linux/virt/kvm/coalesced_mmio.c
Ben Gardon b12ce36a43 kvm: Add memcg accounting to KVM allocations
There are many KVM kernel memory allocations which are tied to the life of
the VM process and should be charged to the VM process's cgroup. If the
allocations aren't tied to the process, the OOM killer will not know
that killing the process will free the associated kernel memory.
Add __GFP_ACCOUNT flags to many of the allocations which are not yet being
charged to the VM process's cgroup.

Tested:
	Ran all kvm-unit-tests on a 64 bit Haswell machine, the patch
	introduced no new failures.
	Ran a kernel memory accounting test which creates a VM to touch
	memory and then checks that the kernel memory allocated for the
	process is within certain bounds.
	With this patch we account for much more of the vmalloc and slab memory
	allocated for the VM.

There remain a few allocations which should be charged to the VM's
cgroup but are not. In they include:
        vcpu->run
        kvm->coalesced_mmio_ring
There allocations are unaccounted in this patch because they are mapped
to userspace, and accounting them to a cgroup causes problems. This
should be addressed in a future patch.

Signed-off-by: Ben Gardon <bgardon@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2019-02-20 22:48:29 +01:00

196 lines
4.4 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* KVM coalesced MMIO
*
* Copyright (c) 2008 Bull S.A.S.
* Copyright 2009 Red Hat, Inc. and/or its affiliates.
*
* Author: Laurent Vivier <Laurent.Vivier@bull.net>
*
*/
#include <kvm/iodev.h>
#include <linux/kvm_host.h>
#include <linux/slab.h>
#include <linux/kvm.h>
#include "coalesced_mmio.h"
static inline struct kvm_coalesced_mmio_dev *to_mmio(struct kvm_io_device *dev)
{
return container_of(dev, struct kvm_coalesced_mmio_dev, dev);
}
static int coalesced_mmio_in_range(struct kvm_coalesced_mmio_dev *dev,
gpa_t addr, int len)
{
/* is it in a batchable area ?
* (addr,len) is fully included in
* (zone->addr, zone->size)
*/
if (len < 0)
return 0;
if (addr + len < addr)
return 0;
if (addr < dev->zone.addr)
return 0;
if (addr + len > dev->zone.addr + dev->zone.size)
return 0;
return 1;
}
static int coalesced_mmio_has_room(struct kvm_coalesced_mmio_dev *dev)
{
struct kvm_coalesced_mmio_ring *ring;
unsigned avail;
/* Are we able to batch it ? */
/* last is the first free entry
* check if we don't meet the first used entry
* there is always one unused entry in the buffer
*/
ring = dev->kvm->coalesced_mmio_ring;
avail = (ring->first - ring->last - 1) % KVM_COALESCED_MMIO_MAX;
if (avail == 0) {
/* full */
return 0;
}
return 1;
}
static int coalesced_mmio_write(struct kvm_vcpu *vcpu,
struct kvm_io_device *this, gpa_t addr,
int len, const void *val)
{
struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
struct kvm_coalesced_mmio_ring *ring = dev->kvm->coalesced_mmio_ring;
if (!coalesced_mmio_in_range(dev, addr, len))
return -EOPNOTSUPP;
spin_lock(&dev->kvm->ring_lock);
if (!coalesced_mmio_has_room(dev)) {
spin_unlock(&dev->kvm->ring_lock);
return -EOPNOTSUPP;
}
/* copy data in first free entry of the ring */
ring->coalesced_mmio[ring->last].phys_addr = addr;
ring->coalesced_mmio[ring->last].len = len;
memcpy(ring->coalesced_mmio[ring->last].data, val, len);
ring->coalesced_mmio[ring->last].pio = dev->zone.pio;
smp_wmb();
ring->last = (ring->last + 1) % KVM_COALESCED_MMIO_MAX;
spin_unlock(&dev->kvm->ring_lock);
return 0;
}
static void coalesced_mmio_destructor(struct kvm_io_device *this)
{
struct kvm_coalesced_mmio_dev *dev = to_mmio(this);
list_del(&dev->list);
kfree(dev);
}
static const struct kvm_io_device_ops coalesced_mmio_ops = {
.write = coalesced_mmio_write,
.destructor = coalesced_mmio_destructor,
};
int kvm_coalesced_mmio_init(struct kvm *kvm)
{
struct page *page;
int ret;
ret = -ENOMEM;
page = alloc_page(GFP_KERNEL | __GFP_ZERO);
if (!page)
goto out_err;
ret = 0;
kvm->coalesced_mmio_ring = page_address(page);
/*
* We're using this spinlock to sync access to the coalesced ring.
* The list doesn't need it's own lock since device registration and
* unregistration should only happen when kvm->slots_lock is held.
*/
spin_lock_init(&kvm->ring_lock);
INIT_LIST_HEAD(&kvm->coalesced_zones);
out_err:
return ret;
}
void kvm_coalesced_mmio_free(struct kvm *kvm)
{
if (kvm->coalesced_mmio_ring)
free_page((unsigned long)kvm->coalesced_mmio_ring);
}
int kvm_vm_ioctl_register_coalesced_mmio(struct kvm *kvm,
struct kvm_coalesced_mmio_zone *zone)
{
int ret;
struct kvm_coalesced_mmio_dev *dev;
if (zone->pio != 1 && zone->pio != 0)
return -EINVAL;
dev = kzalloc(sizeof(struct kvm_coalesced_mmio_dev),
GFP_KERNEL_ACCOUNT);
if (!dev)
return -ENOMEM;
kvm_iodevice_init(&dev->dev, &coalesced_mmio_ops);
dev->kvm = kvm;
dev->zone = *zone;
mutex_lock(&kvm->slots_lock);
ret = kvm_io_bus_register_dev(kvm,
zone->pio ? KVM_PIO_BUS : KVM_MMIO_BUS,
zone->addr, zone->size, &dev->dev);
if (ret < 0)
goto out_free_dev;
list_add_tail(&dev->list, &kvm->coalesced_zones);
mutex_unlock(&kvm->slots_lock);
return 0;
out_free_dev:
mutex_unlock(&kvm->slots_lock);
kfree(dev);
return ret;
}
int kvm_vm_ioctl_unregister_coalesced_mmio(struct kvm *kvm,
struct kvm_coalesced_mmio_zone *zone)
{
struct kvm_coalesced_mmio_dev *dev, *tmp;
if (zone->pio != 1 && zone->pio != 0)
return -EINVAL;
mutex_lock(&kvm->slots_lock);
list_for_each_entry_safe(dev, tmp, &kvm->coalesced_zones, list)
if (zone->pio == dev->zone.pio &&
coalesced_mmio_in_range(dev, zone->addr, zone->size)) {
kvm_io_bus_unregister_dev(kvm,
zone->pio ? KVM_PIO_BUS : KVM_MMIO_BUS, &dev->dev);
kvm_iodevice_destructor(&dev->dev);
}
mutex_unlock(&kvm->slots_lock);
return 0;
}