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Tsirkin" , Paolo Bonzini , Fabiano Rosas , slp@redhat.com, manos.pitsidianakis@linaro.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass client-ip=170.10.133.124; envelope-from=aesteve@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Thu, Oct 16, 2025 at 4:38=E2=80=AFPM Albert Esteve = wrote: > > Add SHMEM_MAP/UNMAP requests to vhost-user for dynamic management of > VIRTIO Shared Memory mappings. > > This implementation introduces VirtioSharedMemoryMapping as a unified > QOM object that manages both the mapping metadata and MemoryRegion > lifecycle. This object provides reference-counted lifecycle management > with automatic cleanup of file descriptors and memory regions > through QOM finalization. > > This request allows backends to dynamically map file descriptors into a > VIRTIO Shared Memory Region identified by their shmid. Maps are created > using memory_region_init_ram_from_fd() with configurable read/write > permissions, and the resulting MemoryRegions are added as subregions to > the shmem container region. The mapped memory is then advertised to the > guest VIRTIO drivers as a base address plus offset for reading and > writting according to the requested mmap flags. > > The backend can unmap memory ranges within a given VIRTIO Shared Memory > Region to free resources. Upon receiving this message, the frontend > removes the MemoryRegion as a subregion and automatically unreferences > the VirtioSharedMemoryMapping object, triggering cleanup if no other > references exist. > > Error handling has been improved to ensure consistent behavior across > handlers that manage their own vhost_user_send_resp() calls. Since > these handlers clear the VHOST_USER_NEED_REPLY_MASK flag, explicit > error checking ensures proper connection closure on failures, > maintaining the expected error flow. > > Note the memory region commit for these operations needs to be delayed > until after we reply to the backend to avoid deadlocks. Otherwise, > the MemoryListener would send a VHOST_USER_SET_MEM_TABLE message > before the reply. > > Reviewed-by: Stefan Hajnoczi > Signed-off-by: Albert Esteve > --- > hw/virtio/vhost-user.c | 267 ++++++++++++++++++++++ > hw/virtio/virtio.c | 199 ++++++++++++++++ > include/hw/virtio/virtio.h | 135 +++++++++++ > subprojects/libvhost-user/libvhost-user.c | 70 ++++++ > subprojects/libvhost-user/libvhost-user.h | 54 +++++ > 5 files changed, 725 insertions(+) > > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c > index 36c9c2e04d..890be55937 100644 > --- a/hw/virtio/vhost-user.c > +++ b/hw/virtio/vhost-user.c > @@ -104,6 +104,7 @@ typedef enum VhostUserRequest { > VHOST_USER_GET_SHARED_OBJECT =3D 41, > VHOST_USER_SET_DEVICE_STATE_FD =3D 42, > VHOST_USER_CHECK_DEVICE_STATE =3D 43, > + VHOST_USER_GET_SHMEM_CONFIG =3D 44, > VHOST_USER_MAX > } VhostUserRequest; > > @@ -115,6 +116,8 @@ typedef enum VhostUserBackendRequest { > VHOST_USER_BACKEND_SHARED_OBJECT_ADD =3D 6, > VHOST_USER_BACKEND_SHARED_OBJECT_REMOVE =3D 7, > VHOST_USER_BACKEND_SHARED_OBJECT_LOOKUP =3D 8, > + VHOST_USER_BACKEND_SHMEM_MAP =3D 9, > + VHOST_USER_BACKEND_SHMEM_UNMAP =3D 10, > VHOST_USER_BACKEND_MAX > } VhostUserBackendRequest; > > @@ -136,6 +139,12 @@ typedef struct VhostUserMemRegMsg { > VhostUserMemoryRegion region; > } VhostUserMemRegMsg; > > +typedef struct VhostUserShMemConfig { > + uint32_t nregions; > + uint32_t padding; > + uint64_t memory_sizes[VIRTIO_MAX_SHMEM_REGIONS]; > +} VhostUserShMemConfig; > + > typedef struct VhostUserLog { > uint64_t mmap_size; > uint64_t mmap_offset; > @@ -192,6 +201,23 @@ typedef struct VhostUserShared { > unsigned char uuid[16]; > } VhostUserShared; > > +/* For the flags field of VhostUserMMap */ > +#define