SBM_MB_UNUSED) {
if (!virtio_mem_could_add_memory(vm, memory_block_size_bytes()))
return -ENOSPC;
rc = virtio_mem_sbm_plug_and_add_mb(vm, mb_id, &nb_sb);
if (rc || !nb_sb)
return rc;
cond_resched();
}
/* Try to prepare, plug and add new blocks */
while (nb_sb) {
if (!virtio_mem_could_add_memory(vm, memory_block_size_bytes()))
return -ENOSPC;
rc = virtio_mem_sbm_prepare_next_mb(vm, &mb_id);
if (rc)
return rc;
rc = virtio_mem_sbm_plug_and_add_mb(vm, mb_id, &nb_sb);
if (rc)
return rc;
cond_resched();
}
return 0;
out_unlock:
mutex_unlock(&vm->hotplug_mutex);
return rc;
}
/*
* Plug a big block and add it to Linux.
*
* Will modify the state of the big block.
*/
static int virtio_mem_bbm_plug_and_add_bb(struct virtio_mem *vm,
unsigned long bb_id)
{
int rc;
if (WARN_ON_ONCE(virtio_mem_bbm_get_bb_state(vm, bb_id) !=
VIRTIO_MEM_BBM_BB_UNUSED))
return -EINVAL;
rc = virtio_mem_bbm_plug_bb(vm, bb_id);
if (rc)
return rc;
virtio_mem_bbm_set_bb_state(vm, bb_id, VIRTIO_MEM_BBM_BB_ADDED);
rc = virtio_mem_bbm_add_bb(vm, bb_id);
if (rc) {
if (!virtio_mem_bbm_unplug_bb(vm, bb_id))
virtio_mem_bbm_set_bb_state(vm, bb_id,
VIRTIO_MEM_BBM_BB_UNUSED);
else
/* Retry from the main loop. */
virtio_mem_bbm_set_bb_state(vm, bb_id,
VIRTIO_MEM_BBM_BB_PLUGGED);
return rc;
}
return 0;
}
/*
* Prepare tracking data for the next big block.
*/
static int virtio_mem_bbm_prepare_next_bb(struct virtio_mem *vm,
unsigned long *bb_id)
{
int rc;
if (vm->bbm.next_bb_id > vm->bbm.last_usable_bb_id)
return -ENOSPC;
/* Resize the big block state array if required. */
rc = virtio_mem_bbm_bb_states_prepare_next_bb(vm);
if (rc)
return rc;
vm->bbm.bb_count[VIRTIO_MEM_BBM_BB_UNUSED]++;
*bb_id = vm->bbm.next_bb_id;
vm->bbm.next_bb_id++;
return 0;
}
static int virtio_mem_bbm_plug_request(struct virtio_mem *vm, uint64_t diff)
{
uint64_t nb_bb = diff / vm->bbm.bb_size;
unsigned long bb_id;
int rc;
if (!nb_bb)
return 0;
/* Try to plug and add unused big blocks */
virtio_mem_bbm_for_each_bb(vm, bb_id, VIRTIO_MEM_BBM_BB_UNUSED) {
if (!virtio_mem_could_add_memory(vm, vm->bbm.bb_size))
return -ENOSPC;
rc = virtio_mem_bbm_plug_and_add_bb(vm, bb_id);
if (!rc)
nb_bb--;
if (rc || !nb_bb)
return rc;
cond_resched();
}
/* Try to prepare, plug and add new big blocks */
while (nb_bb) {
if (!virtio_mem_could_add_memory(vm, vm->bbm.bb_size))
return -ENOSPC;
rc = virtio_mem_bbm_prepare_next_bb(vm, &bb_id);
if (rc)
return rc;
rc = virtio_mem_bbm_plug_and_add_bb(vm, bb_id);
if (!rc)
nb_bb--;
if (rc)
return rc;
cond_resched();
}
return 0;
}
/*
* Try to plug the requested amount of memory.
*/
static int virtio_mem_plug_request(struct virtio_mem *vm, uint64_t diff)
{
if (vm->in_sbm)
return virtio_mem_sbm_plug_request(vm, diff);
return virtio_mem_bbm_plug_request(vm, diff);
}
/*
* Unplug the desired number of plugged subblocks of an offline memory block.
* Will fail if any subblock cannot get unplugged (instead of skipping it).
*
* Will modify the state of the memory block. Might temporarily drop the
* hotplug_mutex.
*
* Note: Can fail after some subblocks were successfully unplugged.
*/
static int virtio_mem_sbm_unplug_any_sb_offline(struct virtio_mem *vm,
unsigned long mb_id,
uint64_t *nb_sb)
{
int rc;
rc = virtio_mem_sbm_unplug_any_sb_raw(vm, mb_id, nb_sb);
/* some subblocks might have been unplugged even on failure */
if (!virtio_mem_sbm_test_sb_plugged(vm, mb_id, 0, vm->sbm.sbs_per_mb))
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL);
if (rc)
return rc;
if (virtio_mem_sbm_test_sb_unplugged(vm, mb_id, 0, vm->sbm.sbs_per_mb)) {
/*
* Remove the block from Linux - this should never fail.
