From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Christie Date: Wed, 23 Sep 2020 19:12:51 +0000 Subject: Re: [PATCH 2/8] vhost: add helper to check if a vq has been setup Message-Id: <63094bae-1f26-c21e-9b3c-3a6aa99a7e24@oracle.com> List-Id: References: <1600712588-9514-1-git-send-email-michael.christie@oracle.com> <1600712588-9514-3-git-send-email-michael.christie@oracle.com> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit To: Jason Wang , martin.petersen@oracle.com, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, mst@redhat.com, pbonzini@redhat.com, stefanha@redhat.com, virtualization@lists.linux-foundation.org On 9/21/20 9:02 PM, Jason Wang wrote: > > On 2020/9/22 上午2:23, 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 >> --- >>   drivers/vhost/vhost.c | 9 +++++++++ >>   drivers/vhost/vhost.h | 1 + >>   2 files changed, 10 insertions(+) >> >> diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c >> index b45519c..5dd9eb1 100644 >> --- a/drivers/vhost/vhost.c >> +++ b/drivers/vhost/vhost.c >> @@ -305,6 +305,15 @@ static void vhost_vring_call_reset(struct vhost_vring_call *call_ctx) >>       spin_lock_init(&call_ctx->ctx_lock); >>   } >>   +bool vhost_vq_is_setup(struct vhost_virtqueue *vq) >> +{ >> +    if (vq->avail && vq->desc && vq->used && vhost_vq_access_ok(vq)) >> +        return true; >> +    else >> +        return false; >> +} >> +EXPORT_SYMBOL_GPL(vhost_vq_is_setup); > > > This is probably ok but I wonder maybe we should have something like what vDPA did (VHOST_SET_VRING_ENABLE) to match virtio 1.0 device definition. It looks like I can make that work. Some questions: 1. Do you mean a generic VHOST_SET_VRING_ENABLE or a SCSI specific one VHOST_SCSI_SET_VRING_ENABLE? 2. I can see the VHOST_VDPA_SET_VRING_ENABLE kernel code and the vhost_set_vring_enable qemu code, so I have an idea of how it should work for vhost scsi. However, I'm not sure the requirements for a generic VHOST_SET_VRING_ENABLE if that is what you meant. I could not find it in the spec either. Could you send me a pointer to the section? For example, for vhost-net we seem to enable a device in the VHOST_NET_SET_BACKEND ioctl, so I'm not sure what behavior should be or needs to be implemented for net and vsock.