We need to set log when updating flags of used ring, otherwise they may
be missed after migration. A helper was introduced to write used_flags
back to guest memory and update the log if necessary.
Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
drivers/vhost/vhost.c | 26 ++++++++++++++++++++++----
drivers/vhost/vhost.h | 2 ++
2 files changed, 24 insertions(+), 4 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 2ab2912..7c46aed 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -573,8 +573,10 @@ static long vhost_set_memory(struct vhost_dev *d, struct vhost_memory __user *m)
static int init_used(struct vhost_virtqueue *vq,
struct vring_used __user *used)
{
- int r = put_user(vq->used_flags, &used->flags);
+ int r;
+ vq->used = used;
+ r = vhost_update_used_flags(vq);
if (r)
return r;
return get_user(vq->last_used_idx, &used->idx);
@@ -700,7 +702,6 @@ static long vhost_set_vring(struct vhost_dev *d, int ioctl, void __user *argp)
vq->desc = (void __user *)(unsigned long)a.desc_user_addr;
vq->avail = (void __user *)(unsigned long)a.avail_user_addr;
vq->log_addr = a.log_guest_addr;
- vq->used = (void __user *)(unsigned long)a.used_user_addr;
break;
case VHOST_SET_VRING_KICK:
if (copy_from_user(&f, argp, sizeof f)) {
@@ -1375,6 +1376,23 @@ void vhost_add_used_and_signal_n(struct vhost_dev *dev,
vhost_signal(dev, vq);
}
+int vhost_update_used_flags(struct vhost_virtqueue *vq)
+{
+ if (put_user(vq->used_flags, &vq->used->flags) < 0)
+ return -EFAULT;
+ if (unlikely(vq->log_used)) {
+ /* Make sure the flag is seen before log. */
+ smp_wmb();
+ /* Log used flag write. */
+ log_write(vq->log_base,
+ vq->log_addr + offsetof(struct vring_used, flags),
+ sizeof vq->used->flags);
+ if (vq->log_ctx)
+ eventfd_signal(vq->log_ctx, 1);
+ }
+ return 0;
+}
+
/* OK, now we need to know about added descriptors. */
bool vhost_enable_notify(struct vhost_virtqueue *vq)
{
@@ -1384,7 +1402,7 @@ bool vhost_enable_notify(struct vhost_virtqueue *vq)
if (!(vq->used_flags & VRING_USED_F_NO_NOTIFY))
return false;
vq->used_flags &= ~VRING_USED_F_NO_NOTIFY;
- r = put_user(vq->used_flags, &vq->used->flags);
+ r = vhost_update_used_flags(vq);
if (r) {
vq_err(vq, "Failed to enable notification at %p: %d\n",
&vq->used->flags, r);
@@ -1411,7 +1429,7 @@ void vhost_disable_notify(struct vhost_virtqueue *vq)
if (vq->used_flags & VRING_USED_F_NO_NOTIFY)
return;
vq->used_flags |= VRING_USED_F_NO_NOTIFY;
- r = put_user(vq->used_flags, &vq->used->flags);
+ r = vhost_update_used_flags(vq);
if (r)
vq_err(vq, "Failed to enable notification at %p: %d\n",
&vq->used->flags, r);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index b3363ae..76f4c61 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -155,6 +155,8 @@ bool vhost_enable_notify(struct vhost_virtqueue *);
int vhost_log_write(struct vhost_virtqueue *vq, struct vhost_log *log,
unsigned int log_num, u64 len);
+int vhost_update_used_flags(struct vhost_virtqueue *vq);
+
#define vq_err(vq, fmt, ...) do { \
pr_debug(pr_fmt(fmt), ##__VA_ARGS__); \
if ((vq)->error_ctx) \
--
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