* Hinder the block from getting onlined by marking it
* unplugged. Temporarily drop the mutex, so
* any pending GOING_ONLINE requests can be serviced/rejected.
*/
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_UNUSED);
mutex_unlock(&vm->hotplug_mutex);
rc = virtio_mem_sbm_remove_mb(vm, mb_id);
BUG_ON(rc);
mutex_lock(&vm->hotplug_mutex);
}
return 0;
}
/*
* Unplug the given plugged subblocks of an online memory block.
*
* Will modify the state of the memory block.
*/
static int virtio_mem_sbm_unplug_sb_online(struct virtio_mem *vm,
unsigned long mb_id, int sb_id,
int count)
{
const unsigned long nr_pages = PFN_DOWN(vm->sbm.sb_size) * count;
const int old_state = virtio_mem_sbm_get_mb_state(vm, mb_id);
unsigned long start_pfn;
int rc;
start_pfn = PFN_DOWN(virtio_mem_mb_id_to_phys(mb_id) +
sb_id * vm->sbm.sb_size);
rc = virtio_mem_fake_offline(start_pfn, nr_pages);
if (rc)
return rc;
/* Try to unplug the allocated memory */
rc = virtio_mem_sbm_unplug_sb(vm, mb_id, sb_id, count);
if (rc) {
/* Return the memory to the buddy. */
virtio_mem_fake_online(start_pfn, nr_pages);
return rc;
}
switch (old_state) {
case VIRTIO_MEM_SBM_MB_KERNEL:
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL);
break;
case VIRTIO_MEM_SBM_MB_MOVABLE:
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL);
break;
}
return 0;
}
/*
* Unplug the desired number of plugged subblocks of an online memory block.
* Will skip subblock that are busy.
*
* Will modify the state of the memory block. Might temporarily drop the
* hotplug_mutex.
*
* Note: Can fail after some subblocks were successfully unplugged. Can
* return 0 even if subblocks were busy and could not get unplugged.
*/
static int virtio_mem_sbm_unplug_any_sb_online(struct virtio_mem *vm,
unsigned long mb_id,
uint64_t *nb_sb)
{
int rc, sb_id;
/* If possible, try to unplug the complete block in one shot. */
if (*nb_sb >= vm->sbm.sbs_per_mb &&
virtio_mem_sbm_test_sb_plugged(vm, mb_id, 0, vm->sbm.sbs_per_mb)) {
rc = virtio_mem_sbm_unplug_sb_online(vm, mb_id, 0,
vm->sbm.sbs_per_mb);
if (!rc) {
*nb_sb -= vm->sbm.sbs_per_mb;
goto unplugged;
} else if (rc != -EBUSY)
return rc;
}
/* Fallback to single subblocks. */
for (sb_id = vm->sbm.sbs_per_mb - 1; sb_id >= 0 && *nb_sb; sb_id--) {
/* Find the next candidate subblock */
while (sb_id >= 0 &&
!virtio_mem_sbm_test_sb_plugged(vm, mb_id, sb_id, 1))
sb_id--;
if (sb_id < 0)
break;
rc = virtio_mem_sbm_unplug_sb_online(vm, mb_id, sb_id, 1);
if (rc == -EBUSY)
continue;
else if (rc)
return rc;
*nb_sb -= 1;
}
unplugged:
/*
* Once all subblocks of a memory block were unplugged, offline and
* remove it. This will usually not fail, as no memory is in use
* anymore - however some other notifiers might NACK the request.
*/
if (virtio_mem_sbm_test_sb_unplugged(vm, mb_id, 0, vm->sbm.sbs_per_mb)) {
mutex_unlock(&vm->hotplug_mutex);
rc = virtio_mem_sbm_offline_and_remove_mb(vm, mb_id);
mutex_lock(&vm->hotplug_mutex);
if (!rc)
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_UNUSED);
}
return 0;
}
/*
* Unplug the desired number of plugged subblocks of a memory block that is
* already added to Linux. Will skip subblock of online memory blocks that are
* busy (by the OS). Will fail if any subblock that's not busy cannot get
* unplugged.
*
* Will modify the state of the memory block. Might temporarily drop the
* hotplug_mutex.
*
* Note: Can fail after some subblocks were successfully unplugged. Can
* return 0 even if subblocks were busy and could not get unplugged.
*/
static int virtio_mem_sbm_unplug_any_sb(struct virtio_mem *vm,
unsigned long mb_id,
uint64_t *nb_sb)
{
const int old_state = virtio_mem_sbm_get_mb_state(vm, mb_id);
switch (old_state) {
case VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL:
case VIRTIO_MEM_SBM_MB_KERNEL:
case VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL:
case VIRTIO_MEM_SBM_MB_MOVABLE:
return virtio_mem_sbm_unplug_any_sb_online(vm, mb_id, nb_sb);
case VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL:
case VIRTIO_MEM_SBM_MB_OFFLINE:
return virtio_mem_sbm_unplug_any_sb_offline(vm, mb_id, nb_sb);
}
return -EINVAL;
}
static int virtio_mem_sbm_unplug_request(struct virtio_mem *vm, uint64_t diff)
{
const int mb_states[] = {
VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL,
VIRTIO_MEM_SBM_MB_OFFLINE,
VIRTIO_MEM_SBM_MB_MOVABLE_PARTIAL,
VIRTIO_MEM_SBM_MB_KERNEL_PARTIAL,
VIRTIO_MEM_SBM_MB_MOVABLE,
VIRTIO_MEM_SBM_MB_KERNEL,
};
uint64_t nb_sb = diff / vm->sbm.sb_size;
unsigned long mb_id;
int rc, i;
if (!nb_sb)
return 0;
/*
* We'll drop the mutex a couple of times when it is safe to do so.
