On Fri, Jun 23, 2023 at 10:14 AM Michael S. Tsirkin <m...@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 <aest...@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:
>
> If you are reusing same message then I would maybe just make all types
> the same - if there's a reply bit backend can reply back with the same
> message - might be good for debugging etc.
>
> Also it's not detailed here but I am guessing LOOKUP at least
> does not send an fd and gets an fd back? Maybe LOOKUP
> at least actually should be a separate message.
>
Lookup sends a UUID and gets a fd back.
Is a good point, having consistent behaviour within
the same type (or message).
Maybe splitting all types into messages as Marc suggested is best after all.
I can do that and then add a feature bit to negotiate.
>
>
> > 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;
>
> BTW all fields in structs that go on the wire should be fixed size.
>
You mean the fd? I may actually be doing it wrong now that I checked...
I think this probably should go into the `fds` field of the VhostUserMsg
struct.
Let me see if I can rework it a bit for the next drop, so that it does not
have
to be in the payload struct.
> > +
> > 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;
> > + 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);
> > + }
> > +
> > + 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
>
>
