linux/mm/memremap.c
Pankaj Gupta 867400af90 mm/memremap.c: map FS_DAX device memory as decrypted
virtio_pmem use devm_memremap_pages() to map the device memory.  By
default this memory is mapped as encrypted with SEV.  Guest reboot changes
the current encryption key and guest no longer properly decrypts the FSDAX
device meta data.

Mark the corresponding device memory region for FSDAX devices (mapped with
memremap_pages) as decrypted to retain the persistent memory property.

Link: https://lkml.kernel.org/r/20221102160728.3184016-1-pankaj.gupta@amd.com
Fixes: b7b3c01b19 ("mm/memremap_pages: support multiple ranges per invocation")
Signed-off-by: Pankaj Gupta <pankaj.gupta@amd.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-11-08 15:57:23 -08:00

551 lines
15 KiB
C

// SPDX-License-Identifier: GPL-2.0
/* Copyright(c) 2015 Intel Corporation. All rights reserved. */
#include <linux/device.h>
#include <linux/io.h>
#include <linux/kasan.h>
#include <linux/memory_hotplug.h>
#include <linux/memremap.h>
#include <linux/pfn_t.h>
#include <linux/swap.h>
#include <linux/mmzone.h>
#include <linux/swapops.h>
#include <linux/types.h>
#include <linux/wait_bit.h>
#include <linux/xarray.h>
#include "internal.h"
static DEFINE_XARRAY(pgmap_array);
/*
* The memremap() and memremap_pages() interfaces are alternately used
* to map persistent memory namespaces. These interfaces place different
* constraints on the alignment and size of the mapping (namespace).
* memremap() can map individual PAGE_SIZE pages. memremap_pages() can
* only map subsections (2MB), and at least one architecture (PowerPC)
* the minimum mapping granularity of memremap_pages() is 16MB.
*
* The role of memremap_compat_align() is to communicate the minimum
* arch supported alignment of a namespace such that it can freely
* switch modes without violating the arch constraint. Namely, do not
* allow a namespace to be PAGE_SIZE aligned since that namespace may be
* reconfigured into a mode that requires SUBSECTION_SIZE alignment.
*/
#ifndef CONFIG_ARCH_HAS_MEMREMAP_COMPAT_ALIGN
unsigned long memremap_compat_align(void)
{
return SUBSECTION_SIZE;
}
EXPORT_SYMBOL_GPL(memremap_compat_align);
#endif
#ifdef CONFIG_FS_DAX
DEFINE_STATIC_KEY_FALSE(devmap_managed_key);
EXPORT_SYMBOL(devmap_managed_key);
static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
{
if (pgmap->type == MEMORY_DEVICE_FS_DAX)
static_branch_dec(&devmap_managed_key);
}
static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
{
if (pgmap->type == MEMORY_DEVICE_FS_DAX)
static_branch_inc(&devmap_managed_key);
}
#else
static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
{
}
static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
{
}
#endif /* CONFIG_FS_DAX */
static void pgmap_array_delete(struct range *range)
{
xa_store_range(&pgmap_array, PHYS_PFN(range->start), PHYS_PFN(range->end),
NULL, GFP_KERNEL);
synchronize_rcu();
}
static unsigned long pfn_first(struct dev_pagemap *pgmap, int range_id)
{
struct range *range = &pgmap->ranges[range_id];
unsigned long pfn = PHYS_PFN(range->start);
if (range_id)
return pfn;
return pfn + vmem_altmap_offset(pgmap_altmap(pgmap));
}
bool pgmap_pfn_valid(struct dev_pagemap *pgmap, unsigned long pfn)
{
int i;
for (i = 0; i < pgmap->nr_range; i++) {
struct range *range = &pgmap->ranges[i];
if (pfn >= PHYS_PFN(range->start) &&
pfn <= PHYS_PFN(range->end))
return pfn >= pfn_first(pgmap, i);
}
return false;
}
static unsigned long pfn_end(struct dev_pagemap *pgmap, int range_id)
{
const struct range *range = &pgmap->ranges[range_id];
return (range->start + range_len(range)) >> PAGE_SHIFT;
}
static unsigned long pfn_len(struct dev_pagemap *pgmap, unsigned long range_id)
{
return (pfn_end(pgmap, range_id) -
pfn_first(pgmap, range_id)) >> pgmap->vmemmap_shift;
}
static void pageunmap_range(struct dev_pagemap *pgmap, int range_id)
{
struct range *range = &pgmap->ranges[range_id];
struct page *first_page;
/* make sure to access a memmap that was actually initialized */