* This might result in some blocks switching the state (online/offline)
* and we could miss them in this run - we will retry again later.
*/
mutex_lock(&vm->hotplug_mutex);
/*
* We try unplug from partially plugged blocks first, to try removing
* whole memory blocks along with metadata. We prioritize ZONE_MOVABLE
* as it's more reliable to unplug memory and remove whole memory
* blocks, and we don't want to trigger a zone imbalances by
* accidentially removing too much kernel memory.
*/
for (i = 0; i < ARRAY_SIZE(mb_states); i++) {
virtio_mem_sbm_for_each_mb_rev(vm, mb_id, mb_states[i]) {
rc = virtio_mem_sbm_unplug_any_sb(vm, mb_id, &nb_sb);
if (rc || !nb_sb)
goto out_unlock;
mutex_unlock(&vm->hotplug_mutex);
cond_resched();
mutex_lock(&vm->hotplug_mutex);
}
if (!unplug_online && i == 1) {
mutex_unlock(&vm->hotplug_mutex);
return 0;
}
}
mutex_unlock(&vm->hotplug_mutex);
return nb_sb ? -EBUSY : 0;
out_unlock:
mutex_unlock(&vm->hotplug_mutex);
return rc;
}
/*
* Try to offline and remove a big block from Linux and unplug it. Will fail
* with -EBUSY if some memory is busy and cannot get unplugged.
*
* Will modify the state of the memory block. Might temporarily drop the
* hotplug_mutex.
*/
static int virtio_mem_bbm_offline_remove_and_unplug_bb(struct virtio_mem *vm,
unsigned long bb_id)
{
const unsigned long start_pfn = PFN_DOWN(virtio_mem_bb_id_to_phys(vm, bb_id));
const unsigned long nr_pages = PFN_DOWN(vm->bbm.bb_size);
unsigned long end_pfn = start_pfn + nr_pages;
unsigned long pfn;
struct page *page;
int rc;
if (WARN_ON_ONCE(virtio_mem_bbm_get_bb_state(vm, bb_id) !=
VIRTIO_MEM_BBM_BB_ADDED))
return -EINVAL;
if (bbm_safe_unplug) {
/*
* Start by fake-offlining all memory. Once we marked the device
* block as fake-offline, all newly onlined memory will
* automatically be kept fake-offline. Protect from concurrent
* onlining/offlining until we have a consistent state.
*/
mutex_lock(&vm->hotplug_mutex);
virtio_mem_bbm_set_bb_state(vm, bb_id,
VIRTIO_MEM_BBM_BB_FAKE_OFFLINE);
for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
page = pfn_to_online_page(pfn);
if (!page)
continue;
rc = virtio_mem_fake_offline(pfn, PAGES_PER_SECTION);
if (rc) {
end_pfn = pfn;
goto rollback_safe_unplug;
}
}
mutex_unlock(&vm->hotplug_mutex);
}
rc = virtio_mem_bbm_offline_and_remove_bb(vm, bb_id);
if (rc) {
if (bbm_safe_unplug) {
mutex_lock(&vm->hotplug_mutex);
goto rollback_safe_unplug;
}
return rc;
}
rc = virtio_mem_bbm_unplug_bb(vm, bb_id);
if (rc)
virtio_mem_bbm_set_bb_state(vm, bb_id,
VIRTIO_MEM_BBM_BB_PLUGGED);
else
virtio_mem_bbm_set_bb_state(vm, bb_id,
VIRTIO_MEM_BBM_BB_UNUSED);
return rc;
rollback_safe_unplug:
for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
page = pfn_to_online_page(pfn);
if (!page)
continue;
virtio_mem_fake_online(pfn, PAGES_PER_SECTION);
}
virtio_mem_bbm_set_bb_state(vm, bb_id, VIRTIO_MEM_BBM_BB_ADDED);
mutex_unlock(&vm->hotplug_mutex);
return rc;
}
/*
* Test if a big block is completely offline.
*/
static bool virtio_mem_bbm_bb_is_offline(struct virtio_mem *vm,
unsigned long bb_id)
{
const unsigned long start_pfn = PFN_DOWN(virtio_mem_bb_id_to_phys(vm, bb_id));
const unsigned long nr_pages = PFN_DOWN(vm->bbm.bb_size);
unsigned long pfn;
for (pfn = start_pfn; pfn < start_pfn + nr_pages;
pfn += PAGES_PER_SECTION) {
if (pfn_to_online_page(pfn))
return false;
}
return true;
}
/*
* Test if a big block is completely onlined to ZONE_MOVABLE (or offline).
