Re: [PATCH v3 3/4] vhost-user: add shared_object msg

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, Jun 23, 2023 at 09:19:29AM +0200, Albert Esteve wrote:
> 
> 
> On Fri, Jun 23, 2023 at 8:45 AM Michael S. Tsirkin <mst@redhat.com> wrote:
> 
>     On Wed, May 24, 2023 at 11:13:32AM +0200, Albert Esteve wrote:
>     > Add new vhost-user protocol message
>     > `VHOST_USER_BACKEND_SHARED_OBJECT`. This new
>     > message is sent from vhost-user back-ends
>     > to interact with the virtio-dmabuf table
>     > in order to add, remove, or lookup for
>     > virtio dma-buf shared objects.
>     >
>     > The action taken in the front-end depends
>     > on the type stored in the payload struct.
>     >
>     > In the libvhost-user library add helper
>     > functions to allow sending messages to
>     > interact with the virtio shared objects
>     > hash table.
>     >
>     > Signed-off-by: Albert Esteve <aesteve@redhat.com>
>     > ---
>     >  docs/interop/vhost-user.rst               | 15 ++++
>     >  hw/virtio/vhost-user.c                    | 68 ++++++++++++++++++
>     >  subprojects/libvhost-user/libvhost-user.c | 88 +++++++++++++++++++++++
>     >  subprojects/libvhost-user/libvhost-user.h | 56 +++++++++++++++
>     >  4 files changed, 227 insertions(+)
>     >
>     > diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst
>     > index 5a070adbc1..d3d8db41e5 100644
>     > --- a/docs/interop/vhost-user.rst
>     > +++ b/docs/interop/vhost-user.rst
>     > @@ -1528,6 +1528,21 @@ is sent by the front-end.
>     > 
>     >    The state.num field is currently reserved and must be set to 0.
>     > 
>     > +``VHOST_USER_BACKEND_SHARED_OBJECT``
>     > +  :id: 6
>     > +  :equivalent ioctl: N/A
>     > +  :request payload: ``struct VhostUserShared``
>     > +  :reply payload: ``struct VhostUserShared`` (only for ``LOOKUP``
>     requests)
>     > +
>     > +  Backends that need to interact with the virtio-dmabuf shared table API
>     > +  can send this message. The operation is determined by the ``type``
>     member
>     > +  of the payload struct. The valid values for the operation type are
>     > +  ``VHOST_SHARED_OBJECT_*`` members, i.e., ``ADD``, ``LOOKUP``, and
>     ``REMOVE``.
>     > +  ``LOOKUP`` operations require the ``VHOST_USER_NEED_REPLY_MASK`` flag
>     to be
>     > +  set by the back-end, and the front-end will then send the dma-buf fd
>     as
>     > +  a response if the UUID matches an object in the table, or a negative
>     value
>     > +  otherwise.
>     > +
>     >  .. _reply_ack:
>     > 
>     >  VHOST_USER_PROTOCOL_F_REPLY_ACK
>     > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
>     > index 74a2a28663..5ac5f0eafd 100644
>     > --- a/hw/virtio/vhost-user.c
>     > +++ b/hw/virtio/vhost-user.c
>     > @@ -10,6 +10,7 @@
>     > 
>     >  #include "qemu/osdep.h"
>     >  #include "qapi/error.h"
>     > +#include "hw/virtio/virtio-dmabuf.h"
>     >  #include "hw/virtio/vhost.h"
>     >  #include "hw/virtio/vhost-user.h"
>     >  #include "hw/virtio/vhost-backend.h"
>     > @@ -20,6 +21,7 @@
>     >  #include "sysemu/kvm.h"
>     >  #include "qemu/error-report.h"
>     >  #include "qemu/main-loop.h"
>     > +#include "qemu/uuid.h"
>     >  #include "qemu/sockets.h"
>     >  #include "sysemu/runstate.h"
>     >  #include "sysemu/cryptodev.h"
>     > @@ -128,6 +130,7 @@ typedef enum VhostUserSlaveRequest {
>     >      VHOST_USER_BACKEND_IOTLB_MSG = 1,
>     >      VHOST_USER_BACKEND_CONFIG_CHANGE_MSG = 2,
>     >      VHOST_USER_BACKEND_VRING_HOST_NOTIFIER_MSG = 3,
>     > +    VHOST_USER_BACKEND_SHARED_OBJECT = 6,
>     >      VHOST_USER_BACKEND_MAX
>     >  }  VhostUserSlaveRequest;
>     > 
>     > @@ -190,6 +193,18 @@ typedef struct VhostUserInflight {
>     >      uint16_t queue_size;
>     >  } VhostUserInflight;
>     > 
>     > +typedef enum VhostUserSharedType {
>     > +    VHOST_SHARED_OBJECT_ADD = 0,
>     > +    VHOST_SHARED_OBJECT_LOOKUP,
>     > +    VHOST_SHARED_OBJECT_REMOVE,
>     > +} VhostUserSharedType;
>     > +
>     > +typedef struct VhostUserShared {
>     > +    unsigned char uuid[16];
>     > +    VhostUserSharedType type;
>     > +    int dmabuf_fd;
>     > +} VhostUserShared;
>     > +
>     >  typedef struct {
>     >      VhostUserRequest request;
>     > 
>     > @@ -214,6 +229,7 @@ typedef union {
>     >          VhostUserCryptoSession session;
>     >          VhostUserVringArea area;
>     >          VhostUserInflight inflight;
>     > +        VhostUserShared object;
>     >  } VhostUserPayload;
>     > 
>     >  typedef struct VhostUserMsg {
>     > @@ -1582,6 +1598,52 @@ static int
>     vhost_user_slave_handle_vring_host_notifier(struct vhost_dev *dev,
>     >      return 0;
>     >  }
>     > 
>     > +static int vhost_user_backend_handle_shared_object(VhostUserShared
>     *object)
>     > +{
>     > +    QemuUUID uuid;
> 
>     Can we initialize it here? uuid = { .data = object->uuid } ?
> 
>     Also, pls put space after variable declaration.
> 
>     > +    memcpy(uuid.data, object->uuid, sizeof(object->uuid));
>     > +
>     > +    switch (object->type) {
>     > +    case VHOST_SHARED_OBJECT_ADD:
>     > +        return virtio_add_dmabuf(&uuid, object->dmabuf_fd);
>     > +    case VHOST_SHARED_OBJECT_LOOKUP:
>     > +        object->dmabuf_fd = virtio_lookup_dmabuf(&uuid);
>     > +        if (object->dmabuf_fd < 0) {
>     > +            return object->dmabuf_fd;
>     > +        }
>     > +        break;
>     > +    case VHOST_SHARED_OBJECT_REMOVE:
>     > +        return virtio_remove_resource(&uuid);
>     > +    }
>     > +
> 
>     I couldn't figure out why, but if I commit this then run checkpatch,
>     like this
>     ./scripts/checkpatch.pl HEAD~1..HEAD
> 
>     then it is unhappy about the : in case. Any idea why?
> 
> 
> I don't see any errors / warnings. What do you get?


