[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [qemu-xen stable-4.16] virtio: use virtio accessor to access packed descriptor flags
commit df1c9c3039e5ded39ae6b37b62b8d064acfe7dd5 Author: Jason Wang <jasowang@xxxxxxxxxx> AuthorDate: Thu Nov 11 14:38:53 2021 +0800 Commit: Michael Roth <michael.roth@xxxxxxx> CommitDate: Tue Dec 14 14:43:18 2021 -0600 virtio: use virtio accessor to access packed descriptor flags We used to access packed descriptor flags via address_space_{write|read}_cached(). When we hit the cache, memcpy() is used which is not an atomic operation which may lead a wrong value is read or wrote. So this patch switches to use virito_{stw|lduw}_phys_cached() to make sure the aceess is atomic. Fixes: 86044b24e865f ("virtio: basic packed virtqueue support") Cc: qemu-stable@xxxxxxxxxx Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx> Message-Id: <20211111063854.29060-1-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 f463e761a41ee71e59892121e1c74d9c25c985d2) Signed-off-by: Michael Roth <michael.roth@xxxxxxx> --- hw/virtio/virtio.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 874377f37a..2dbccb6b3f 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -509,11 +509,9 @@ static void vring_packed_desc_read_flags(VirtIODevice *vdev, MemoryRegionCache *cache, int i) { - address_space_read_cached(cache, - i * sizeof(VRingPackedDesc) + - offsetof(VRingPackedDesc, flags), - flags, sizeof(*flags)); - virtio_tswap16s(vdev, flags); + hwaddr off = i * sizeof(VRingPackedDesc) + offsetof(VRingPackedDesc, flags); + + *flags = virtio_lduw_phys_cached(vdev, cache, off); } static void vring_packed_desc_read(VirtIODevice *vdev, @@ -566,8 +564,7 @@ static void vring_packed_desc_write_flags(VirtIODevice *vdev, { hwaddr off = i * sizeof(VRingPackedDesc) + offsetof(VRingPackedDesc, flags); - virtio_tswap16s(vdev, &desc->flags); - address_space_write_cached(cache, off, &desc->flags, sizeof(desc->flags)); + virtio_stw_phys_cached(vdev, cache, off, desc->flags); address_space_cache_invalidate(cache, off, sizeof(desc->flags)); } -- generated by git-patchbot for /home/xen/git/qemu-xen.git#stable-4.16
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