*/
static bool virtio_mem_bbm_bb_is_movable(struct virtio_mem *vm,
unsigned long bb_id)
{
const unsigned long start_pfn = PFN_DOWN(virtio_mem_bb_id_to_phys(vm, bb_id));
const unsigned long nr_pages = PFN_DOWN(vm->bbm.bb_size);
struct page *page;
unsigned long pfn;
for (pfn = start_pfn; pfn < start_pfn + nr_pages;
pfn += PAGES_PER_SECTION) {
page = pfn_to_online_page(pfn);
if (!page)
continue;
if (page_zonenum(page) != ZONE_MOVABLE)
return false;
}
return true;
}
static int virtio_mem_bbm_unplug_request(struct virtio_mem *vm, uint64_t diff)
{
uint64_t nb_bb = diff / vm->bbm.bb_size;
uint64_t bb_id;
int rc, i;
if (!nb_bb)
return 0;
/*
* Try to unplug big blocks. Similar to SBM, start with offline
* big blocks.
*/
for (i = 0; i < 3; i++) {
virtio_mem_bbm_for_each_bb_rev(vm, bb_id, VIRTIO_MEM_BBM_BB_ADDED) {
cond_resched();
/*
* As we're holding no locks, these checks are racy,
* but we don't care.
*/
if (i == 0 && !virtio_mem_bbm_bb_is_offline(vm, bb_id))
continue;
if (i == 1 && !virtio_mem_bbm_bb_is_movable(vm, bb_id))
continue;
rc = virtio_mem_bbm_offline_remove_and_unplug_bb(vm, bb_id);
if (rc == -EBUSY)
continue;
if (!rc)
nb_bb--;
if (rc || !nb_bb)
return rc;
}
if (i == 0 && !unplug_online)
return 0;
}
return nb_bb ? -EBUSY : 0;
}
/*
* Try to unplug the requested amount of memory.
*/
static int virtio_mem_unplug_request(struct virtio_mem *vm, uint64_t diff)
{
if (vm->in_sbm)
return virtio_mem_sbm_unplug_request(vm, diff);
return virtio_mem_bbm_unplug_request(vm, diff);
}
/*
* Try to unplug all blocks that couldn't be unplugged before, for example,
* because the hypervisor was busy.
*/
static int virtio_mem_unplug_pending_mb(struct virtio_mem *vm)
{
unsigned long id;
int rc;
if (!vm->in_sbm) {
virtio_mem_bbm_for_each_bb(vm, id,
VIRTIO_MEM_BBM_BB_PLUGGED) {
rc = virtio_mem_bbm_unplug_bb(vm, id);
if (rc)
return rc;
virtio_mem_bbm_set_bb_state(vm, id,
VIRTIO_MEM_BBM_BB_UNUSED);
}
return 0;
}
virtio_mem_sbm_for_each_mb(vm, id, VIRTIO_MEM_SBM_MB_PLUGGED) {
rc = virtio_mem_sbm_unplug_mb(vm, id);
if (rc)
return rc;
virtio_mem_sbm_set_mb_state(vm, id,
VIRTIO_MEM_SBM_MB_UNUSED);
}
return 0;
}
/*
* Update all parts of the config that could have changed.
*/
static void virtio_mem_refresh_config(struct virtio_mem *vm)
{
const struct range pluggable_range = mhp_get_pluggable_range(true);
uint64_t new_plugged_size, usable_region_size, end_addr;
/* the plugged_size is just a reflection of what _we_ did previously */
virtio_cread_le(vm->vdev, struct virtio_mem_config, plugged_size,
&new_plugged_size);
if (WARN_ON_ONCE(new_plugged_size != vm->plugged_size))
vm->plugged_size = new_plugged_size;
/* calculate the last usable memory block id */
virtio_cread_le(vm->vdev, struct virtio_mem_config,
usable_region_size, &usable_region_size);
end_addr = min(vm->addr + usable_region_size - 1,
pluggable_range.end);
if (vm->in_sbm) {
vm->sbm.last_usable_mb_id = virtio_mem_phys_to_mb_id(end_addr);
if (!IS_ALIGNED(end_addr + 1, memory_block_size_bytes()))
vm->sbm.last_usable_mb_id--;
} else {
vm->bbm.last_usable_bb_id = virtio_mem_phys_to_bb_id(vm,
end_addr);
if (!IS_ALIGNED(end_addr + 1, vm->bbm.bb_size))
vm->bbm.last_usable_bb_id--;
}
/*
* If we cannot plug any of our device memory (e.g., nothing in the
* usable region is addressable), the last usable memory block id will
* be smaller than the first usable memory block id. We'll stop
* attempting to add memory with -ENOSPC from our main loop.
*/
/* see if there is a request to change the size */
virtio_cread_le(vm->vdev, struct virtio_mem_config, requested_size,
&vm->requested_size);
dev_info(&vm->vdev->dev, "plugged size: 0x%llx", vm->plugged_size);
dev_info(&vm->vdev->dev, "requested size: 0x%llx", vm->requested_size);
}
/*
* Workqueue function for handling plug/unplug requests and config updates.
