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Revert "vhost: access vq metadata through kernel virtual address"

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This reverts commit 7f466032dc ("vhost: access vq metadata through
kernel virtual address").  The commit caused a bunch of issues, and
while commit 73f628ec9e ("vhost: disable metadata prefetch
optimization") disabled the optimization it's not nice to keep lots of
dead code around.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
Michael S. Tsirkin 2019-08-10 13:53:21 -04:00
parent 896fc242bc
commit 3d2c7d3704
2 changed files with 3 additions and 553 deletions
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515
drivers/vhost/vhost.c
View File

@ -297,160 +297,6 @@ static void vhost_vq_meta_reset(struct vhost_dev *d)
__vhost_vq_meta_reset(d->vqs[i]);
}
#if VHOST_ARCH_CAN_ACCEL_UACCESS
static void vhost_map_unprefetch(struct vhost_map *map)
{
kfree(map->pages);
map->pages = NULL;
map->npages = 0;
map->addr = NULL;
}
static void vhost_uninit_vq_maps(struct vhost_virtqueue *vq)
{
struct vhost_map *map[VHOST_NUM_ADDRS];
int i;
spin_lock(&vq->mmu_lock);
for (i = 0; i < VHOST_NUM_ADDRS; i++) {
map[i] = rcu_dereference_protected(vq->maps[i],
lockdep_is_held(&vq->mmu_lock));
if (map[i])
rcu_assign_pointer(vq->maps[i], NULL);
}
spin_unlock(&vq->mmu_lock);
synchronize_rcu();
for (i = 0; i < VHOST_NUM_ADDRS; i++)
if (map[i])
vhost_map_unprefetch(map[i]);
}
static void vhost_reset_vq_maps(struct vhost_virtqueue *vq)
{
int i;
vhost_uninit_vq_maps(vq);
for (i = 0; i < VHOST_NUM_ADDRS; i++)
vq->uaddrs[i].size = 0;
}
static bool vhost_map_range_overlap(struct vhost_uaddr *uaddr,
unsigned long start,
unsigned long end)
{
if (unlikely(!uaddr->size))
return false;
return !(end < uaddr->uaddr || start > uaddr->uaddr - 1 + uaddr->size);
}
static void vhost_invalidate_vq_start(struct vhost_virtqueue *vq,
int index,
unsigned long start,
unsigned long end)
{
struct vhost_uaddr *uaddr = &vq->uaddrs[index];
struct vhost_map *map;
int i;
if (!vhost_map_range_overlap(uaddr, start, end))
return;
spin_lock(&vq->mmu_lock);
++vq->invalidate_count;
map = rcu_dereference_protected(vq->maps[index],
lockdep_is_held(&vq->mmu_lock));
if (map) {
if (uaddr->write) {
for (i = 0; i < map->npages; i++)
set_page_dirty(map->pages[i]);
}
rcu_assign_pointer(vq->maps[index], NULL);
}
spin_unlock(&vq->mmu_lock);
if (map) {
synchronize_rcu();
vhost_map_unprefetch(map);
}
}
static void vhost_invalidate_vq_end(struct vhost_virtqueue *vq,
int index,
unsigned long start,
unsigned long end)
{
if (!vhost_map_range_overlap(&vq->uaddrs[index], start, end))
return;
spin_lock(&vq->mmu_lock);
--vq->invalidate_count;
spin_unlock(&vq->mmu_lock);
}
static int vhost_invalidate_range_start(struct mmu_notifier *mn,
const struct mmu_notifier_range *range)
{
struct vhost_dev *dev = container_of(mn, struct vhost_dev,
mmu_notifier);
int i, j;
if (!mmu_notifier_range_blockable(range))
return -EAGAIN;
for (i = 0; i < dev->nvqs; i++) {
struct vhost_virtqueue *vq = dev->vqs[i];
for (j = 0; j < VHOST_NUM_ADDRS; j++)
vhost_invalidate_vq_start(vq, j,
range->start,
range->end);
}
return 0;
}
static void vhost_invalidate_range_end(struct mmu_notifier *mn,
const struct mmu_notifier_range *range)
{
struct vhost_dev *dev = container_of(mn, struct vhost_dev,
mmu_notifier);
int i, j;
for (i = 0; i < dev->nvqs; i++) {
struct vhost_virtqueue *vq = dev->vqs[i];