first_page = pfn_to_page(pfn_first(pgmap, range_id));
/* pages are dead and unused, undo the arch mapping */
mem_hotplug_begin();
remove_pfn_range_from_zone(page_zone(first_page), PHYS_PFN(range->start),
PHYS_PFN(range_len(range)));
if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
__remove_pages(PHYS_PFN(range->start),
PHYS_PFN(range_len(range)), NULL);
} else {
arch_remove_memory(range->start, range_len(range),
pgmap_altmap(pgmap));
kasan_remove_zero_shadow(__va(range->start), range_len(range));
}
mem_hotplug_done();
untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range));
pgmap_array_delete(range);
}
void memunmap_pages(struct dev_pagemap *pgmap)
{
int i;
percpu_ref_kill(&pgmap->ref);
if (pgmap->type != MEMORY_DEVICE_PRIVATE &&
pgmap->type != MEMORY_DEVICE_COHERENT)
for (i = 0; i < pgmap->nr_range; i++)
percpu_ref_put_many(&pgmap->ref, pfn_len(pgmap, i));
wait_for_completion(&pgmap->done);
for (i = 0; i < pgmap->nr_range; i++)
pageunmap_range(pgmap, i);
percpu_ref_exit(&pgmap->ref);
WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
devmap_managed_enable_put(pgmap);
}
EXPORT_SYMBOL_GPL(memunmap_pages);
static void devm_memremap_pages_release(void *data)
{
memunmap_pages(data);
}
static void dev_pagemap_percpu_release(struct percpu_ref *ref)
{
struct dev_pagemap *pgmap = container_of(ref, struct dev_pagemap, ref);
complete(&pgmap->done);
}
static int pagemap_range(struct dev_pagemap *pgmap, struct mhp_params *params,
int range_id, int nid)
{
const bool is_private = pgmap->type == MEMORY_DEVICE_PRIVATE;
struct range *range = &pgmap->ranges[range_id];
struct dev_pagemap *conflict_pgmap;
int error, is_ram;
if (WARN_ONCE(pgmap_altmap(pgmap) && range_id > 0,
"altmap not supported for multiple ranges\n"))
return -EINVAL;
conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->start), NULL);
if (conflict_pgmap) {
WARN(1, "Conflicting mapping in same section\n");
put_dev_pagemap(conflict_pgmap);
return -ENOMEM;
}
conflict_pgmap = get_dev_pagemap(PHYS_PFN(range->end), NULL);
if (conflict_pgmap) {
WARN(1, "Conflicting mapping in same section\n");
put_dev_pagemap(conflict_pgmap);
return -ENOMEM;
}
is_ram = region_intersects(range->start, range_len(range),
IORESOURCE_SYSTEM_RAM, IORES_DESC_NONE);
if (is_ram != REGION_DISJOINT) {
WARN_ONCE(1, "attempted on %s region %#llx-%#llx\n",
is_ram == REGION_MIXED ? "mixed" : "ram",
range->start, range->end);
return -ENXIO;
}
error = xa_err(xa_store_range(&pgmap_array, PHYS_PFN(range->start),
PHYS_PFN(range->end), pgmap, GFP_KERNEL));
if (error)
return error;
if (nid < 0)
nid = numa_mem_id();
error = track_pfn_remap(NULL, &params->pgprot, PHYS_PFN(range->start), 0,
range_len(range));
if (error)
goto err_pfn_remap;
if (!mhp_range_allowed(range->start, range_len(range), !is_private)) {
error = -EINVAL;
goto err_kasan;
}
mem_hotplug_begin();
/*
* For device private memory we call add_pages() as we only need to
* allocate and initialize struct page for the device memory. More-
* over the device memory is un-accessible thus we do not want to
* create a linear mapping for the memory like arch_add_memory()
* would do.
*
* For all other device memory types, which are accessible by
* the CPU, we do want the linear mapping and thus use
* arch_add_memory().
*/
if (is_private) {
error = add_pages(nid, PHYS_PFN(range->start),
PHYS_PFN(range_len(range)), params);
} else {
error = kasan_add_zero_shadow(__va(range->start), range_len(range));
if (error) {
mem_hotplug_done();
goto err_kasan;
}
error = arch_add_memory(nid, range->start, range_len(range),
params);
}
if (!error) {
struct zone *zone;
zone = &NODE_DATA(nid)->node_zones[ZONE_DEVICE];
move_pfn_range_to_zone(zone, PHYS_PFN(range->start),
PHYS_PFN(range_len(range)), params->altmap,
MIGRATE_MOVABLE);
}
mem_hotplug_done();
if (error)
goto err_add_memory;
/*
* Initialization of the pages has been deferred until now in order
* to allow us to do the work while not holding the hotplug lock.
