Re: [PATCH 1/5] vhost: add helper to check if a vq has been setup

Re: [PATCH 1/5] vhost: add helper to check if a vq has been setup

[Jason Wang]

On 2020/11/10 下午1:33, Mike Christie wrote:
> This adds a helper check if a vq has been setup. The next patches
> will use this when we move the vhost scsi cmd preallocation from per
> session to per vq. In the per vq case, we only want to allocate cmds
> for vqs that have actually been setup and not for all the possible
> vqs.
>
> Signed-off-by: Mike Christie <michael.christie@oracle.com>
> ---
>   drivers/vhost/vhost.c | 6 ++++++
>   drivers/vhost/vhost.h | 1 +
>   2 files changed, 7 insertions(+)
>
> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> index 5c835a2..a262e12 100644
> --- a/drivers/vhost/vhost.c
> +++ b/drivers/vhost/vhost.c
> @@ -304,6 +304,12 @@ static void vhost_vring_call_reset(struct vhost_vring_call *call_ctx)
>   	memset(&call_ctx->producer, 0x0, sizeof(struct irq_bypass_producer));
>   }
>   
> +bool vhost_vq_is_setup(struct vhost_virtqueue *vq)
> +{
> +	return vq->avail && vq->desc && vq->used && vhost_vq_access_ok(vq);
> +}
> +EXPORT_SYMBOL_GPL(vhost_vq_is_setup);
> +
>   static void vhost_vq_reset(struct vhost_dev *dev,
>   			   struct vhost_virtqueue *vq)
>   {
> diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
> index e016cd3..b063324 100644
> --- a/drivers/vhost/vhost.h
> +++ b/drivers/vhost/vhost.h
> @@ -190,6 +190,7 @@ int vhost_get_vq_desc(struct vhost_virtqueue *,
>   		      struct vhost_log *log, unsigned int *log_num);
>   void vhost_discard_vq_desc(struct vhost_virtqueue *, int n);
>   
> +bool vhost_vq_is_setup(struct vhost_virtqueue *vq);
>   int vhost_vq_init_access(struct vhost_virtqueue *);
>   int vhost_add_used(struct vhost_virtqueue *, unsigned int head, int len);
>   int vhost_add_used_n(struct vhost_virtqueue *, struct vring_used_elem *heads,


Acked-by: Jason Wang <jasowang@redhat.com>


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Re: [PATCH 0/5 V5] vhost-scsi: IO error fixups

[Stefan Hajnoczi]

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On Mon, Nov 09, 2020 at 11:33:18PM -0600, Mike Christie wrote:
> The following patches were made over Michael's vhost branch:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git/log/?h=vhost
> 
> They fixe a couple issues where the guest is getting IO errors:
> 1. The admin may set num_queues and cmd_per_lun/virtqueue_size
> in a way that allows the guest to send more IO that vhost-scsi
> was coded for.
> 
> 2. A race where vhost-scsi completes the cmd to the guest before
> it's fully completed in the target/vhost-scsi layers so if the
> guest sends a new IO too quicky we fail it.
> 
> 3. If the real/physical storage (lio backend device) hits a transient
> error then vhost-scsi would fail commands instead of relying on
> the lower levels error recovery to do what the admin had set up.
> 
> V5:
> - Bring back V1 but move flush patches to a separate clean up set
> - Modify test in vhost_vq_is_setup
> 
> V4:
> - really really fix compile errors
> - dropped threading patches so we can figure that out separately.
> 
> V3:
> - fix compile errors
> - fix possible crash where cmd could be freed while adding it to
> completion list
> - fix issue where we added the worker thread to the blk cgroup but
> the blk IO was submitted by a driver workqueue.
> 
> V2:
> - fix use before set cpu var errors
> - drop vhost_vq_is_setup
> - include patches to do a worker thread per scsi IO vq
> 
> 

Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

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