On Thu, Apr 14, 2022 at 12:32 AM Eugenio Pérez <epere...@redhat.com> wrote:
>
> This allows qemu to inject packets to the device without guest's notice.
Does it mean it can support guests without _F_ANNOUNCE?
>
> This will be use to inject net CVQ messages to restore status in the
> destination
I guess for restoring, we should set cvq.ready = true but all other
(TX/RX) as false before we complete the restoring? If yes, I don't see
codes to do that.
>
> Signed-off-by: Eugenio Pérez <epere...@redhat.com>
> ---
> hw/virtio/vhost-shadow-virtqueue.h | 5 +
> hw/virtio/vhost-shadow-virtqueue.c | 179 +++++++++++++++++++++++++----
> 2 files changed, 160 insertions(+), 24 deletions(-)
>
> diff --git a/hw/virtio/vhost-shadow-virtqueue.h
> b/hw/virtio/vhost-shadow-virtqueue.h
> index e06ac52158..2a5229e77f 100644
> --- a/hw/virtio/vhost-shadow-virtqueue.h
> +++ b/hw/virtio/vhost-shadow-virtqueue.h
> @@ -17,6 +17,9 @@
>
> typedef struct SVQElement {
> VirtQueueElement elem;
> + hwaddr in_iova;
> + hwaddr out_iova;
> + bool not_from_guest;
Let's add a comment for those fields.
> } SVQElement;
>
> typedef void (*VirtQueueElementCallback)(VirtIODevice *vdev,
> @@ -106,6 +109,8 @@ typedef struct VhostShadowVirtqueue {
>
> bool vhost_svq_valid_features(uint64_t features, Error **errp);
>
> +bool vhost_svq_inject(VhostShadowVirtqueue *svq, const struct iovec *iov,
> + size_t out_num, size_t in_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,
> diff --git a/hw/virtio/vhost-shadow-virtqueue.c
> b/hw/virtio/vhost-shadow-virtqueue.c
> index 87980e2a9c..f3600df133 100644
> --- a/hw/virtio/vhost-shadow-virtqueue.c
> +++ b/hw/virtio/vhost-shadow-virtqueue.c
> @@ -16,6 +16,7 @@
> #include "qemu/log.h"
> #include "qemu/memalign.h"
> #include "linux-headers/linux/vhost.h"
> +#include "qemu/iov.h"
>
> /**
> * Validate the transport device features that both guests can use with the
> SVQ
> @@ -122,7 +123,8 @@ static bool vhost_svq_translate_addr(const
> VhostShadowVirtqueue *svq,
> return true;
> }
>
> -static bool vhost_svq_vring_write_descs(VhostShadowVirtqueue *svq, hwaddr
> *sg,
> +static bool vhost_svq_vring_write_descs(VhostShadowVirtqueue *svq,
> + SVQElement *svq_elem, hwaddr *sg,
> const struct iovec *iovec, size_t
> num,
> bool more_descs, bool write)
> {
> @@ -130,15 +132,39 @@ static bool
> vhost_svq_vring_write_descs(VhostShadowVirtqueue *svq, hwaddr *sg,
> unsigned n;
> uint16_t flags = write ? cpu_to_le16(VRING_DESC_F_WRITE) : 0;
> vring_desc_t *descs = svq->vring.desc;
> - bool ok;
>
> if (num == 0) {
> return true;
> }
>
> - ok = vhost_svq_translate_addr(svq, sg, iovec, num);
> - if (unlikely(!ok)) {
> - return false;
> + if (svq_elem->not_from_guest) {
> + DMAMap map = {
> + .translated_addr = (hwaddr)iovec->iov_base,
> + .size = ROUND_UP(iovec->iov_len, 4096) - 1,
> + .perm = write ? IOMMU_RW : IOMMU_RO,
> + };
> + int r;
> +
> + if (unlikely(num != 1)) {
> + error_report("Unexpected chain of element injected");
> + return false;
> + }
> + r = vhost_iova_tree_map_alloc(svq->iova_tree, &map);
> + if (unlikely(r != IOVA_OK)) {
> + error_report("Cannot map injected element");
> + return false;
> + }
> +
> + r = svq->map_ops->map(map.iova, map.size + 1,