15/90 Checking commit 6cd801b0656b (vhost-user: add shared_object msg)
ERROR: spaces required around that ':' (ctx:VxE)
#187: FILE: hw/virtio/vhost-user.c:1619:
+    case VHOST_SHARED_OBJECT_ADD:
                                 ^

ERROR: spaces required around that ':' (ctx:VxE)
#189: FILE: hw/virtio/vhost-user.c:1621:
+    case VHOST_SHARED_OBJECT_LOOKUP:
                                    ^

ERROR: spaces required around that ':' (ctx:VxE)
#195: FILE: hw/virtio/vhost-user.c:1627:
+    case VHOST_SHARED_OBJECT_REMOVE:
                                    ^

ERROR: spaces required around that ':' (ctx:VxE)
#234: FILE: hw/virtio/vhost-user.c:1716:
+    case VHOST_USER_BACKEND_SHARED_OBJECT:
                                          ^

total: 4 errors, 0 warnings, 305 lines checked


which is wrong.


> 
>     > +    return 0;
>     > +}
>     > +
>     > +static bool
>     > +vhost_user_backend_send_dmabuf_fd(QIOChannel *ioc, VhostUserHeader *hdr,
>     > +                                  VhostUserPayload *payload)
>     > +{
>     > +    Error *local_err = NULL;
>     > +    struct iovec iov[2];
>     > +    if (hdr->flags & VHOST_USER_NEED_REPLY_MASK) {
>     > +        hdr->flags &= ~VHOST_USER_NEED_REPLY_MASK;
>     > +        hdr->flags |= VHOST_USER_REPLY_MASK;
>     > +
>     > +        hdr->size = sizeof(payload->object);
>     > +
>     > +        iov[0].iov_base = hdr;
>     > +        iov[0].iov_len = VHOST_USER_HDR_SIZE;
>     > +        iov[1].iov_base = payload;
>     > +        iov[1].iov_len = hdr->size;
>     > +
>     > +        if (qio_channel_writev_all(ioc, iov, ARRAY_SIZE(iov), &
>     local_err)) {
>     > +            error_report_err(local_err);
>     > +            return false;
>     > +        }
>     > +    }
>     > +    return true;
>     > +}
>     > +
>     >  static void close_slave_channel(struct vhost_user *u)
>     >  {
>     >      g_source_destroy(u->slave_src);
>     > @@ -1639,6 +1701,12 @@ static gboolean slave_read(QIOChannel *ioc,
>     GIOCondition condition,
>     >          ret = vhost_user_slave_handle_vring_host_notifier(dev, &
>     payload.area,
>     >                                                            fd ? fd[0] :
>     -1);
>     >          break;
>     > +    case VHOST_USER_BACKEND_SHARED_OBJECT:
>     > +        ret = vhost_user_backend_handle_shared_object(&payload.object);
>     > +        if (!vhost_user_backend_send_dmabuf_fd(ioc, &hdr, &payload)) {
>     > +            goto err;
>     > +        }
>     > +        break;
>     >      default:
>     >          error_report("Received unexpected msg type: %d.", hdr.request);
>     >          ret = -EINVAL;
>     > diff --git a/subprojects/libvhost-user/libvhost-user.c b/subprojects/
>     libvhost-user/libvhost-user.c
>     > index 8fb61e2df2..27f16d292a 100644
>     > --- a/subprojects/libvhost-user/libvhost-user.c
>     > +++ b/subprojects/libvhost-user/libvhost-user.c
>     > @@ -1403,6 +1403,94 @@ bool vu_set_queue_host_notifier(VuDev *dev,
>     VuVirtq *vq, int fd,
>     >      return vu_process_message_reply(dev, &vmsg);
>     >  }
>     > 
>     > +bool
>     > +vu_get_shared_object(VuDev *dev, unsigned char uuid[UUID_LEN], int
>     *dmabuf_fd)
>     > +{
>     > +    bool result = false;
