This commit refactors vhost_svq_add_split and vhost_svq_add to simplify
their implementation and prepare for the addition of packed vqs in the
following commits.
Signed-off-by: Sahil Siddiq <sahilcdq@proton.me>
---
No changes from v4 -> v5.
hw/virtio/vhost-shadow-virtqueue.c | 107 +++++++++++------------------
1 file changed, 41 insertions(+), 66 deletions(-)
diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c
index 2481d49345..4f74ad402a 100644
--- a/hw/virtio/vhost-shadow-virtqueue.c
+++ b/hw/virtio/vhost-shadow-virtqueue.c
@@ -139,87 +139,48 @@ 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
- * @addr: Descriptors' GPAs, if backed by guest memory
- * @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,
- const hwaddr *addr, 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, addr);
- 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 = svq->desc_next[i];
}
svq->free_head = svq->desc_next[last];
- return true;
-}
-
-static bool vhost_svq_add_split(VhostShadowVirtqueue *svq,
- const struct iovec *out_sg, size_t out_num,
- const hwaddr *out_addr,
- const struct iovec *in_sg, size_t in_num,
- const hwaddr *in_addr, 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));
-
- *head = svq->free_head;
-
- /* 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;
- }
-
- ok = vhost_svq_vring_write_descs(svq, sgs, out_sg, out_num, out_addr,
- in_num > 0, false);
- if (unlikely(!ok)) {
- return false;
- }
-
- ok = vhost_svq_vring_write_descs(svq, sgs, in_sg, in_num, in_addr, false,
- true);
- if (unlikely(!ok)) {
- return false;
- }
/*
* Put the entry in the available array (but don't update avail->idx until
@@ -233,7 +194,6 @@ static bool vhost_svq_add_split(VhostShadowVirtqueue *svq,
smp_wmb();
avail->idx = cpu_to_le16(svq->shadow_avail_idx);
- return true;
}
static void vhost_svq_kick(VhostShadowVirtqueue *svq)
@@ -276,16 +236,31 @@ 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, out_addr, in_sg, in_num,
- in_addr, &qemu_head);
+ g_autofree hwaddr *sgs = g_new(hwaddr, ndescs);
+ ok = vhost_svq_translate_addr(svq, sgs, out_sg, out_num, out_addr);
if (unlikely(!ok)) {
return -EINVAL;
}
+ ok = vhost_svq_translate_addr(svq, sgs + out_num, in_sg, in_num, in_addr);
+ if (unlikely(!ok)) {
+ return -EINVAL;
+ }
+
+ 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;
--
2.48.1On Mon, Mar 24, 2025 at 2:59 PM Sahil Siddiq <icegambit91@gmail.com> wrote:
>
> This commit refactors vhost_svq_add_split and vhost_svq_add to simplify
> their implementation and prepare for the addition of packed vqs in the
> following commits.
>
> Signed-off-by: Sahil Siddiq <sahilcdq@proton.me>
> ---
> No changes from v4 -> v5.
>
You can carry the Acked-by from previous series if you make no changes
(or even small changes).
Acked-by: Eugenio Pérez <eperezma@redhat.com>
> hw/virtio/vhost-shadow-virtqueue.c | 107 +++++++++++------------------
> 1 file changed, 41 insertions(+), 66 deletions(-)
>
> diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c
> index 2481d49345..4f74ad402a 100644
> --- a/hw/virtio/vhost-shadow-virtqueue.c
> +++ b/hw/virtio/vhost-shadow-virtqueue.c
> @@ -139,87 +139,48 @@ 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
> - * @addr: Descriptors' GPAs, if backed by guest memory
> - * @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,
> - const hwaddr *addr, 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, addr);
> - 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 = svq->desc_next[i];
> }
>
> svq->free_head = svq->desc_next[last];
> - return true;
> -}
> -
> -static bool vhost_svq_add_split(VhostShadowVirtqueue *svq,
> - const struct iovec *out_sg, size_t out_num,
> - const hwaddr *out_addr,
> - const struct iovec *in_sg, size_t in_num,
> - const hwaddr *in_addr, 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));
> -
> - *head = svq->free_head;
> -
> - /* 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;
> - }
> -
> - ok = vhost_svq_vring_write_descs(svq, sgs, out_sg, out_num, out_addr,
> - in_num > 0, false);
> - if (unlikely(!ok)) {
> - return false;
> - }
> -
> - ok = vhost_svq_vring_write_descs(svq, sgs, in_sg, in_num, in_addr, false,
> - true);
> - if (unlikely(!ok)) {
> - return false;
> - }
>
> /*
> * Put the entry in the available array (but don't update avail->idx until
> @@ -233,7 +194,6 @@ static bool vhost_svq_add_split(VhostShadowVirtqueue *svq,
> smp_wmb();
> avail->idx = cpu_to_le16(svq->shadow_avail_idx);
>
> - return true;
> }
>
> static void vhost_svq_kick(VhostShadowVirtqueue *svq)
> @@ -276,16 +236,31 @@ 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, out_addr, in_sg, in_num,
> - in_addr, &qemu_head);
> + g_autofree hwaddr *sgs = g_new(hwaddr, ndescs);
> + ok = vhost_svq_translate_addr(svq, sgs, out_sg, out_num, out_addr);
> if (unlikely(!ok)) {
> return -EINVAL;
> }
>
> + ok = vhost_svq_translate_addr(svq, sgs + out_num, in_sg, in_num, in_addr);
> + if (unlikely(!ok)) {
> + return -EINVAL;
> + }
> +
> + 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;
> --
> 2.48.1
>
Hi, On 3/26/25 4:55 PM, Eugenio Perez Martin wrote: > On Mon, Mar 24, 2025 at 2:59 PM Sahil Siddiq <icegambit91@gmail.com> wrote: >> >> This commit refactors vhost_svq_add_split and vhost_svq_add to simplify >> their implementation and prepare for the addition of packed vqs in the >> following commits. >> >> Signed-off-by: Sahil Siddiq <sahilcdq@proton.me> >> --- >> No changes from v4 -> v5. >> > > You can carry the Acked-by from previous series if you make no changes > (or even small changes). > > Acked-by: Eugenio Pérez <eperezma@redhat.com> > Understood. Thanks, Sahil
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