Re: [PATCH 3/3] vhost-user: Don't pass file descriptor for VHOST_USER_REM_MEM_REG

[Raphael Norwitz]

On Thu, Apr 07, 2022 at 03:36:57PM +0200, Kevin Wolf wrote:
> The spec clarifies now that QEMU should not send a file descriptor in a
> request to remove a memory region. Change it accordingly.
> 
> For libvhost-user, this is a bug fix that makes it compatible with
> rust-vmm's implementation that doesn't send a file descriptor. Keep
> accepting, but ignoring a file descriptor for compatibility with older
> QEMU versions.
> 
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>

Reviewed-by: Raphael Norwitz <raphael.norwitz@nutanix.com>

> ---
>  hw/virtio/vhost-user.c                    | 2 +-
>  subprojects/libvhost-user/libvhost-user.c | 8 ++++----
>  2 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index 6abbc9da32..82caf607e5 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -751,7 +751,7 @@ static int send_remove_regions(struct vhost_dev *dev,
>              vhost_user_fill_msg_region(&region_buffer, shadow_reg, 0);
>              msg->payload.mem_reg.region = region_buffer;
>  
> -            ret = vhost_user_write(dev, msg, &fd, 1);
> +            ret = vhost_user_write(dev, msg, NULL, 0);
>              if (ret < 0) {
>                  return ret;
>              }
> diff --git a/subprojects/libvhost-user/libvhost-user.c 
> b/subprojects/libvhost-user/libvhost-user.c
> index eccaff5168..d0041c864b 100644
> --- a/subprojects/libvhost-user/libvhost-user.c
> +++ b/subprojects/libvhost-user/libvhost-user.c
> @@ -822,15 +822,15 @@ vu_rem_mem_reg(VuDev *dev, VhostUserMsg *vmsg) {
>      int i;
>      bool found = false;
>  
> -    if (vmsg->fd_num != 1) {
> +    if (vmsg->fd_num > 1) {
>          vmsg_close_fds(vmsg);
> -        vu_panic(dev, "VHOST_USER_REM_MEM_REG received %d fds - only 1 fd "
> +        vu_panic(dev, "VHOST_USER_REM_MEM_REG received %d fds - at most 1 fd 
> "
>                        "should be sent for this message type", vmsg->fd_num);
>          return false;
>      }
>  
>      if (vmsg->size < VHOST_USER_MEM_REG_SIZE) {
> -        close(vmsg->fds[0]);
> +        vmsg_close_fds(vmsg);
>          vu_panic(dev, "VHOST_USER_REM_MEM_REG requires a message size of at "
>                        "least %d bytes and only %d bytes were received",
>                        VHOST_USER_MEM_REG_SIZE, vmsg->size);
> @@ -877,7 +877,7 @@ vu_rem_mem_reg(VuDev *dev, VhostUserMsg *vmsg) {
>          vu_panic(dev, "Specified region not found\n");
>      }
>  
> -    close(vmsg->fds[0]);
> +    vmsg_close_fds(vmsg);
>  
>      return false;
>  }
> -- 
> 2.35.1
>