*/
static void virtio_mem_run_wq(struct work_struct *work)
{
struct virtio_mem *vm = container_of(work, struct virtio_mem, wq);
uint64_t diff;
int rc;
if (unlikely(vm->in_kdump)) {
dev_warn_once(&vm->vdev->dev,
"unexpected workqueue run in kdump kernel\n");
return;
}
hrtimer_cancel(&vm->retry_timer);
if (vm->broken)
return;
atomic_set(&vm->wq_active, 1);
retry:
rc = 0;
/* Make sure we start with a clean state if there are leftovers. */
if (unlikely(vm->unplug_all_required))
rc = virtio_mem_send_unplug_all_request(vm);
if (atomic_read(&vm->config_changed)) {
atomic_set(&vm->config_changed, 0);
virtio_mem_refresh_config(vm);
}
/* Unplug any leftovers from previous runs */
if (!rc)
rc = virtio_mem_unplug_pending_mb(vm);
if (!rc && vm->requested_size != vm->plugged_size) {
if (vm->requested_size > vm->plugged_size) {
diff = vm->requested_size - vm->plugged_size;
rc = virtio_mem_plug_request(vm, diff);
} else {
diff = vm->plugged_size - vm->requested_size;
rc = virtio_mem_unplug_request(vm, diff);
}
}
switch (rc) {
case 0:
vm->retry_timer_ms = VIRTIO_MEM_RETRY_TIMER_MIN_MS;
break;
case -ENOSPC:
/*
* We cannot add any more memory (alignment, physical limit)
* or we have too many offline memory blocks.
*/
break;
case -ETXTBSY:
/*
* The hypervisor cannot process our request right now
* (e.g., out of memory, migrating);
*/
case -EBUSY:
/*
* We cannot free up any memory to unplug it (all plugged memory
* is busy).
*/
case -ENOMEM:
/* Out of memory, try again later. */
hrtimer_start(&vm->retry_timer, ms_to_ktime(vm->retry_timer_ms),
HRTIMER_MODE_REL);
break;
case -EAGAIN:
/* Retry immediately (e.g., the config changed). */
goto retry;
default:
/* Unknown error, mark as broken */
dev_err(&vm->vdev->dev,
"unknown error, marking device broken: %d\n", rc);
vm->broken = true;
}
atomic_set(&vm->wq_active, 0);
}
static enum hrtimer_restart virtio_mem_timer_expired(struct hrtimer *timer)
{
struct virtio_mem *vm = container_of(timer, struct virtio_mem,
retry_timer);
virtio_mem_retry(vm);
vm->retry_timer_ms = min_t(unsigned int, vm->retry_timer_ms * 2,
VIRTIO_MEM_RETRY_TIMER_MAX_MS);
return HRTIMER_NORESTART;
}
static void virtio_mem_handle_response(struct virtqueue *vq)
{
struct virtio_mem *vm = vq->vdev->priv;
wake_up(&vm->host_resp);
}
static int virtio_mem_init_vq(struct virtio_mem *vm)
{
struct virtqueue *vq;
vq = virtio_find_single_vq(vm->vdev, virtio_mem_handle_response,
"guest-request");
if (IS_ERR(vq))
return PTR_ERR(vq);
vm->vq = vq;
return 0;
}
static int virtio_mem_init_hotplug(struct virtio_mem *vm)
{
const struct range pluggable_range = mhp_get_pluggable_range(true);
uint64_t unit_pages, sb_size, addr;
int rc;
/* bad device setup - warn only */
if (!IS_ALIGNED(vm->addr, memory_block_size_bytes()))
dev_warn(&vm->vdev->dev,
"The alignment of the physical start address can make some memory unusable.\n");
if (!IS_ALIGNED(vm->addr + vm->region_size, memory_block_size_bytes()))
dev_warn(&vm->vdev->dev,
"The alignment of the physical end address can make some memory unusable.\n");
if (vm->addr < pluggable_range.start ||
vm->addr + vm->region_size - 1 > pluggable_range.end)
dev_warn(&vm->vdev->dev,
"Some device memory is not addressable/pluggable. This can make some memory unusable.\n");
/* Prepare the offline threshold - make sure we can add two blocks. */
vm->offline_threshold = max_t(uint64_t, 2 * memory_block_size_bytes(),
VIRTIO_MEM_DEFAULT_OFFLINE_THRESHOLD);
/*
* We want subblocks to span at least MAX_ORDER_NR_PAGES and
* pageblock_nr_pages pages. This:
* - Simplifies our page onlining code (virtio_mem_online_page_cb)
* and fake page onlining code (virtio_mem_fake_online).
* - Is required for now for alloc_contig_range() to work reliably -
* it doesn't properly handle smaller granularity on ZONE_NORMAL.
