vhost: rework IOTLB messaging

This patch reworks IOTLB messaging to prepare for vhost-user
device IOTLB support.

IOTLB messages handling is extracted from vhost-kernel backend,
so that only the messages transport remains backend specifics.

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/virtio/vhost-backend.c

@@ -192,7 +192,6 @@ static void vhost_kernel_iotlb_read(void *opaque)
     ssize_t len;
 
     while ((len = read((uintptr_t)dev->opaque, &msg, sizeof msg)) > 0) {
-        struct vhost_iotlb_msg *imsg = &msg.iotlb;
         if (len < sizeof msg) {
             error_report("Wrong vhost message len: %d", (int)len);
             break;
@@ -201,49 +200,18 @@ static void vhost_kernel_iotlb_read(void *opaque)
             error_report("Unknown vhost iotlb message type");
             break;
         }
-        switch (imsg->type) {
+
-        case VHOST_IOTLB_MISS:
+        vhost_backend_handle_iotlb_msg(dev, &msg.iotlb);
-            vhost_device_iotlb_miss(dev, imsg->iova,
-                                    imsg->perm != VHOST_ACCESS_RO);
-            break;
-        case VHOST_IOTLB_UPDATE:
-        case VHOST_IOTLB_INVALIDATE:
-            error_report("Unexpected IOTLB message type");
-            break;
-        case VHOST_IOTLB_ACCESS_FAIL:
-            /* FIXME: report device iotlb error */
-            break;
-        default:
-            break;
-        }
     }
 }
 
-static int vhost_kernel_update_device_iotlb(struct vhost_dev *dev,
+static int vhost_kernel_send_device_iotlb_msg(struct vhost_dev *dev,
-                                            uint64_t iova, uint64_t uaddr,
+                                              struct vhost_iotlb_msg *imsg)
-                                            uint64_t len,
-                                            IOMMUAccessFlags perm)
 {
     struct vhost_msg msg;
-    msg.type = VHOST_IOTLB_MSG;
-    msg.iotlb.iova =  iova;
-    msg.iotlb.uaddr = uaddr;
-    msg.iotlb.size = len;
-    msg.iotlb.type = VHOST_IOTLB_UPDATE;
 
-    switch (perm) {
+    msg.type = VHOST_IOTLB_MSG;
-    case IOMMU_RO:
+    msg.iotlb = *imsg;
-        msg.iotlb.perm = VHOST_ACCESS_RO;
-        break;
-    case IOMMU_WO:
-        msg.iotlb.perm = VHOST_ACCESS_WO;
-        break;
-    case IOMMU_RW:
-        msg.iotlb.perm = VHOST_ACCESS_RW;
-        break;
-    default:
-        g_assert_not_reached();
-    }
 
     if (write((uintptr_t)dev->opaque, &msg, sizeof msg) != sizeof msg) {
         error_report("Fail to update device iotlb");
@@ -253,24 +221,6 @@ static int vhost_kernel_update_device_iotlb(struct vhost_dev *dev,
     return 0;
 }
 
-static int vhost_kernel_invalidate_device_iotlb(struct vhost_dev *dev,
-                                                uint64_t iova, uint64_t len)
-{
-    struct vhost_msg msg;
-
-    msg.type = VHOST_IOTLB_MSG;
-    msg.iotlb.iova = iova;
-    msg.iotlb.size = len;
-    msg.iotlb.type = VHOST_IOTLB_INVALIDATE;
-
-    if (write((uintptr_t)dev->opaque, &msg, sizeof msg) != sizeof msg) {
-        error_report("Fail to invalidate device iotlb");
-        return -EFAULT;
-    }
-
-    return 0;
-}
-
 static void vhost_kernel_set_iotlb_callback(struct vhost_dev *dev,
                                            int enabled)
 {
@@ -311,8 +261,7 @@ static const VhostOps kernel_ops = {
         .vhost_vsock_set_running = vhost_kernel_vsock_set_running,
 #endif /* CONFIG_VHOST_VSOCK */
         .vhost_set_iotlb_callback = vhost_kernel_set_iotlb_callback,
-        .vhost_update_device_iotlb = vhost_kernel_update_device_iotlb,
+        .vhost_send_device_iotlb_msg = vhost_kernel_send_device_iotlb_msg,
-        .vhost_invalidate_device_iotlb = vhost_kernel_invalidate_device_iotlb,
 };
 
 int vhost_set_backend_type(struct vhost_dev *dev, VhostBackendType backend_type)
@@ -333,3 +282,70 @@ int vhost_set_backend_type(struct vhost_dev *dev, VhostBackendType backend_type)
 
