Jason Wang
2020-Sep-24 07:22 UTC
[PATCH 2/8] vhost: add helper to check if a vq has been setup
On 2020/9/24 ??3:12, Mike Christie wrote:> On 9/21/20 9:02 PM, Jason Wang wrote: >> On 2020/9/22 ??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 <michael.christie at oracle.com> >>> --- >>> ? 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?It would be better if we can make it generic.> > 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?In the spec, for PCI, it's the queue_enable for modern device.> > 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.Yes, but VHOST_NET_SET_BACKEND is for the whole device not a specific virtqueue. Thanks>