On Thu, Apr 14, 2022 at 5:48 AM Jason Wang <jasow...@redhat.com> wrote: > > > 在 2022/4/14 00:31, Eugenio Pérez 写道: > > Only the first one of them were properly enqueued back. > > > I wonder if it's better to use two patches: > > 1) using private chain > > 2) fix the chain issue > > Patch looks good itself. > > Thanks >
Sure, it can be done that way for the next version. Thanks! > > > > > While we're at it, harden SVQ: The device could have access to modify > > them, and it definitely have access when we implement packed vq. Harden > > SVQ maintaining a private copy of the descriptor chain. Other fields > > like buffer addresses are already maintained sepparatedly. > > > > Fixes: 100890f7ca ("vhost: Shadow virtqueue buffers forwarding") > > > > Signed-off-by: Eugenio Pérez <epere...@redhat.com> > > --- > > hw/virtio/vhost-shadow-virtqueue.h | 6 ++++++ > > hw/virtio/vhost-shadow-virtqueue.c | 27 +++++++++++++++++++++------ > > 2 files changed, 27 insertions(+), 6 deletions(-) > > > > diff --git a/hw/virtio/vhost-shadow-virtqueue.h > > b/hw/virtio/vhost-shadow-virtqueue.h > > index e5e24c536d..c132c994e9 100644 > > --- a/hw/virtio/vhost-shadow-virtqueue.h > > +++ b/hw/virtio/vhost-shadow-virtqueue.h > > @@ -53,6 +53,12 @@ typedef struct VhostShadowVirtqueue { > > /* Next VirtQueue element that guest made available */ > > VirtQueueElement *next_guest_avail_elem; > > > > + /* > > + * Backup next field for each descriptor so we can recover securely, > > not > > + * needing to trust the device access. > > + */ > > + uint16_t *desc_next; > > + > > /* Next head to expose to the device */ > > uint16_t shadow_avail_idx; > > > > diff --git a/hw/virtio/vhost-shadow-virtqueue.c > > b/hw/virtio/vhost-shadow-virtqueue.c > > index b232803d1b..a2531d5874 100644 > > --- a/hw/virtio/vhost-shadow-virtqueue.c > > +++ b/hw/virtio/vhost-shadow-virtqueue.c > > @@ -138,6 +138,7 @@ static void > > vhost_vring_write_descs(VhostShadowVirtqueue *svq, hwaddr *sg, > > for (n = 0; n < num; n++) { > > if (more_descs || (n + 1 < num)) { > > descs[i].flags = flags | cpu_to_le16(VRING_DESC_F_NEXT); > > + descs[i].next = cpu_to_le16(svq->desc_next[i]); > > } else { > > descs[i].flags = flags; > > } > > @@ -145,10 +146,10 @@ static void > > vhost_vring_write_descs(VhostShadowVirtqueue *svq, hwaddr *sg, > > descs[i].len = cpu_to_le32(iovec[n].iov_len); > > > > last = i; > > - i = cpu_to_le16(descs[i].next); > > + i = cpu_to_le16(svq->desc_next[i]); > > } > > > > - svq->free_head = le16_to_cpu(descs[last].next); > > + svq->free_head = le16_to_cpu(svq->desc_next[last]); > > } > > > > static bool vhost_svq_add_split(VhostShadowVirtqueue *svq, > > @@ -333,13 +334,22 @@ static void > > vhost_svq_disable_notification(VhostShadowVirtqueue *svq) > > svq->vring.avail->flags |= cpu_to_le16(VRING_AVAIL_F_NO_INTERRUPT); > > } > > > > +static uint16_t vhost_svq_last_desc_of_chain(const VhostShadowVirtqueue > > *svq, > > + uint16_t num, uint16_t i) > > +{ > > + for (uint16_t j = 0; j < num; ++j) { > > + i = le16_to_cpu(svq->desc_next[i]); > > + } > > + > > + return i; > > +} > > + > > static VirtQueueElement *vhost_svq_get_buf(VhostShadowVirtqueue *svq, > > uint32_t *len) > > { > > - vring_desc_t *descs = svq->vring.desc; > > const vring_used_t *used = svq->vring.used; > > vring_used_elem_t used_elem; > > - uint16_t last_used; > > + uint16_t last_used, last_used_chain, num; > > > > if (!vhost_svq_more_used(svq)) { > > return NULL; > > @@ -365,7 +375,10 @@ static VirtQueueElement > > *vhost_svq_get_buf(VhostShadowVirtqueue *svq, > > return NULL; > > } > > > > - descs[used_elem.id].next = svq->free_head; > > + num = svq->ring_id_maps[used_elem.id]->in_num + > > + svq->ring_id_maps[used_elem.id]->out_num; > > + last_used_chain = vhost_svq_last_desc_of_chain(svq, num, used_elem.id); > > + svq->desc_next[last_used_chain] = svq->free_head; > > svq->free_head = used_elem.id; > > > > *len = used_elem.len; > > @@ -540,8 +553,9 @@ void vhost_svq_start(VhostShadowVirtqueue *svq, > > VirtIODevice *vdev, > > svq->vring.used = qemu_memalign(qemu_real_host_page_size, > > device_size); > > memset(svq->vring.used, 0, device_size); > > svq->ring_id_maps = g_new0(VirtQueueElement *, svq->vring.num); > > + svq->desc_next = g_new0(uint16_t, svq->vring.num); > > for (unsigned i = 0; i < svq->vring.num - 1; i++) { > > - svq->vring.desc[i].next = cpu_to_le16(i + 1); > > + svq->desc_next[i] = cpu_to_le16(i + 1); > > } > > } > > > > @@ -574,6 +588,7 @@ void vhost_svq_stop(VhostShadowVirtqueue *svq) > > virtqueue_detach_element(svq->vq, next_avail_elem, 0); > > } > > svq->vq = NULL; > > + g_free(svq->desc_next); > > g_free(svq->ring_id_maps); > > qemu_vfree(svq->vring.desc); > > qemu_vfree(svq->vring.used); >