>     > +    VhostUserMsg msg_reply;
>     > +    VhostUserMsg msg = {
>     > +        .request = VHOST_USER_BACKEND_SHARED_OBJECT,
>     > +        .size = sizeof(msg.payload.object),
>     > +        .flags = VHOST_USER_VERSION | VHOST_USER_NEED_REPLY_MASK,
>     > +        .payload.object = {
>     > +            .type = VHOST_SHARED_OBJECT_LOOKUP,
>     > +        },
>     > +    };
>     > +
>     > +    memcpy(msg.payload.object.uuid, uuid, sizeof(uuid[0]) * UUID_LEN);
>     > +
>     > +    pthread_mutex_lock(&dev->slave_mutex);
>     > +    if (!vu_message_write(dev, dev->slave_fd, &msg)) {
>     > +        goto out;
>     > +    }
>     > +
>     > +    if (!vu_message_read_default(dev, dev->slave_fd, &msg_reply)) {
>     > +        goto out;
>     > +    }
>     > +
>     > +    if (msg_reply.request != msg.request) {
>     > +        DPRINT("Received unexpected msg type. Expected %d, received %d",
>     > +               msg.request, msg_reply.request);
>     > +        goto out;
>     > +    }
>     > +
>     > +    *dmabuf_fd = msg_reply.payload.object.dmabuf_fd;
>     > +    result = *dmabuf_fd > 0;
>     > +out:
>     > +    pthread_mutex_unlock(&dev->slave_mutex);
>     > +
>     > +    return result;
>     > +}
>     > +
>     > +static bool
>     > +vu_send_message(VuDev *dev, VhostUserMsg *vmsg)
>     > +{
>     > +    bool result = false;
>     > +    pthread_mutex_lock(&dev->slave_mutex);
>     > +    if (!vu_message_write(dev, dev->slave_fd, vmsg)) {
>     > +        goto out;
>     > +    }
>     > +
>     > +    result = true;
>     > +out:
>     > +    pthread_mutex_unlock(&dev->slave_mutex);
>     > +
>     > +    return result;
>     > +}
>     > +
>     > +bool
>     > +vu_add_shared_object(VuDev *dev, unsigned char uuid[UUID_LEN], int
>     dmabuf_fd)
>     > +{
>     > +    VhostUserMsg msg = {
>     > +        .request = VHOST_USER_BACKEND_SHARED_OBJECT,
>     > +        .size = sizeof(msg.payload.object),
>     > +        .flags = VHOST_USER_VERSION,
>     > +        .payload.object = {
>     > +            .dmabuf_fd = dmabuf_fd,
>     > +            .type = VHOST_SHARED_OBJECT_ADD,
>     > +        },
>     > +    };
>     > +    memcpy(msg.payload.object.uuid, uuid, sizeof(uuid[0]) * UUID_LEN);
>     > +
>     > +    return vu_send_message(dev, &msg);
>     > +}
>     > +
>     > +bool
>     > +vu_rm_shared_object(VuDev *dev, unsigned char uuid[UUID_LEN])
>     > +{
>     > +    VhostUserMsg msg = {
>     > +        .request = VHOST_USER_BACKEND_SHARED_OBJECT,
>     > +        .size = sizeof(msg.payload.object),
>     > +        .flags = VHOST_USER_VERSION,
>     > +        .payload.object = {
>     > +            .type = VHOST_SHARED_OBJECT_REMOVE,
>     > +        },
>     > +    };
>     > +    memcpy(msg.payload.object.uuid, uuid, sizeof(uuid[0]) * UUID_LEN);
>     > +
>     > +    return vu_send_message(dev, &msg);
>     > +}
>     > +
>     >  static bool
>     >  vu_set_vring_call_exec(VuDev *dev, VhostUserMsg *vmsg)
>     >  {
>     > diff --git a/subprojects/libvhost-user/libvhost-user.h b/subprojects/
>     libvhost-user/libvhost-user.h
>     > index 49208cceaa..a43d115bd7 100644
>     > --- a/subprojects/libvhost-user/libvhost-user.h
>     > +++ b/subprojects/libvhost-user/libvhost-user.h