*/
sb_size = max_t(uint64_t, MAX_ORDER_NR_PAGES,
pageblock_nr_pages) * PAGE_SIZE;
sb_size = max_t(uint64_t, vm->device_block_size, sb_size);
if (sb_size < memory_block_size_bytes() && !force_bbm) {
/* SBM: At least two subblocks per Linux memory block. */
vm->in_sbm = true;
vm->sbm.sb_size = sb_size;
vm->sbm.sbs_per_mb = memory_block_size_bytes() /
vm->sbm.sb_size;
/* Round up to the next full memory block */
addr = max_t(uint64_t, vm->addr, pluggable_range.start) +
memory_block_size_bytes() - 1;
vm->sbm.first_mb_id = virtio_mem_phys_to_mb_id(addr);
vm->sbm.next_mb_id = vm->sbm.first_mb_id;
} else {
/* BBM: At least one Linux memory block. */
vm->bbm.bb_size = max_t(uint64_t, vm->device_block_size,
memory_block_size_bytes());
if (bbm_block_size) {
if (!is_power_of_2(bbm_block_size)) {
dev_warn(&vm->vdev->dev,
"bbm_block_size is not a power of 2");
} else if (bbm_block_size < vm->bbm.bb_size) {
dev_warn(&vm->vdev->dev,
"bbm_block_size is too small");
} else {
vm->bbm.bb_size = bbm_block_size;
}
}
/* Round up to the next aligned big block */
addr = max_t(uint64_t, vm->addr, pluggable_range.start) +
vm->bbm.bb_size - 1;
vm->bbm.first_bb_id = virtio_mem_phys_to_bb_id(vm, addr);
vm->bbm.next_bb_id = vm->bbm.first_bb_id;
/* Make sure we can add two big blocks. */
vm->offline_threshold = max_t(uint64_t, 2 * vm->bbm.bb_size,
vm->offline_threshold);
}
dev_info(&vm->vdev->dev, "memory block size: 0x%lx",
memory_block_size_bytes());
if (vm->in_sbm)
dev_info(&vm->vdev->dev, "subblock size: 0x%llx",
(unsigned long long)vm->sbm.sb_size);
else
dev_info(&vm->vdev->dev, "big block size: 0x%llx",
(unsigned long long)vm->bbm.bb_size);
/* create the parent resource for all memory */
rc = virtio_mem_create_resource(vm);
if (rc)
return rc;
/* use a single dynamic memory group to cover the whole memory device */
if (vm->in_sbm)
unit_pages = PHYS_PFN(memory_block_size_bytes());
else
unit_pages = PHYS_PFN(vm->bbm.bb_size);
rc = memory_group_register_dynamic(vm->nid, unit_pages);
if (rc < 0)
goto out_del_resource;
vm->mgid = rc;
/*
* If we still have memory plugged, we have to unplug all memory first.
* Registering our parent resource makes sure that this memory isn't
* actually in use (e.g., trying to reload the driver).
*/
if (vm->plugged_size) {
vm->unplug_all_required = true;
dev_info(&vm->vdev->dev, "unplugging all memory is required\n");
}
/* register callbacks */
vm->memory_notifier.notifier_call = virtio_mem_memory_notifier_cb;
rc = register_memory_notifier(&vm->memory_notifier);
if (rc)
goto out_unreg_group;
rc = register_virtio_mem_device(vm);
if (rc)
goto out_unreg_mem;
return 0;
out_unreg_mem:
unregister_memory_notifier(&vm->memory_notifier);
out_unreg_group:
memory_group_unregister(vm->mgid);
out_del_resource:
virtio_mem_delete_resource(vm);
return rc;
}
#ifdef CONFIG_PROC_VMCORE
static int virtio_mem_send_state_request(struct virtio_mem *vm, uint64_t addr,
uint64_t size)
{
const uint64_t nb_vm_blocks = size / vm->device_block_size;
const struct virtio_mem_req req = {
.type = cpu_to_virtio16(vm->vdev, VIRTIO_MEM_REQ_STATE),
.u.state.addr = cpu_to_virtio64(vm->vdev, addr),
.u.state.nb_blocks = cpu_to_virtio16(vm->vdev, nb_vm_blocks),
};
int rc = -ENOMEM;
dev_dbg(&vm->vdev->dev, "requesting state: 0x%llx - 0x%llx\n", addr,
addr + size - 1);
switch (virtio_mem_send_request(vm, &req)) {
case VIRTIO_MEM_RESP_ACK:
return virtio16_to_cpu(vm->vdev, vm->resp.u.state.state);
case VIRTIO_MEM_RESP_ERROR:
rc = -EINVAL;
break;
default:
break;
}
dev_dbg(&vm->vdev->dev, "requesting state failed: %d\n", rc);
return rc;
}
static bool virtio_mem_vmcore_pfn_is_ram(struct vmcore_cb *cb,
unsigned long pfn)
{
struct virtio_mem *vm = container_of(cb, struct virtio_mem,
vmcore_cb);
uint64_t addr = PFN_PHYS(pfn);
bool is_ram;
int rc;
if (!virtio_mem_contains_range(vm, addr, PAGE_SIZE))
return true;
if (!vm->plugged_size)
return false;
/*
* We have to serialize device requests and access to the information
* about the block queried last.
