| Message ID | 20240802112138.46831-2-sahilcdq@proton.me |
|---|---|
| State | New |
| Headers | show |
| Series | Add packed virtqueue to shadow virtqueue | expand |
On Fri, Aug 2, 2024 at 1:22 PM Sahil Siddiq <icegambit91@gmail.com> wrote: > > This is the first patch in a series to add support for packed > virtqueues in vhost_shadow_virtqueue. This patch implements the > insertion of available buffers in the descriptor area. It takes > into account descriptor chains, but does not consider indirect > descriptors. > > Signed-off-by: Sahil Siddiq <sahilcdq@proton.me> > --- > Changes v2 -> v3: > * vhost-shadow-virtqueue.c > - Move parts common to "vhost_svq_add_split" and > "vhost_svq_add_packed" to "vhost_svq_add". > (vhost_svq_add_packed): > - Refactor to minimize duplicate code between > this and "vhost_svq_add_split" > - Fix code style issues. > (vhost_svq_add_split): > - Merge with "vhost_svq_vring_write_descs()" > - Refactor to minimize duplicate code between > this and "vhost_svq_add_packed" > (vhost_svq_add): > - Refactor to minimize duplicate code between > split and packed version of "vhost_svq_add" > > hw/virtio/vhost-shadow-virtqueue.c | 174 +++++++++++++++++++---------- > 1 file changed, 115 insertions(+), 59 deletions(-) > > diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c > index fc5f408f77..4c308ee53d 100644 > --- a/hw/virtio/vhost-shadow-virtqueue.c > +++ b/hw/virtio/vhost-shadow-virtqueue.c > @@ -124,97 +124,132 @@ static bool vhost_svq_translate_addr(const VhostShadowVirtqueue *svq, > } > > /** > - * Write descriptors to SVQ vring > + * Write descriptors to SVQ split vring > * > * @svq: The shadow virtqueue > - * @sg: Cache for hwaddr > - * @iovec: The iovec from the guest > - * @num: iovec length > - * @more_descs: True if more descriptors come in the chain > - * @write: True if they are writeable descriptors > - * > - * Return true if success, false otherwise and print error. > + * @out_sg: The iovec to the guest > + * @out_num: Outgoing iovec length > + * @in_sg: The iovec from the guest > + * @in_num: Incoming iovec length > + * @sgs: Cache for hwaddr > + * @head: Saves current free_head > */ > -static bool vhost_svq_vring_write_descs(VhostShadowVirtqueue *svq, hwaddr *sg, > - const struct iovec *iovec, size_t num, > - bool more_descs, bool write) > +static void vhost_svq_add_split(VhostShadowVirtqueue *svq, > + const struct iovec *out_sg, size_t out_num, > + const struct iovec *in_sg, size_t in_num, > + hwaddr *sgs, unsigned *head) > { > + unsigned avail_idx, n; > uint16_t i = svq->free_head, last = svq->free_head; > - unsigned n; > - uint16_t flags = write ? cpu_to_le16(VRING_DESC_F_WRITE) : 0; > + vring_avail_t *avail = svq->vring.avail; > vring_desc_t *descs = svq->vring.desc; > - bool ok; > - > - if (num == 0) { > - return true; > - } > + size_t num = in_num + out_num; > > - ok = vhost_svq_translate_addr(svq, sg, iovec, num); > - if (unlikely(!ok)) { > - return false; > - } > + *head = svq->free_head; > > 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].flags = cpu_to_le16(n < out_num ? 