On Fri, Jul 8, 2022 at 11:05 AM Mike Christie
<michael.christie@xxxxxxxxxx> wrote:
>
> Qemu takes it's num_queues limit then adds the fixed queues (control and
> event) to the total it will request from the kernel. So when a user
> requests 128 (or qemu does it's num_queues calculation based on vCPUS
> and other system limits), we hit errors due to userspace trying to setup
> 130 queues when vhost-scsi has a hard coded limit of 128.
>
> This has vhost-scsi adjust it's max so we can do a total of 130 virtqueues
> (128 IO and 2 fixed). For the case where the user has 128 vCPUs the guest
> OS can then nicely map each IO virtqueue to a vCPU and not have the odd case
> where 2 vCPUs share a virtqueue.
>
> Signed-off-by: Mike Christie <michael.christie@xxxxxxxxxx>
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
> drivers/vhost/scsi.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c
> index ffd9e6c2ffc1..8d6b4eef554d 100644
> --- a/drivers/vhost/scsi.c
> +++ b/drivers/vhost/scsi.c
> @@ -159,7 +159,7 @@ enum {
> };
>
> #define VHOST_SCSI_MAX_TARGET 256
> -#define VHOST_SCSI_MAX_VQ 128
> +#define VHOST_SCSI_MAX_VQ 128 + VHOST_SCSI_VQ_IO
> #define VHOST_SCSI_MAX_EVENT 128
>
> struct vhost_scsi_virtqueue {
> --
> 2.25.1
>
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