On Fri, Jul 26, 2024 at 11:59 AM Sahil Siddiq <icegambi...@gmail.com> wrote:
>
> Allocate memory for the packed vq format and support
> packed vq in the SVQ "start" operation.
>
> Signed-off-by: Sahil Siddiq <sahil...@proton.me>
> ---
> Changes v1 -> v2:
> * vhost-shadow-virtqueue.h
> (struct VhostShadowVirtqueue): New member "is_packed"
> (vhost_svq_get_vring_addr): Renamed function.
> (vhost_svq_get_vring_addr_packed): New function.
> (vhost_svq_memory_packed): Likewise.
> * vhost-shadow-virtqueue.c:
> (vhost_svq_add): Use "is_packed" to check vq format.
> (vhost_svq_get_vring_addr): Rename function.
> (vhost_svq_get_vring_addr_packed): New function but is yet to be
> implemented.
> (vhost_svq_memory_packed): New function.
> (vhost_svq_start): Support packed vq format.
> * vhost-vdpa.c
> (vhost_svq_get_vring_addr): Rename function.
>
>
> hw/virtio/vhost-shadow-virtqueue.c | 70 ++++++++++++++++++++++--------
> hw/virtio/vhost-shadow-virtqueue.h | 10 ++++-
> hw/virtio/vhost-vdpa.c | 4 +-
> 3 files changed, 63 insertions(+), 21 deletions(-)
>
> diff --git a/hw/virtio/vhost-shadow-virtqueue.c
> b/hw/virtio/vhost-shadow-virtqueue.c
> index c7b7e0c477..045c07304c 100644
> --- a/hw/virtio/vhost-shadow-virtqueue.c
> +++ b/hw/virtio/vhost-shadow-virtqueue.c
> @@ -343,7 +343,7 @@ int vhost_svq_add(VhostShadowVirtqueue *svq, const struct
> iovec *out_sg,
> return -ENOSPC;
> }
>
> - if (virtio_vdev_has_feature(svq->vdev, VIRTIO_F_RING_PACKED)) {
> + if (svq->is_packed) {
> ok = vhost_svq_add_packed(svq, out_sg, out_num,
> in_sg, in_num, &qemu_head);
> } else {
> @@ -679,18 +679,29 @@ void vhost_svq_set_svq_call_fd(VhostShadowVirtqueue
> *svq, int call_fd)
> }
>
> /**
> - * Get the shadow vq vring address.
> + * Get the split shadow vq vring address.
> * @svq: Shadow virtqueue
> * @addr: Destination to store address
> */
> -void vhost_svq_get_vring_addr(const VhostShadowVirtqueue *svq,
> - struct vhost_vring_addr *addr)
> +void vhost_svq_get_vring_addr_split(const VhostShadowVirtqueue *svq,
> + struct vhost_vring_addr *addr)
> {
> addr->desc_user_addr = (uint64_t)(uintptr_t)svq->vring.desc;
> addr->avail_user_addr = (uint64_t)(uintptr_t)svq->vring.avail;
> addr->used_user_addr = (uint64_t)(uintptr_t)svq->vring.used;
> }
>
> +/**
> + * Get the packed shadow vq vring address.
> + * @svq: Shadow virtqueue
> + * @addr: Destination to store address
> + */
> +void vhost_svq_get_vring_addr_packed(const VhostShadowVirtqueue *svq,
> + struct vhost_vring_addr *addr)
> +{
> + /* TODO */
> +}
> +
> size_t vhost_svq_driver_area_size(const VhostShadowVirtqueue *svq)
> {
> size_t desc_size = sizeof(vring_desc_t) * svq->vring.num;
> @@ -707,6 +718,16 @@ size_t vhost_svq_device_area_size(const
> VhostShadowVirtqueue *svq)
> return ROUND_UP(used_size, qemu_real_host_page_size());
> }
>
> +size_t vhost_svq_memory_packed(const VhostShadowVirtqueue *svq)
> +{
> + size_t desc_size = sizeof(struct vring_packed_desc) * svq->num_free;
> + size_t driver_event_suppression = sizeof(struct vring_packed_desc_event);
> + size_t device_event_suppression = sizeof(struct vring_packed_desc_event);
> +
> + return ROUND_UP(desc_size + driver_event_suppression +
> device_event_suppression,
> + qemu_real_host_page_size());
> +}
> +
> /**
> * Set a new file descriptor for the guest to kick the SVQ and notify for
> avail
> *
> @@ -759,19 +780,34 @@ void vhost_svq_start(VhostShadowVirtqueue *svq,
> VirtIODevice *vdev,
> svq->vq = vq;
> svq->iova_tree = iova_tree;
>
> - svq->vring.num = virtio_queue_get_num(vdev, virtio_get_queue_index(vq));
> - svq->num_free = svq->vring.num;
> - svq->vring.desc = mmap(NULL, vhost_svq_driver_area_size(svq),
> - PROT_READ | PROT_WRITE, MAP_SHARED |
> MAP_ANONYMOUS,
> - -1, 0);
> - desc_size = sizeof(vring_desc_t) * svq->vring.num;
> - svq->vring.avail = (void *)((char *)svq->vring.desc + desc_size);
> - svq->vring.used = mmap(NULL, vhost_svq_device_area_size(svq),
> - PROT_READ | PROT_WRITE, MAP_SHARED |
> MAP_ANONYMOUS,
> - -1, 0);
> - svq->desc_state = g_new0(SVQDescState, svq->vring.num);
> - svq->desc_next = g_new0(uint16_t, svq->vring.num);
> - for (unsigned i = 0; i < svq->vring.num - 1; i++) {
> + if (virtio_vdev_has_feature(svq->vdev, VIRTIO_F_RING_PACKED)) {
> + svq->is_packed = true;
> + svq->vring_packed.vring.num = virtio_queue_get_num(vdev,
> virtio_get_queue_index(vq));
> + svq->num_free = svq->vring_packed.vring.num;
> + svq->vring_packed.vring.desc = mmap(NULL,
> vhost_svq_memory_packed(svq),
> + PROT_READ | PROT_WRITE,
> MAP_SHARED | MAP_ANONYMOUS,
> + -1, 0);
> + desc_size = sizeof(struct vring_packed_desc) * svq->vring.num;
> + svq->vring_packed.vring.driver = (void *)((char
> *)svq->vring_packed.vring.desc + desc_size);
(Expanding on the cover letter comment) Here the driver area is
aligned properly too as each descriptor is 16 bytes length, and
required alignment for the driver area is 4 bytes by VirtIO standard.