0 : VRING_DESC_F_WRITE); > + if (n + 1 < num) { > + descs[i].flags |= cpu_to_le16(VRING_DESC_F_NEXT); > descs[i].next = cpu_to_le16(svq->desc_next[i]); > + } > + > + descs[i].addr = cpu_to_le64(sgs[n]); > + if (n < out_num) { > + descs[i].len = cpu_to_le32(out_sg[n].iov_len); > } else { > - descs[i].flags = flags; > + descs[i].len = cpu_to_le32(in_sg[n - out_num].iov_len); > } > - descs[i].addr = cpu_to_le64(sg[n]); > - descs[i].len = cpu_to_le32(iovec[n].iov_len); > > last = i; > i = cpu_to_le16(svq->desc_next[i]); > } > > svq->free_head = le16_to_cpu(svq->desc_next[last]); > - return true; > + > + /* > + * Put the entry in the available array (but don't update avail->idx until > + * they do sync). > + */ > + avail_idx = svq->shadow_avail_idx & (svq->vring.num - 1); > + avail->ring[avail_idx] = cpu_to_le16(*head); > + svq->shadow_avail_idx++; > + > + /* Update the avail index after write the descriptor */ > + smp_wmb(); > + avail->idx = cpu_to_le16(svq->shadow_avail_idx); > } > I think this code is already in a very good shape. But actual testing is needed before acks. As a suggestion, we can split it into: 1) Refactor in vhost_svq_translate_addr to support out_num+in_num. No functional change. 2) Refactor vhost_svq_add_split to extract common code into vhost_svq_add. No functional change. 3) Adding packed code. How to split or merge the patches is not a well-defined thing, so I'm happy with this patch if you think the reactor is not worth it. > -static bool vhost_svq_add_split(VhostShadowVirtqueue *svq, > +/** > + * Write descriptors to SVQ packed vring > + * > + * @svq: The shadow virtqueue > + * @out_sg: The iovec to the guest > + * @out_num: Outgoing iovec length > + * @in_sg: The iovec from the guest > + * @in_num: Incoming iovec length > + * @sgs: Cache for hwaddr > + * @head: Saves current free_head > + */ > +static void vhost_svq_add_packed(VhostShadowVirtqueue *svq, > const struct iovec *out_sg, size_t out_num, > const struct iovec *in_sg, size_t in_num, > - unsigned *head) > + hwaddr *sgs, unsigned *head) > { > - unsigned avail_idx; > - vring_avail_t *avail = svq->vring.avail; > - bool ok; > - g_autofree hwaddr *sgs = g_new(hwaddr, MAX(out_num, in_num)); > + uint16_t id, curr, i, head_flags = 0; > + size_t num = out_num + in_num; > + unsigned n; > > - *head = svq->free_head; > + struct vring_packed_desc *descs = svq->vring_packed.vring.desc; > > - /* We need some descriptors here */ > - if (unlikely(!out_num && !in_num)) { > - qemu_log_mask(LOG_GUEST_ERROR, > - "Guest provided element with no descriptors"); > - return false; > - } > + *head = svq->vring_packed.next_avail_idx; > + i = *head; > + id = svq->free_head; > + curr = id; > > - ok = vhost_svq_vring_write_descs(svq, sgs, out_sg, out_num, in_num > 0, > - false); > - if (unlikely(!ok)) { > - return false; > + /* Write descriptors to SVQ packed vring */ > + for (n = 0; n < num; n++) { > + uint16_t flags = cpu_to_le16(svq->vring_packed.avail_used_flags | > + (n < out_num ? 0 : VRING_DESC_F_WRITE) | > + (n + 1 == num ? 