Add VHOST_USER_GET_CONFIG/VHOST_USER_SET_CONFIG messages which can be
used for live migration of vhost user devices, also vhost user devices
can benefit from the messages to get/set virtio config space from/to the
I/O target. For the purpose to support virtio config space change,
VHOST_USER_SLAVE_CONFIG_CHANGE_MSG message is added as the event notifier
in case virtio config space change in the slave I/O target.

Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
---
 docs/interop/vhost-user.txt       |  53 +++++++++++++++++
 hw/virtio/vhost-user.c            | 118 ++++++++++++++++++++++++++++++++++++++
 hw/virtio/vhost.c                 |  32 +++++++++++
 include/hw/virtio/vhost-backend.h |  12 ++++
 include/hw/virtio/vhost.h         |  15 +++++
 5 files changed, 230 insertions(+)

diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt
index 954771d..1788fff 100644
--- a/docs/interop/vhost-user.txt
+++ b/docs/interop/vhost-user.txt
@@ -116,6 +116,19 @@ Depending on the request type, payload can be:
     - 3: IOTLB invalidate
     - 4: IOTLB access fail
 
+ * Virtio device config space
+   -----------------------------------
+   | offset | size | flags | payload |
+   -----------------------------------
+
+   Offset: a 32-bit offset of virtio device's configuration space
+   Size: a 32-bit configuration space access size in bytes
+   Flags: a 32-bit value:
+    - 0: Vhost master messages used for writeable fields
+    - 1: Vhost master messages used for live migration
+   Payload: Size bytes array holding the contents of the virtio
+       device's configuration space
+
 In QEMU the vhost-user message is implemented with the following struct:
 
 typedef struct VhostUserMsg {
@@ -129,6 +142,7 @@ typedef struct VhostUserMsg {
         VhostUserMemory memory;
         VhostUserLog log;
         struct vhost_iotlb_msg iotlb;
+        VhostUserConfig config;
     };
 } QEMU_PACKED VhostUserMsg;
 
@@ -596,6 +610,30 @@ Master message types
       and expect this message once (per VQ) during device configuration
       (ie. before the master starts the VQ).
 
+ * VHOST_USER_GET_CONFIG
+
+      Id: 24
+      Equivalent ioctl: N/A
+      Slave payload: virtio device config space
+
+      Submitted by the vhost-user master to fetch the contents of the virtio
+      device configuration space, vhost-user slave's payload size MUST match
+      master's request, vhost-user slave uses zero length of payload to
+      indicate an error to vhost-user master. The vhost-user master may
+      cache the contents to avoid repeated VHOST_USER_GET_CONFIG calls.
+
+* VHOST_USER_SET_CONFIG
+
+      Id: 25
+      Equivalent ioctl: N/A
+      Master payload: virtio device config space
+
+      Submitted by the vhost-user master when the Guest changes the virtio
+      device configuration space and also can be used for live migration
+      on the destination host. The vhost-user slave must check the flags
+      field, and slaves MUST NOT accept SET_CONFIG for read-only
+      configuration space fields unless the live migration bit is set.
+
 Slave message types
 -------------------
 
@@ -614,6 +652,21 @@ Slave message types
       This request should be send only when VIRTIO_F_IOMMU_PLATFORM feature
       has been successfully negotiated.
 
+* VHOST_USER_SLAVE_CONFIG_CHANGE_MSG
+
+     Id: 2
+     Equivalent ioctl: N/A
+     Slave payload: N/A
+     Master payload: N/A
+
+     Vhost-user slave sends such messages to notify that the virtio device's
+     configuration space has changed, for those host devices which can support
+     such feature, host driver can send VHOST_USER_GET_CONFIG message to slave
+     to get the latest content. If VHOST_USER_PROTOCOL_F_REPLY_ACK is
+     negotiated, and slave set the VHOST_USER_NEED_REPLY flag, master must
+     respond with zero when operation is successfully completed, or non-zero
+     otherwise.
+
 VHOST_USER_PROTOCOL_F_REPLY_ACK:
 -------------------------------
 The original vhost-user specification only demands replies for certain
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 093675e..8b94688 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -26,6 +26,11 @@
 #define VHOST_MEMORY_MAX_NREGIONS    8
 #define VHOST_USER_F_PROTOCOL_FEATURES 30
 
+/*
+ * Maximum size of virtio device config space
+ */
+#define VHOST_USER_MAX_CONFIG_SIZE 256
+
 enum VhostUserProtocolFeature {
     VHOST_USER_PROTOCOL_F_MQ = 0,
     VHOST_USER_PROTOCOL_F_LOG_SHMFD = 1,
@@ -65,12 +70,15 @@ typedef enum VhostUserRequest {
     VHOST_USER_SET_SLAVE_REQ_FD = 21,
     VHOST_USER_IOTLB_MSG = 22,
     VHOST_USER_SET_VRING_ENDIAN = 23,
+    VHOST_USER_GET_CONFIG = 24,
+    VHOST_USER_SET_CONFIG = 25,
     VHOST_USER_MAX
 } VhostUserRequest;
 
 typedef enum VhostUserSlaveRequest {
     VHOST_USER_SLAVE_NONE = 0,
     VHOST_USER_SLAVE_IOTLB_MSG = 1,
+    VHOST_USER_SLAVE_CONFIG_CHANGE_MSG = 2,
     VHOST_USER_SLAVE_MAX
 }  VhostUserSlaveRequest;
 
@@ -92,6 +100,18 @@ typedef struct VhostUserLog {
     uint64_t mmap_offset;
 } VhostUserLog;
 
+typedef struct VhostUserConfig {
+    uint32_t offset;
+    uint32_t size;
+    uint32_t flags;
+    uint8_t region[VHOST_USER_MAX_CONFIG_SIZE];
+} VhostUserConfig;
+
+static VhostUserConfig c __attribute__ ((unused));
+#define VHOST_USER_CONFIG_HDR_SIZE (sizeof(c.offset) \
+                                   + sizeof(c.size) \
+                                   + sizeof(c.flags))
+
 typedef struct VhostUserMsg {
     VhostUserRequest request;
 
@@ -109,6 +129,7 @@ typedef struct VhostUserMsg {
         VhostUserMemory memory;
         VhostUserLog log;
         struct vhost_iotlb_msg iotlb;
+        VhostUserConfig config;
     } payload;
 } QEMU_PACKED VhostUserMsg;
 