for (j = 0; j < VHOST_NUM_ADDRS; j++)
vhost_invalidate_vq_end(vq, j,
range->start,
range->end);
}
}
static const struct mmu_notifier_ops vhost_mmu_notifier_ops = {
.invalidate_range_start = vhost_invalidate_range_start,
.invalidate_range_end = vhost_invalidate_range_end,
};
static void vhost_init_maps(struct vhost_dev *dev)
{
struct vhost_virtqueue *vq;
int i, j;
dev->mmu_notifier.ops = &vhost_mmu_notifier_ops;
for (i = 0; i < dev->nvqs; ++i) {
vq = dev->vqs[i];
for (j = 0; j < VHOST_NUM_ADDRS; j++)
RCU_INIT_POINTER(vq->maps[j], NULL);
}
}
#endif
static void vhost_vq_reset(struct vhost_dev *dev,
struct vhost_virtqueue *vq)
{
@ -479,11 +325,7 @@ static void vhost_vq_reset(struct vhost_dev *dev,
vq->busyloop_timeout = 0;
vq->umem = NULL;
vq->iotlb = NULL;
vq->invalidate_count = 0;
__vhost_vq_meta_reset(vq);
#if VHOST_ARCH_CAN_ACCEL_UACCESS
vhost_reset_vq_maps(vq);
#endif
}
static int vhost_worker(void *data)
@ -633,9 +475,7 @@ void vhost_dev_init(struct vhost_dev *dev,
INIT_LIST_HEAD(&dev->read_list);
INIT_LIST_HEAD(&dev->pending_list);
spin_lock_init(&dev->iotlb_lock);
#if VHOST_ARCH_CAN_ACCEL_UACCESS
vhost_init_maps(dev);
#endif
for (i = 0; i < dev->nvqs; ++i) {
vq = dev->vqs[i];
@ -644,7 +484,6 @@ void vhost_dev_init(struct vhost_dev *dev,
vq->heads = NULL;
vq->dev = dev;
mutex_init(&vq->mutex);
spin_lock_init(&vq->mmu_lock);
vhost_vq_reset(dev, vq);
if (vq->handle_kick)
vhost_poll_init(&vq->poll, vq->handle_kick,
@ -724,18 +563,7 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
if (err)
goto err_cgroup;
#if VHOST_ARCH_CAN_ACCEL_UACCESS
err = mmu_notifier_register(&dev->mmu_notifier, dev->mm);
if (err)
goto err_mmu_notifier;
#endif
return 0;
#if VHOST_ARCH_CAN_ACCEL_UACCESS
err_mmu_notifier:
vhost_dev_free_iovecs(dev);
#endif
err_cgroup:
kthread_stop(worker);
dev->worker = NULL;
@ -826,107 +654,6 @@ static void vhost_clear_msg(struct vhost_dev *dev)
spin_unlock(&dev->iotlb_lock);
}
#if VHOST_ARCH_CAN_ACCEL_UACCESS
static void vhost_setup_uaddr(struct vhost_virtqueue *vq,
int index, unsigned long uaddr,
size_t size, bool write)
{
struct vhost_uaddr *addr = &vq->uaddrs[index];
addr->uaddr = uaddr;
addr->size = size;
addr->write = write;
}
static void vhost_setup_vq_uaddr(struct vhost_virtqueue *vq)
{
vhost_setup_uaddr(vq, VHOST_ADDR_DESC,
(unsigned long)vq->desc,
vhost_get_desc_size(vq, vq->num),
false);
vhost_setup_uaddr(vq, VHOST_ADDR_AVAIL,
(unsigned long)vq->avail,
vhost_get_avail_size(vq, vq->num),
false);
vhost_setup_uaddr(vq, VHOST_ADDR_USED,
(unsigned long)vq->used,
vhost_get_used_size(vq, vq->num),
true);
}
static int vhost_map_prefetch(struct vhost_virtqueue *vq,
int index)
{
struct vhost_map *map;
struct vhost_uaddr *uaddr = &vq->uaddrs[index];
struct page **pages;
int npages = DIV_ROUND_UP(uaddr->size, PAGE_SIZE);
int npinned;
void *vaddr, *v;
int err;
int i;
spin_lock(&vq->mmu_lock);
err = -EFAULT;
if (vq->invalidate_count)
goto err;
err = -ENOMEM;
map = kmalloc(sizeof(*map), GFP_ATOMIC);
if (!map)
goto err;
pages = kmalloc_array(npages, sizeof(struct page *), GFP_ATOMIC);
if (!pages)
goto err_pages;
err = EFAULT;
npinned = __get_user_pages_fast(uaddr->uaddr, npages,
uaddr->write, pages);
if (npinned > 0)
release_pages(pages, npinned);
if (npinned != npages)
goto err_gup;
for (i = 0; i < npinned; i++)
if (PageHighMem(pages[i]))
goto err_gup;
vaddr = v = page_address(pages[0]);
/* For simplicity, fallback to userspace address if VA is not
* contigious.
