From 3a5f44900a64ea2bdf809f1a8df8a4a255dbe014 Mon Sep 17 00:00:00 2001

From: "plai@redhat.com" <plai@redhat.com>

Date: Thu, 21 Jun 2018 18:54:44 +0200

Subject: [PATCH 35/57] vhost-user: support registering external host notifiers

RH-Author: plai@redhat.com

Message-id: <1529607285-9942-10-git-send-email-plai@redhat.com>

Patchwork-id: 80940

O-Subject: [RHEL7.6 PATCH BZ 1526645 09/10] vhost-user: support registering external host notifiers

Bugzilla: 1526645

RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>

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

RH-Acked-by: Laurent Vivier <lvivier@redhat.com>

From: Tiwei Bie <tiwei.bie@intel.com>

This patch introduces VHOST_USER_PROTOCOL_F_HOST_NOTIFIER.

With this feature negotiated, vhost-user backend can register

memory region based host notifiers. And it will allow the guest

driver in the VM to notify the hardware accelerator at the

vhost-user backend directly.

Signed-off-by: Tiwei Bie <tiwei.bie@intel.com>

Reviewed-by: Michael S. Tsirkin <mst@redhat.com>

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

(cherry picked from commit 44866521bd6ea8e5152a87664dea1eee90c9438b)

Signed-off-by: Paul Lai <plai@redhat.com>

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

---

 docs/interop/vhost-user.txt    |  33 ++++++++++++

 hw/virtio/vhost-user.c         | 113 +++++++++++++++++++++++++++++++++++++++++

 include/hw/virtio/vhost-user.h |   8 +++

 3 files changed, 154 insertions(+)

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

index 682a683..d51fd58 100644

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

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

@@ -132,6 +132,16 @@ Depending on the request type, payload can be:

    Payload: Size bytes array holding the contents of the virtio

        device's configuration space

+ * Vring area description

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

+   | u64 | size | offset |

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

+

+   u64: a 64-bit integer contains vring index and flags

+   Size: a 64-bit size of this area

+   Offset: a 64-bit offset of this area from the start of the

+       supplied file descriptor

+

 In QEMU the vhost-user message is implemented with the following struct:

 typedef struct VhostUserMsg {

@@ -146,6 +156,7 @@ typedef struct VhostUserMsg {

         VhostUserLog log;

         struct vhost_iotlb_msg iotlb;

         VhostUserConfig config;

+        VhostUserVringArea area;

     };

 } QEMU_PACKED VhostUserMsg;

@@ -385,6 +396,7 @@ Protocol features

 #define VHOST_USER_PROTOCOL_F_PAGEFAULT      8

 #define VHOST_USER_PROTOCOL_F_CONFIG         9

 #define VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD  10

+#define VHOST_USER_PROTOCOL_F_HOST_NOTIFIER  11

 Master message types

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

@@ -782,6 +794,27 @@ Slave message types

      the VHOST_USER_NEED_REPLY flag, master must respond with zero when

      operation is successfully completed, or non-zero otherwise.

+ * VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG

+

+      Id: 3

+      Equivalent ioctl: N/A

+      Slave payload: vring area description

+      Master payload: N/A

+

+      Sets host notifier for a specified queue. The queue index is contained

+      in the u64 field of the vring area description. The host notifier is

+      described by the file descriptor (typically it's a VFIO device fd) which

+      is passed as ancillary data and the size (which is mmap size and should

+      be the same as host page size) and offset (which is mmap offset) carried

+      in the vring area description. QEMU can mmap the file descriptor based

+      on the size and offset to get a memory range. Registering a host notifier

+      means mapping this memory range to the VM as the specified queue's notify

+      MMIO region. Slave sends this request to tell QEMU to de-register the

+      existing notifier if any and register the new notifier if the request is

+      sent with a file descriptor.

+      This request should be sent only when VHOST_USER_PROTOCOL_F_HOST_NOTIFIER

+      protocol feature has been successfully negotiated.

+

 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 a715c5c..c30fc3d 100644

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

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

@@ -13,6 +13,7 @@

 #include "hw/virtio/vhost.h"

 #include "hw/virtio/vhost-user.h"

 #include "hw/virtio/vhost-backend.h"

+#include "hw/virtio/virtio.h"

 #include "hw/virtio/virtio-net.h"

 #include "chardev/char-fe.h"

 #include "sysemu/kvm.h"

@@ -50,6 +51,7 @@ enum VhostUserProtocolFeature {

     VHOST_USER_PROTOCOL_F_PAGEFAULT = 8,

     VHOST_USER_PROTOCOL_F_CONFIG = 9,

     VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD = 10,

+    VHOST_USER_PROTOCOL_F_HOST_NOTIFIER = 11,

     VHOST_USER_PROTOCOL_F_MAX

 };

@@ -94,6 +96,7 @@ typedef enum VhostUserSlaveRequest {

     VHOST_USER_SLAVE_NONE = 0,

     VHOST_USER_SLAVE_IOTLB_MSG = 1,

     VHOST_USER_SLAVE_CONFIG_CHANGE_MSG = 2,

+    VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG = 3,

     VHOST_USER_SLAVE_MAX

 }  VhostUserSlaveRequest;

@@ -138,6 +141,12 @@ static VhostUserConfig c __attribute__ ((unused));

                                    + sizeof(c.size) \

                                    + sizeof(c.flags))

+typedef struct VhostUserVringArea {

+    uint64_t u64;

+    uint64_t size;

+    uint64_t offset;

+} VhostUserVringArea;

+

 typedef struct {

     VhostUserRequest request;

@@ -159,6 +168,7 @@ typedef union {

         struct vhost_iotlb_msg iotlb;

         VhostUserConfig config;

         VhostUserCryptoSession session;