@@ -608,6 +629,21 @@ static int vhost_user_reset_device(struct vhost_dev *dev)
     return 0;
 }
 
+static int vhost_user_slave_handle_config_change(struct vhost_dev *dev)
+{
+    int ret = -1;
+
+    if (!dev->config_ops) {
+        return -1;
+    }
+
+    if (dev->config_ops->vhost_dev_config_notifier) {
+        ret = dev->config_ops->vhost_dev_config_notifier(dev);
+    }
+
+    return ret;
+}
+
 static void slave_read(void *opaque)
 {
     struct vhost_dev *dev = opaque;
@@ -640,6 +676,9 @@ static void slave_read(void *opaque)
     case VHOST_USER_SLAVE_IOTLB_MSG:
         ret = vhost_backend_handle_iotlb_msg(dev, &msg.payload.iotlb);
         break;
+    case VHOST_USER_SLAVE_CONFIG_CHANGE_MSG :
+        ret = vhost_user_slave_handle_config_change(dev);
+        break;
     default:
         error_report("Received unexpected msg type.");
         ret = -EINVAL;
@@ -922,6 +961,83 @@ static void vhost_user_set_iotlb_callback(struct vhost_dev *dev, int enabled)
     /* No-op as the receive channel is not dedicated to IOTLB messages. */
 }
 
+static int vhost_user_get_config(struct vhost_dev *dev, uint8_t *config,
+                                 uint32_t config_len)
+{
+    VhostUserMsg msg = {
+        msg.request = VHOST_USER_GET_CONFIG,
+        msg.flags = VHOST_USER_VERSION,
+        msg.size = VHOST_USER_CONFIG_HDR_SIZE + config_len,
+    };
+
+    if (config_len > VHOST_USER_MAX_CONFIG_SIZE) {
+        return -1;
+    }
+
+    msg.payload.config.offset = 0;
+    msg.payload.config.size = config_len;
+    if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
+        return -1;
+    }
+
+    if (vhost_user_read(dev, &msg) < 0) {
+        return -1;
+    }
+
+    if (msg.request != VHOST_USER_GET_CONFIG) {
+        error_report("Received unexpected msg type. Expected %d received %d",
+                     VHOST_USER_GET_CONFIG, msg.request);
+        return -1;
+    }
+
+    if (msg.size != VHOST_USER_CONFIG_HDR_SIZE + config_len) {
+        error_report("Received bad msg size.");
+        return -1;
+    }
+
+    memcpy(config, msg.payload.config.region, config_len);
+
+    return 0;
+}
+
+static int vhost_user_set_config(struct vhost_dev *dev, const uint8_t *data,
+                                 uint32_t offset, uint32_t size, uint32_t flags)
+{
+    uint8_t *p;
+    bool reply_supported = virtio_has_feature(dev->protocol_features,
+                                              VHOST_USER_PROTOCOL_F_REPLY_ACK);
+
+    VhostUserMsg msg = {
+        msg.request = VHOST_USER_SET_CONFIG,
+        msg.flags = VHOST_USER_VERSION,
+        msg.size = VHOST_USER_CONFIG_HDR_SIZE + size,
+    };
+
+    if (reply_supported) {
+        msg.flags |= VHOST_USER_NEED_REPLY_MASK;
+    }
+
+    if (size > VHOST_USER_MAX_CONFIG_SIZE) {
+        return -1;
+    }
+
+    msg.payload.config.offset = offset,
+    msg.payload.config.size = size,
+    msg.payload.config.flags = flags,
+    p = msg.payload.config.region;
+    memcpy(p, data, size);
+
+    if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
+        return -1;
+    }
+
+    if (reply_supported) {
+        return process_message_reply(dev, &msg);
+    }
+
+    return 0;
+}
+
 const VhostOps user_ops = {
         .backend_type = VHOST_BACKEND_TYPE_USER,
         .vhost_backend_init = vhost_user_init,
@@ -948,4 +1064,6 @@ const VhostOps user_ops = {
         .vhost_net_set_mtu = vhost_user_net_set_mtu,
         .vhost_set_iotlb_callback = vhost_user_set_iotlb_callback,
         .vhost_send_device_iotlb_msg = vhost_user_send_device_iotlb_msg,
+        .vhost_get_config = vhost_user_get_config,
+        .vhost_set_config = vhost_user_set_config,
 };
diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
index e4290ce..386aef8 100644
--- a/hw/virtio/vhost.c
+++ b/hw/virtio/vhost.c
@@ -1505,6 +1505,38 @@ void vhost_ack_features(struct vhost_dev *hdev, const int *feature_bits,
     }
 }
 
+int vhost_dev_get_config(struct vhost_dev *hdev, uint8_t *config,
+                         uint32_t config_len)
+{
+    assert(hdev->vhost_ops);
+
+    if (hdev->vhost_ops->vhost_get_config) {
+        return hdev->vhost_ops->vhost_get_config(hdev, config, config_len);
+    }
+
+    return -1;
+}
+
+int vhost_dev_set_config(struct vhost_dev *hdev, const uint8_t *data,
+                         uint32_t offset, uint32_t size, uint32_t flags)
+{
+    assert(hdev->vhost_ops);
+
+    if (hdev->vhost_ops->vhost_set_config) {
+        return hdev->vhost_ops->vhost_set_config(hdev, data, offset,
+                                                 size, flags);
+    }
+
+    return -1;
+}
+
+void vhost_dev_set_config_notifier(struct vhost_dev *hdev,
+                                   const VhostDevConfigOps *ops)
+{
+    assert(hdev->vhost_ops);
+    hdev->config_ops = ops;
+}
+
 /* Host notifiers must be enabled at this point. */
 int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)
 {
diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h
index a7a5f22..592254f 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -20,6 +20,11 @@ typedef enum VhostBackendType {
     VHOST_BACKEND_TYPE_MAX = 3,
 } VhostBackendType;
 
