[PATCH v3 0/6] Vhost-vdpa Shadow Virtqueue multiqueue support.

[PATCH v3 0/6] Vhost-vdpa Shadow Virtqueue multiqueue support.

[Eugenio Pérez]

This series enables shadowed CVQ to intercept multiqueue commands through
shadowed CVQ, update the virtio NIC device model so qemu send it in a
migration, and the restore of that MQ state in the destination.

It needs to be applied on top of [1].

[1] https://lists.gnu.org/archive/html/qemu-devel/2022-08/msg02965.html

v2:
* Add vhost_vdpa_net_load_cmd helper to avoid out buffers castings.
* Make cvq_cmd_in_buffer virtio_net_ctrl_ack type.

Eugenio Pérez (6):
  vdpa: Make VhostVDPAState cvq_cmd_in_buffer control ack type
  vdpa: extract vhost_vdpa_net_load_mac from vhost_vdpa_net_load
  vdpa: Add vhost_vdpa_net_load_mq
  vdpa: validate MQ CVQ commands
  virtio-net: Update virtio-net curr_queue_pairs in vdpa backends
  vdpa: Allow MQ feature in SVQ

 hw/net/virtio-net.c |  17 +++----
 net/vhost-vdpa.c    | 119 ++++++++++++++++++++++++++++++++------------
 2 files changed, 93 insertions(+), 43 deletions(-)

-- 
2.31.1

[PATCH v3 1/6] vdpa: Make VhostVDPAState cvq_cmd_in_buffer control ack type

[Eugenio Pérez]

This allows to simplify the code. Rename to status while we're at it.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
v3: Rename it to status.
---
 net/vhost-vdpa.c | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index 6ce68fcd3f..535315c1d0 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -35,7 +35,9 @@ typedef struct VhostVDPAState {
     VHostNetState *vhost_net;
 
     /* Control commands shadow buffers */
-    void *cvq_cmd_out_buffer, *cvq_cmd_in_buffer;
+    void *cvq_cmd_out_buffer;
+    virtio_net_ctrl_ack *status;
+
     bool started;
 } VhostVDPAState;
 
@@ -158,7 +160,7 @@ static void vhost_vdpa_cleanup(NetClientState *nc)
     struct vhost_dev *dev = &s->vhost_net->dev;
 
     qemu_vfree(s->cvq_cmd_out_buffer);
-    qemu_vfree(s->cvq_cmd_in_buffer);
+    qemu_vfree(s->status);
     if (dev->vq_index + dev->nvqs == dev->vq_index_end) {
         g_clear_pointer(&s->vhost_vdpa.iova_tree, vhost_iova_tree_delete);
     }
@@ -310,7 +312,7 @@ static int vhost_vdpa_net_cvq_start(NetClientState *nc)
         return r;
     }
 
-    r = vhost_vdpa_cvq_map_buf(&s->vhost_vdpa, s->cvq_cmd_in_buffer,
+    r = vhost_vdpa_cvq_map_buf(&s->vhost_vdpa, s->status,
                                vhost_vdpa_net_cvq_cmd_page_len(), true);
     if (unlikely(r < 0)) {
         vhost_vdpa_cvq_unmap_buf(&s->vhost_vdpa, s->cvq_cmd_out_buffer);
@@ -327,7 +329,7 @@ static void vhost_vdpa_net_cvq_stop(NetClientState *nc)
 
     if (s->vhost_vdpa.shadow_vqs_enabled) {
         vhost_vdpa_cvq_unmap_buf(&s->vhost_vdpa, s->cvq_cmd_out_buffer);
-        vhost_vdpa_cvq_unmap_buf(&s->vhost_vdpa, s->cvq_cmd_in_buffer);
+        vhost_vdpa_cvq_unmap_buf(&s->vhost_vdpa, s->status);
     }
 }
 
@@ -340,7 +342,7 @@ static ssize_t vhost_vdpa_net_cvq_add(VhostVDPAState *s, size_t out_len,
         .iov_len = out_len,
     };
     const struct iovec in = {
-        .iov_base = s->cvq_cmd_in_buffer,
+        .iov_base = s->status,
         .iov_len = sizeof(virtio_net_ctrl_ack),
     };
     VhostShadowVirtqueue *svq = g_ptr_array_index(s->vhost_vdpa.shadow_vqs, 0);
@@ -396,7 +398,7 @@ static int vhost_vdpa_net_load(NetClientState *nc)
             return dev_written;
         }
 
-        return *((virtio_net_ctrl_ack *)s->cvq_cmd_in_buffer) != VIRTIO_NET_OK;
+        return *s->status != VIRTIO_NET_OK;
     }
 
     return 0;
@@ -491,8 +493,7 @@ static int vhost_vdpa_net_handle_ctrl_avail(VhostShadowVirtqueue *svq,
         goto out;
     }
 
-    memcpy(&status, s->cvq_cmd_in_buffer, sizeof(status));
-    if (status != VIRTIO_NET_OK) {
+    if (*s->status != VIRTIO_NET_OK) {
         return VIRTIO_NET_ERR;
     }
 