0 : VRING_DESC_F_NEXT)); > + if (i == *head) { > + head_flags = flags; > + } else { > + descs[i].flags = flags; > + } > + > + descs[i].addr = cpu_to_le64(sgs[n]); > + descs[i].id = id; > + if (n < out_num) { > + descs[i].len = cpu_to_le32(out_sg[n].iov_len); > + } else { > + descs[i].len = cpu_to_le32(in_sg[n - out_num].iov_len); > + } > + > + curr = cpu_to_le16(svq->desc_next[curr]); > + > + if (++i >= svq->vring_packed.vring.num) { > + i = 0; > + svq->vring_packed.avail_used_flags ^= > + 1 << VRING_PACKED_DESC_F_AVAIL | > + 1 << VRING_PACKED_DESC_F_USED; > + } > } > > - ok = vhost_svq_vring_write_descs(svq, sgs, in_sg, in_num, false, true); > - if (unlikely(!ok)) { > - return false; > + if (i <= *head) { > + svq->vring_packed.avail_wrap_counter ^= 1; > } > > + svq->vring_packed.next_avail_idx = i; > + svq->free_head = curr; > + > /* > - * Put the entry in the available array (but don't update avail->idx until > - * they do sync). > + * A driver MUST NOT make the first descriptor in the list > + * available before all subsequent descriptors comprising > + * the list are made available. > */ > - avail_idx = svq->shadow_avail_idx & (svq->vring.num - 1); > - avail->ring[avail_idx] = cpu_to_le16(*head); > - svq->shadow_avail_idx++; > - > - /* Update the avail index after write the descriptor */ > smp_wmb(); > - avail->idx = cpu_to_le16(svq->shadow_avail_idx); > - > - return true; > + svq->vring_packed.vring.desc[*head].flags = head_flags; > } > > static void vhost_svq_kick(VhostShadowVirtqueue *svq) > @@ -254,15 +289,36 @@ int vhost_svq_add(VhostShadowVirtqueue *svq, const struct iovec *out_sg, > unsigned ndescs = in_num + out_num; > bool ok; > > + /* We need some descriptors here */ > + if (unlikely(!ndescs)) { > + qemu_log_mask(LOG_GUEST_ERROR, > + "Guest provided element with no descriptors"); > + return -EINVAL; > + } > + > if (unlikely(ndescs > vhost_svq_available_slots(svq))) { > return -ENOSPC; > } > > - ok = vhost_svq_add_split(svq, out_sg, out_num, in_sg, in_num, &qemu_head); > + g_autofree hwaddr *sgs = g_new(hwaddr, ndescs); > + ok = vhost_svq_translate_addr(svq, sgs, out_sg, out_num); > if (unlikely(!ok)) { > return -EINVAL; > } > > + ok = vhost_svq_translate_addr(svq, sgs + out_num, in_sg, in_num); > + if (unlikely(!ok)) { > + return -EINVAL; > + } > + > + if (virtio_vdev_has_feature(svq->vdev, VIRTIO_F_RING_PACKED)) { > + vhost_svq_add_packed(svq, out_sg, out_num, in_sg, > + in_num, sgs, &qemu_head); > + } else { > + vhost_svq_add_split(svq, out_sg, out_num, in_sg, > + in_num, sgs, &qemu_head); > + } > + > svq->num_free -= ndescs; > svq->desc_state[qemu_head].elem = elem; > svq->desc_state[qemu_head].ndescs = ndescs; > -- > 2.45.2 >
diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c index fc5f408f77..4c308ee53d 100644 --- a/hw/virtio/vhost-shadow-virtqueue.c +++ b/hw/virtio/vhost-shadow-virtqueue.c @@ -124,97 +124,132 @@ static bool vhost_svq_translate_addr(const VhostShadowVirtqueue *svq, } /** - * Write descriptors to SVQ vring + * Write descriptors to SVQ split vring * * @svq: The shadow virtqueue - * @sg: Cache for hwaddr - * @iovec: The iovec from the guest - * @num: iovec length - * @more_descs: True if more descriptors come in the chain - * @write: True if they are writeable descriptors - * - * Return true if success, false otherwise and print error. + * @out_sg: The iovec to the guest + * @out_num: Outgoing iovec length + * @in_sg: The iovec from the guest + * @in_num: Incoming iovec length + * @sgs: Cache for hwaddr + * @head: Saves current free_head */ -static bool vhost_svq_vring_write_descs(VhostShadowVirtqueue *svq, hwaddr *sg, - const struct iovec *iovec, size_t num, - bool more_descs, bool write) +static