+typedef enum VhostSetConfigType {
+    VHOST_SET_CONFIG_TYPE_MASTER = 0,
+    VHOST_SET_CONFIG_TYPE_MIGRATION = 1,
+} VhostSetConfigType;
+
 struct vhost_dev;
 struct vhost_log;
 struct vhost_memory;
@@ -84,6 +89,11 @@ typedef void (*vhost_set_iotlb_callback_op)(struct vhost_dev *dev,
                                            int enabled);
 typedef int (*vhost_send_device_iotlb_msg_op)(struct vhost_dev *dev,
                                               struct vhost_iotlb_msg *imsg);
+typedef int (*vhost_set_config_op)(struct vhost_dev *dev, const uint8_t *data,
+                                   uint32_t offset, uint32_t size,
+                                   uint32_t flags);
+typedef int (*vhost_get_config_op)(struct vhost_dev *dev, uint8_t *config,
+                                   uint32_t config_len);
 
 typedef struct VhostOps {
     VhostBackendType backend_type;
@@ -118,6 +128,8 @@ typedef struct VhostOps {
     vhost_vsock_set_running_op vhost_vsock_set_running;
     vhost_set_iotlb_callback_op vhost_set_iotlb_callback;
     vhost_send_device_iotlb_msg_op vhost_send_device_iotlb_msg;
+    vhost_get_config_op vhost_get_config;
+    vhost_set_config_op vhost_set_config;
 } VhostOps;
 
 extern const VhostOps user_ops;
diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
index 467dc77..1dc2d73 100644
--- a/include/hw/virtio/vhost.h
+++ b/include/hw/virtio/vhost.h
@@ -46,6 +46,12 @@ struct vhost_iommu {
     QLIST_ENTRY(vhost_iommu) iommu_next;
 };
 
+typedef struct VhostDevConfigOps {
+    /* Vhost device config space changed callback
+     */
+    int (*vhost_dev_config_notifier)(struct vhost_dev *dev);
+} VhostDevConfigOps;
+
 struct vhost_memory;
 struct vhost_dev {
     VirtIODevice *vdev;
@@ -76,6 +82,7 @@ struct vhost_dev {
     QLIST_ENTRY(vhost_dev) entry;
     QLIST_HEAD(, vhost_iommu) iommu_list;
     IOMMUNotifier n;
+    const VhostDevConfigOps *config_ops;
 };
 
 int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
@@ -106,4 +113,12 @@ int vhost_net_set_backend(struct vhost_dev *hdev,
                           struct vhost_vring_file *file);
 
 int vhost_device_iotlb_miss(struct vhost_dev *dev, uint64_t iova, int write);
+int vhost_dev_get_config(struct vhost_dev *dev, uint8_t *config,
+                         uint32_t config_len);
+int vhost_dev_set_config(struct vhost_dev *dev, const uint8_t *data,
+                         uint32_t offset, uint32_t size, uint32_t flags);
+/* notifier callback in case vhost device config space changed
+ */
+void vhost_dev_set_config_notifier(struct vhost_dev *dev,
+                                   const VhostDevConfigOps *ops);
 #endif
-- 
1.9.3

 Hi

On Tue, Jan 2, 2018 at 4:55 AM, Changpeng Liu <changpeng.liu@intel.com> wrote:
> Add VHOST_USER_GET_CONFIG/VHOST_USER_SET_CONFIG messages which can be
> used for live migration of vhost user devices, also vhost user devices
> can benefit from the messages to get/set virtio config space from/to the
> I/O target. For the purpose to support virtio config space change,
> VHOST_USER_SLAVE_CONFIG_CHANGE_MSG message is added as the event notifier
> in case virtio config space change in the slave I/O target.
>
> Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
> ---
>  docs/interop/vhost-user.txt       |  53 +++++++++++++++++
>  hw/virtio/vhost-user.c            | 118 ++++++++++++++++++++++++++++++++++++++
>  hw/virtio/vhost.c                 |  32 +++++++++++
>  include/hw/virtio/vhost-backend.h |  12 ++++
>  include/hw/virtio/vhost.h         |  15 +++++
>  5 files changed, 230 insertions(+)
>
> diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt
> index 954771d..1788fff 100644
> --- a/docs/interop/vhost-user.txt
> +++ b/docs/interop/vhost-user.txt
> @@ -116,6 +116,19 @@ Depending on the request type, payload can be:
>      - 3: IOTLB invalidate
>      - 4: IOTLB access fail
>
> + * Virtio device config space
> +   -----------------------------------
> +   | offset | size | flags | payload |
> +   -----------------------------------
> +
> +   Offset: a 32-bit offset of virtio device's configuration space
> +   Size: a 32-bit configuration space access size in bytes
> +   Flags: a 32-bit value:
> +    - 0: Vhost master messages used for writeable fields
> +    - 1: Vhost master messages used for live migration
> +   Payload: Size bytes array holding the contents of the virtio
> +       device's configuration space
> +
>  In QEMU the vhost-user message is implemented with the following struct:
>
>  typedef struct VhostUserMsg {
> @@ -129,6 +142,7 @@ typedef struct VhostUserMsg {
>          VhostUserMemory memory;
>          VhostUserLog log;
>          struct vhost_iotlb_msg iotlb;
> +        VhostUserConfig config;
>      };
>  } QEMU_PACKED VhostUserMsg;
>
> @@ -596,6 +610,30 @@ Master message types
>        and expect this message once (per VQ) during device configuration
>        (ie. before the master starts the VQ).
>
> + * VHOST_USER_GET_CONFIG
> +
> +      Id: 24
> +      Equivalent ioctl: N/A

Please document the Master payload. (msg.size != 0)


> +      Slave payload: virtio device config space
> +
> +      Submitted by the vhost-user master to fetch the contents of the virtio
> +      device configuration space, vhost-user slave's payload size MUST match
> +      master's request, vhost-user slave uses zero length of payload to
> +      indicate an error to vhost-user master. The vhost-user master may
> +      cache the contents to avoid repeated VHOST_USER_GET_CONFIG calls.
> +
> +* VHOST_USER_SET_CONFIG
> +
> +      Id: 25
> +      Equivalent ioctl: N/A