VHOST_USER_FLAG_MAP_RW (1u << 0) > + > +typedef struct { > + /* VIRTIO Shared Memory Region ID */ > + uint8_t shmid; > + uint8_t padding[7]; > + /* File offset */ > + uint64_t fd_offset; > + /* Offset within the VIRTIO Shared Memory Region */ > + uint64_t shm_offset; > + /* Size of the mapping */ > + uint64_t len; > + /* Flags for the mmap operation, from VHOST_USER_FLAG_MAP_* */ > + uint64_t flags; > +} VhostUserMMap; > + > typedef struct { > VhostUserRequest request; > > @@ -224,6 +250,8 @@ typedef union { > VhostUserInflight inflight; > VhostUserShared object; > VhostUserTransferDeviceState transfer_state; > + VhostUserMMap mmap; > + VhostUserShMemConfig shmem; > } VhostUserPayload; > > typedef struct VhostUserMsg { > @@ -1768,6 +1796,196 @@ vhost_user_backend_handle_shared_object_lookup(st= ruct vhost_user *u, > return 0; > } > > +/** > + * vhost_user_backend_handle_shmem_map() - Handle SHMEM_MAP backend requ= est > + * @dev: vhost device > + * @ioc: QIOChannel for communication > + * @hdr: vhost-user message header > + * @payload: message payload containing mapping details > + * @fd: file descriptor for the shared memory region > + * > + * Handles VHOST_USER_BACKEND_SHMEM_MAP requests from the backend. Creat= es > + * a VhostUserShmemObject to manage the shared memory mapping and adds i= t > + * to the appropriate VirtIO shared memory region. The VhostUserShmemObj= ect > + * serves as an intermediate parent for the MemoryRegion, ensuring prope= r > + * lifecycle management with reference counting. > + * > + * Returns: 0 on success, negative errno on failure > + */ > +static int > +vhost_user_backend_handle_shmem_map(struct vhost_dev *dev, > + QIOChannel *ioc, > + VhostUserHeader *hdr, > + VhostUserPayload *payload, > + int fd) > +{ > + VirtioSharedMemory *shmem; > + VhostUserMMap *vu_mmap =3D &payload->mmap; > + VirtioSharedMemoryMapping *existing; > + Error *local_err =3D NULL; > + int ret =3D 0; > + > + if (fd < 0) { > + error_report("Bad fd for map"); > + ret =3D -EBADF; > + goto send_reply; > + } > + > + if (QSIMPLEQ_EMPTY(&dev->vdev->shmem_list)) { > + error_report("Device has no VIRTIO Shared Memory Regions. " > + "Requested ID: %d", vu_mmap->shmid); > + ret =3D -EFAULT; > + goto send_reply; > + } > + > + shmem =3D virtio_find_shmem_region(dev->vdev, vu_mmap->shmid); > + if (!shmem) { > + error_report("VIRTIO Shared Memory Region at " > + "ID %d not found or uninitialized", vu_mmap->shmid)= ; > + ret =3D -EFAULT; > + goto send_reply; > + } > + > + if ((vu_mmap->shm_offset + vu_mmap->len) < vu_mmap->len || > + (vu_mmap->shm_offset + vu_mmap->len) > shmem->mr.size) { > + error_report("Bad offset/len for mmap %" PRIx64 "+%" PRIx64, > + vu_mmap->shm_offset, vu_mmap->len); > + ret =3D -EFAULT; > + goto send_reply; > + } > + > + QTAILQ_FOREACH(existing, &shmem->mmaps, link) { > + if (ranges_overlap(existing->offset, existing->len, > + vu_mmap->shm_offset, vu_mmap->len)) { > + error_report("VIRTIO Shared Memory mapping overlap"); > + ret =3D -EFAULT; > + goto send_reply; > + } > + } > + > + memory_region_transaction_begin(); > + > + /* Create VirtioSharedMemoryMapping object */ > + VirtioSharedMemoryMapping *mapping =3D virtio_shared_memory_mapping_= new( > + vu_mmap->shmid, fd, vu_mmap->fd_offset, vu_mmap->shm_offset, > + vu_mmap->len, vu_mmap->flags & VHOST_USER_FLAG_MAP_RW); > + > + if (!mapping) { > + ret =3D -EFAULT; > + goto send_reply_commit; > + } > + > + /* Add the mapping to the shared memory region */ > + if (virtio_add_shmem_map(shmem, mapping) !