diff options
author | Paolo Bonzini <pbonzini@redhat.com> | 2015-04-02 19:50:44 +0200 |
---|---|---|
committer | Stefan Hajnoczi <stefanha@redhat.com> | 2015-04-08 10:39:18 +0100 |
commit | 2a6cdd6d35158bc7a6aacd92b5b0302f28ec480e (patch) | |
tree | 51b158464e2013fd972bc2401d74ca13d4281743 | |
parent | e4603fe139e2161464d7e75faa3a650e31f057fc (diff) | |
download | hqemu-2a6cdd6d35158bc7a6aacd92b5b0302f28ec480e.zip hqemu-2a6cdd6d35158bc7a6aacd92b5b0302f28ec480e.tar.gz |
virtio-blk: correctly dirty guest memory
After qemu_iovec_destroy, the QEMUIOVector's size is zeroed and
the zero size ultimately is used to compute virtqueue_push's len
argument. Therefore, reads from virtio-blk devices did not
migrate their results correctly. (Writes were okay).
Save the size in virtio_blk_handle_request, and use it when the request
is completed.
Based on a patch by Wen Congyang.
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Tested-by: Li Zhijian <lizhijian@cn.fujitsu.com>
Message-id: 1427997044-392-1-git-send-email-pbonzini@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
-rw-r--r-- | hw/block/dataplane/virtio-blk.c | 3 | ||||
-rw-r--r-- | hw/block/virtio-blk.c | 13 | ||||
-rw-r--r-- | include/hw/virtio/virtio-blk.h | 1 |
3 files changed, 14 insertions, 3 deletions
diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c index cd41478..3db139b 100644 --- a/hw/block/dataplane/virtio-blk.c +++ b/hw/block/dataplane/virtio-blk.c @@ -77,8 +77,7 @@ static void complete_request_vring(VirtIOBlockReq *req, unsigned char status) VirtIOBlockDataPlane *s = req->dev->dataplane; stb_p(&req->in->status, status); - vring_push(s->vdev, &req->dev->dataplane->vring, &req->elem, - req->qiov.size + sizeof(*req->in)); + vring_push(s->vdev, &req->dev->dataplane->vring, &req->elem, req->in_len); /* Suppress notification to guest by BH and its scheduled * flag because requests are completed as a batch after io diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c index 000c38d..9546fd2 100644 --- a/hw/block/virtio-blk.c +++ b/hw/block/virtio-blk.c @@ -33,6 +33,7 @@ VirtIOBlockReq *virtio_blk_alloc_request(VirtIOBlock *s) VirtIOBlockReq *req = g_slice_new(VirtIOBlockReq); req->dev = s; req->qiov.size = 0; + req->in_len = 0; req->next = NULL; req->mr_next = NULL; return req; @@ -54,7 +55,7 @@ static void virtio_blk_complete_request(VirtIOBlockReq *req, trace_virtio_blk_req_complete(req, status); stb_p(&req->in->status, status); - virtqueue_push(s->vq, &req->elem, req->qiov.size + sizeof(*req->in)); + virtqueue_push(s->vq, &req->elem, req->in_len); virtio_notify(vdev, s->vq); } @@ -102,6 +103,14 @@ static void virtio_blk_rw_complete(void *opaque, int ret) if (ret) { int p = virtio_ldl_p(VIRTIO_DEVICE(req->dev), &req->out.type); bool is_read = !(p & VIRTIO_BLK_T_OUT); + /* Note that memory may be dirtied on read failure. If the + * virtio request is not completed here, as is the case for + * BLOCK_ERROR_ACTION_STOP, the memory may not be copied + * correctly during live migration. While this is ugly, + * it is acceptable because the device is free to write to + * the memory until the request is completed (which will + * happen on the other side of the migration). + */ if (virtio_blk_handle_rw_error(req, -ret, is_read)) { continue; } @@ -496,6 +505,8 @@ void virtio_blk_handle_request(VirtIOBlockReq *req, MultiReqBuffer *mrb) exit(1); } + /* We always touch the last byte, so just see how big in_iov is. */ + req->in_len = iov_size(in_iov, in_num); req->in = (void *)in_iov[in_num - 1].iov_base + in_iov[in_num - 1].iov_len - sizeof(struct virtio_blk_inhdr); diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-blk.h index b3ffcd9..6bf5905 100644 --- a/include/hw/virtio/virtio-blk.h +++ b/include/hw/virtio/virtio-blk.h @@ -67,6 +67,7 @@ typedef struct VirtIOBlockReq { struct virtio_blk_inhdr *in; struct virtio_blk_outhdr out; QEMUIOVector qiov; + size_t in_len; struct VirtIOBlockReq *next; struct VirtIOBlockReq *mr_next; BlockAcctCookie acct; |