Same here

> +      Master payload: virtio device config space
> +
> +      Submitted by the vhost-user master when the Guest changes the virtio
> +      device configuration space and also can be used for live migration
> +      on the destination host. The vhost-user slave must check the flags
> +      field, and slaves MUST NOT accept SET_CONFIG for read-only
> +      configuration space fields unless the live migration bit is set.
> +
>  Slave message types
>  -------------------
>
> @@ -614,6 +652,21 @@ Slave message types
>        This request should be send only when VIRTIO_F_IOMMU_PLATFORM feature
>        has been successfully negotiated.
>
> +* VHOST_USER_SLAVE_CONFIG_CHANGE_MSG
> +
> +     Id: 2
> +     Equivalent ioctl: N/A
> +     Slave payload: N/A
> +     Master payload: N/A
> +
> +     Vhost-user slave sends such messages to notify that the virtio device's
> +     configuration space has changed, for those host devices which can support
> +     such feature, host driver can send VHOST_USER_GET_CONFIG message to slave
> +     to get the latest content. If VHOST_USER_PROTOCOL_F_REPLY_ACK is
> +     negotiated, and slave set the VHOST_USER_NEED_REPLY flag, master must
> +     respond with zero when operation is successfully completed, or non-zero
> +     otherwise.
> +
>  VHOST_USER_PROTOCOL_F_REPLY_ACK:
>  -------------------------------
>  The original vhost-user specification only demands replies for certain
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index 093675e..8b94688 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -26,6 +26,11 @@
>  #define VHOST_MEMORY_MAX_NREGIONS    8
>  #define VHOST_USER_F_PROTOCOL_FEATURES 30
>
> +/*
> + * Maximum size of virtio device config space
> + */
> +#define VHOST_USER_MAX_CONFIG_SIZE 256
> +
>  enum VhostUserProtocolFeature {
>      VHOST_USER_PROTOCOL_F_MQ = 0,
>      VHOST_USER_PROTOCOL_F_LOG_SHMFD = 1,
> @@ -65,12 +70,15 @@ typedef enum VhostUserRequest {
>      VHOST_USER_SET_SLAVE_REQ_FD = 21,
>      VHOST_USER_IOTLB_MSG = 22,
>      VHOST_USER_SET_VRING_ENDIAN = 23,
> +    VHOST_USER_GET_CONFIG = 24,
> +    VHOST_USER_SET_CONFIG = 25,
>      VHOST_USER_MAX
>  } VhostUserRequest;
>
>  typedef enum VhostUserSlaveRequest {
>      VHOST_USER_SLAVE_NONE = 0,
>      VHOST_USER_SLAVE_IOTLB_MSG = 1,
> +    VHOST_USER_SLAVE_CONFIG_CHANGE_MSG = 2,
>      VHOST_USER_SLAVE_MAX
>  }  VhostUserSlaveRequest;
>
> @@ -92,6 +100,18 @@ typedef struct VhostUserLog {
>      uint64_t mmap_offset;
>  } VhostUserLog;
>
> +typedef struct VhostUserConfig {
> +    uint32_t offset;
> +    uint32_t size;
> +    uint32_t flags;
> +    uint8_t region[VHOST_USER_MAX_CONFIG_SIZE];
> +} VhostUserConfig;
> +
> +static VhostUserConfig c __attribute__ ((unused));
> +#define VHOST_USER_CONFIG_HDR_SIZE (sizeof(c.offset) \
> +                                   + sizeof(c.size) \
> +                                   + sizeof(c.flags))
> +
>  typedef struct VhostUserMsg {
>      VhostUserRequest request;
>
> @@ -109,6 +129,7 @@ typedef struct VhostUserMsg {
>          VhostUserMemory memory;
>          VhostUserLog log;
>          struct vhost_iotlb_msg iotlb;
> +        VhostUserConfig config;
>      } payload;
>  } QEMU_PACKED VhostUserMsg;
>
> @@ -608,6 +629,21 @@ static int vhost_user_reset_device(struct vhost_dev *dev)
>      return 0;
>  }
>
> +static int vhost_user_slave_handle_config_change(struct vhost_dev *dev)
> +{
> +    int ret = -1;
> +
> +    if (!dev->config_ops) {
> +        return -1;
> +    }
> +
> +    if (dev->config_ops->vhost_dev_config_notifier) {
> +        ret = dev->config_ops->vhost_dev_config_notifier(dev);
> +    }
> +
> +    return ret;
> +}
> +
>  static void slave_read(void *opaque)
>  {
>      struct vhost_dev *dev = opaque;
> @@ -640,6 +676,9 @@ static void slave_read(void *opaque)
>      case VHOST_USER_SLAVE_IOTLB_MSG:
>          ret = vhost_backend_handle_iotlb_msg(dev, &msg.payload.iotlb);
>          break;
> +    case VHOST_USER_SLAVE_CONFIG_CHANGE_MSG :
> +        ret = vhost_user_slave_handle_config_change(dev);
> +        break;
>      default:
>          error_report("Received unexpected msg type.");
>          ret = -EINVAL;
> @@ -922,6 +961,83 @@ static void vhost_user_set_iotlb_callback(struct vhost_dev *dev, int enabled)
>      /* No-op as the receive channel is not dedicated to IOTLB messages. */
>  }
>
> +static int vhost_user_get_config(struct vhost_dev *dev, uint8_t *config,
> +                                 uint32_t config_len)
> +{
> +    VhostUserMsg msg = {
> +        msg.request = VHOST_USER_GET_CONFIG,
> +        msg.flags = VHOST_USER_VERSION,
> +        msg.size = VHOST_USER_CONFIG_HDR_SIZE + config_len,

Not really clear to me why we would need to send config_len zero's for region[].

