Hi Stefan,
I have sent a version 2 and it should fix this issue.
I also test it several times and I did not meet this issue again.
Thanks for your report.
Best Regards
Jin
> -----Original Message-----
> From: Stefan Hajnoczi <stefa...@redhat.com>
> Sent: Tuesday, November 3, 2020 12:57 AM
> To: qemu-de...@nongnu.org
> Cc: qemu-block@nongnu.org; Raphael Norwitz
> <raphael.norw...@nutanix.com>; Max Reitz <mre...@redhat.com>; Kevin
> Wolf <kw...@redhat.com>; Michael S. Tsirkin <m...@redhat.com>; Stefan
> Hajnoczi <stefa...@redhat.com>; Yu, Jin <jin...@intel.com>
> Subject: [PATCH] Revert "vhost-blk: set features before setting inflight
> feature"
>
> This reverts commit adb29c027341ba095a3ef4beef6aaef86d3a520e.
>
> The commit broke -device vhost-user-blk-pci because the
> vhost_dev_prepare_inflight() function it introduced segfaults in
> vhost_dev_set_features() when attempting to access struct vhost_dev's vdev
> pointer before it has been assigned.
>
> To reproduce the segfault simply launch a vhost-user-blk device with the
> contrib vhost-user-blk device backend:
>
> $ build/contrib/vhost-user-blk/vhost-user-blk -s /tmp/vhost-user-blk.sock -r
> -b /var/tmp/foo.img
> $ build/qemu-system-x86_64 \
> -device vhost-user-blk-pci,id=drv0,chardev=char1,addr=4.0 \
> -object memory-backend-memfd,id=mem,size=1G,share=on \
> -M memory-backend=mem,accel=kvm \
> -chardev socket,id=char1,path=/tmp/vhost-user-blk.sock
> Segmentation fault (core dumped)
>
> Cc: Jin Yu <jin...@intel.com>
> Cc: Raphael Norwitz <raphael.norw...@nutanix.com>
> Cc: Michael S. Tsirkin <m...@redhat.com>
> Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com>
> ---
> include/hw/virtio/vhost.h | 1 -
> hw/block/vhost-user-blk.c | 6 ------
> hw/virtio/vhost.c | 18 ------------------
> 3 files changed, 25 deletions(-)
>
> diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h index
> 839bfb153c..94585067f7 100644
> --- a/include/hw/virtio/vhost.h
> +++ b/include/hw/virtio/vhost.h
> @@ -141,7 +141,6 @@ void vhost_dev_reset_inflight(struct vhost_inflight
> *inflight); void vhost_dev_free_inflight(struct vhost_inflight *inflight);
> void
> vhost_dev_save_inflight(struct vhost_inflight *inflight, QEMUFile *f); int
> vhost_dev_load_inflight(struct vhost_inflight *inflight, QEMUFile *f); -int
> vhost_dev_prepare_inflight(struct vhost_dev *hdev); int
> vhost_dev_set_inflight(struct vhost_dev *dev,
> struct vhost_inflight *inflight); int
> vhost_dev_get_inflight(struct vhost_dev *dev, uint16_t queue_size, diff --git
> a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c index
> f67b29bbf3..a076b1e54d 100644
> --- a/hw/block/vhost-user-blk.c
> +++ b/hw/block/vhost-user-blk.c
> @@ -131,12 +131,6 @@ static int vhost_user_blk_start(VirtIODevice *vdev)
>
> s->dev.acked_features = vdev->guest_features;
>
> - ret = vhost_dev_prepare_inflight(&s->dev);
> - if (ret < 0) {
> - error_report("Error set inflight format: %d", -ret);
> - goto err_guest_notifiers;
> - }
> -
> if (!s->inflight->addr) {
> ret = vhost_dev_get_inflight(&s->dev, s->queue_size, s->inflight);
> if (ret < 0) {
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index
> f2482378c6..79b2be20df 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -1645,24 +1645,6 @@ int vhost_dev_load_inflight(struct vhost_inflight
> *inflight, QEMUFile *f)
> return 0;
> }
>
> -int vhost_dev_prepare_inflight(struct vhost_dev *hdev) -{
> - int r;
> -
> - if (hdev->vhost_ops->vhost_get_inflight_fd == NULL ||
> - hdev->vhost_ops->vhost_set_inflight_fd == NULL) {
> - return 0;
> - }
> -
> - r = vhost_dev_set_features(hdev, hdev->log_enabled);
> - if (r < 0) {
> - VHOST_OPS_DEBUG("vhost_dev_prepare_inflight failed");
> - return r;
> - }
> -
> - return 0;
> -}
> -
> int vhost_dev_set_inflight(struct vhost_dev *dev,
> struct vhost_inflight *inflight) {
> --
> 2.28.0