*/
for (i = 1; i < npinned; i++) {
v += PAGE_SIZE;
if (v != page_address(pages[i]))
goto err_gup;
}
map->addr = vaddr + (uaddr->uaddr & (PAGE_SIZE - 1));
map->npages = npages;
map->pages = pages;
rcu_assign_pointer(vq->maps[index], map);
/* No need for a synchronize_rcu(). This function should be
* called by dev->worker so we are serialized with all
* readers.
*/
spin_unlock(&vq->mmu_lock);
return 0;
err_gup:
kfree(pages);
err_pages:
kfree(map);
err:
spin_unlock(&vq->mmu_lock);
return err;
}
#endif
void vhost_dev_cleanup(struct vhost_dev *dev)
{
int i;
@ -956,16 +683,8 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
kthread_stop(dev->worker);
dev->worker = NULL;
}
if (dev->mm) {
#if VHOST_ARCH_CAN_ACCEL_UACCESS
mmu_notifier_unregister(&dev->mmu_notifier, dev->mm);
#endif
if (dev->mm)
mmput(dev->mm);
}
#if VHOST_ARCH_CAN_ACCEL_UACCESS
for (i = 0; i < dev->nvqs; i++)
vhost_uninit_vq_maps(dev->vqs[i]);
#endif
dev->mm = NULL;
}
EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
@ -1194,26 +913,6 @@ static inline void __user *__vhost_get_user(struct vhost_virtqueue *vq,
static inline int vhost_put_avail_event(struct vhost_virtqueue *vq)
{
#if VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_used *used;
if (!vq->iotlb) {
rcu_read_lock();
map = rcu_dereference(vq->maps[VHOST_ADDR_USED]);
if (likely(map)) {
used = map->addr;
*((__virtio16 *)&used->ring[vq->num]) =
cpu_to_vhost16(vq, vq->avail_idx);
rcu_read_unlock();
return 0;
}
rcu_read_unlock();
}
#endif
return vhost_put_user(vq, cpu_to_vhost16(vq, vq->avail_idx),
vhost_avail_event(vq));
}
@ -1222,27 +921,6 @@ static inline int vhost_put_used(struct vhost_virtqueue *vq,
struct vring_used_elem *head, int idx,
int count)
{
#if VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_used *used;
size_t size;
if (!vq->iotlb) {
rcu_read_lock();
map = rcu_dereference(vq->maps[VHOST_ADDR_USED]);
if (likely(map)) {
used = map->addr;
size = count * sizeof(*head);
memcpy(used->ring + idx, head, size);
rcu_read_unlock();
return 0;
}
rcu_read_unlock();
}
#endif
return vhost_copy_to_user(vq, vq->used->ring + idx, head,
count * sizeof(*head));
}
@ -1250,25 +928,6 @@ static inline int vhost_put_used(struct vhost_virtqueue *vq,
static inline int vhost_put_used_flags(struct vhost_virtqueue *vq)
{
#if VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_used *used;
if (!vq->iotlb) {
rcu_read_lock();
map = rcu_dereference(vq->maps[VHOST_ADDR_USED]);
if (likely(map)) {
used = map->addr;
used->flags = cpu_to_vhost16(vq, vq->used_flags);
rcu_read_unlock();
return 0;
}
rcu_read_unlock();
}
#endif
return vhost_put_user(vq, cpu_to_vhost16(vq, vq->used_flags),
&vq->used->flags);
}
@ -1276,25 +935,6 @@ static inline int vhost_put_used_flags(struct vhost_virtqueue *vq)
static inline int vhost_put_used_idx(struct vhost_virtqueue *vq)
{
#if VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_used *used;
if (!vq->iotlb) {
rcu_read_lock();
map = rcu_dereference(vq->maps[VHOST_ADDR_USED]);
if (likely(map)) {
used = map->addr;
used->idx = cpu_to_vhost16(vq, vq->last_used_idx);
rcu_read_unlock();
return 0;
}
rcu_read_unlock();
}
#endif
return vhost_put_user(vq, cpu_to_vhost16(vq, vq->last_used_idx),
&vq->used->idx);
}
@ -1340,50 +980,12 @@ static void vhost_dev_unlock_vqs(struct vhost_dev *d)
static inline int vhost_get_avail_idx(struct vhost_virtqueue *vq,
__virtio16 *idx)
{
#if VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_avail *avail;
if (!vq->iotlb) {