> +    };
> +
> +    if (config_len > VHOST_USER_MAX_CONFIG_SIZE) {
> +        return -1;
> +    }
> +
> +    msg.payload.config.offset = 0;
> +    msg.payload.config.size = config_len;
> +    if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
> +        return -1;
> +    }
> +
> +    if (vhost_user_read(dev, &msg) < 0) {
> +        return -1;
> +    }
> +
> +    if (msg.request != VHOST_USER_GET_CONFIG) {
> +        error_report("Received unexpected msg type. Expected %d received %d",
> +                     VHOST_USER_GET_CONFIG, msg.request);
> +        return -1;
> +    }
> +
> +    if (msg.size != VHOST_USER_CONFIG_HDR_SIZE + config_len) {
> +        error_report("Received bad msg size.");
> +        return -1;
> +    }
> +
> +    memcpy(config, msg.payload.config.region, config_len);
> +
> +    return 0;
> +}
> +
> +static int vhost_user_set_config(struct vhost_dev *dev, const uint8_t *data,
> +                                 uint32_t offset, uint32_t size, uint32_t flags)
> +{
> +    uint8_t *p;
> +    bool reply_supported = virtio_has_feature(dev->protocol_features,
> +                                              VHOST_USER_PROTOCOL_F_REPLY_ACK);
> +
> +    VhostUserMsg msg = {
> +        msg.request = VHOST_USER_SET_CONFIG,
> +        msg.flags = VHOST_USER_VERSION,
> +        msg.size = VHOST_USER_CONFIG_HDR_SIZE + size,
> +    };
> +
> +    if (reply_supported) {
> +        msg.flags |= VHOST_USER_NEED_REPLY_MASK;
> +    }
> +
> +    if (size > VHOST_USER_MAX_CONFIG_SIZE) {
> +        return -1;
> +    }
> +
> +    msg.payload.config.offset = offset,
> +    msg.payload.config.size = size,
> +    msg.payload.config.flags = flags,
> +    p = msg.payload.config.region;
> +    memcpy(p, data, size);
> +
> +    if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
> +        return -1;
> +    }
> +
> +    if (reply_supported) {
> +        return process_message_reply(dev, &msg);
> +    }
> +
> +    return 0;
> +}
> +
>  const VhostOps user_ops = {
>          .backend_type = VHOST_BACKEND_TYPE_USER,
>          .vhost_backend_init = vhost_user_init,
> @@ -948,4 +1064,6 @@ const VhostOps user_ops = {
>          .vhost_net_set_mtu = vhost_user_net_set_mtu,
>          .vhost_set_iotlb_callback = vhost_user_set_iotlb_callback,
>          .vhost_send_device_iotlb_msg = vhost_user_send_device_iotlb_msg,
> +        .vhost_get_config = vhost_user_get_config,
> +        .vhost_set_config = vhost_user_set_config,
>  };
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index e4290ce..386aef8 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -1505,6 +1505,38 @@ void vhost_ack_features(struct vhost_dev *hdev, const int *feature_bits,
>      }
>  }
>
> +int vhost_dev_get_config(struct vhost_dev *hdev, uint8_t *config,
> +                         uint32_t config_len)
> +{
> +    assert(hdev->vhost_ops);
> +
> +    if (hdev->vhost_ops->vhost_get_config) {
> +        return hdev->vhost_ops->vhost_get_config(hdev, config, config_len);
> +    }
> +
> +    return -1;
> +}
> +
> +int vhost_dev_set_config(struct vhost_dev *hdev, const uint8_t *data,
> +                         uint32_t offset, uint32_t size, uint32_t flags)
> +{
> +    assert(hdev->vhost_ops);
> +
> +    if (hdev->vhost_ops->vhost_set_config) {
> +        return hdev->vhost_ops->vhost_set_config(hdev, data, offset,
> +                                                 size, flags);
> +    }
> +
> +    return -1;
> +}
> +
> +void vhost_dev_set_config_notifier(struct vhost_dev *hdev,
> +                                   const VhostDevConfigOps *ops)
> +{
> +    assert(hdev->vhost_ops);
> +    hdev->config_ops = ops;
> +}
> +
>  /* Host notifiers must be enabled at this point. */
>  int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)
>  {
> diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h
> index a7a5f22..592254f 100644
> --- a/include/hw/virtio/vhost-backend.h
> +++ b/include/hw/virtio/vhost-backend.h
> @@ -20,6 +20,11 @@ typedef enum VhostBackendType {
>      VHOST_BACKEND_TYPE_MAX = 3,
>  } VhostBackendType;
>
> +typedef enum VhostSetConfigType {
> +    VHOST_SET_CONFIG_TYPE_MASTER = 0,
> +    VHOST_SET_CONFIG_TYPE_MIGRATION = 1,
> +} VhostSetConfigType;
> +
>  struct vhost_dev;
>  struct vhost_log;
>  struct vhost_memory;
> @@ -84,6 +89,11 @@ typedef void (*vhost_set_iotlb_callback_op)(struct vhost_dev *dev,
>                                             int enabled);
>  typedef int (*vhost_send_device_iotlb_msg_op)(struct vhost_dev *dev,
>                                                struct vhost_iotlb_msg *imsg);
> +typedef int (*vhost_set_config_op)(struct vhost_dev *dev, const uint8_t *data,
> +                                   uint32_t offset, uint32_t size,
> +                                   uint32_t flags);
> +typedef int (*vhost_get_config_op)(struct vhost_dev *dev, uint8_t *config,
> +                                   uint32_t config_len);
>
>  typedef struct VhostOps {
>      VhostBackendType backend_type;
> @@ -118,6 +128,8 @@ typedef struct VhostOps {
>      vhost_vsock_set_running_op vhost_vsock_set_running;
>      vhost_set_iotlb_callback_op vhost_set_iotlb_callback;
>      vhost_send_device_iotlb_msg_op vhost_send_device_iotlb_msg;
> +    vhost_get_config_op vhost_get_config;
> +    vhost_set_config_op vhost_set_config;
>  } VhostOps;
>
>  extern const VhostOps user_ops;
> diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
> index 467dc77..1dc2d73 100644
> --- a/include/hw/virtio/vhost.h
> +++ b/include/hw/virtio/vhost.h
> @@ -46,6 +46,12 @@ struct vhost_iommu {
>      QLIST_ENTRY(vhost_iommu) iommu_next;
>  };
>
> +typedef struct VhostDevConfigOps {
> +    /* Vhost device config space changed callback
> +     */
> +    int (*vhost_dev_config_notifier)(struct vhost_dev *dev);
> +} VhostDevConfigOps;
> +
>  struct vhost_memory;
>  struct vhost_dev {
>      VirtIODevice *vdev;
> @@ -76,6 +82,7 @@ struct vhost_dev {
>      QLIST_ENTRY(vhost_dev) entry;
>      QLIST_HEAD(, vhost_iommu) iommu_list;
>      IOMMUNotifier n;
> +    const VhostDevConfigOps *config_ops;
>  };
>
>  int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
> @@ -106,4 +113,12 @@ int vhost_net_set_backend(struct vhost_dev *hdev,
>                            struct vhost_vring_file *file);
>
>  int vhost_device_iotlb_miss(struct vhost_dev *dev, uint64_t iova, int write);
> +int vhost_dev_get_config(struct vhost_dev *dev, uint8_t *config,
> +                         uint32_t config_len);
> +int vhost_dev_set_config(struct vhost_dev *dev, const uint8_t *data,
> +                         uint32_t offset, uint32_t size, uint32_t flags);
> +/* notifier callback in case vhost device config space changed
> + */
> +void vhost_dev_set_config_notifier(struct vhost_dev *dev,
> +                                   const VhostDevConfigOps *ops);
>  #endif
> --
> 1.9.3
>
>