=3D 0) { > + error_report("Failed to add shared memory mapping"); > + object_unref(OBJECT(mapping)); > + ret =3D -EFAULT; > + goto send_reply_commit; > + } > + > +send_reply_commit: > + /* Send reply and commit after transaction started */ > + if (hdr->flags & VHOST_USER_NEED_REPLY_MASK) { > + payload->u64 =3D !!ret; > + hdr->size =3D sizeof(payload->u64); > + if (!vhost_user_send_resp(ioc, hdr, payload, &local_err)) { > + error_report_err(local_err); > + memory_region_transaction_commit(); > + return -EFAULT; > + } > + } > + memory_region_transaction_commit(); > + return 0; > + > +send_reply: > + if (hdr->flags & VHOST_USER_NEED_REPLY_MASK) { > + payload->u64 =3D !!ret; > + hdr->size =3D sizeof(payload->u64); > + if (!vhost_user_send_resp(ioc, hdr, payload, &local_err)) { > + error_report_err(local_err); > + return -EFAULT; > + } > + } > + return 0; > +} > + > +/** > + * vhost_user_backend_handle_shmem_unmap() - Handle SHMEM_UNMAP backend = request > + * @dev: vhost device > + * @ioc: QIOChannel for communication > + * @hdr: vhost-user message header > + * @payload: message payload containing unmapping details > + * > + * Handles VHOST_USER_BACKEND_SHMEM_UNMAP requests from the backend. Rem= oves > + * the specified memory mapping from the VirtIO shared memory region. Th= is > + * automatically unreferences the associated VhostUserShmemObject, which= may > + * trigger its finalization and cleanup (munmap, close fd) if no other > + * references exist. > + * > + * Returns: 0 on success, negative errno on failure > + */ > +static int > +vhost_user_backend_handle_shmem_unmap(struct vhost_dev *dev, > + QIOChannel *ioc, > + VhostUserHeader *hdr, > + VhostUserPayload *payload) > +{ > + VirtioSharedMemory *shmem; > + VirtioSharedMemoryMapping *mmap =3D NULL; > + VhostUserMMap *vu_mmap =3D &payload->mmap; > + Error *local_err =3D NULL; > + int ret =3D 0; > + > + if (QSIMPLEQ_EMPTY(&dev->vdev->shmem_list)) { > + error_report("Device has no VIRTIO Shared Memory Regions. " > + "Requested ID: %d", vu_mmap->shmid); > + ret =3D -EFAULT; > + goto send_reply; > + } > + > + shmem =3D virtio_find_shmem_region(dev->vdev, vu_mmap->shmid); > + if (!shmem) { > + error_report("VIRTIO Shared Memory Region at " > + "ID %d not found or uninitialized", vu_mmap->shmid)= ; > + ret =3D -EFAULT; > + goto send_reply; > + } > + > + if ((vu_mmap->shm_offset + vu_mmap->len) < vu_mmap->len || > + (vu_mmap->shm_offset + vu_mmap->len) > shmem->mr.size) { > + error_report("Bad offset/len for unmmap %" PRIx64 "+%" PRIx64, > + vu_mmap->shm_offset, vu_mmap->len); > + ret =3D -EFAULT; > + goto send_reply; > + } > + > + mmap =3D virtio_find_shmem_map(shmem, vu_mmap->shm_offset, vu_mmap->= len); > + if (!mmap) { > + error_report("Shared memory mapping not found at offset %" PRIx6= 4 > + " with length %" PRIx64, > + vu_mmap->shm_offset, vu_mmap->len); > + ret =3D -EFAULT; > + goto send_reply; > + } > + > +send_reply: > + if (hdr->flags & VHOST_USER_NEED_REPLY_MASK) { > + payload->u64 =3D !!ret; > + hdr->size =3D sizeof(payload->u64); > + if (!vhost_user_send_resp(ioc, hdr, payload, &local_err)) { > + error_report_err(local_err); > + return -EFAULT; > + } > + } > + > + if (!ret && mmap) { > + /* Free the MemoryRegion only after reply */ > + virtio_del_shmem_map(shmem, vu_mmap->shm_offset, vu_mmap->len); > + } > + > + return 0; > +} > + > static void close_backend_channel(struct vhost_user *u) > { > g_source_destroy(u->backend_src); > @@ -1836,6 +2054,19 @@ static gboolean backend_read(QIOChannel *ioc, GIOC= ondition condition, > ret =3D vhost_user_backend_handle_shared_object_lookup(dev->opaq= ue, ioc, > &hdr, &payl= oad); > break; > + case VHOST_USER_BACKEND_SHMEM_MAP: > + /* Handler manages its own response, check error and close conne= ction */ > + if (vhost_user_backend_handle_shmem_map(dev, ioc, &hdr, &payload= , > + fd ? fd[0] : -1) < 0) { > + goto err; > + } > + break; > + case VHOST_USER_BACKEND_SHMEM_UNMAP: > + /* Handler manages its own response, check error and close conne= ction */ > + if (vhost_user_backend_handle_shmem_unmap(dev, ioc, &hdr, &paylo= ad) < 0) { > + goto err; > + } > + break; Once this patch lands: https://lists.gnu.org/archive/html/qemu-devel/2025-10/msg03932.html These two handlers will need a `reply_ack =3D false;` before being invoked. What's the best way to proceed in this case? If I can chose, I'd prefer to integrate this one first and then I can rebase the one I linked and set the reply_ack where needed. > default: > error_report("Received unexpected msg type: %d.", hdr.request); > ret =3D -EINVAL; > @@ -3013,6 +3244,41 @@ static int vhost_user_check_device_state(struct vh= ost_dev *dev, Error **errp) > return 0; > } > > +static int vhost_user_get_shmem_config(struct vhost_dev *dev, > + int *nregions, > + uint64_t *memory_sizes, > + Error **errp) > +{ > + int ret; > + VhostUserMsg msg =3D { > + .hdr.request =3D VHOST_USER_GET_SHMEM_CONFIG, > + .hdr.flags =3D VHOST_USER_VERSION, > + }; > + > + if (!virtio_has_feature(dev->protocol_features, > + VHOST_USER_PROTOCOL_F_SHMEM)) { > + *nregions =3D 0; > + return 0; > + } > + > + ret =3D vhost_user_write(dev, &msg, NULL, 0); > + if (ret < 0) { > + return ret; > + } > + > + ret =3D vhost_user_read(dev, &msg); > + if (ret < 0) { > + return ret; > + } > + > + assert(msg.payload.shmem.nregions <=3D VIRTIO_MAX_SHMEM_REGIONS); > + *nregions =3D msg.payload.shmem.nregions; > + memcpy(memory_sizes, > + &msg.payload.shmem.memory_sizes, > + sizeof(uint64_t) * VIRTIO_MAX_SHMEM_REGIONS); > + return 0; > +} > + > const VhostOps user_ops =3D { > .backend_type =3D VHOST_BACKEND_TYPE_USER, > .vhost_backend_init =3D vhost_user_backend_init, > @@ -3051,4 +3317,5 @@ const VhostOps user_ops =3D { > .vhost_supports_device_state =3D vhost_user_supports_device_stat= e, > .vhost_set_device_state_fd =3D vhost_user_set_device_state_fd, > .vhost_check_device_state =3D vhost_user_check_device_state, > + .vhost_get_shmem_config =3D vhost_user_get_shmem_config, > }; > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c > index 153ee0a0cf..f96ed43c18 100644 > --- a/hw/virtio/virtio.c > +++ b/hw/virtio/virtio.c > @@ -3086,6 +3086,173 @@ int virtio_save(VirtIODevice *vdev, QEMUFile *f) > return vmstate_save_state(f, &vmstate_virtio, vdev, NULL, &error_fat= al); > } > > +VirtioSharedMemory *virtio_new_shmem_region(VirtIODevice *vdev, uint8_t = shmid, uint64_t size) > +{ > + VirtioSharedMemory *elem; > + g_autofree char *name =3D NULL; > + > + elem =3D g_new0(VirtioSharedMemory, 1); > + elem->shmid =3D shmid; > + > + /* Initialize embedded MemoryRegion as container for shmem mappings = */ > + name =3D g_strdup_printf("virtio-shmem-%d", shmid); > + memory_region_init(&elem->mr, OBJECT(vdev), name, size); > + QTAILQ_INIT(&elem->mmaps); > + QSIMPLEQ_INSERT_TAIL(&vdev->shmem_list, elem, entry); > + return elem; > +} > + > +VirtioSharedMemory *virtio_find_shmem_region(VirtIODevice *vdev, uint8_t= shmid) > +{ > + VirtioSharedMemory *shmem, *next; > + QSIMPLEQ_FOREACH_SAFE(shmem, &vdev->shmem_list, entry, next) { > + if (shmem->shmid =3D=3D shmid) { > + return shmem; > + } > + } > + return NULL; > +} > + > +static void virtio_shared_memory_mapping_instance_init(Object *obj) > +{ > + VirtioSharedMemoryMapping *mapping =3D VIRTIO_SHARED_MEMORY_MAPPING(= obj); > + > + mapping->shmid =3D 0; > + mapping->offset =3D 0; > + mapping->len =3D 0; > + mapping->mr =3D NULL; > +} > + > +static void virtio_shared_memory_mapping_instance_finalize(Object *obj) > +{ > + VirtioSharedMemoryMapping *mapping =3D VIRTIO_SHARED_MEMORY_MAPPING(= obj); > + > + /* Clean up MemoryRegion if it exists */ > + if (mapping->mr) { > + /* Unparent the MemoryRegion to trigger cleanup */ > + object_unparent(OBJECT(mapping->mr)); > + mapping->mr =3D NULL; > + } > +} > + > +VirtioSharedMemoryMapping *virtio_shared_memory_mapping_new(uint8_t shmi= d, > + int fd, > + uint64_t fd_= offset, > + uint64_t shm= _offset, > + uint64_t len= , > + bool allow_w= rite) > +{ > + VirtioSharedMemoryMapping *mapping; > + MemoryRegion *mr; > + g_autoptr(GString) mr_name =3D g_string_new(NULL); > + uint32_t ram_flags; > + Error *local_err =3D NULL; > + > + if (len =3D=3D 0) { > + error_report("Shared memory mapping size cannot be zero"); > + return NULL; > + } > + > + fd =3D dup(fd); > + if (fd < 0) { > + error_report("Failed to duplicate fd: %s", strerror(errno)); > + return NULL; > + } > + > + /* Determine RAM flags */ > + ram_flags =3D RAM_SHARED; > + if (!allow_write) { > + ram_flags |=3D RAM_READONLY_FD; > + } > + > + /* Create the VirtioSharedMemoryMapping */ > + mapping =3D VIRTIO_SHARED_MEMORY_MAPPING( > + object_new(TYPE_VIRTIO_SHARED_MEMORY_MAPPING)); > + > + /* Set up object properties */ > + mapping->shmid =3D shmid; > + mapping->offset =3D shm_offset; > + mapping->len =3D len; > + > + /* Create MemoryRegion as a child of this object */ > + mr =3D g_new0(MemoryRegion, 1); > + g_string_printf(mr_name, "virtio-shmem-%d-%" PRIx64, shmid, shm_offs= et); > + > + /* Initialize MemoryRegion with file descriptor */ > + if (!memory_region_init_ram_from_fd(mr, OBJECT(mapping), mr_name->st= r, > + len, ram_flags, fd, fd_offset, > + &local_err)) { > + error_report_err(local_err); > + g_free(mr); > + close(fd); > + object_unref(OBJECT(mapping)); > + return NULL; > + } > + > + mapping->mr =3D mr; > + return mapping; > +} > + > +int virtio_add_shmem_map(VirtioSharedMemory *shmem, > + VirtioSharedMemoryMapping *mapping) > +{ > + if (!mapping) { > + error_report("VirtioSharedMemoryMapping cannot be NULL"); > + return -1; > + } > + if (!mapping->mr) { > + error_report("VirtioSharedMemoryMapping has no MemoryRegion"); > + return -1; > + } > + > + /* Validate boundaries against the VIRTIO shared memory region */ > + if (mapping->offset + mapping->len > shmem->mr.size) { > + error_report("Memory exceeds the shared memory boundaries"); > + return -1; > + } > + > + /* Add as subregion to the VIRTIO shared memory */ > + memory_region_add_subregion(&shmem->mr, mapping->offset, mapping->mr= ); > + > + /* Add to the mapped regions list */ > + QTAILQ_INSERT_TAIL(&shmem->mmaps, mapping, link); > + > + return 0; > +} > + > +VirtioSharedMemoryMapping *virtio_find_shmem_map(VirtioSharedMemory *shm= em, > + hwaddr offset, uint64_t size) > +{ > + VirtioSharedMemoryMapping *mapping; > + QTAILQ_FOREACH(mapping, &shmem->mmaps, link) { > + if (mapping->offset =3D=3D offset && mapping->mr->size =3D=3D si= ze) { > + return mapping; > + } > + } > + return NULL; > +} > + > +void virtio_del_shmem_map(VirtioSharedMemory *shmem, hwaddr offset, > + uint64_t size) > +{ > + VirtioSharedMemoryMapping *mapping =3D virtio_find_shmem_map(shmem, = offset, size); > + if (mapping =3D=3D NULL) { > + return; > + } > + > + /* > + * Remove from memory region first > + */ > + memory_region_del_subregion(&shmem->mr, mapping->mr); > + > + /* > + * Remove from list and unref the mapping which will trigger automat= ic cleanup > + * when the reference count reaches zero. > + */ > + QTAILQ_REMOVE(&shmem->mmaps, mapping, link); > + object_unref(OBJECT(mapping)); > +} > + > /* A wrapper for use as a VMState .put function */ > static int virtio_device_put(QEMUFile *f, void *opaque, size_t size, > const VMStateField *field, JSONWriter *vmd= esc) > @@ -3212,6 +3379,7 @@ void virtio_reset(void *opaque) > { > VirtIODevice *vdev =3D opaque; > VirtioDeviceClass *k =3D VIRTIO_DEVICE_GET_CLASS(vdev); > + VirtioSharedMemory *shmem; > uint64_t features[VIRTIO_FEATURES_NU64S]; > int i; > > @@ -3251,6 +3419,14 @@ void virtio_reset(void *opaque) > for (i =3D 0; i < VIRTIO_QUEUE_MAX; i++) { > __virtio_queue_reset(vdev, i); > } > + > + /* Mappings are removed to prevent stale fds from remaining open. */ > + QSIMPLEQ_FOREACH(shmem, &vdev->shmem_list, entry) { > + while (!QTAILQ_EMPTY(&shmem->mmaps)) { > + VirtioSharedMemoryMapping *mapping =3D QTAILQ_FIRST(&shmem->= mmaps); > + virtio_del_shmem_map(shmem, mapping->offset, mapping->mr->si= ze); > + } > + } > } > > static void virtio_device_check_notification_compatibility(VirtIODevice = *vdev, > @@ -3574,6 +3750,7 @@ void virtio_init(VirtIODevice *vdev, uint16_t devic= e_id, size_t config_size) > NULL, virtio_vmstate_change, vdev); > vdev->device_endian =3D virtio_default_endian(); > vdev->use_guest_notifier_mask =3D true; > + QSIMPLEQ_INIT(&vdev->shmem_list); > } > > /* > @@ -4085,11 +4262,24 @@ static void virtio_device_free_virtqueues(VirtIOD= evice *vdev) > static void virtio_device_instance_finalize(Object *obj) > { > VirtIODevice *vdev =3D VIRTIO_DEVICE(obj); > + VirtioSharedMemory *shmem; > > virtio_device_free_virtqueues(vdev); > > g_free(vdev->config); > g_free(vdev->vector_queues); > + while (!QSIMPLEQ_EMPTY(&vdev->shmem_list)) { > + shmem =3D QSIMPLEQ_FIRST(&vdev->shmem_list); > + while (!QTAILQ_EMPTY(&shmem->mmaps)) { > + VirtioSharedMemoryMapping *mapping =3D QTAILQ_FIRST(&shmem->= mmaps); > + virtio_del_shmem_map(shmem, mapping->offset, mapping->mr->si= ze); > + } > + > + /* Clean up the embedded MemoryRegion */ > + object_unparent(OBJECT(&shmem->mr)); > + QSIMPLEQ_REMOVE_HEAD(&vdev->shmem_list, entry); > + g_free(shmem); > + } > } > > static const Property virtio_properties[] =3D { > @@ -4455,9 +4645,18 @@ static const TypeInfo virtio_device_info =3D { > .class_size =3D sizeof(VirtioDeviceClass), > }; > > +static const TypeInfo virtio_shared_memory_mapping_info =3D { > + .name =3D TYPE_VIRTIO_SHARED_MEMORY_MAPPING, > + .parent =3D TYPE_OBJECT, > + .instance_size =3D sizeof(VirtioSharedMemoryMapping), > + .instance_init =3D virtio_shared_memory_mapping_instance_init, > + .instance_finalize =3D virtio_shared_memory_mapping_instance_finaliz= e, > +}; > + > static void virtio_register_types(void) > { > type_register_static(&virtio_device_info); > + type_register_static(&virtio_shared_memory_mapping_info); > } > > type_init(virtio_register_types) > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h > index d97529c3f1..3f6dfba321 100644 > --- a/include/hw/virtio/virtio.h > +++ b/include/hw/virtio/virtio.h > @@ -99,6 +99,45 @@ enum virtio_device_endian { > VIRTIO_DEVICE_ENDIAN_BIG, > }; > > +#define TYPE_VIRTIO_SHARED_MEMORY_MAPPING "virtio-shared-memory-mapping" > +OBJECT_DECLARE_SIMPLE_TYPE(VirtioSharedMemoryMapping, VIRTIO_SHARED_MEMO= RY_MAPPING) > + > +/** > + * VirtioSharedMemoryMapping: > + * @parent: Parent QOM object > + * @shmid: VIRTIO Shared Memory Region ID > + * @fd: File descriptor for the shared memory region > + * @offset: Offset within the VIRTIO Shared Memory Region > + * @len: Size of the mapping > + * @mr: MemoryRegion associated with this shared memory mapping > + * @link: List entry for the shared memory region's mapping list > + * > + * A QOM object that represents an individual file descriptor-based shar= ed > + * memory mapping within a VIRTIO Shared Memory Region. It manages the > + * MemoryRegion lifecycle and file descriptor cleanup through QOM refere= nce > + * counting. When the object is unreferenced and its reference count dro= ps > + * to zero, it automatically cleans up the MemoryRegion and closes the f= ile > + * descriptor. > + */ > +struct VirtioSharedMemoryMapping { > + Object parent; > + > + uint8_t shmid; > + hwaddr offset; > + uint64_t len; > + MemoryRegion *mr; > + QTAILQ_ENTRY(VirtioSharedMemoryMapping) link; > +}; > + > +struct VirtioSharedMemory { > + uint8_t shmid; > + MemoryRegion