void vhost_svq_add_split(VhostShadowVirtqueue *svq, + const struct iovec *out_sg, size_t out_num, + const struct iovec *in_sg, size_t in_num, + hwaddr *sgs, unsigned *head) { + unsigned avail_idx, n; uint16_t i = svq->free_head, last = svq->free_head; - unsigned n; - uint16_t flags = write ? cpu_to_le16(VRING_DESC_F_WRITE) : 0; + vring_avail_t *avail = svq->vring.avail; vring_desc_t *descs = svq->vring.desc; - bool ok; - - if (num == 0) { - return true; - } + size_t num = in_num + out_num; - ok = vhost_svq_translate_addr(svq, sg, iovec, num); - if (unlikely(!ok)) { - return false; - } + *head = svq->free_head; 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].flags = cpu_to_le16(n < out_num ? 0 : VRING_DESC_F_WRITE); + if (n + 1 < num) { + descs[i].flags |= cpu_to_le16(VRING_DESC_F_NEXT); descs[i].next = cpu_to_le16(svq->desc_next[i]); + } + + descs[i].addr = cpu_to_le64(sgs[n]); + if (n < out_num) { + descs[i].len = cpu_to_le32(out_sg[n].iov_len); } else { - descs[i].flags = flags; + descs[i].len = cpu_to_le32(in_sg[n - out_num].iov_len); } - descs[i].addr = cpu_to_le64(sg[n]); - descs[i].len = cpu_to_le32(iovec[n].iov_len); last = i; i = cpu_to_le16(svq->desc_next[i]); } svq->free_head = le16_to_cpu(svq->desc_next[last]); - return true; + + /* + * Put the entry in the available array (but don't update avail->idx until + * they do sync). + */ + avail_idx = svq->shadow_avail_idx & (svq->vring.num - 1); + avail->ring[avail_idx] = cpu_to_le16(*head); + svq->shadow_avail_idx++; + + /* Update the avail index after write the descriptor */ + smp_wmb(); + avail->idx = cpu_to_le16(svq->shadow_avail_idx); } -static bool vhost_svq_add_split(VhostShadowVirtqueue *svq, +/** + * Write descriptors to SVQ packed vring + * + * @svq: The shadow virtqueue + * @out_sg: The iovec to the guest + * @out_num: Outgoing iovec length + * @in_sg: The iovec from the guest + * @in_num: Incoming iovec length + * @sgs: Cache for hwaddr + * @head: Saves current free_head + */ +static void vhost_svq_add_packed(VhostShadowVirtqueue *svq, const struct iovec *out_sg, size_t out_num, const struct iovec *in_sg, size_t in_num, - unsigned *head) + hwaddr *sgs, unsigned *head) { - unsigned avail_idx; - vring_avail_t *avail = svq->vring.avail; - bool ok; - g_autofree hwaddr *sgs = g_new(hwaddr, MAX(out_num, in_num)); + uint16_t id, curr, i, head_flags = 0; + size_t num = out_num + in_num; + unsigned n; - *head = svq->free_head; + struct vring_packed_desc *descs = svq->vring_packed.vring.desc; - /* We need some descriptors here */ - if (unlikely(!out_num && !in_num)) { - qemu_log_mask(LOG_GUEST_ERROR, - "Guest provided element with no descriptors"); - return false; - } + *head = svq->vring_packed.next_avail_idx; + i = *head; + id = svq->free_head; + curr = id; - ok = vhost_svq_vring_write_descs(svq, sgs, out_sg, out_num, in_num > 0, - false); - if (unlikely(!ok)) { - return false; + /* Write descriptors to SVQ packed vring */ + for (n = 0; n < num; n++) { + uint16_t flags = cpu_to_le16(svq->vring_packed.avail_used_flags | + (n < out_num ? 0 : VRING_DESC_F_WRITE) | + (n + 1 == num ? 