> + svq->vring_packed.vring.device = (void *)((char
> *)svq->vring_packed.vring.driver +
> + sizeof(struct
> vring_packed_desc_event));
> + } else {
> + svq->is_packed = false;
> + svq->vring.num = virtio_queue_get_num(vdev,
> virtio_get_queue_index(vq));
> + svq->num_free = svq->vring.num;
Nitpicks,
The variables is_packed and num_free can be merged out of the if/else
to reduce code duplication.
Also it is clearer to me to assign svq->is_packed =
virtio_vdev_has_feature(...) and then check the variable in the if.
But other parts of QEMU do as you do here so I don't have a strong
opinion.
> + svq->vring.desc = mmap(NULL, vhost_svq_driver_area_size(svq),
> + PROT_READ | PROT_WRITE, MAP_SHARED |
> MAP_ANONYMOUS,
> + -1, 0);
> + desc_size = sizeof(vring_desc_t) * svq->vring.num;
> + svq->vring.avail = (void *)((char *)svq->vring.desc + desc_size);
> + svq->vring.used = mmap(NULL, vhost_svq_device_area_size(svq),
> + PROT_READ | PROT_WRITE, MAP_SHARED |
> MAP_ANONYMOUS,
> + -1, 0);
> + }
> +
> + svq->desc_state = g_new0(SVQDescState, svq->num_free);
> + svq->desc_next = g_new0(uint16_t, svq->num_free);
> + for (unsigned i = 0; i < svq->num_free - 1; i++) {
> svq->desc_next[i] = cpu_to_le16(i + 1);
> }
> }
> diff --git a/hw/virtio/vhost-shadow-virtqueue.h
> b/hw/virtio/vhost-shadow-virtqueue.h
> index ee1a87f523..b396daf57d 100644
> --- a/hw/virtio/vhost-shadow-virtqueue.h
> +++ b/hw/virtio/vhost-shadow-virtqueue.h
> @@ -67,6 +67,9 @@ struct vring_packed {
>
> /* Shadow virtqueue to relay notifications */
> typedef struct VhostShadowVirtqueue {
> + /* True if packed virtqueue */
> + bool is_packed;
> +
> /* Virtio queue shadowing */
> VirtQueue *vq;
>
> @@ -146,10 +149,13 @@ size_t vhost_svq_poll(VhostShadowVirtqueue *svq, size_t
> num);
>
> void vhost_svq_set_svq_kick_fd(VhostShadowVirtqueue *svq, int svq_kick_fd);
> void vhost_svq_set_svq_call_fd(VhostShadowVirtqueue *svq, int call_fd);
> -void vhost_svq_get_vring_addr(const VhostShadowVirtqueue *svq,
> - struct vhost_vring_addr *addr);
> +void vhost_svq_get_vring_addr_split(const VhostShadowVirtqueue *svq,
> + struct vhost_vring_addr *addr);
> +void vhost_svq_get_vring_addr_packed(const VhostShadowVirtqueue *svq,
> + struct vhost_vring_addr *addr);
> size_t vhost_svq_driver_area_size(const VhostShadowVirtqueue *svq);
> size_t vhost_svq_device_area_size(const VhostShadowVirtqueue *svq);
> +size_t vhost_svq_memory_packed(const VhostShadowVirtqueue *svq);
Ok now I get the question on the cover letter better,
It is ok to reuse the already present functions, no need to create new
ones to export in this header.
Thanks!
>
> void vhost_svq_start(VhostShadowVirtqueue *svq, VirtIODevice *vdev,
> VirtQueue *vq, VhostIOVATree *iova_tree);
> diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
> index 3cdaa12ed5..688de4a662 100644
> --- a/hw/virtio/vhost-vdpa.c
> +++ b/hw/virtio/vhost-vdpa.c
> @@ -1130,7 +1130,7 @@ static void vhost_vdpa_svq_unmap_rings(struct vhost_dev
> *dev,
> struct vhost_vdpa *v = dev->opaque;
> struct vhost_vring_addr svq_addr;
>
> - vhost_svq_get_vring_addr(svq, &svq_addr);
> + vhost_svq_get_vring_addr_split(svq, &svq_addr);
>
> vhost_vdpa_svq_unmap_ring(v, svq_addr.desc_user_addr);
>
> @@ -1189,7 +1189,7 @@ static bool vhost_vdpa_svq_map_rings(struct vhost_dev
> *dev,
> size_t avail_offset;
> bool ok;
>
> - vhost_svq_get_vring_addr(svq, &svq_addr);
> + vhost_svq_get_vring_addr_split(svq, &svq_addr);
>
> driver_region = (DMAMap) {
> .translated_addr = svq_addr.desc_user_addr,
> --
> 2.45.2
>