-- 
Marc-André Lureau

> -----Original Message-----
> From: Marc-André Lureau [mailto:marcandre.lureau@gmail.com]
> Sent: Tuesday, January 2, 2018 11:20 PM
> To: Liu, Changpeng <changpeng.liu@intel.com>
> Cc: QEMU <qemu-devel@nongnu.org>; Harris, James R <james.r.harris@intel.com>;
> Michael S. Tsirkin <mst@redhat.com>; Stefan Hajnoczi <stefanha@gmail.com>;
> Paolo Bonzini <pbonzini@redhat.com>; Felipe Franciosi <felipe@nutanix.com>
> Subject: Re: [Qemu-devel] [PATCH v8 1/4] vhost-user: add new vhost user messages
> to support virtio config space
> 
>  Hi
> 
> On Tue, Jan 2, 2018 at 4:55 AM, Changpeng Liu <changpeng.liu@intel.com> wrote:
> > Add VHOST_USER_GET_CONFIG/VHOST_USER_SET_CONFIG messages which can
> be
> > used for live migration of vhost user devices, also vhost user devices
> > can benefit from the messages to get/set virtio config space from/to the
> > I/O target. For the purpose to support virtio config space change,
> > VHOST_USER_SLAVE_CONFIG_CHANGE_MSG message is added as the event
> notifier
> > in case virtio config space change in the slave I/O target.
> >
> > Signed-off-by: Changpeng Liu <changpeng.liu@intel.com>
> > ---
> >  docs/interop/vhost-user.txt       |  53 +++++++++++++++++
> >  hw/virtio/vhost-user.c            | 118 ++++++++++++++++++++++++++++++++++++++
> >  hw/virtio/vhost.c                 |  32 +++++++++++
> >  include/hw/virtio/vhost-backend.h |  12 ++++
> >  include/hw/virtio/vhost.h         |  15 +++++
> >  5 files changed, 230 insertions(+)
> >
> > diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt
> > index 954771d..1788fff 100644
> > --- a/docs/interop/vhost-user.txt
> > +++ b/docs/interop/vhost-user.txt
> > @@ -116,6 +116,19 @@ Depending on the request type, payload can be:
> >      - 3: IOTLB invalidate
> >      - 4: IOTLB access fail
> >
> > + * Virtio device config space
> > +   -----------------------------------
> > +   | offset | size | flags | payload |
> > +   -----------------------------------
> > +
> > +   Offset: a 32-bit offset of virtio device's configuration space
> > +   Size: a 32-bit configuration space access size in bytes
> > +   Flags: a 32-bit value:
> > +    - 0: Vhost master messages used for writeable fields
> > +    - 1: Vhost master messages used for live migration
> > +   Payload: Size bytes array holding the contents of the virtio
> > +       device's configuration space
> > +
> >  In QEMU the vhost-user message is implemented with the following struct:
> >
> >  typedef struct VhostUserMsg {
> > @@ -129,6 +142,7 @@ typedef struct VhostUserMsg {
> >          VhostUserMemory memory;
> >          VhostUserLog log;
> >          struct vhost_iotlb_msg iotlb;
> > +        VhostUserConfig config;
> >      };
> >  } QEMU_PACKED VhostUserMsg;
> >
> > @@ -596,6 +610,30 @@ Master message types
> >        and expect this message once (per VQ) during device configuration
> >        (ie. before the master starts the VQ).
> >
> > + * VHOST_USER_GET_CONFIG
> > +
> > +      Id: 24
> > +      Equivalent ioctl: N/A
> 
> Please document the Master payload. (msg.size != 0)
Ok, will add.
> 
> 
> > +      Slave payload: virtio device config space
> > +
> > +      Submitted by the vhost-user master to fetch the contents of the virtio
> > +      device configuration space, vhost-user slave's payload size MUST match
> > +      master's request, vhost-user slave uses zero length of payload to
> > +      indicate an error to vhost-user master. The vhost-user master may
> > +      cache the contents to avoid repeated VHOST_USER_GET_CONFIG calls.
> > +
> > +* VHOST_USER_SET_CONFIG
> > +
> > +      Id: 25
> > +      Equivalent ioctl: N/A
> 
> Same here
Ok.
> 
> > +      Master payload: virtio device config space
> > +
> > +      Submitted by the vhost-user master when the Guest changes the virtio
> > +      device configuration space and also can be used for live migration
> > +      on the destination host. The vhost-user slave must check the flags
> > +      field, and slaves MUST NOT accept SET_CONFIG for read-only
> > +      configuration space fields unless the live migration bit is set.
> > +
> >  Slave message types
> >  -------------------
> >
> > @@ -614,6 +652,21 @@ Slave message types
> >        This request should be send only when VIRTIO_F_IOMMU_PLATFORM
> feature
> >        has been successfully negotiated.
> >
> > +* VHOST_USER_SLAVE_CONFIG_CHANGE_MSG
> > +
> > +     Id: 2
> > +     Equivalent ioctl: N/A
> > +     Slave payload: N/A
> > +     Master payload: N/A
> > +
> > +     Vhost-user slave sends such messages to notify that the virtio device's
> > +     configuration space has changed, for those host devices which can support
> > +     such feature, host driver can send VHOST_USER_GET_CONFIG message to
> slave
> > +     to get the latest content. If VHOST_USER_PROTOCOL_F_REPLY_ACK is
> > +     negotiated, and slave set the VHOST_USER_NEED_REPLY flag, master must
> > +     respond with zero when operation is successfully completed, or non-zero
> > +     otherwise.
> > +
> >  VHOST_USER_PROTOCOL_F_REPLY_ACK:
> >  -------------------------------
> >  The original vhost-user specification only demands replies for certain
> > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> > index 093675e..8b94688 100644
> > --- a/hw/virtio/vhost-user.c
> > +++ b/hw/virtio/vhost-user.c
> > @@ -26,6 +26,11 @@
> >  #define VHOST_MEMORY_MAX_NREGIONS    8
> >  #define VHOST_USER_F_PROTOCOL_FEATURES 30