*/
mutex_lock(&vm->hotplug_mutex);
addr = ALIGN_DOWN(addr, vm->device_block_size);
if (addr != vm->last_block_addr) {
rc = virtio_mem_send_state_request(vm, addr,
vm->device_block_size);
/* On any kind of error, we're going to signal !ram. */
if (rc == VIRTIO_MEM_STATE_PLUGGED)
vm->last_block_plugged = true;
else
vm->last_block_plugged = false;
vm->last_block_addr = addr;
}
is_ram = vm->last_block_plugged;
mutex_unlock(&vm->hotplug_mutex);
return is_ram;
}
#endif /* CONFIG_PROC_VMCORE */
static int virtio_mem_init_kdump(struct virtio_mem *vm)
{
#ifdef CONFIG_PROC_VMCORE
dev_info(&vm->vdev->dev, "memory hot(un)plug disabled in kdump kernel\n");
vm->vmcore_cb.pfn_is_ram = virtio_mem_vmcore_pfn_is_ram;
register_vmcore_cb(&vm->vmcore_cb);
return 0;
#else /* CONFIG_PROC_VMCORE */
dev_warn(&vm->vdev->dev, "disabled in kdump kernel without vmcore\n");
return -EBUSY;
#endif /* CONFIG_PROC_VMCORE */
}
static int virtio_mem_init(struct virtio_mem *vm)
{
uint16_t node_id;
if (!vm->vdev->config->get) {
dev_err(&vm->vdev->dev, "config access disabled\n");
return -EINVAL;
}
/* Fetch all properties that can't change. */
virtio_cread_le(vm->vdev, struct virtio_mem_config, plugged_size,
&vm->plugged_size);
virtio_cread_le(vm->vdev, struct virtio_mem_config, block_size,
&vm->device_block_size);
virtio_cread_le(vm->vdev, struct virtio_mem_config, node_id,
&node_id);
vm->nid = virtio_mem_translate_node_id(vm, node_id);
virtio_cread_le(vm->vdev, struct virtio_mem_config, addr, &vm->addr);
virtio_cread_le(vm->vdev, struct virtio_mem_config, region_size,
&vm->region_size);
/* Determine the nid for the device based on the lowest address. */
if (vm->nid == NUMA_NO_NODE)
vm->nid = memory_add_physaddr_to_nid(vm->addr);
dev_info(&vm->vdev->dev, "start address: 0x%llx", vm->addr);
dev_info(&vm->vdev->dev, "region size: 0x%llx", vm->region_size);
dev_info(&vm->vdev->dev, "device block size: 0x%llx",
(unsigned long long)vm->device_block_size);
if (vm->nid != NUMA_NO_NODE && IS_ENABLED(CONFIG_NUMA))
dev_info(&vm->vdev->dev, "nid: %d", vm->nid);
/*
* We don't want to (un)plug or reuse any memory when in kdump. The
* memory is still accessible (but not exposed to Linux).
*/
if (vm->in_kdump)
return virtio_mem_init_kdump(vm);
return virtio_mem_init_hotplug(vm);
}
static int virtio_mem_create_resource(struct virtio_mem *vm)
{
/*
* When force-unloading the driver and removing the device, we
* could have a garbage pointer. Duplicate the string.
*/
const char *name = kstrdup(dev_name(&vm->vdev->dev), GFP_KERNEL);
if (!name)
return -ENOMEM;
/* Disallow mapping device memory via /dev/mem completely. */
vm->parent_resource = __request_mem_region(vm->addr, vm->region_size,
name, IORESOURCE_SYSTEM_RAM |
IORESOURCE_EXCLUSIVE);
if (!vm->parent_resource) {
kfree(name);
dev_warn(&vm->vdev->dev, "could not reserve device region\n");
dev_info(&vm->vdev->dev,
"reloading the driver is not supported\n");
return -EBUSY;
}
/* The memory is not actually busy - make add_memory() work. */
vm->parent_resource->flags &= ~IORESOURCE_BUSY;
return 0;
}
static void virtio_mem_delete_resource(struct virtio_mem *vm)
{
const char *name;
if (!vm->parent_resource)
return;
name = vm->parent_resource->name;
release_resource(vm->parent_resource);
kfree(vm->parent_resource);
kfree(name);
vm->parent_resource = NULL;
}
static int virtio_mem_range_has_system_ram(struct resource *res, void *arg)
{
return 1;
}
static bool virtio_mem_has_memory_added(struct virtio_mem *vm)
{
const unsigned long flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
return walk_iomem_res_desc(IORES_DESC_NONE, flags, vm->addr,
vm->addr + vm->region_size, NULL,
virtio_mem_range_has_system_ram) == 1;
}
static int virtio_mem_probe(struct virtio_device *vdev)
{
struct virtio_mem *vm;
int rc;
BUILD_BUG_ON(sizeof(struct virtio_mem_req) != 24);
BUILD_BUG_ON(sizeof(struct virtio_mem_resp) != 10);
vdev->priv = vm = kzalloc(sizeof(*vm), GFP_KERNEL);
if (!vm)
return -ENOMEM;
init_waitqueue_head(&vm->host_resp);
vm->vdev = vdev;
INIT_WORK(&vm->wq, virtio_mem_run_wq);
mutex_init(&vm->hotplug_mutex);
INIT_LIST_HEAD(&vm->next);
spin_lock_init(&vm->removal_lock);
hrtimer_init(&vm->retry_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
vm->retry_timer.function = virtio_mem_timer_expired;
vm->retry_timer_ms = VIRTIO_MEM_RETRY_TIMER_MIN_MS;
vm->in_kdump = is_kdump_kernel();
/* register the virtqueue */
rc = virtio_mem_init_vq(vm);
if (rc)
goto out_free_vm;
/* initialize the device by querying the config */
rc = virtio_mem_init(vm);
if (rc)
goto out_del_vq;
virtio_device_ready(vdev);
/* trigger a config update to start processing the requested_size */
if (!vm->in_kdump) {
atomic_set(&vm->config_changed, 1);
queue_work(system_freezable_wq, &vm->wq);
}
return 0;
out_del_vq:
vdev->config->del_vqs(vdev);
out_free_vm:
kfree(vm);
vdev->priv = NULL;
return rc;
}
static void virtio_mem_deinit_hotplug(struct virtio_mem *vm)
{
unsigned long mb_id;
int rc;
/*
* Make sure the workqueue won't be triggered anymore and no memory
* blocks can be onlined/offlined until we're finished here.