@@ -549,9 +550,9 @@ static NetClientState *net_vhost_vdpa_init(NetClientState *peer,
         s->cvq_cmd_out_buffer = qemu_memalign(qemu_real_host_page_size(),
                                             vhost_vdpa_net_cvq_cmd_page_len());
         memset(s->cvq_cmd_out_buffer, 0, vhost_vdpa_net_cvq_cmd_page_len());
-        s->cvq_cmd_in_buffer = qemu_memalign(qemu_real_host_page_size(),
-                                            vhost_vdpa_net_cvq_cmd_page_len());
-        memset(s->cvq_cmd_in_buffer, 0, vhost_vdpa_net_cvq_cmd_page_len());
+        s->status = qemu_memalign(qemu_real_host_page_size(),
+                                  vhost_vdpa_net_cvq_cmd_page_len());
+        memset(s->status, 0, vhost_vdpa_net_cvq_cmd_page_len());
 
         s->vhost_vdpa.shadow_vq_ops = &vhost_vdpa_net_svq_ops;
         s->vhost_vdpa.shadow_vq_ops_opaque = s;
-- 
2.31.1

[PATCH v3 2/6] vdpa: extract vhost_vdpa_net_load_mac from vhost_vdpa_net_load

[Eugenio Pérez]

Since there may be many commands we need to issue to load the NIC
state, let's split them in individual functions

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
--
v2: Add vhost_vdpa_net_load_cmd helper
v3: Move ctrl header definition to vhost_vdpa_net_load_cmd
---
 net/vhost-vdpa.c | 62 +++++++++++++++++++++++++++++++-----------------
 1 file changed, 40 insertions(+), 22 deletions(-)

diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index 535315c1d0..e799e744cd 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -365,12 +365,47 @@ static ssize_t vhost_vdpa_net_cvq_add(VhostVDPAState *s, size_t out_len,
     return vhost_svq_poll(svq);
 }
 
+static ssize_t vhost_vdpa_net_load_cmd(VhostVDPAState *s, uint8_t class,
+                                       uint8_t cmd, const void *data,
+                                       size_t data_size)
+{
+    const struct virtio_net_ctrl_hdr ctrl = {
+        .class = class,
+        .cmd = cmd,
+    };
+
+    assert(data_size < vhost_vdpa_net_cvq_cmd_page_len() - sizeof(ctrl));
+
+    memcpy(s->cvq_cmd_out_buffer, &ctrl, sizeof(ctrl));
+    memcpy(s->cvq_cmd_out_buffer + sizeof(ctrl), data, data_size);
+
+    return vhost_vdpa_net_cvq_add(s, sizeof(ctrl) + data_size,
+                                  sizeof(virtio_net_ctrl_ack));
+}
+
+static int vhost_vdpa_net_load_mac(VhostVDPAState *s, const VirtIONet *n)
+{
+    uint64_t features = n->parent_obj.guest_features;
+    if (features & BIT_ULL(VIRTIO_NET_F_CTRL_MAC_ADDR)) {
+        ssize_t dev_written = vhost_vdpa_net_load_cmd(s, VIRTIO_NET_CTRL_MAC,
+                                                  VIRTIO_NET_CTRL_MAC_ADDR_SET,
+                                                  n->mac, sizeof(n->mac));
+        if (unlikely(dev_written < 0)) {
+            return dev_written;
+        }
+
+        return *s->status != VIRTIO_NET_OK;
+    }
+
+    return 0;
+}
+
 static int vhost_vdpa_net_load(NetClientState *nc)
 {
     VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
-    const struct vhost_vdpa *v = &s->vhost_vdpa;
+    struct vhost_vdpa *v = &s->vhost_vdpa;
     const VirtIONet *n;
-    uint64_t features;
+    int r;
 
     assert(nc->info->type == NET_CLIENT_DRIVER_VHOST_VDPA);
 
@@ -379,26 +414,9 @@ static int vhost_vdpa_net_load(NetClientState *nc)
     }
 
     n = VIRTIO_NET(v->dev->vdev);
-    features = n->parent_obj.guest_features;
-    if (features & BIT_ULL(VIRTIO_NET_F_CTRL_MAC_ADDR)) {
-        const struct virtio_net_ctrl_hdr ctrl = {
-            .class = VIRTIO_NET_CTRL_MAC,
-            .cmd = VIRTIO_NET_CTRL_MAC_ADDR_SET,
-        };
-        char *cursor = s->cvq_cmd_out_buffer;
-        ssize_t dev_written;
-
-        memcpy(cursor, &ctrl, sizeof(ctrl));
-        cursor += sizeof(ctrl);
-        memcpy(cursor, n->mac, sizeof(n->mac));
-
-        dev_written = vhost_vdpa_net_cvq_add(s, sizeof(ctrl) + sizeof(n->mac),
-                                             sizeof(virtio_net_ctrl_ack));
-        if (unlikely(dev_written < 0)) {
-            return dev_written;
-        }
-
-        return *s->status != VIRTIO_NET_OK;
+    r = vhost_vdpa_net_load_mac(s, n);
+    if (unlikely(r < 0)) {
+        return r;
     }
 
     return 0;
-- 
2.31.1

[PATCH v3 3/6] vdpa: Add vhost_vdpa_net_load_mq

[Eugenio Pérez]

