vhost: dirty log should be per backend type

There could be a mix of both vhost-user and vhost-kernel clients
in the same QEMU process, where separate vhost loggers for the
specific vhost type have to be used. Make the vhost logger per
backend type, and have them properly reference counted.

Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
Message-Id: <1710448055-11709-1-git-send-email-si-wei.liu@oracle.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 33 insertions, 12 deletions

diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index 4acd77e..a1e8b79 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -43,8 +43,8 @@
     do { } while (0)
 #endif
 
-static struct vhost_log *vhost_log;
-static struct vhost_log *vhost_log_shm;
+static struct vhost_log *vhost_log[VHOST_BACKEND_TYPE_MAX];
+static struct vhost_log *vhost_log_shm[VHOST_BACKEND_TYPE_MAX];
 
 /* Memslots used by backends that support private memslots (without an fd). */
 static unsigned int used_memslots;
@@ -287,6 +287,10 @@ static int vhost_set_backend_type(struct vhost_dev *dev,
         r = -1;
     }
 
+    if (r == 0) {
+        assert(dev->vhost_ops->backend_type == backend_type);
+    }
+
     return r;
 }
 
@@ -319,16 +323,22 @@ static struct vhost_log *vhost_log_alloc(uint64_t size, bool share)
     return log;
 }
 
-static struct vhost_log *vhost_log_get(uint64_t size, bool share)
+static struct vhost_log *vhost_log_get(VhostBackendType backend_type,
+                                       uint64_t size, bool share)
 {
-    struct vhost_log *log = share ? vhost_log_shm : vhost_log;
+    struct vhost_log *log;
+
+    assert(backend_type > VHOST_BACKEND_TYPE_NONE);
+    assert(backend_type < VHOST_BACKEND_TYPE_MAX);
+
+    log = share ? vhost_log_shm[backend_type] : vhost_log[backend_type];
 
     if (!log || log->size != size) {
         log = vhost_log_alloc(size, share);
         if (share) {
-            vhost_log_shm = log;
+            vhost_log_shm[backend_type] = log;
         } else {
-            vhost_log = log;
+            vhost_log[backend_type] = log;
         }
     } else {
         ++log->refcnt;
@@ -340,11 +350,20 @@ static struct vhost_log *vhost_log_get(uint64_t size, bool share)
 static void vhost_log_put(struct vhost_dev *dev, bool sync)
 {
     struct vhost_log *log = dev->log;
+    VhostBackendType backend_type;
 
     if (!log) {
         return;
     }
 
+    assert(dev->vhost_ops);
+    backend_type = dev->vhost_ops->backend_type;
+
+    if (backend_type == VHOST_BACKEND_TYPE_NONE ||
+        backend_type >= VHOST_BACKEND_TYPE_MAX) {
+        return;
+    }
+
     --log->refcnt;
     if (log->refcnt == 0) {
         /* Sync only the range covered by the old log */
@@ -352,13 +371,13 @@ static void vhost_log_put(struct vhost_dev *dev, bool sync)
             vhost_log_sync_range(dev, 0, dev->log_size * VHOST_LOG_CHUNK - 1);
         }
 
-        if (vhost_log == log) {
+        if (vhost_log[backend_type] == log) {
             g_free(log->log);
-            vhost_log = NULL;
-        } else if (vhost_log_shm == log) {
+            vhost_log[backend_type] = NULL;
+        } else if (vhost_log_shm[backend_type] == log) {
             qemu_memfd_free(log->log, log->size * sizeof(*(log->log)),
                             log->fd);
-            vhost_log_shm = NULL;
+            vhost_log_shm[backend_type] = NULL;
         }
 
         g_free(log);
@@ -376,7 +395,8 @@ static bool vhost_dev_log_is_shared(struct vhost_dev *dev)
 
 static inline void vhost_dev_log_resize(struct vhost_dev *dev, uint64_t size)
 {
-    struct vhost_log *log = vhost_log_get(size, vhost_dev_log_is_shared(dev));
+    struct vhost_log *log = vhost_log_get(dev->vhost_ops->backend_type,
+                                          size, vhost_dev_log_is_shared(dev));
     uint64_t log_base = (uintptr_t)log->log;
     int r;
 
@@ -2044,7 +2064,8 @@ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev, bool vrings)
         uint64_t log_base;
 
         hdev->log_size = vhost_get_log_size(hdev);
-        hdev->log = vhost_log_get(hdev->log_size,
+        hdev->log = vhost_log_get(hdev->vhost_ops->backend_type,
+                                  hdev->log_size,
                                   vhost_dev_log_is_shared(hdev));
         log_base = (uintptr_t)hdev->log->log;
         r = hdev->vhost_ops->vhost_set_log_base(hdev,