> + (void *)map.translated_addr, !write,
> + svq->map_ops_opaque);
> + assert(r == 0);
> + sg[0] = map.iova;
> + } else {
> + bool ok = vhost_svq_translate_addr(svq, sg, iovec, num);
> + if (unlikely(!ok)) {
> + return false;
> + }
> }
>
> for (n = 0; n < num; n++) {
> @@ -166,7 +192,8 @@ static bool vhost_svq_add_split(VhostShadowVirtqueue
> *svq, SVQElement *svq_elem,
> unsigned avail_idx;
> vring_avail_t *avail = svq->vring.avail;
> bool ok;
> - g_autofree hwaddr *sgs = g_new(hwaddr, MAX(elem->out_num, elem->in_num));
> + g_autofree hwaddr *sgs = NULL;
> + hwaddr *in_sgs, *out_sgs;
>
> *head = svq->free_head;
>
> @@ -177,15 +204,23 @@ static bool vhost_svq_add_split(VhostShadowVirtqueue
> *svq, SVQElement *svq_elem,
> return false;
> }
>
> - ok = vhost_svq_vring_write_descs(svq, sgs, elem->out_sg, elem->out_num,
> - elem->in_num > 0, false);
> + if (!svq_elem->not_from_guest) {
> + sgs = g_new(hwaddr, MAX(elem->out_num, elem->in_num));
> + in_sgs = out_sgs = sgs;
> + } else {
> + in_sgs = &svq_elem->in_iova;
> + out_sgs = &svq_elem->out_iova;
> + }
> + ok = vhost_svq_vring_write_descs(svq, svq_elem, out_sgs, elem->out_sg,
> + elem->out_num, elem->in_num > 0, false);
> if (unlikely(!ok)) {
> return false;
> }
>
> - ok = vhost_svq_vring_write_descs(svq, sgs, elem->in_sg, elem->in_num,
> false,
> - true);
> + ok = vhost_svq_vring_write_descs(svq, svq_elem, in_sgs, elem->in_sg,
> + elem->in_num, false, true);
> if (unlikely(!ok)) {
> + /* TODO unwind out_sg */
> return false;
> }
>
> @@ -230,6 +265,43 @@ static void vhost_svq_kick(VhostShadowVirtqueue *svq)
> event_notifier_set(&svq->hdev_kick);
> }
>
> +bool vhost_svq_inject(VhostShadowVirtqueue *svq, const struct iovec *iov,
> + size_t out_num, size_t in_num)
> +{
> + size_t out_size = iov_size(iov, out_num);
> + size_t out_buf_size = ROUND_UP(out_size, 4096);
> + size_t in_size = iov_size(iov + out_num, in_num);
> + size_t in_buf_size = ROUND_UP(in_size, 4096);
> + SVQElement *svq_elem;
> + uint16_t num_slots = (in_num ? 1 : 0) + (out_num ? 1 : 0);
> +
> + if (unlikely(num_slots == 0 || svq->next_guest_avail_elem ||
> + vhost_svq_available_slots(svq) < num_slots)) {
> + return false;
> + }
> +
> + svq_elem = virtqueue_alloc_element(sizeof(SVQElement), 1, 1);
> + if (out_num) {
> + void *out = qemu_memalign(4096, out_buf_size);
> + svq_elem->elem.out_sg[0].iov_base = out;
> + svq_elem->elem.out_sg[0].iov_len = out_size;
> + iov_to_buf(iov, out_num, 0, out, out_size);
> + memset(out + out_size, 0, out_buf_size - out_size);
> + }
> + if (in_num) {
> + void *in = qemu_memalign(4096, in_buf_size);
> + svq_elem->elem.in_sg[0].iov_base = in;
> + svq_elem->elem.in_sg[0].iov_len = in_size;
> + memset(in, 0, in_buf_size);
> + }
> +
> + svq_elem->not_from_guest = true;
> + vhost_svq_add(svq, svq_elem);
> + vhost_svq_kick(svq);
> +
Should we wait for the completion before moving forward? Otherwise we
will have a race.
And if we wait for the completion (e.g doing busy polling), I think we
can avoid the auxiliary structures like
in_iova/out_iova/not_from_guest by doing mapping before
vhost_svq_add() to keep it clean.
Thanks
> + return true;
> +}
> +
> /**
> * Forward available buffers.