rcu_read_lock();
map = rcu_dereference(vq->maps[VHOST_ADDR_AVAIL]);
if (likely(map)) {
avail = map->addr;
*idx = avail->idx;
rcu_read_unlock();
return 0;
}
rcu_read_unlock();
}
#endif
return vhost_get_avail(vq, *idx, &vq->avail->idx);
}
static inline int vhost_get_avail_head(struct vhost_virtqueue *vq,
__virtio16 *head, int idx)
{
#if VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_avail *avail;
if (!vq->iotlb) {
rcu_read_lock();
map = rcu_dereference(vq->maps[VHOST_ADDR_AVAIL]);
if (likely(map)) {
avail = map->addr;
*head = avail->ring[idx & (vq->num - 1)];
rcu_read_unlock();
return 0;
}
rcu_read_unlock();
}
#endif
return vhost_get_avail(vq, *head,
&vq->avail->ring[idx & (vq->num - 1)]);
}
@ -1391,98 +993,24 @@ static inline int vhost_get_avail_head(struct vhost_virtqueue *vq,
static inline int vhost_get_avail_flags(struct vhost_virtqueue *vq,
__virtio16 *flags)
{
#if VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_avail *avail;
if (!vq->iotlb) {
rcu_read_lock();
map = rcu_dereference(vq->maps[VHOST_ADDR_AVAIL]);
if (likely(map)) {
avail = map->addr;
*flags = avail->flags;
rcu_read_unlock();
return 0;
}
rcu_read_unlock();
}
#endif
return vhost_get_avail(vq, *flags, &vq->avail->flags);
}
static inline int vhost_get_used_event(struct vhost_virtqueue *vq,
__virtio16 *event)
{
#if VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_avail *avail;
if (!vq->iotlb) {
rcu_read_lock();
map = rcu_dereference(vq->maps[VHOST_ADDR_AVAIL]);
if (likely(map)) {
avail = map->addr;
*event = (__virtio16)avail->ring[vq->num];
rcu_read_unlock();
return 0;
}
rcu_read_unlock();
}
#endif
return vhost_get_avail(vq, *event, vhost_used_event(vq));
}
static inline int vhost_get_used_idx(struct vhost_virtqueue *vq,
__virtio16 *idx)
{
#if VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_used *used;
if (!vq->iotlb) {
rcu_read_lock();
map = rcu_dereference(vq->maps[VHOST_ADDR_USED]);
if (likely(map)) {
used = map->addr;
*idx = used->idx;
rcu_read_unlock();
return 0;
}
rcu_read_unlock();
}
#endif
return vhost_get_used(vq, *idx, &vq->used->idx);
}
static inline int vhost_get_desc(struct vhost_virtqueue *vq,
struct vring_desc *desc, int idx)
{
#if VHOST_ARCH_CAN_ACCEL_UACCESS
struct vhost_map *map;
struct vring_desc *d;
if (!vq->iotlb) {
rcu_read_lock();
map = rcu_dereference(vq->maps[VHOST_ADDR_DESC]);
if (likely(map)) {
d = map->addr;
*desc = *(d + idx);
rcu_read_unlock();
return 0;
}
rcu_read_unlock();
}
#endif
return vhost_copy_from_user(vq, desc, vq->desc + idx, sizeof(*desc));
}
@ -1823,32 +1351,12 @@ static bool iotlb_access_ok(struct vhost_virtqueue *vq,
return true;
}
#if VHOST_ARCH_CAN_ACCEL_UACCESS
static void vhost_vq_map_prefetch(struct vhost_virtqueue *vq)
{
struct vhost_map __rcu *map;
int i;
for (i = 0; i < VHOST_NUM_ADDRS; i++) {
rcu_read_lock();
map = rcu_dereference(vq->maps[i]);
rcu_read_unlock();
if (unlikely(!map))
vhost_map_prefetch(vq, i);
}
}
#endif
int vq_meta_prefetch(struct vhost_virtqueue *vq)
{
unsigned int num = vq->num;
if (!vq->iotlb) {
#if VHOST_ARCH_CAN_ACCEL_UACCESS
vhost_vq_map_prefetch(vq);
#endif
if (!vq->iotlb)
return 1;
}
return iotlb_access_ok(vq, VHOST_ACCESS_RO, (u64)(uintptr_t)vq->desc,
vhost_get_desc_size(vq, num), VHOST_ADDR_DESC) &&
@ -2059,16 +1567,6 @@ static long vhost_vring_set_num_addr(struct vhost_dev *d,
mutex_lock(&vq->mutex);
#if VHOST_ARCH_CAN_ACCEL_UACCESS
/* Unregister MMU notifer to allow invalidation callback
* can access vq->uaddrs[] without holding a lock.
