Re: [PATCH net-next V2 6/8] vhost: packed ring support
From: Tiwei Bie <hidden>
Date: 2018-10-12 14:34:05
Also in:
kvm, lkml
On Mon, Jul 16, 2018 at 11:28:09AM +0800, Jason Wang wrote: [...]
quoted hunk ↗ jump to hunk
@@ -1367,10 +1397,48 @@ long vhost_vring_ioctl(struct vhost_dev *d, unsigned int ioctl, void __user *arg vq->last_avail_idx = s.num; /* Forget the cached index value. */ vq->avail_idx = vq->last_avail_idx; + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) { + vq->last_avail_wrap_counter = wrap_counter; + vq->avail_wrap_counter = vq->last_avail_wrap_counter; + } break; case VHOST_GET_VRING_BASE: s.index = idx; s.num = vq->last_avail_idx; + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) + s.num |= vq->last_avail_wrap_counter << 31; + if (copy_to_user(argp, &s, sizeof(s))) + r = -EFAULT; + break; + case VHOST_SET_VRING_USED_BASE: + /* Moving base with an active backend? + * You don't want to do that. + */ + if (vq->private_data) { + r = -EBUSY; + break; + } + if (copy_from_user(&s, argp, sizeof(s))) { + r = -EFAULT; + break; + } + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) { + wrap_counter = s.num >> 31; + s.num &= ~(1 << 31); + } + if (s.num > 0xffff) { + r = -EINVAL; + break; + }
Do we want to put wrap_counter at bit 15? If put wrap_counter at bit 31, the check (s.num > 0xffff) won't be able to catch the illegal index 0x8000~0xffff for packed ring.
+ vq->last_used_idx = s.num; + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) + vq->last_used_wrap_counter = wrap_counter; + break; + case VHOST_GET_VRING_USED_BASE:
Do we need the new VHOST_GET_VRING_USED_BASE and VHOST_SET_VRING_USED_BASE ops? We are going to merge below series in DPDK: http://patches.dpdk.org/patch/45874/ We may need to reach an agreement first.
+ s.index = idx; + s.num = vq->last_used_idx; + if (vhost_has_feature(vq, VIRTIO_F_RING_PACKED)) + s.num |= vq->last_used_wrap_counter << 31; if (copy_to_user(argp, &s, sizeof s)) r = -EFAULT; break;
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