     return r;
 }
+
+int vhost_backend_update_device_iotlb(struct vhost_dev *dev,
+                                             uint64_t iova, uint64_t uaddr,
+                                             uint64_t len,
+                                             IOMMUAccessFlags perm)
+{
+    struct vhost_iotlb_msg imsg;
+
+    imsg.iova =  iova;
+    imsg.uaddr = uaddr;
+    imsg.size = len;
+    imsg.type = VHOST_IOTLB_UPDATE;
+
+    switch (perm) {
+    case IOMMU_RO:
+        imsg.perm = VHOST_ACCESS_RO;
+        break;
+    case IOMMU_WO:
+        imsg.perm = VHOST_ACCESS_WO;
+        break;
+    case IOMMU_RW:
+        imsg.perm = VHOST_ACCESS_RW;
+        break;
+    default:
+        return -EINVAL;
+    }
+
+    return dev->vhost_ops->vhost_send_device_iotlb_msg(dev, &imsg);
+}
+
+int vhost_backend_invalidate_device_iotlb(struct vhost_dev *dev,
+                                                 uint64_t iova, uint64_t len)
+{
+    struct vhost_iotlb_msg imsg;
+
+    imsg.iova = iova;
+    imsg.size = len;
+    imsg.type = VHOST_IOTLB_INVALIDATE;
+
+    return dev->vhost_ops->vhost_send_device_iotlb_msg(dev, &imsg);
+}
+
+int vhost_backend_handle_iotlb_msg(struct vhost_dev *dev,
+                                          struct vhost_iotlb_msg *imsg)
+{
+    int ret = 0;
+
+    switch (imsg->type) {
+    case VHOST_IOTLB_MISS:
+        ret = vhost_device_iotlb_miss(dev, imsg->iova,
+                                      imsg->perm != VHOST_ACCESS_RO);
+        break;
+    case VHOST_IOTLB_ACCESS_FAIL:
+        /* FIXME: report device iotlb error */
+        error_report("Access failure IOTLB message type not supported");
+        ret = -ENOTSUP;
+        break;
+    case VHOST_IOTLB_UPDATE:
+    case VHOST_IOTLB_INVALIDATE:
+    default:
+        error_report("Unexpected IOTLB message type");
+        ret = -EINVAL;
+        break;
+    }
+
+    return ret;
+}

hw/virtio/vhost.c

@@ -724,7 +724,7 @@ static void vhost_iommu_unmap_notify(IOMMUNotifier *n, IOMMUTLBEntry *iotlb)
     struct vhost_dev *hdev = iommu->hdev;
     hwaddr iova = iotlb->iova + iommu->iommu_offset;
 
-    if (hdev->vhost_ops->vhost_invalidate_device_iotlb(hdev, iova,
+    if (vhost_backend_invalidate_device_iotlb(hdev, iova,
                                               iotlb->addr_mask + 1)) {
         error_report("Fail to invalidate device iotlb");
     }
@@ -993,7 +993,7 @@ int vhost_device_iotlb_miss(struct vhost_dev *dev, uint64_t iova, int write)
         len = MIN(iotlb.addr_mask + 1, len);
         iova = iova & ~iotlb.addr_mask;
 
-        ret = dev->vhost_ops->vhost_update_device_iotlb(dev, iova, uaddr,
+        ret = vhost_backend_update_device_iotlb(dev, iova, uaddr,
                                                 len, iotlb.perm);
         if (ret) {
             error_report("Fail to update device iotlb");

include/hw/virtio/vhost-backend.h

@@ -27,6 +27,7 @@ struct vhost_vring_file;
 struct vhost_vring_state;
 struct vhost_vring_addr;
 struct vhost_scsi_target;
+struct vhost_iotlb_msg;
 
 typedef int (*vhost_backend_init)(struct vhost_dev *dev, void *opaque);
 typedef int (*vhost_backend_cleanup)(struct vhost_dev *dev);
@@ -81,12 +82,8 @@ typedef int (*vhost_vsock_set_guest_cid_op)(struct vhost_dev *dev,
 typedef int (*vhost_vsock_set_running_op)(struct vhost_dev *dev, int start);
 typedef void (*vhost_set_iotlb_callback_op)(struct vhost_dev *dev,
                                            int enabled);
-typedef int (*vhost_update_device_iotlb_op)(struct vhost_dev *dev,
+typedef int (*vhost_send_device_iotlb_msg_op)(struct vhost_dev *dev,
-                                            uint64_t iova, uint64_t uaddr,
+                                              struct vhost_iotlb_msg *imsg);
-                                            uint64_t len,
-                                            IOMMUAccessFlags perm);
-typedef int (*vhost_invalidate_device_iotlb_op)(struct vhost_dev *dev,
-                                                uint64_t iova, uint64_t len);
 
 typedef struct VhostOps {
     VhostBackendType backend_type;
@@ -120,8 +117,7 @@ typedef struct VhostOps {
     vhost_vsock_set_guest_cid_op vhost_vsock_set_guest_cid;
     vhost_vsock_set_running_op vhost_vsock_set_running;
     vhost_set_iotlb_callback_op vhost_set_iotlb_callback;
-    vhost_update_device_iotlb_op vhost_update_device_iotlb;
+    vhost_send_device_iotlb_msg_op vhost_send_device_iotlb_msg;
-    vhost_invalidate_device_iotlb_op vhost_invalidate_device_iotlb;
 } VhostOps;
 
 extern const VhostOps user_ops;
@@ -129,4 +125,15 @@ extern const VhostOps user_ops;
 int vhost_set_backend_type(struct vhost_dev *dev,
                            VhostBackendType backend_type);
 
+int vhost_backend_update_device_iotlb(struct vhost_dev *dev,
+                                             uint64_t iova, uint64_t uaddr,
+                                             uint64_t len,
+                                             IOMMUAccessFlags perm);
+
+int vhost_backend_invalidate_device_iotlb(struct vhost_dev *dev,
+                                                 uint64_t iova, uint64_t len);
+
+int vhost_backend_handle_iotlb_msg(struct vhost_dev *dev,
+                                          struct vhost_iotlb_msg *imsg);
+
 #endif /* VHOST_BACKEND_H */