Jason Wang
2020-Dec-30 06:49 UTC
[PATCH 12/21] vhost-vdpa: introduce uAPI to get the number of virtqueue groups
On 2020/12/29 ??8:24, Eli Cohen wrote:> On Wed, Dec 16, 2020 at 02:48:09PM +0800, Jason Wang wrote: >> Follows the vDPA support for multiple address spaces, this patch >> introduce uAPI for the userspace to know the number of virtqueue >> groups supported by the vDPA device. > Can you explain what exactly you mean be userspace?It's the userspace that uses the uAPI introduced in this patch.> Is it just qemu or > is it destined to the virtio_net driver run by the qemu process?It could be Qemu, DPDK or other userspace program. The guest virtio-net driver will not use this but talks to the virtio device emulated by Qemu.> Also can you say for what purpose?This can be used for facilitate the checking of whether the control vq could be supported. E.g if the device support less than 2 groups, qemu won't advertise control vq. Yes, #groups could be inferred from GET_VRING_GROUP. But it's not straightforward as this. Thanks> >> Signed-off-by: Jason Wang <jasowang at redhat.com> >> --- >> drivers/vhost/vdpa.c | 4 ++++ >> include/uapi/linux/vhost.h | 3 +++ >> 2 files changed, 7 insertions(+) >> >> diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c >> index 060d5b5b7e64..1ba5901b28e7 100644 >> --- a/drivers/vhost/vdpa.c >> +++ b/drivers/vhost/vdpa.c >> @@ -536,6 +536,10 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep, >> case VHOST_VDPA_GET_VRING_NUM: >> r = vhost_vdpa_get_vring_num(v, argp); >> break; >> + case VHOST_VDPA_GET_GROUP_NUM: >> + r = copy_to_user(argp, &v->vdpa->ngroups, >> + sizeof(v->vdpa->ngroups)); >> + break; >> case VHOST_SET_LOG_BASE: >> case VHOST_SET_LOG_FD: >> r = -ENOIOCTLCMD; >> diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h >> index 59c6c0fbaba1..8a4e6e426bbf 100644 >> --- a/include/uapi/linux/vhost.h >> +++ b/include/uapi/linux/vhost.h >> @@ -145,4 +145,7 @@ >> /* Get the valid iova range */ >> #define VHOST_VDPA_GET_IOVA_RANGE _IOR(VHOST_VIRTIO, 0x78, \ >> struct vhost_vdpa_iova_range) >> +/* Get the number of virtqueue groups. */ >> +#define VHOST_VDPA_GET_GROUP_NUM _IOR(VHOST_VIRTIO, 0x79, unsigned int) >> + >> #endif >> -- >> 2.25.1 >>