*/
if (d->mm)
mmu_notifier_unregister(&d->mmu_notifier, d->mm);
vhost_uninit_vq_maps(vq);
#endif
switch (ioctl) {
case VHOST_SET_VRING_NUM:
r = vhost_vring_set_num(d, vq, argp);
@ -2080,13 +1578,6 @@ static long vhost_vring_set_num_addr(struct vhost_dev *d,
BUG();
}
#if VHOST_ARCH_CAN_ACCEL_UACCESS
vhost_setup_vq_uaddr(vq);
if (d->mm)
mmu_notifier_register(&d->mmu_notifier, d->mm);
#endif
mutex_unlock(&vq->mutex);
return r;

41
drivers/vhost/vhost.h
View File

@ -12,9 +12,6 @@
#include <linux/virtio_config.h>
#include <linux/virtio_ring.h>
#include <linux/atomic.h>
#include <linux/pagemap.h>
#include <linux/mmu_notifier.h>
#include <asm/cacheflush.h>
struct vhost_work;
typedef void (*vhost_work_fn_t)(struct vhost_work *work);
@ -83,24 +80,6 @@ enum vhost_uaddr_type {
VHOST_NUM_ADDRS = 3,
};
struct vhost_map {
int npages;
void *addr;
struct page **pages;
};
struct vhost_uaddr {
unsigned long uaddr;
size_t size;
bool write;
};
#if defined(CONFIG_MMU_NOTIFIER) && ARCH_IMPLEMENTS_FLUSH_DCACHE_PAGE == 0
#define VHOST_ARCH_CAN_ACCEL_UACCESS 0
#else
#define VHOST_ARCH_CAN_ACCEL_UACCESS 0
#endif
/* The virtqueue structure describes a queue attached to a device. */
struct vhost_virtqueue {
struct vhost_dev *dev;
@ -111,22 +90,7 @@ struct vhost_virtqueue {
struct vring_desc __user *desc;
struct vring_avail __user *avail;
struct vring_used __user *used;
#if VHOST_ARCH_CAN_ACCEL_UACCESS
/* Read by memory accessors, modified by meta data
* prefetching, MMU notifier and vring ioctl().
* Synchonrized through mmu_lock (writers) and RCU (writers
* and readers).
*/
struct vhost_map __rcu *maps[VHOST_NUM_ADDRS];
/* Read by MMU notifier, modified by vring ioctl(),
* synchronized through MMU notifier
* registering/unregistering.
*/
struct vhost_uaddr uaddrs[VHOST_NUM_ADDRS];
#endif
const struct vhost_umem_node *meta_iotlb[VHOST_NUM_ADDRS];
struct file *kick;
struct eventfd_ctx *call_ctx;
struct eventfd_ctx *error_ctx;
@ -181,8 +145,6 @@ struct vhost_virtqueue {
bool user_be;
#endif
u32 busyloop_timeout;
spinlock_t mmu_lock;
int invalidate_count;
};
struct vhost_msg_node {
@ -196,9 +158,6 @@ struct vhost_msg_node {
struct vhost_dev {
struct mm_struct *mm;
#ifdef CONFIG_MMU_NOTIFIER
struct mmu_notifier mmu_notifier;
#endif
struct mutex mutex;
struct vhost_virtqueue **vqs;
int nvqs;