>     > @@ -119,6 +119,7 @@ typedef enum VhostUserSlaveRequest {
>     >      VHOST_USER_BACKEND_VRING_HOST_NOTIFIER_MSG = 3,
>     >      VHOST_USER_BACKEND_VRING_CALL = 4,
>     >      VHOST_USER_BACKEND_VRING_ERR = 5,
>     > +    VHOST_USER_BACKEND_SHARED_OBJECT = 6,
>     >      VHOST_USER_BACKEND_MAX
>     >  }  VhostUserSlaveRequest;
>     > 
>     > @@ -172,6 +173,20 @@ typedef struct VhostUserInflight {
>     >      uint16_t queue_size;
>     >  } VhostUserInflight;
>     > 
>     > +typedef enum VhostUserSharedType {
>     > +    VHOST_SHARED_OBJECT_ADD = 0,
>     > +    VHOST_SHARED_OBJECT_LOOKUP,
>     > +    VHOST_SHARED_OBJECT_REMOVE,
>     > +} VhostUserSharedType;
>     > +
>     > +#define UUID_LEN 16
>     > +
>     > +typedef struct VhostUserShared {
>     > +    unsigned char uuid[UUID_LEN];
>     > +    VhostUserSharedType type;
>     > +    int dmabuf_fd;
>     > +} VhostUserShared;
>     > +
>     >  #if defined(_WIN32) && (defined(__x86_64__) || defined(__i386__))
>     >  # define VU_PACKED __attribute__((gcc_struct, packed))
>     >  #else
>     > @@ -199,6 +214,7 @@ typedef struct VhostUserMsg {
>     >          VhostUserConfig config;
>     >          VhostUserVringArea area;
>     >          VhostUserInflight inflight;
>     > +        VhostUserShared object;
>     >      } payload;
>     > 
>     >      int fds[VHOST_MEMORY_BASELINE_NREGIONS];
>     > @@ -539,6 +555,46 @@ void vu_set_queue_handler(VuDev *dev, VuVirtq *vq,
>     >  bool vu_set_queue_host_notifier(VuDev *dev, VuVirtq *vq, int fd,
>     >                                  int size, int offset);
>     > 
>     > +/**
>     > + * vu_get_shared_object:
>     > + * @dev: a VuDev context
>     > + * @uuid: UUID of the shared object
>     > + * @dmabuf_fd: output dma-buf file descriptor
>     > + *
>     > + * Lookup for a virtio shared object (i.e., dma-buf fd) associated with
>     the
>     > + * received UUID. Result, if found, is stored in the dmabuf_fd argument.
>     > + *
>     > + * Returns: whether the virtio object was found.
>     > + */
>     > +bool vu_get_shared_object(VuDev *dev, unsigned char uuid[UUID_LEN],
>     > +                          int *dmabuf_fd);
>     > +
>     > +/**
>     > + * vu_add_shared_object:
>     > + * @dev: a VuDev context
>     > + * @uuid: UUID of the shared object
>     > + * @dmabuf_fd: output dma-buf file descriptor
>     > + *
>     > + * Stores a new shared object (i.e., dma-buf fd) in the hash table, and
>     > + * associates it with the received UUID.
>     > + *
>     > + * Returns: TRUE on success, FALSE on failure.
>     > + */
>     > +bool vu_add_shared_object(VuDev *dev, unsigned char uuid[UUID_LEN],
>     > +                          int dmabuf_fd);
>     > +
>     > +/**
>     > + * vu_rm_shared_object:
>     > + * @dev: a VuDev context
>     > + * @uuid: UUID of the shared object
>     > + *
>     > + * Removes a shared object (i.e., dma-buf fd) associated with the
>     > + * received UUID from the hash table.
>     > + *
>     > + * Returns: TRUE on success, FALSE on failure.
>     > + */
>     > +bool vu_rm_shared_object(VuDev *dev, unsigned char uuid[UUID_LEN]);
>     > +
>     >  /**
>     >   * vu_queue_set_notification:
>     >   * @dev: a VuDev context
>     > --
>     > 2.40.0
> 
>