> >
> > +/*
> > + * Maximum size of virtio device config space
> > + */
> > +#define VHOST_USER_MAX_CONFIG_SIZE 256
> > +
> >  enum VhostUserProtocolFeature {
> >      VHOST_USER_PROTOCOL_F_MQ = 0,
> >      VHOST_USER_PROTOCOL_F_LOG_SHMFD = 1,
> > @@ -65,12 +70,15 @@ typedef enum VhostUserRequest {
> >      VHOST_USER_SET_SLAVE_REQ_FD = 21,
> >      VHOST_USER_IOTLB_MSG = 22,
> >      VHOST_USER_SET_VRING_ENDIAN = 23,
> > +    VHOST_USER_GET_CONFIG = 24,
> > +    VHOST_USER_SET_CONFIG = 25,
> >      VHOST_USER_MAX
> >  } VhostUserRequest;
> >
> >  typedef enum VhostUserSlaveRequest {
> >      VHOST_USER_SLAVE_NONE = 0,
> >      VHOST_USER_SLAVE_IOTLB_MSG = 1,
> > +    VHOST_USER_SLAVE_CONFIG_CHANGE_MSG = 2,
> >      VHOST_USER_SLAVE_MAX
> >  }  VhostUserSlaveRequest;
> >
> > @@ -92,6 +100,18 @@ typedef struct VhostUserLog {
> >      uint64_t mmap_offset;
> >  } VhostUserLog;
> >
> > +typedef struct VhostUserConfig {
> > +    uint32_t offset;
> > +    uint32_t size;
> > +    uint32_t flags;
> > +    uint8_t region[VHOST_USER_MAX_CONFIG_SIZE];
> > +} VhostUserConfig;
> > +
> > +static VhostUserConfig c __attribute__ ((unused));
> > +#define VHOST_USER_CONFIG_HDR_SIZE (sizeof(c.offset) \
> > +                                   + sizeof(c.size) \
> > +                                   + sizeof(c.flags))
> > +
> >  typedef struct VhostUserMsg {
> >      VhostUserRequest request;
> >
> > @@ -109,6 +129,7 @@ typedef struct VhostUserMsg {
> >          VhostUserMemory memory;
> >          VhostUserLog log;
> >          struct vhost_iotlb_msg iotlb;
> > +        VhostUserConfig config;
> >      } payload;
> >  } QEMU_PACKED VhostUserMsg;
> >
> > @@ -608,6 +629,21 @@ static int vhost_user_reset_device(struct vhost_dev
> *dev)
> >      return 0;
> >  }
> >
> > +static int vhost_user_slave_handle_config_change(struct vhost_dev *dev)
> > +{
> > +    int ret = -1;
> > +
> > +    if (!dev->config_ops) {
> > +        return -1;
> > +    }
> > +
> > +    if (dev->config_ops->vhost_dev_config_notifier) {
> > +        ret = dev->config_ops->vhost_dev_config_notifier(dev);
> > +    }
> > +
> > +    return ret;
> > +}
> > +
> >  static void slave_read(void *opaque)
> >  {
> >      struct vhost_dev *dev = opaque;
> > @@ -640,6 +676,9 @@ static void slave_read(void *opaque)
> >      case VHOST_USER_SLAVE_IOTLB_MSG:
> >          ret = vhost_backend_handle_iotlb_msg(dev, &msg.payload.iotlb);
> >          break;
> > +    case VHOST_USER_SLAVE_CONFIG_CHANGE_MSG :
> > +        ret = vhost_user_slave_handle_config_change(dev);
> > +        break;
> >      default:
> >          error_report("Received unexpected msg type.");
> >          ret = -EINVAL;
> > @@ -922,6 +961,83 @@ static void vhost_user_set_iotlb_callback(struct
> vhost_dev *dev, int enabled)
> >      /* No-op as the receive channel is not dedicated to IOTLB messages. */
> >  }
> >
> > +static int vhost_user_get_config(struct vhost_dev *dev, uint8_t *config,
> > +                                 uint32_t config_len)
> > +{
> > +    VhostUserMsg msg = {
> > +        msg.request = VHOST_USER_GET_CONFIG,
> > +        msg.flags = VHOST_USER_VERSION,
> > +        msg.size = VHOST_USER_CONFIG_HDR_SIZE + config_len,
> 
> Not really clear to me why we would need to send config_len zero's for region[].
It's better to let host device driver, e.g: vhost-user-blk driver to get the whole configuration space
at once, some parameters inside the struct virtio_blk_config may not continuous, so that the master
should send such request for many times.
> 
> > +    };
> > +
> > +    if (config_len > VHOST_USER_MAX_CONFIG_SIZE) {
> > +        return -1;
> > +    }
> > +
> > +    msg.payload.config.offset = 0;
> > +    msg.payload.config.size = config_len;
> > +    if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
> > +        return -1;
> > +    }
> > +
> > +    if (vhost_user_read(dev, &msg) < 0) {
> > +        return -1;
> > +    }
> > +
> > +    if (msg.request != VHOST_USER_GET_CONFIG) {
> > +        error_report("Received unexpected msg type. Expected %d received %d",
> > +                     VHOST_USER_GET_CONFIG, msg.request);
> > +        return -1;
> > +    }
> > +
> > +    if (msg.size != VHOST_USER_CONFIG_HDR_SIZE + config_len) {
> > +        error_report("Received bad msg size.");
> > +        return -1;
> > +    }
> > +
> > +    memcpy(config, msg.payload.config.region, config_len);
> > +
> > +    return 0;
> > +}
> > +
> > +static int vhost_user_set_config(struct vhost_dev *dev, const uint8_t *data,
> > +                                 uint32_t offset, uint32_t size, uint32_t flags)
> > +{
> > +    uint8_t *p;
> > +    bool reply_supported = virtio_has_feature(dev->protocol_features,
> > +                                              VHOST_USER_PROTOCOL_F_REPLY_ACK);
> > +
> > +    VhostUserMsg msg = {
> > +        msg.request = VHOST_USER_SET_CONFIG,
> > +        msg.flags = VHOST_USER_VERSION,
> > +        msg.size = VHOST_USER_CONFIG_HDR_SIZE + size,
> > +    };
> > +
> > +    if (reply_supported) {
> > +        msg.flags |= VHOST_USER_NEED_REPLY_MASK;
> > +    }
> > +
> > +    if (size > VHOST_USER_MAX_CONFIG_SIZE) {
> > +        return -1;
> > +    }
> > +
> > +    msg.payload.config.offset = offset,
> > +    msg.payload.config.size = size,
> > +    msg.payload.config.flags = flags,
> > +    p = msg.payload.config.region;
> > +    memcpy(p, data, size);
> > +