0 : VRING_DESC_F_NEXT)); + if (i == *head) { + head_flags = flags; + } else { + descs[i].flags = flags; + } + + descs[i].addr = cpu_to_le64(sgs[n]); + descs[i].id = id; + if (n < out_num) { + descs[i].len = cpu_to_le32(out_sg[n].iov_len); + } else { + descs[i].len = cpu_to_le32(in_sg[n - out_num].iov_len); + } + + curr = cpu_to_le16(svq->desc_next[curr]); + + if (++i >= svq->vring_packed.vring.num) { + i = 0; + svq->vring_packed.avail_used_flags ^= + 1 << VRING_PACKED_DESC_F_AVAIL | + 1 << VRING_PACKED_DESC_F_USED; + } } - ok = vhost_svq_vring_write_descs(svq, sgs, in_sg, in_num, false, true); - if (unlikely(!ok)) { - return false; + if (i <= *head) { + svq->vring_packed.avail_wrap_counter ^= 1; } + svq->vring_packed.next_avail_idx = i; + svq->free_head = curr; + /* - * Put the entry in the available array (but don't update avail->idx until - * they do sync). + * A driver MUST NOT make the first descriptor in the list + * available before all subsequent descriptors comprising + * the list are made available. */ - avail_idx = svq->shadow_avail_idx & (svq->vring.num - 1); - avail->ring[avail_idx] = cpu_to_le16(*head); - svq->shadow_avail_idx++; - - /* Update the avail index after write the descriptor */ smp_wmb(); - avail->idx = cpu_to_le16(svq->shadow_avail_idx); - - return true; + svq->vring_packed.vring.desc[*head].flags = head_flags; } static void vhost_svq_kick(VhostShadowVirtqueue *svq) @@ -254,15 +289,36 @@ int vhost_svq_add(VhostShadowVirtqueue *svq, const struct iovec *out_sg, unsigned ndescs = in_num + out_num; bool ok; + /* We need some descriptors here */ + if (unlikely(!ndescs)) { + qemu_log_mask(LOG_GUEST_ERROR, + "Guest provided element with no descriptors"); + return -EINVAL; + } + if (unlikely(ndescs > vhost_svq_available_slots(svq))) { return -ENOSPC; } - ok = vhost_svq_add_split(svq, out_sg, out_num, in_sg, in_num, &qemu_head); + g_autofree hwaddr *sgs = g_new(hwaddr, ndescs); + ok = vhost_svq_translate_addr(svq, sgs, out_sg, out_num); if (unlikely(!ok)) { return -EINVAL; } + ok = vhost_svq_translate_addr(svq, sgs + out_num, in_sg, in_num); + if (unlikely(!ok)) { + return -EINVAL; + } + + if (virtio_vdev_has_feature(svq->vdev, VIRTIO_F_RING_PACKED)) { + vhost_svq_add_packed(svq, out_sg, out_num, in_sg, + in_num, sgs, &qemu_head); + } else { + vhost_svq_add_split(svq, out_sg, out_num, in_sg, + in_num, sgs, &qemu_head); + } + svq->num_free -= ndescs; svq->desc_state[qemu_head].elem = elem; svq->desc_state[qemu_head].ndescs = ndescs;
This is the first patch in a series to add support for packed virtqueues in vhost_shadow_virtqueue. This patch implements the insertion of available buffers in the descriptor area. It takes into account descriptor chains, but does not consider indirect descriptors. Signed-off-by: Sahil Siddiq <sahilcdq@proton.me> --- Changes v2 -> v3: * vhost-shadow-virtqueue.c - Move parts common to "vhost_svq_add_split" and "vhost_svq_add_packed" to "vhost_svq_add". (vhost_svq_add_packed): - Refactor to minimize duplicate code between this and "vhost_svq_add_split" - Fix code style issues. (vhost_svq_add_split): - Merge with "vhost_svq_vring_write_descs()" - Refactor to minimize duplicate code between this and "vhost_svq_add_packed" (vhost_svq_add): - Refactor to minimize duplicate code between split and packed version of "vhost_svq_add" hw/virtio/vhost-shadow-virtqueue.c | 174 +++++++++++++++++++---------- 1 file changed, 115 insertions(+), 59 deletions(-)