+        VhostUserVringArea area;

 } VhostUserPayload;

 typedef struct VhostUserMsg {

@@ -640,9 +650,37 @@ static int vhost_user_set_vring_num(struct vhost_dev *dev,

     return vhost_set_vring(dev, VHOST_USER_SET_VRING_NUM, ring);

 }

+static void vhost_user_host_notifier_restore(struct vhost_dev *dev,

+                                             int queue_idx)

+{

+    struct vhost_user *u = dev->opaque;

+    VhostUserHostNotifier *n = &u->user->notifier[queue_idx];

+    VirtIODevice *vdev = dev->vdev;

+

+    if (n->addr && !n->set) {

+        virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, true);

+        n->set = true;

+    }

+}

+

+static void vhost_user_host_notifier_remove(struct vhost_dev *dev,

+                                            int queue_idx)

+{

+    struct vhost_user *u = dev->opaque;

+    VhostUserHostNotifier *n = &u->user->notifier[queue_idx];

+    VirtIODevice *vdev = dev->vdev;

+

+    if (n->addr && n->set) {

+        virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, false);

+        n->set = false;

+    }

+}

+

 static int vhost_user_set_vring_base(struct vhost_dev *dev,

                                      struct vhost_vring_state *ring)

 {

+    vhost_user_host_notifier_restore(dev, ring->index);

+

     return vhost_set_vring(dev, VHOST_USER_SET_VRING_BASE, ring);

 }

@@ -676,6 +714,8 @@ static int vhost_user_get_vring_base(struct vhost_dev *dev,

         .hdr.size = sizeof(msg.payload.state),

     };

+    vhost_user_host_notifier_remove(dev, ring->index);

+

     if (vhost_user_write(dev, &msg, NULL, 0) < 0) {

         return -1;

     }

@@ -849,6 +889,66 @@ static int vhost_user_slave_handle_config_change(struct vhost_dev *dev)

     return ret;

 }

+static int vhost_user_slave_handle_vring_host_notifier(struct vhost_dev *dev,

+                                                       VhostUserVringArea *area,

+                                                       int fd)

+{

+    int queue_idx = area->u64 & VHOST_USER_VRING_IDX_MASK;

+    size_t page_size = qemu_real_host_page_size;

+    struct vhost_user *u = dev->opaque;

+    VhostUserState *user = u->user;

+    VirtIODevice *vdev = dev->vdev;

+    VhostUserHostNotifier *n;

+    void *addr;

+    char *name;

+

+    if (!virtio_has_feature(dev->protocol_features,

+                            VHOST_USER_PROTOCOL_F_HOST_NOTIFIER) ||

+        vdev == NULL || queue_idx >= virtio_get_num_queues(vdev)) {

+        return -1;

+    }

+

+    n = &user->notifier[queue_idx];

+

+    if (n->addr) {

+        virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, false);

+        object_unparent(OBJECT(&n->mr));

+        munmap(n->addr, page_size);

+        n->addr = NULL;

+    }

+

+    if (area->u64 & VHOST_USER_VRING_NOFD_MASK) {

+        return 0;

+    }

+

+    /* Sanity check. */

+    if (area->size != page_size) {

+        return -1;

+    }

+

+    addr = mmap(NULL, page_size, PROT_READ | PROT_WRITE, MAP_SHARED,

+                fd, area->offset);

+    if (addr == MAP_FAILED) {

+        return -1;

+    }

+

+    name = g_strdup_printf("vhost-user/host-notifier@%p mmaps[%d]",

+                           user, queue_idx);

+    memory_region_init_ram_device_ptr(&n->mr, OBJECT(vdev), name,

+                                      page_size, addr);

+    g_free(name);

+

+    if (virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, true)) {

+        munmap(addr, page_size);

+        return -1;

+    }

+

+    n->addr = addr;

+    n->set = true;

+

+    return 0;

+}

+

 static void slave_read(void *opaque)

 {

     struct vhost_dev *dev = opaque;

@@ -917,6 +1017,10 @@ static void slave_read(void *opaque)

     case VHOST_USER_SLAVE_CONFIG_CHANGE_MSG :

         ret = vhost_user_slave_handle_config_change(dev);

         break;

+    case VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG:

+        ret = vhost_user_slave_handle_vring_host_notifier(dev, &payload.area,

+                                                          fd[0]);

+        break;

     default:

         error_report("Received unexpected msg type.");

         ret = -EINVAL;

@@ -1648,6 +1752,15 @@ VhostUserState *vhost_user_init(void)

 void vhost_user_cleanup(VhostUserState *user)

 {

+    int i;

+

+    for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {

+        if (user->notifier[i].addr) {

+            object_unparent(OBJECT(&user->notifier[i].mr));

+            munmap(user->notifier[i].addr, qemu_real_host_page_size);

+            user->notifier[i].addr = NULL;

+        }

+    }

 }

 const VhostOps user_ops = {

diff --git a/include/hw/virtio/vhost-user.h b/include/hw/virtio/vhost-user.h

index eb8bc0d..fd66039 100644

--- a/include/hw/virtio/vhost-user.h

+++ b/include/hw/virtio/vhost-user.h

@@ -9,9 +9,17 @@

 #define HW_VIRTIO_VHOST_USER_H

 #include "chardev/char-fe.h"

+#include "hw/virtio/virtio.h"

+

+typedef struct VhostUserHostNotifier {

+    MemoryRegion mr;

+    void *addr;

+    bool set;

+} VhostUserHostNotifier;

 typedef struct VhostUserState {

     CharBackend *chr;

+    VhostUserHostNotifier notifier[VIRTIO_QUEUE_MAX];

 } VhostUserState;

 VhostUserState *vhost_user_init(void);

-- 

1.8.3.1