mr; > + QTAILQ_HEAD(, VirtioSharedMemoryMapping) mmaps; > + QSIMPLEQ_ENTRY(VirtioSharedMemory) entry; > +}; > + > +typedef struct VirtioSharedMemory VirtioSharedMemory; > + > /** > * struct VirtIODevice - common VirtIO structure > * @name: name of the device > @@ -168,6 +207,8 @@ struct VirtIODevice > */ > EventNotifier config_notifier; > bool device_iotlb_enabled; > + /* Shared memory region for mappings. */ > + QSIMPLEQ_HEAD(, VirtioSharedMemory) shmem_list; > }; > > struct VirtioDeviceClass { > @@ -298,6 +339,100 @@ void virtio_notify(VirtIODevice *vdev, VirtQueue *v= q); > > int virtio_save(VirtIODevice *vdev, QEMUFile *f); > > +/** > + * virtio_new_shmem_region() - Create a new shared memory region > + * @vdev: VirtIODevice > + * @shmid: Shared memory ID > + * @size: Size of the shared memory region > + * > + * Creates a new VirtioSharedMemory region for the given device and ID. > + * The returned VirtioSharedMemory is owned by the VirtIODevice and will > + * be automatically freed when the device is destroyed. The caller > + * should not free the returned pointer. > + * > + * Returns: Pointer to the new VirtioSharedMemory region, or NULL on fai= lure > + */ > +VirtioSharedMemory *virtio_new_shmem_region(VirtIODevice *vdev, uint8_t = shmid, uint64_t size); > + > +/** > + * virtio_find_shmem_region() - Find an existing shared memory region > + * @vdev: VirtIODevice > + * @shmid: Shared memory ID to find > + * > + * Finds an existing VirtioSharedMemory region by ID. The returned point= er > + * is owned by the VirtIODevice and should not be freed by the caller. > + * > + * Returns: Pointer to the VirtioSharedMemory region, or NULL if not fou= nd > + */ > +VirtioSharedMemory *virtio_find_shmem_region(VirtIODevice *vdev, uint8_t= shmid); > + > +/** > + * virtio_shared_memory_mapping_new() - Create a new VirtioSharedMemoryM= apping > + * @shmid: VIRTIO Shared Memory Region ID > + * @fd: File descriptor for the shared memory > + * @fd_offset: Offset within the file descriptor > + * @shm_offset: Offset within the VIRTIO Shared Memory Region > + * @len: Size of the mapping > + * @allow_write: Whether to allow write access to the mapping > + * > + * Creates a new VirtioSharedMemoryMapping that manages a shared memory = mapping. > + * The object will create a MemoryRegion using memory_region_init_ram_fr= om_fd() > + * as a child object. When the object is finalized, it will automaticall= y > + * clean up the MemoryRegion and close the file descriptor. > + * > + * Return: A new VirtioSharedMemoryMapping on success, NULL on error. > + */ > +VirtioSharedMemoryMapping *virtio_shared_memory_mapping_new(uint8_t shmi= d, > + int fd, > + uint64_t fd_= offset, > + uint64_t shm= _offset, > + uint64_t len= , > + bool allow_w= rite); > + > +/** > + * virtio_add_shmem_map() - Add a memory mapping to a shared region > + * @shmem: VirtioSharedMemory region > + * @mapping: VirtioSharedMemoryMapping to add (transfers ownership) > + * > + * Adds a memory mapping to the shared memory region. The VirtioSharedMe= moryMapping > + * ownership is transferred to the shared memory region and will be auto= matically > + * cleaned up through QOM reference counting when virtio_del_shmem_map()= is > + * called or when the shared memory region is destroyed. > + * > + * Returns: 0 on success, negative errno on failure > + */ > +int virtio_add_shmem_map(VirtioSharedMemory *shmem, > + VirtioSharedMemoryMapping *mapping); > + > +/** > + * virtio_find_shmem_map() - Find a memory mapping in a shared region > + * @shmem: VirtioSharedMemory region > + * @offset: Offset within the shared memory region > + * @size: Size of the mapping to find > + * > + * Finds an existing memory mapping that covers the specified range. > + * The returned