> *
> @@ -267,6 +339,7 @@ static void vhost_handle_guest_kick(VhostShadowVirtqueue
> *svq)
> break;
> }
>
> + svq_elem->not_from_guest = false;
> elem = &svq_elem->elem;
> if (elem->out_num + elem->in_num >
> vhost_svq_available_slots(svq)) {
> /*
> @@ -391,6 +464,31 @@ static SVQElement
> *vhost_svq_get_buf(VhostShadowVirtqueue *svq, uint32_t *len)
> return g_steal_pointer(&svq->ring_id_maps[used_elem.id]);
> }
>
> +static int vhost_svq_unmap(VhostShadowVirtqueue *svq, hwaddr iova, size_t
> size)
> +{
> + DMAMap needle = {
> + .iova = iova,
> + .size = size,
> + };
> + const DMAMap *overlap;
> +
> + while ((overlap = vhost_iova_tree_find(svq->iova_tree, &needle))) {
> + DMAMap needle = *overlap;
> +
> + if (svq->map_ops->unmap) {
> + int r = svq->map_ops->unmap(overlap->iova, overlap->size + 1,
> + svq->map_ops_opaque);
> + if (unlikely(r != 0)) {
> + return r;
> + }
> + }
> + qemu_vfree((void *)overlap->translated_addr);
> + vhost_iova_tree_remove(svq->iova_tree, &needle);
> + }
> +
> + return 0;
> +}
> +
> static void vhost_svq_flush(VhostShadowVirtqueue *svq,
> bool check_for_avail_queue)
> {
> @@ -410,23 +508,56 @@ static void vhost_svq_flush(VhostShadowVirtqueue *svq,
> }
>
> elem = &svq_elem->elem;
> - if (unlikely(i >= svq->vring.num)) {
> - qemu_log_mask(LOG_GUEST_ERROR,
> - "More than %u used buffers obtained in a %u size
> SVQ",
> - i, svq->vring.num);
> - virtqueue_fill(vq, elem, len, i);
> - virtqueue_flush(vq, i);
> - return;
> - }
> - virtqueue_fill(vq, elem, len, i++);
> -
> if (svq->ops && svq->ops->used_elem_handler) {
> svq->ops->used_elem_handler(svq->vdev, elem);
> }
> +
> + if (svq_elem->not_from_guest) {
> + if (unlikely(!elem->out_num && elem->out_num != 1)) {
> + error_report("Unexpected out_num > 1");
> + return;
> + }
> +
> + if (elem->out_num) {
> + int r = vhost_svq_unmap(svq, svq_elem->out_iova,
> + elem->out_sg[0].iov_len);
> + if (unlikely(r != 0)) {
> + error_report("Cannot unmap out buffer");
> + return;
> + }
> + }
> +
> + if (unlikely(!elem->in_num && elem->in_num != 1)) {
> + error_report("Unexpected in_num > 1");
> + return;
> + }
> +
> + if (elem->in_num) {
> + int r = vhost_svq_unmap(svq, svq_elem->in_iova,
> + elem->in_sg[0].iov_len);
> + if (unlikely(r != 0)) {
> + error_report("Cannot unmap out buffer");
> + return;
> + }
> + }
> + } else {
> + if (unlikely(i >= svq->vring.num)) {
> + qemu_log_mask(
> + LOG_GUEST_ERROR,
> + "More than %u used buffers obtained in a %u size
> SVQ",
> + i, svq->vring.num);
> + virtqueue_fill(vq, elem, len, i);
> + virtqueue_flush(vq, i);
> + return;
> + }
> + virtqueue_fill(vq, elem, len, i++);
> + }
> }
>
> - virtqueue_flush(vq, i);
> - event_notifier_set(&svq->svq_call);
> + if (i > 0) {
> + virtqueue_flush(vq, i);
> + event_notifier_set(&svq->svq_call);
> + }
>
> if (check_for_avail_queue && svq->next_guest_avail_elem) {
> /*
> @@ -590,13 +721,13 @@ void vhost_svq_stop(VhostShadowVirtqueue *svq)
> for (unsigned i = 0; i < svq->vring.num; ++i) {
> g_autofree SVQElement *svq_elem = NULL;
> svq_elem = g_steal_pointer(&svq->ring_id_maps[i]);
> - if (svq_elem) {
> + if (svq_elem && !svq_elem->not_from_guest) {
> virtqueue_detach_element(svq->vq, &svq_elem->elem, 0);
> }
> }
>
> next_avail_elem = g_steal_pointer(&svq->next_guest_avail_elem);
> - if (next_avail_elem) {
> + if (next_avail_elem && !next_avail_elem->not_from_guest) {
> virtqueue_detach_element(svq->vq, &next_avail_elem->elem, 0);
> }
> svq->vq = NULL;
> --
> 2.27.0
>
