vdpa: map shadow vrings with MAP_SHARED

The vdpa devices that use va addresses neeeds these maps shared.
Otherwise, vhost_vdpa checks will refuse to accept the maps.

The mmap call will always return a page aligned address, so removing the
qemu_memalign call.  Keeping the ROUND_UP for the size as we still need
to DMA-map them in full.

Not applying fixes tag as it never worked with va devices.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20230602143854.1879091-4-eperezma@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/virtio/vhost-shadow-virtqueue.c

@@ -649,7 +649,7 @@ void vhost_svq_set_svq_kick_fd(VhostShadowVirtqueue *svq, int svq_kick_fd)
 void vhost_svq_start(VhostShadowVirtqueue *svq, VirtIODevice *vdev,
                      VirtQueue *vq, VhostIOVATree *iova_tree)
 {
-    size_t desc_size, driver_size, device_size;
+    size_t desc_size;
 
     event_notifier_set_handler(&svq->hdev_call, vhost_svq_handle_call);
     svq->next_guest_avail_elem = NULL;
@@ -662,14 +662,14 @@ void vhost_svq_start(VhostShadowVirtqueue *svq, VirtIODevice *vdev,
 
     svq->vring.num = virtio_queue_get_num(vdev, virtio_get_queue_index(vq));
     svq->num_free = svq->vring.num;
-    driver_size = vhost_svq_driver_area_size(svq);
-    device_size = vhost_svq_device_area_size(svq);
-    svq->vring.desc = qemu_memalign(qemu_real_host_page_size(), driver_size);
+    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);
-    memset(svq->vring.desc, 0, driver_size);
-    svq->vring.used = qemu_memalign(qemu_real_host_page_size(), device_size);
-    memset(svq->vring.used, 0, device_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++) {
@@ -712,8 +712,8 @@ void vhost_svq_stop(VhostShadowVirtqueue *svq)
     svq->vq = NULL;
     g_free(svq->desc_next);
     g_free(svq->desc_state);
-    qemu_vfree(svq->vring.desc);
-    qemu_vfree(svq->vring.used);
+    munmap(svq->vring.desc, vhost_svq_driver_area_size(svq));
+    munmap(svq->vring.used, vhost_svq_device_area_size(svq));
     event_notifier_set_handler(&svq->hdev_call, NULL);
 }
 

net/vhost-vdpa.c

@@ -205,8 +205,8 @@ static void vhost_vdpa_cleanup(NetClientState *nc)
 {
     VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
 
-    qemu_vfree(s->cvq_cmd_out_buffer);
-    qemu_vfree(s->status);
+    munmap(s->cvq_cmd_out_buffer, vhost_vdpa_net_cvq_cmd_page_len());
+    munmap(s->status, vhost_vdpa_net_cvq_cmd_page_len());
     if (s->vhost_net) {
         vhost_net_cleanup(s->vhost_net);
         g_free(s->vhost_net);
@@ -903,12 +903,12 @@ static NetClientState *net_vhost_vdpa_init(NetClientState *peer,
         vhost_vdpa_net_valid_svq_features(features,
                                           &s->vhost_vdpa.migration_blocker);
     } else if (!is_datapath) {
-        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->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->cvq_cmd_out_buffer = mmap(NULL, vhost_vdpa_net_cvq_cmd_page_len(),
+                                     PROT_READ | PROT_WRITE,
+                                     MAP_SHARED | MAP_ANONYMOUS, -1, 0);
+        s->status = mmap(NULL, vhost_vdpa_net_cvq_cmd_page_len(),
+                         PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS,
+                         -1, 0);
 
         s->vhost_vdpa.shadow_vq_ops = &vhost_vdpa_net_svq_ops;
         s->vhost_vdpa.shadow_vq_ops_opaque = s;