*/
memmap_init_zone_device(&NODE_DATA(nid)->node_zones[ZONE_DEVICE],
PHYS_PFN(range->start),
PHYS_PFN(range_len(range)), pgmap);
if (pgmap->type != MEMORY_DEVICE_PRIVATE &&
pgmap->type != MEMORY_DEVICE_COHERENT)
percpu_ref_get_many(&pgmap->ref, pfn_len(pgmap, range_id));
return 0;
err_add_memory:
if (!is_private)
kasan_remove_zero_shadow(__va(range->start), range_len(range));
err_kasan:
untrack_pfn(NULL, PHYS_PFN(range->start), range_len(range));
err_pfn_remap:
pgmap_array_delete(range);
return error;
}
/*
* Not device managed version of devm_memremap_pages, undone by
* memunmap_pages(). Please use devm_memremap_pages if you have a struct
* device available.
*/
void *memremap_pages(struct dev_pagemap *pgmap, int nid)
{
struct mhp_params params = {
.altmap = pgmap_altmap(pgmap),
.pgmap = pgmap,
.pgprot = PAGE_KERNEL,
};
const int nr_range = pgmap->nr_range;
int error, i;
if (WARN_ONCE(!nr_range, "nr_range must be specified\n"))
return ERR_PTR(-EINVAL);
switch (pgmap->type) {
case MEMORY_DEVICE_PRIVATE:
if (!IS_ENABLED(CONFIG_DEVICE_PRIVATE)) {
WARN(1, "Device private memory not supported\n");
return ERR_PTR(-EINVAL);
}
if (!pgmap->ops || !pgmap->ops->migrate_to_ram) {
WARN(1, "Missing migrate_to_ram method\n");
return ERR_PTR(-EINVAL);
}
if (!pgmap->ops->page_free) {
WARN(1, "Missing page_free method\n");
return ERR_PTR(-EINVAL);
}
if (!pgmap->owner) {
WARN(1, "Missing owner\n");
return ERR_PTR(-EINVAL);
}
break;
case MEMORY_DEVICE_COHERENT:
if (!pgmap->ops->page_free) {
WARN(1, "Missing page_free method\n");
return ERR_PTR(-EINVAL);
}
if (!pgmap->owner) {
WARN(1, "Missing owner\n");
return ERR_PTR(-EINVAL);
}
break;
case MEMORY_DEVICE_FS_DAX:
if (IS_ENABLED(CONFIG_FS_DAX_LIMITED)) {
WARN(1, "File system DAX not supported\n");
return ERR_PTR(-EINVAL);
}
params.pgprot = pgprot_decrypted(params.pgprot);
break;
case MEMORY_DEVICE_GENERIC:
break;
case MEMORY_DEVICE_PCI_P2PDMA:
params.pgprot = pgprot_noncached(params.pgprot);
break;
default:
WARN(1, "Invalid pgmap type %d\n", pgmap->type);
break;
}
init_completion(&pgmap->done);
error = percpu_ref_init(&pgmap->ref, dev_pagemap_percpu_release, 0,
GFP_KERNEL);
if (error)
return ERR_PTR(error);
devmap_managed_enable_get(pgmap);
/*
* Clear the pgmap nr_range as it will be incremented for each
* successfully processed range. This communicates how many
* regions to unwind in the abort case.
*/
pgmap->nr_range = 0;
error = 0;
for (i = 0; i < nr_range; i++) {
error = pagemap_range(pgmap, &params, i, nid);
if (error)
break;
pgmap->nr_range++;
}
if (i < nr_range) {
memunmap_pages(pgmap);
pgmap->nr_range = nr_range;
return ERR_PTR(error);
}
return __va(pgmap->ranges[0].start);
}
EXPORT_SYMBOL_GPL(memremap_pages);
/**
* devm_memremap_pages - remap and provide memmap backing for the given resource
* @dev: hosting device for @res
* @pgmap: pointer to a struct dev_pagemap
*
* Notes:
* 1/ At a minimum the res and type members of @pgmap must be initialized
* by the caller before passing it to this function
*
* 2/ The altmap field may optionally be initialized, in which case
* PGMAP_ALTMAP_VALID must be set in pgmap->flags.
*
* 3/ The ref field may optionally be provided, in which pgmap->ref must be
* 'live' on entry and will be killed and reaped at
* devm_memremap_pages_release() time, or if this routine fails.
*
* 4/ range is expected to be a host memory range that could feasibly be
* treated as a "System RAM" range, i.e. not a device mmio range, but
* this is not enforced.