> > +    if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
> > +        return -1;
> > +    }
> > +
> > +    if (reply_supported) {
> > +        return process_message_reply(dev, &msg);
> > +    }
> > +
> > +    return 0;
> > +}
> > +
> >  const VhostOps user_ops = {
> >          .backend_type = VHOST_BACKEND_TYPE_USER,
> >          .vhost_backend_init = vhost_user_init,
> > @@ -948,4 +1064,6 @@ const VhostOps user_ops = {
> >          .vhost_net_set_mtu = vhost_user_net_set_mtu,
> >          .vhost_set_iotlb_callback = vhost_user_set_iotlb_callback,
> >          .vhost_send_device_iotlb_msg = vhost_user_send_device_iotlb_msg,
> > +        .vhost_get_config = vhost_user_get_config,
> > +        .vhost_set_config = vhost_user_set_config,
> >  };
> > diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> > index e4290ce..386aef8 100644
> > --- a/hw/virtio/vhost.c
> > +++ b/hw/virtio/vhost.c
> > @@ -1505,6 +1505,38 @@ void vhost_ack_features(struct vhost_dev *hdev,
> const int *feature_bits,
> >      }
> >  }
> >
> > +int vhost_dev_get_config(struct vhost_dev *hdev, uint8_t *config,
> > +                         uint32_t config_len)
> > +{
> > +    assert(hdev->vhost_ops);
> > +
> > +    if (hdev->vhost_ops->vhost_get_config) {
> > +        return hdev->vhost_ops->vhost_get_config(hdev, config, config_len);
> > +    }
> > +
> > +    return -1;
> > +}
> > +
> > +int vhost_dev_set_config(struct vhost_dev *hdev, const uint8_t *data,
> > +                         uint32_t offset, uint32_t size, uint32_t flags)
> > +{
> > +    assert(hdev->vhost_ops);
> > +
> > +    if (hdev->vhost_ops->vhost_set_config) {
> > +        return hdev->vhost_ops->vhost_set_config(hdev, data, offset,
> > +                                                 size, flags);
> > +    }
> > +
> > +    return -1;
> > +}
> > +
> > +void vhost_dev_set_config_notifier(struct vhost_dev *hdev,
> > +                                   const VhostDevConfigOps *ops)
> > +{
> > +    assert(hdev->vhost_ops);
> > +    hdev->config_ops = ops;
> > +}
> > +
> >  /* Host notifiers must be enabled at this point. */
> >  int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev)
> >  {
> > diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-
> backend.h
> > index a7a5f22..592254f 100644
> > --- a/include/hw/virtio/vhost-backend.h
> > +++ b/include/hw/virtio/vhost-backend.h
> > @@ -20,6 +20,11 @@ typedef enum VhostBackendType {
> >      VHOST_BACKEND_TYPE_MAX = 3,
> >  } VhostBackendType;
> >
> > +typedef enum VhostSetConfigType {
> > +    VHOST_SET_CONFIG_TYPE_MASTER = 0,
> > +    VHOST_SET_CONFIG_TYPE_MIGRATION = 1,
> > +} VhostSetConfigType;
> > +
> >  struct vhost_dev;
> >  struct vhost_log;
> >  struct vhost_memory;
> > @@ -84,6 +89,11 @@ typedef void (*vhost_set_iotlb_callback_op)(struct
> vhost_dev *dev,
> >                                             int enabled);
> >  typedef int (*vhost_send_device_iotlb_msg_op)(struct vhost_dev *dev,
> >                                                struct vhost_iotlb_msg *imsg);
> > +typedef int (*vhost_set_config_op)(struct vhost_dev *dev, const uint8_t *data,
> > +                                   uint32_t offset, uint32_t size,
> > +                                   uint32_t flags);
> > +typedef int (*vhost_get_config_op)(struct vhost_dev *dev, uint8_t *config,
> > +                                   uint32_t config_len);
> >
> >  typedef struct VhostOps {
> >      VhostBackendType backend_type;
> > @@ -118,6 +128,8 @@ typedef struct VhostOps {
> >      vhost_vsock_set_running_op vhost_vsock_set_running;
> >      vhost_set_iotlb_callback_op vhost_set_iotlb_callback;
> >      vhost_send_device_iotlb_msg_op vhost_send_device_iotlb_msg;
> > +    vhost_get_config_op vhost_get_config;
> > +    vhost_set_config_op vhost_set_config;
> >  } VhostOps;
> >
> >  extern const VhostOps user_ops;
> > diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h
> > index 467dc77..1dc2d73 100644
> > --- a/include/hw/virtio/vhost.h
> > +++ b/include/hw/virtio/vhost.h
> > @@ -46,6 +46,12 @@ struct vhost_iommu {
> >      QLIST_ENTRY(vhost_iommu) iommu_next;
> >  };
> >
> > +typedef struct VhostDevConfigOps {
> > +    /* Vhost device config space changed callback
> > +     */
> > +    int (*vhost_dev_config_notifier)(struct vhost_dev *dev);
> > +} VhostDevConfigOps;
> > +
> >  struct vhost_memory;
> >  struct vhost_dev {
> >      VirtIODevice *vdev;
> > @@ -76,6 +82,7 @@ struct vhost_dev {
> >      QLIST_ENTRY(vhost_dev) entry;
> >      QLIST_HEAD(, vhost_iommu) iommu_list;
> >      IOMMUNotifier n;
> > +    const VhostDevConfigOps *config_ops;
> >  };
> >
> >  int vhost_dev_init(struct vhost_dev *hdev, void *opaque,
> > @@ -106,4 +113,12 @@ int vhost_net_set_backend(struct vhost_dev *hdev,
> >                            struct vhost_vring_file *file);
> >
> >  int vhost_device_iotlb_miss(struct vhost_dev *dev, uint64_t iova, int write);
> > +int vhost_dev_get_config(struct vhost_dev *dev, uint8_t *config,
> > +                         uint32_t config_len);
> > +int vhost_dev_set_config(struct vhost_dev *dev, const uint8_t *data,
> > +                         uint32_t offset, uint32_t size, uint32_t flags);
> > +/* notifier callback in case vhost device config space changed
> > + */
> > +void vhost_dev_set_config_notifier(struct vhost_dev *dev,
> > +                                   const VhostDevConfigOps *ops);
> >  #endif
> > --
> > 1.9.3
> >
> >
> 
> 
> 
> --
> Marc-André Lureau