mirror of https://github.com/xemu-project/xemu.git
spec/vhost-user spec: Add IOMMU support
This patch specifies and implements the master/slave communication to support device IOTLB in slave. The vhost_iotlb_msg structure introduced for kernel backends is re-used, making the design close between the two backends. An exception is the use of the secondary channel to enable the slave to send IOTLB miss requests to the master. 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>
This commit is contained in:
Maxime Coquelin
Michael S. Tsirkin
parent
4bbeeba023
commit
6dcdd06e3b
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@ -97,6 +97,25 @@ Depending on the request type, payload can be:
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log offset: offset from start of supplied file descriptor
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where logging starts (i.e. where guest address 0 would be logged)
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* An IOTLB message
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---------------------------------------------------------
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| iova | size | user address | permissions flags | type |
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---------------------------------------------------------
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IOVA: a 64-bit I/O virtual address programmed by the guest
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Size: a 64-bit size
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User address: a 64-bit user address
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Permissions: a 8-bit value:
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- 0: No access
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- 1: Read access
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- 2: Write access
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- 3: Read/Write access
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Type: a 8-bit IOTLB message type:
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- 1: IOTLB miss
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- 2: IOTLB update
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- 3: IOTLB invalidate
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- 4: IOTLB access fail
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In QEMU the vhost-user message is implemented with the following struct:
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typedef struct VhostUserMsg {
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@ -109,6 +128,7 @@ typedef struct VhostUserMsg {
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struct vhost_vring_addr addr;
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VhostUserMemory memory;
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VhostUserLog log;
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struct vhost_iotlb_msg iotlb;
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};
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} QEMU_PACKED VhostUserMsg;
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@ -253,6 +273,38 @@ Once the source has finished migration, rings will be stopped by
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the source. No further update must be done before rings are
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restarted.
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IOMMU support
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-------------
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When the VIRTIO_F_IOMMU_PLATFORM feature has been negotiated, the master
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sends IOTLB entries update & invalidation by sending VHOST_USER_IOTLB_MSG
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requests to the slave with a struct vhost_iotlb_msg as payload. For update
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events, the iotlb payload has to be filled with the update message type (2),
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the I/O virtual address, the size, the user virtual address, and the
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permissions flags. Addresses and size must be within vhost memory regions set
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via the VHOST_USER_SET_MEM_TABLE request. For invalidation events, the iotlb
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payload has to be filled with the invalidation message type (3), the I/O virtual
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address and the size. On success, the slave is expected to reply with a zero
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payload, non-zero otherwise.
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The slave relies on the slave communcation channel (see "Slave communication"
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section below) to send IOTLB miss and access failure events, by sending
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VHOST_USER_SLAVE_IOTLB_MSG requests to the master with a struct vhost_iotlb_msg
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as payload. For miss events, the iotlb payload has to be filled with the miss
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message type (1), the I/O virtual address and the permissions flags. For access
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failure event, the iotlb payload has to be filled with the access failure
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message type (4), the I/O virtual address and the permissions flags.
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For synchronization purpose, the slave may rely on the reply-ack feature,
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so the master may send a reply when operation is completed if the reply-ack
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feature is negotiated and slaves requests a reply. For miss events, completed
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operation means either master sent an update message containing the IOTLB entry
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containing requested address and permission, or master sent nothing if the IOTLB
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miss message is invalid (invalid IOVA or permission).
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The master isn't expected to take the initiative to send IOTLB update messages,
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as the slave sends IOTLB miss messages for the guest virtual memory areas it
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needs to access.
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Slave communication
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-------------------
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@ -514,6 +566,38 @@ Master message types
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If VHOST_USER_PROTOCOL_F_REPLY_ACK is negotiated, slave must respond
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with zero for success, non-zero otherwise.
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* VHOST_USER_IOTLB_MSG
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Id: 22
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Equivalent ioctl: N/A (equivalent to VHOST_IOTLB_MSG message type)
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Master payload: struct vhost_iotlb_msg
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Slave payload: u64
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Send IOTLB messages with struct vhost_iotlb_msg as payload.
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Master sends such requests to update and invalidate entries in the device
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IOTLB. The slave has to acknowledge the request with sending zero as u64
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payload for success, non-zero otherwise.
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This request should be send only when VIRTIO_F_IOMMU_PLATFORM feature
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has been successfully negotiated.
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Slave message types
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-------------------
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* VHOST_USER_SLAVE_IOTLB_MSG
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Id: 1
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Equivalent ioctl: N/A (equivalent to VHOST_IOTLB_MSG message type)
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Slave payload: struct vhost_iotlb_msg
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Master payload: N/A
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Send IOTLB messages with struct vhost_iotlb_msg as payload.
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Slave sends such requests to notify of an IOTLB miss, or an IOTLB
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access failure. If VHOST_USER_PROTOCOL_F_REPLY_ACK is negotiated,
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and slave set the VHOST_USER_NEED_REPLY flag, master must respond with
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zero when operation is successfully completed, or non-zero otherwise.
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This request should be send only when VIRTIO_F_IOMMU_PLATFORM feature
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has been successfully negotiated.