*/
mutex_lock(&vm->hotplug_mutex);
spin_lock_irq(&vm->removal_lock);
vm->removing = true;
spin_unlock_irq(&vm->removal_lock);
mutex_unlock(&vm->hotplug_mutex);
/* wait until the workqueue stopped */
cancel_work_sync(&vm->wq);
hrtimer_cancel(&vm->retry_timer);
if (vm->in_sbm) {
/*
* After we unregistered our callbacks, user space can online
* partially plugged offline blocks. Make sure to remove them.
*/
virtio_mem_sbm_for_each_mb(vm, mb_id,
VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL) {
rc = virtio_mem_sbm_remove_mb(vm, mb_id);
BUG_ON(rc);
virtio_mem_sbm_set_mb_state(vm, mb_id,
VIRTIO_MEM_SBM_MB_UNUSED);
}
/*
* After we unregistered our callbacks, user space can no longer
* offline partially plugged online memory blocks. No need to
* worry about them.
*/
}
/* unregister callbacks */
unregister_virtio_mem_device(vm);
unregister_memory_notifier(&vm->memory_notifier);
/*
* There is no way we could reliably remove all memory we have added to
* the system. And there is no way to stop the driver/device from going
* away. Warn at least.
*/
if (virtio_mem_has_memory_added(vm)) {
dev_warn(&vm->vdev->dev,
"device still has system memory added\n");
} else {
virtio_mem_delete_resource(vm);
kfree_const(vm->resource_name);
memory_group_unregister(vm->mgid);
}
/* remove all tracking data - no locking needed */
if (vm->in_sbm) {
vfree(vm->sbm.mb_states);
vfree(vm->sbm.sb_states);
} else {
vfree(vm->bbm.bb_states);
}
}
static void virtio_mem_deinit_kdump(struct virtio_mem *vm)
{
#ifdef CONFIG_PROC_VMCORE
unregister_vmcore_cb(&vm->vmcore_cb);
#endif /* CONFIG_PROC_VMCORE */
}
static void virtio_mem_remove(struct virtio_device *vdev)
{
struct virtio_mem *vm = vdev->priv;
if (vm->in_kdump)
virtio_mem_deinit_kdump(vm);
else
virtio_mem_deinit_hotplug(vm);
/* reset the device and cleanup the queues */
vdev->config->reset(vdev);
vdev->config->del_vqs(vdev);
kfree(vm);
vdev->priv = NULL;
}
static void virtio_mem_config_changed(struct virtio_device *vdev)
{
struct virtio_mem *vm = vdev->priv;
if (unlikely(vm->in_kdump))
return;
atomic_set(&vm->config_changed, 1);
virtio_mem_retry(vm);
}
#ifdef CONFIG_PM_SLEEP
static int virtio_mem_freeze(struct virtio_device *vdev)
{
/*
* When restarting the VM, all memory is usually unplugged. Don't
* allow to suspend/hibernate.
*/
dev_err(&vdev->dev, "save/restore not supported.\n");
return -EPERM;
}
static int virtio_mem_restore(struct virtio_device *vdev)
{
return -EPERM;
}
#endif
static unsigned int virtio_mem_features[] = {
#if defined(CONFIG_NUMA) && defined(CONFIG_ACPI_NUMA)
VIRTIO_MEM_F_ACPI_PXM,
#endif
VIRTIO_MEM_F_UNPLUGGED_INACCESSIBLE,
};
static const struct virtio_device_id virtio_mem_id_table[] = {
{ VIRTIO_ID_MEM, VIRTIO_DEV_ANY_ID },
{ 0 },
};
static struct virtio_driver virtio_mem_driver = {
.feature_table = virtio_mem_features,
.feature_table_size = ARRAY_SIZE(virtio_mem_features),
.driver.name = KBUILD_MODNAME,
.driver.owner = THIS_MODULE,
.id_table = virtio_mem_id_table,
.probe = virtio_mem_probe,
.remove = virtio_mem_remove,
.config_changed = virtio_mem_config_changed,
#ifdef CONFIG_PM_SLEEP
.freeze = virtio_mem_freeze,
.restore = virtio_mem_restore,
#endif
};
module_virtio_driver(virtio_mem_driver);
MODULE_DEVICE_TABLE(virtio, virtio_mem_id_table);
MODULE_AUTHOR("David Hildenbrand <david@redhat.com>");
MODULE_DESCRIPTION("Virtio-mem driver");
MODULE_LICENSE("GPL");
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