From f2ef472de8d94edcb42b419116611d3ffc51d099 Mon Sep 17 00:00:00 2001

From: Maxime Coquelin <maxime.coquelin@redhat.com>

Date: Tue, 6 Jun 2017 12:05:23 +0200

Subject: [PATCH 12/17] vhost-user: add slave-req-fd support

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RH-Author: Maxime Coquelin <maxime.coquelin@redhat.com>

Message-id: <20170606120524.3050-5-maxime.coquelin@redhat.com>

Patchwork-id: 75500

O-Subject: [RHV-7.4 qemu-kvm-rhev PATCH 4/5] vhost-user: add slave-req-fd support

Bugzilla: 1451862

RH-Acked-by: Peter Xu <peterx@redhat.com>

RH-Acked-by: Xiao Wang <jasowang@redhat.com>

RH-Acked-by: Jens Freimann <jfreiman@redhat.com>

From: Marc-André Lureau <marcandre.lureau@redhat.com>

Learn to give a socket to the slave to let him make requests to the

master.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>

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>

(cherry picked from commit 4bbeeba023f22c117d7a4c561354b91a0bf62e42)

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 docs/specs/vhost-user.txt |  32 +++++++++++-

 hw/virtio/vhost-user.c    | 127 ++++++++++++++++++++++++++++++++++++++++++++++

 2 files changed, 157 insertions(+), 2 deletions(-)

diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt

index 036890f..5fa7016 100644

--- a/docs/specs/vhost-user.txt

+++ b/docs/specs/vhost-user.txt

@@ -139,6 +139,7 @@ in the ancillary data:

  * VHOST_USER_SET_VRING_KICK

  * VHOST_USER_SET_VRING_CALL

  * VHOST_USER_SET_VRING_ERR

+ * VHOST_USER_SET_SLAVE_REQ_FD

 If Master is unable to send the full message or receives a wrong reply it will

 close the connection. An optional reconnection mechanism can be implemented.

@@ -252,6 +253,18 @@ Once the source has finished migration, rings will be stopped by

 the source. No further update must be done before rings are

 restarted.

+Slave communication

+-------------------

+

+An optional communication channel is provided if the slave declares

+VHOST_USER_PROTOCOL_F_SLAVE_REQ protocol feature, to allow the slave to make

+requests to the master.

+

+The fd is provided via VHOST_USER_SET_SLAVE_REQ_FD ancillary data.

+

+A slave may then send VHOST_USER_SLAVE_* messages to the master

+using this fd communication channel.

+

 Protocol features

 -----------------

@@ -260,9 +273,10 @@ Protocol features

 #define VHOST_USER_PROTOCOL_F_RARP           2

 #define VHOST_USER_PROTOCOL_F_REPLY_ACK      3

 #define VHOST_USER_PROTOCOL_F_MTU            4

+#define VHOST_USER_PROTOCOL_F_SLAVE_REQ      5

-Message types

--------------

+Master message types

+--------------------

  * VHOST_USER_GET_FEATURES

@@ -486,6 +500,20 @@ Message types

       If VHOST_USER_PROTOCOL_F_REPLY_ACK is negotiated, slave must respond

       with zero in case the specified MTU is valid, or non-zero otherwise.

+ * VHOST_USER_SET_SLAVE_REQ_FD

+

+      Id: 21

+      Equivalent ioctl: N/A

+      Master payload: N/A

+

+      Set the socket file descriptor for slave initiated requests. It is passed

+      in the ancillary data.

+      This request should be sent only when VHOST_USER_F_PROTOCOL_FEATURES

+      has been negotiated, and protocol feature bit VHOST_USER_PROTOCOL_F_SLAVE_REQ

+      bit is present in VHOST_USER_GET_PROTOCOL_FEATURES.

+      If VHOST_USER_PROTOCOL_F_REPLY_ACK is negotiated, slave must respond

+      with zero for success, 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 325319f..0faf5df 100644

--- a/hw/virtio/vhost-user.c

+++ b/hw/virtio/vhost-user.c

@@ -33,6 +33,7 @@ enum VhostUserProtocolFeature {

     VHOST_USER_PROTOCOL_F_RARP = 2,

     VHOST_USER_PROTOCOL_F_REPLY_ACK = 3,

     VHOST_USER_PROTOCOL_F_NET_MTU = 4,

+    VHOST_USER_PROTOCOL_F_SLAVE_REQ = 5,

     VHOST_USER_PROTOCOL_F_MAX

 };

@@ -61,9 +62,15 @@ typedef enum VhostUserRequest {

     VHOST_USER_SET_VRING_ENABLE = 18,

     VHOST_USER_SEND_RARP = 19,

     VHOST_USER_NET_SET_MTU = 20,

+    VHOST_USER_SET_SLAVE_REQ_FD = 21,

     VHOST_USER_MAX

 } VhostUserRequest;

+typedef enum VhostUserSlaveRequest {

+    VHOST_USER_SLAVE_NONE = 0,

+    VHOST_USER_SLAVE_MAX

+}  VhostUserSlaveRequest;

+

 typedef struct VhostUserMemoryRegion {

     uint64_t guest_phys_addr;

     uint64_t memory_size;

