[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [qemu-xen stable-4.16] virtio: use virtio accessor to access packed event
commit 08e46e6d92b979743f4f0fb36e587b5e75a0bde6 Author: Jason Wang <jasowang@xxxxxxxxxx> AuthorDate: Thu Nov 11 14:38:54 2021 +0800 Commit: Michael Roth <michael.roth@xxxxxxx> CommitDate: Tue Dec 14 14:43:25 2021 -0600 virtio: use virtio accessor to access packed event We used to access packed descriptor event and off_wrap via address_space_{write|read}_cached(). When we hit the cache, memcpy() is used which is not atomic which may lead a wrong value to be read or wrote. This patch fixes this by switching to use virito_{stw|lduw}_phys_cached() to make sure the access is atomic. Fixes: 683f7665679c1 ("virtio: event suppression support for packed ring") Cc: qemu-stable@xxxxxxxxxx Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx> Message-Id: <20211111063854.29060-2-jasowang@xxxxxxxxxx> Reviewed-by: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx> Reviewed-by: Michael S. Tsirkin <mst@xxxxxxxxxx> Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> (cherry picked from commit d152cdd6f6fad381e804c8185f0ba938030ccac9) Signed-off-by: Michael Roth <michael.roth@xxxxxxx> --- hw/virtio/virtio.c | 13 ++++--------- 1 file changed, 4 insertions(+), 9 deletions(-) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 2dbccb6b3f..c9567f09ed 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -249,13 +249,10 @@ static void vring_packed_event_read(VirtIODevice *vdev, hwaddr off_off = offsetof(VRingPackedDescEvent, off_wrap); hwaddr off_flags = offsetof(VRingPackedDescEvent, flags); - address_space_read_cached(cache, off_flags, &e->flags, - sizeof(e->flags)); + e->flags = virtio_lduw_phys_cached(vdev, cache, off_flags); /* Make sure flags is seen before off_wrap */ smp_rmb(); - address_space_read_cached(cache, off_off, &e->off_wrap, - sizeof(e->off_wrap)); - virtio_tswap16s(vdev, &e->off_wrap); + e->off_wrap = virtio_lduw_phys_cached(vdev, cache, off_off); virtio_tswap16s(vdev, &e->flags); } @@ -265,8 +262,7 @@ static void vring_packed_off_wrap_write(VirtIODevice *vdev, { hwaddr off = offsetof(VRingPackedDescEvent, off_wrap); - virtio_tswap16s(vdev, &off_wrap); - address_space_write_cached(cache, off, &off_wrap, sizeof(off_wrap)); + virtio_stw_phys_cached(vdev, cache, off, off_wrap); address_space_cache_invalidate(cache, off, sizeof(off_wrap)); } @@ -275,8 +271,7 @@ static void vring_packed_flags_write(VirtIODevice *vdev, { hwaddr off = offsetof(VRingPackedDescEvent, flags); - virtio_tswap16s(vdev, &flags); - address_space_write_cached(cache, off, &flags, sizeof(flags)); + virtio_stw_phys_cached(vdev, cache, off, flags); address_space_cache_invalidate(cache, off, sizeof(flags)); } -- generated by git-patchbot for /home/xen/git/qemu-xen.git#stable-4.16
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