On Fri, Dec 8, 2023 at 2:53 AM Si-Wei Liu <si-wei....@oracle.com> wrote: > > Getting it ahead at initialization time instead of start time allows > decision making independent of device status, while reducing failure > possibility in starting device or during migration. > > Adding function vhost_vdpa_probe_desc_group() for that end. This > function will be used to probe the descriptor group for data vqs. > > Signed-off-by: Si-Wei Liu <si-wei....@oracle.com> > --- > net/vhost-vdpa.c | 89 > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 89 insertions(+) > > diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c > index 887c329..0cf3147 100644 > --- a/net/vhost-vdpa.c > +++ b/net/vhost-vdpa.c > @@ -1688,6 +1688,95 @@ out: > return r; > } > > +static int vhost_vdpa_probe_desc_group(int device_fd, uint64_t features, > + int vq_index, int64_t *desc_grpidx, > + Error **errp) > +{ > + uint64_t backend_features; > + int64_t vq_group, desc_group; > + uint8_t saved_status = 0; > + uint8_t status = 0; > + int r; > + > + ERRP_GUARD(); > + > + r = ioctl(device_fd, VHOST_GET_BACKEND_FEATURES, &backend_features); > + if (unlikely(r < 0)) { > + error_setg_errno(errp, errno, "Cannot get vdpa backend_features"); > + return r; > + } > + > + if (!(backend_features & BIT_ULL(VHOST_BACKEND_F_IOTLB_ASID))) { > + return 0; > + } > + > + if (!(backend_features & BIT_ULL(VHOST_BACKEND_F_DESC_ASID))) { > + return 0; > + } > + > + r = ioctl(device_fd, VHOST_VDPA_GET_STATUS, &saved_status); > + if (unlikely(r)) { > + error_setg_errno(errp, -r, "Cannot get device status"); > + goto out; > + }
I wonder what's the reason for the status being saved and restored? We don't do this in vhost_vdpa_probe_cvq_isolation(). Thanks