Same way as with the MAC, restore the expected number of queues at
device's start.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 net/vhost-vdpa.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index e799e744cd..3950e4f25d 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -400,6 +400,28 @@ static int vhost_vdpa_net_load_mac(VhostVDPAState *s, const VirtIONet *n)
     return 0;
 }
 
+static int vhost_vdpa_net_load_mq(VhostVDPAState *s,
+                                  const VirtIONet *n)
+{
+    struct virtio_net_ctrl_mq mq;
+    uint64_t features = n->parent_obj.guest_features;
+    ssize_t dev_written;
+
+    if (!(features & BIT_ULL(VIRTIO_NET_F_MQ))) {
+        return 0;
+    }
+
+    mq.virtqueue_pairs = cpu_to_le16(n->curr_queue_pairs);
+    dev_written = vhost_vdpa_net_load_cmd(s, VIRTIO_NET_CTRL_MQ,
+                                          VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET, &mq,
+                                          sizeof(mq));
+    if (unlikely(dev_written < 0)) {
+        return dev_written;
+    }
+
+    return *s->status != VIRTIO_NET_OK;
+}
+
 static int vhost_vdpa_net_load(NetClientState *nc)
 {
     VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
@@ -418,6 +440,10 @@ static int vhost_vdpa_net_load(NetClientState *nc)
     if (unlikely(r < 0)) {
         return r;
     }
+    r = vhost_vdpa_net_load_mq(s, n);
+    if (unlikely(r)) {
+        return r;
+    }
 
     return 0;
 }
-- 
2.31.1

[PATCH v3 4/6] vdpa: validate MQ CVQ commands

[Eugenio Pérez]

So we are sure we can update the device model properly before sending to
the device.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 net/vhost-vdpa.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index 3950e4f25d..c6cbe2fb5c 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -486,6 +486,15 @@ static bool vhost_vdpa_net_cvq_validate_cmd(const void *out_buf, size_t len)
                           __func__, ctrl.cmd);
         };
         break;
+    case VIRTIO_NET_CTRL_MQ:
+        switch (ctrl.cmd) {
+        case VIRTIO_NET_CTRL_MQ_VQ_PAIRS_SET:
+            return true;
+        default:
+            qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid mq cmd %u\n",
+                          __func__, ctrl.cmd);
+        };
+        break;
     default:
         qemu_log_mask(LOG_GUEST_ERROR, "%s: invalid control class %u\n",
                       __func__, ctrl.class);
-- 
2.31.1

[PATCH v3 5/6] virtio-net: Update virtio-net curr_queue_pairs in vdpa backends

[Eugenio Pérez]

It was returned as error before. Instead of it, simply update the
corresponding field so qemu can send it in the migration data.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 hw/net/virtio-net.c | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index dd0d056fde..63a8332cd0 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -1412,19 +1412,14 @@ static int virtio_net_handle_mq(VirtIONet *n, uint8_t cmd,
         return VIRTIO_NET_ERR;
     }
 
-    /* Avoid changing the number of queue_pairs for vdpa device in
-     * userspace handler. A future fix is needed to handle the mq
-     * change in userspace handler with vhost-vdpa. Let's disable
-     * the mq handling from userspace for now and only allow get
-     * done through the kernel. Ripples may be seen when falling
-     * back to userspace, but without doing it qemu process would
-     * crash on a recursive entry to virtio_net_set_status().
-     */
+    n->curr_queue_pairs = queue_pairs;
     if (nc->peer && nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_VDPA) {
-        return VIRTIO_NET_ERR;
+        /*
+         * Avoid updating the backend for a vdpa device: We're only interested
+         * in updating the device model queues.
+         */
+        return VIRTIO_NET_OK;
     }
-
-    n->curr_queue_pairs = queue_pairs;
     /* stop the backend before changing the number of queue_pairs to avoid handling a
      * disabled queue */
     virtio_net_set_status(vdev, vdev->status);
-- 
2.31.1

[PATCH v3 6/6] vdpa: Allow MQ feature in SVQ

[Eugenio Pérez]

Finally enable SVQ with MQ feature.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 net/vhost-vdpa.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index c6cbe2fb5c..4bc3fd01a8 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -94,6 +94,7 @@ static const uint64_t vdpa_svq_device_features =
     BIT_ULL(VIRTIO_NET_F_MRG_RXBUF) |
     BIT_ULL(VIRTIO_NET_F_STATUS) |
     BIT_ULL(VIRTIO_NET_F_CTRL_VQ) |
+    BIT_ULL(VIRTIO_NET_F_MQ) |
     BIT_ULL(VIRTIO_F_ANY_LAYOUT) |
     BIT_ULL(VIRTIO_NET_F_CTRL_MAC_ADDR) |
     BIT_ULL(VIRTIO_NET_F_RSC_EXT) |
-- 
2.31.1