@@ -113,6 +120,7 @@ static VhostUserMsg m __attribute__ ((unused));

 struct vhost_user {

     CharBackend *chr;

+    int slave_fd;

 };

 static bool ioeventfd_enabled(void)

@@ -579,6 +587,115 @@ static int vhost_user_reset_device(struct vhost_dev *dev)

     return 0;

 }

+static void slave_read(void *opaque)

+{

+    struct vhost_dev *dev = opaque;

+    struct vhost_user *u = dev->opaque;

+    VhostUserMsg msg = { 0, };

+    int size, ret = 0;

+

+    /* Read header */

+    size = read(u->slave_fd, &msg, VHOST_USER_HDR_SIZE);

+    if (size != VHOST_USER_HDR_SIZE) {

+        error_report("Failed to read from slave.");

+        goto err;

+    }

+

+    if (msg.size > VHOST_USER_PAYLOAD_SIZE) {

+        error_report("Failed to read msg header."

+                " Size %d exceeds the maximum %zu.", msg.size,

+                VHOST_USER_PAYLOAD_SIZE);

+        goto err;

+    }

+

+    /* Read payload */

+    size = read(u->slave_fd, &msg.payload, msg.size);

+    if (size != msg.size) {

+        error_report("Failed to read payload from slave.");

+        goto err;

+    }

+

+    switch (msg.request) {

+    default:

+        error_report("Received unexpected msg type.");

+        ret = -EINVAL;

+    }

+

+    /*

+     * REPLY_ACK feature handling. Other reply types has to be managed

+     * directly in their request handlers.

+     */

+    if (msg.flags & VHOST_USER_NEED_REPLY_MASK) {

+        msg.flags &= ~VHOST_USER_NEED_REPLY_MASK;

+        msg.flags |= VHOST_USER_REPLY_MASK;

+

+        msg.payload.u64 = !!ret;

+        msg.size = sizeof(msg.payload.u64);

+

+        size = write(u->slave_fd, &msg, VHOST_USER_HDR_SIZE + msg.size);

+        if (size != VHOST_USER_HDR_SIZE + msg.size) {

+            error_report("Failed to send msg reply to slave.");

+            goto err;

+        }

+    }

+

+    return;

+

+err:

+    qemu_set_fd_handler(u->slave_fd, NULL, NULL, NULL);

+    close(u->slave_fd);

+    u->slave_fd = -1;

+    return;

+}

+

+static int vhost_setup_slave_channel(struct vhost_dev *dev)

+{

+    VhostUserMsg msg = {

+        .request = VHOST_USER_SET_SLAVE_REQ_FD,

+        .flags = VHOST_USER_VERSION,

+    };

+    struct vhost_user *u = dev->opaque;

+    int sv[2], ret = 0;

+    bool reply_supported = virtio_has_feature(dev->protocol_features,

+                                              VHOST_USER_PROTOCOL_F_REPLY_ACK);

+

+    if (!virtio_has_feature(dev->protocol_features,

+                            VHOST_USER_PROTOCOL_F_SLAVE_REQ)) {

+        return 0;

+    }

+

+    if (socketpair(PF_UNIX, SOCK_STREAM, 0, sv) == -1) {

+        error_report("socketpair() failed");

+        return -1;

+    }

+

+    u->slave_fd = sv[0];

+    qemu_set_fd_handler(u->slave_fd, slave_read, NULL, dev);

+

+    if (reply_supported) {

+        msg.flags |= VHOST_USER_NEED_REPLY_MASK;

+    }

+

+    ret = vhost_user_write(dev, &msg, &sv[1], 1);

+    if (ret) {

+        goto out;

+    }

+

+    if (reply_supported) {

+        ret = process_message_reply(dev, &msg;;

+    }

+

+out:

+    close(sv[1]);

+    if (ret) {

+        qemu_set_fd_handler(u->slave_fd, NULL, NULL, NULL);

+        close(u->slave_fd);

+        u->slave_fd = -1;

+    }

+

+    return ret;

+}

+

 static int vhost_user_init(struct vhost_dev *dev, void *opaque)

 {

     uint64_t features;

@@ -589,6 +706,7 @@ static int vhost_user_init(struct vhost_dev *dev, void *opaque)

     u = g_new0(struct vhost_user, 1);

     u->chr = opaque;

+    u->slave_fd = -1;

     dev->opaque = u;

     err = vhost_user_get_features(dev, &features);

@@ -629,6 +747,11 @@ static int vhost_user_init(struct vhost_dev *dev, void *opaque)

                    "VHOST_USER_PROTOCOL_F_LOG_SHMFD feature.");

     }

+    err = vhost_setup_slave_channel(dev);

+    if (err < 0) {

+        return err;

+    }

+

     return 0;

 }

@@ -639,6 +762,10 @@ static int vhost_user_cleanup(struct vhost_dev *dev)

     assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_USER);

     u = dev->opaque;

+    if (u->slave_fd >= 0) {

+        close(u->slave_fd);

+        u->slave_fd = -1;

+    }

     g_free(u);

     dev->opaque = 0;

-- 

1.8.3.1