*/
void *devm_memremap_pages(struct device *dev, struct dev_pagemap *pgmap)
{
int error;
void *ret;
ret = memremap_pages(pgmap, dev_to_node(dev));
if (IS_ERR(ret))
return ret;
error = devm_add_action_or_reset(dev, devm_memremap_pages_release,
pgmap);
if (error)
return ERR_PTR(error);
return ret;
}
EXPORT_SYMBOL_GPL(devm_memremap_pages);
void devm_memunmap_pages(struct device *dev, struct dev_pagemap *pgmap)
{
devm_release_action(dev, devm_memremap_pages_release, pgmap);
}
EXPORT_SYMBOL_GPL(devm_memunmap_pages);
unsigned long vmem_altmap_offset(struct vmem_altmap *altmap)
{
/* number of pfns from base where pfn_to_page() is valid */
if (altmap)
return altmap->reserve + altmap->free;
return 0;
}
void vmem_altmap_free(struct vmem_altmap *altmap, unsigned long nr_pfns)
{
altmap->alloc -= nr_pfns;
}
/**
* get_dev_pagemap() - take a new live reference on the dev_pagemap for @pfn
* @pfn: page frame number to lookup page_map
* @pgmap: optional known pgmap that already has a reference
*
* If @pgmap is non-NULL and covers @pfn it will be returned as-is. If @pgmap
* is non-NULL but does not cover @pfn the reference to it will be released.
*/
struct dev_pagemap *get_dev_pagemap(unsigned long pfn,
struct dev_pagemap *pgmap)
{
resource_size_t phys = PFN_PHYS(pfn);
/*
* In the cached case we're already holding a live reference.
*/
if (pgmap) {
if (phys >= pgmap->range.start && phys <= pgmap->range.end)
return pgmap;
put_dev_pagemap(pgmap);
}
/* fall back to slow path lookup */
rcu_read_lock();
pgmap = xa_load(&pgmap_array, PHYS_PFN(phys));
if (pgmap && !percpu_ref_tryget_live_rcu(&pgmap->ref))
pgmap = NULL;
rcu_read_unlock();
return pgmap;
}
EXPORT_SYMBOL_GPL(get_dev_pagemap);
void free_zone_device_page(struct page *page)
{
if (WARN_ON_ONCE(!page->pgmap->ops || !page->pgmap->ops->page_free))
return;
mem_cgroup_uncharge(page_folio(page));
/*
* Note: we don't expect anonymous compound pages yet. Once supported
* and we could PTE-map them similar to THP, we'd have to clear
* PG_anon_exclusive on all tail pages.
*/
VM_BUG_ON_PAGE(PageAnon(page) && PageCompound(page), page);
if (PageAnon(page))
__ClearPageAnonExclusive(page);
/*
* When a device managed page is freed, the page->mapping field
* may still contain a (stale) mapping value. For example, the
* lower bits of page->mapping may still identify the page as an
* anonymous page. Ultimately, this entire field is just stale
* and wrong, and it will cause errors if not cleared. One
* example is:
*
* migrate_vma_pages()
* migrate_vma_insert_page()
* page_add_new_anon_rmap()
* __page_set_anon_rmap()
* ...checks page->mapping, via PageAnon(page) call,
* and incorrectly concludes that the page is an
* anonymous page. Therefore, it incorrectly,
* silently fails to set up the new anon rmap.
*
* For other types of ZONE_DEVICE pages, migration is either
* handled differently or not done at all, so there is no need
* to clear page->mapping.
*/
page->mapping = NULL;
page->pgmap->ops->page_free(page);
if (page->pgmap->type != MEMORY_DEVICE_PRIVATE &&
page->pgmap->type != MEMORY_DEVICE_COHERENT)
/*
* Reset the page count to 1 to prepare for handing out the page
* again.
*/
set_page_count(page, 1);
else
put_dev_pagemap(page->pgmap);
}
void zone_device_page_init(struct page *page)
{
/*
* Drivers shouldn't be allocating pages after calling
* memunmap_pages().
*/
WARN_ON_ONCE(!percpu_ref_tryget_live(&page->pgmap->ref));
set_page_count(page, 1);
lock_page(page);
}
EXPORT_SYMBOL_GPL(zone_device_page_init);
#ifdef CONFIG_FS_DAX
bool __put_devmap_managed_page_refs(struct page *page, int refs)
{
if (page->pgmap->type != MEMORY_DEVICE_FS_DAX)
return false;
/*
* fsdax page refcounts are 1-based, rather than 0-based: if
* refcount is 1, then the page is free and the refcount is
* stable because nobody holds a reference on the page.
*/
if (page_ref_sub_return(page, refs) == 1)
wake_up_var(&page->_refcount);
return true;
}
EXPORT_SYMBOL(__put_devmap_managed_page_refs);
#endif /* CONFIG_FS_DAX */