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VHOST_USER_PROTOCOL_F_REPLY_ACK:
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-------------------------------
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The original vhost-user specification only demands replies for certain
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@ -77,6 +77,7 @@ static const int user_feature_bits[] = {
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VIRTIO_NET_F_HOST_UFO,
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VIRTIO_NET_F_MRG_RXBUF,
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VIRTIO_NET_F_MTU,
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VIRTIO_F_IOMMU_PLATFORM,
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/* This bit implies RARP isn't sent by QEMU out of band */
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VIRTIO_NET_F_GUEST_ANNOUNCE,
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@ -62,11 +62,13 @@ typedef enum VhostUserRequest {
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VHOST_USER_SEND_RARP = 19,
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VHOST_USER_NET_SET_MTU = 20,
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VHOST_USER_SET_SLAVE_REQ_FD = 21,
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VHOST_USER_IOTLB_MSG = 22,
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VHOST_USER_MAX
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} VhostUserRequest;
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typedef enum VhostUserSlaveRequest {
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VHOST_USER_SLAVE_NONE = 0,
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VHOST_USER_SLAVE_IOTLB_MSG = 1,
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VHOST_USER_SLAVE_MAX
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} VhostUserSlaveRequest;
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@ -104,6 +106,7 @@ typedef struct VhostUserMsg {
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struct vhost_vring_addr addr;
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VhostUserMemory memory;
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VhostUserLog log;
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struct vhost_iotlb_msg iotlb;
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} payload;
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} QEMU_PACKED VhostUserMsg;
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@ -615,6 +618,9 @@ static void slave_read(void *opaque)
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}
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switch (msg.request) {
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case VHOST_USER_SLAVE_IOTLB_MSG:
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ret = vhost_backend_handle_iotlb_msg(dev, &msg.payload.iotlb);
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break;
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default:
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error_report("Received unexpected msg type.");
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ret = -EINVAL;
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@ -697,7 +703,7 @@ out:
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static int vhost_user_init(struct vhost_dev *dev, void *opaque)
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{
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uint64_t features;
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uint64_t features, protocol_features;
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struct vhost_user *u;
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int err;
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@ -717,12 +723,13 @@ static int vhost_user_init(struct vhost_dev *dev, void *opaque)
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dev->backend_features |= 1ULL << VHOST_USER_F_PROTOCOL_FEATURES;
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err = vhost_user_get_u64(dev, VHOST_USER_GET_PROTOCOL_FEATURES,
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&features);
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&protocol_features);
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if (err < 0) {
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return err;
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}
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dev->protocol_features = features & VHOST_USER_PROTOCOL_FEATURE_MASK;
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dev->protocol_features =
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protocol_features & VHOST_USER_PROTOCOL_FEATURE_MASK;
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err = vhost_user_set_protocol_features(dev, dev->protocol_features);
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if (err < 0) {
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return err;
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@ -736,6 +743,16 @@ static int vhost_user_init(struct vhost_dev *dev, void *opaque)
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return err;
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}
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}
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if (virtio_has_feature(features, VIRTIO_F_IOMMU_PLATFORM) &&
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!(virtio_has_feature(dev->protocol_features,
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VHOST_USER_PROTOCOL_F_SLAVE_REQ) &&
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virtio_has_feature(dev->protocol_features,
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VHOST_USER_PROTOCOL_F_REPLY_ACK))) {
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error_report("IOMMU support requires reply-ack and "
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"slave-req protocol features.");
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return -1;
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}
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}
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if (dev->migration_blocker == NULL &&
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@ -862,6 +879,29 @@ static int vhost_user_net_set_mtu(struct vhost_dev *dev, uint16_t mtu)
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return 0;
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}
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static int vhost_user_send_device_iotlb_msg(struct vhost_dev *dev,
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struct vhost_iotlb_msg *imsg)
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{
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VhostUserMsg msg = {
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.request = VHOST_USER_IOTLB_MSG,
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.size = sizeof(msg.payload.iotlb),
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.flags = VHOST_USER_VERSION | VHOST_USER_NEED_REPLY_MASK,
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.payload.iotlb = *imsg,
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};
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if (vhost_user_write(dev, &msg, NULL, 0) < 0) {
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return -EFAULT;
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}
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return process_message_reply(dev, &msg);
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}
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static void vhost_user_set_iotlb_callback(struct vhost_dev *dev, int enabled)
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{
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/* No-op as the receive channel is not dedicated to IOTLB messages. */
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}
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const VhostOps user_ops = {
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.backend_type = VHOST_BACKEND_TYPE_USER,
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.vhost_backend_init = vhost_user_init,
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@ -886,4 +926,6 @@ const VhostOps user_ops = {
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.vhost_migration_done = vhost_user_migration_done,
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.vhost_backend_can_merge = vhost_user_can_merge,
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.vhost_net_set_mtu = vhost_user_net_set_mtu,
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.vhost_set_iotlb_callback = vhost_user_set_iotlb_callback,
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.vhost_send_device_iotlb_msg = vhost_user_send_device_iotlb_msg,
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};
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