VirtioSharedMemoryMapping is owned by the VirtioSharedMe= mory > + * region and should not be freed by the caller. > + * > + * Returns: Pointer to the VirtioSharedMemoryMapping, or NULL if not fou= nd > + */ > +VirtioSharedMemoryMapping *virtio_find_shmem_map(VirtioSharedMemory *shm= em, > + hwaddr offset, uint64_t size); > + > +/** > + * virtio_del_shmem_map() - Remove a memory mapping from a shared region > + * @shmem: VirtioSharedMemory region > + * @offset: Offset of the mapping to remove > + * @size: Size of the mapping to remove > + * > + * Removes a memory mapping from the shared memory region. This will > + * automatically unref the associated VhostUserShmemObject, which may > + * trigger its finalization and cleanup if no other references exist. > + * The mapping's MemoryRegion will be properly unmapped and cleaned up. > + */ > +void virtio_del_shmem_map(VirtioSharedMemory *shmem, hwaddr offset, > + uint64_t size); > + > extern const VMStateInfo virtio_vmstate_info; > > #define VMSTATE_VIRTIO_DEVICE \ > diff --git a/subprojects/libvhost-user/libvhost-user.c b/subprojects/libv= host-user/libvhost-user.c > index 9c630c2170..034cbfdc3c 100644 > --- a/subprojects/libvhost-user/libvhost-user.c > +++ b/subprojects/libvhost-user/libvhost-user.c > @@ -1592,6 +1592,76 @@ vu_rm_shared_object(VuDev *dev, unsigned char uuid= [UUID_LEN]) > return vu_send_message(dev, &msg); > } > > +bool > +vu_shmem_map(VuDev *dev, uint8_t shmid, uint64_t fd_offset, > + uint64_t shm_offset, uint64_t len, uint64_t flags, int fd) > +{ > + VhostUserMsg vmsg =3D { > + .request =3D VHOST_USER_BACKEND_SHMEM_MAP, > + .size =3D sizeof(vmsg.payload.mmap), > + .flags =3D VHOST_USER_VERSION, > + .payload.mmap =3D { > + .shmid =3D shmid, > + .fd_offset =3D fd_offset, > + .shm_offset =3D shm_offset, > + .len =3D len, > + .flags =3D flags, > + }, > + .fd_num =3D 1, > + .fds[0] =3D fd, > + }; > + > + if (!vu_has_protocol_feature(dev, VHOST_USER_PROTOCOL_F_SHMEM)) { > + return false; > + } > + > + if (vu_has_protocol_feature(dev, VHOST_USER_PROTOCOL_F_REPLY_ACK)) { > + vmsg.flags |=3D VHOST_USER_NEED_REPLY_MASK; > + } > + > + pthread_mutex_lock(&dev->backend_mutex); > + if (!vu_message_write(dev, dev->backend_fd, &vmsg)) { > + pthread_mutex_unlock(&dev->backend_mutex); > + return false; > + } > + > + /* Also unlocks the backend_mutex */ > + return vu_process_message_reply(dev, &vmsg); > +} > + > +bool > +vu_shmem_unmap(VuDev *dev, uint8_t shmid, uint64_t shm_offset, uint64_t = len) > +{ > + VhostUserMsg vmsg =3D { > + .request =3D VHOST_USER_BACKEND_SHMEM_UNMAP, > + .size =3D sizeof(vmsg.payload.mmap), > + .flags =3D VHOST_USER_VERSION, > + .payload.mmap =3D { > + .shmid =3D shmid, > + .fd_offset =3D 0, > + .shm_offset =3D shm_offset, > + .len =3D len, > + }, > + }; > + > + if (!vu_has_protocol_feature(dev, VHOST_USER_PROTOCOL_F_SHMEM)) { > + return false; > + } > + > + if (vu_has_protocol_feature(dev, VHOST_USER_PROTOCOL_F_REPLY_ACK)) { > + vmsg.flags |=3D VHOST_USER_NEED_REPLY_MASK; > + } > + > + pthread_mutex_lock(&dev->backend_mutex); > + if (!vu_message_write(dev, dev->backend_fd, &vmsg)) { > + pthread_mutex_unlock(&dev->backend_mutex); > + return false; > + } > + > + /* Also unlocks the backend_mutex */ > + return vu_process_message_reply(dev, &vmsg); > +} > + > static bool > vu_set_vring_call_exec(VuDev *dev, VhostUserMsg *vmsg) > { > diff --git a/subprojects/libvhost-user/libvhost-user.h b/subprojects/libv= host-user/libvhost-user.h > index 2ffc58c11b..6a2d0f9fae 100644 > --- a/subprojects/libvhost-user/libvhost-user.h > +++ b/subprojects/libvhost-user/libvhost-user.h > @@ -69,6 +69,8 @@ enum VhostUserProtocolFeature { > /* Feature 16 is reserved for VHOST_USER_PROTOCOL_F_STATUS. */ > /* Feature 17 reserved for VHOST_USER_PROTOCOL_F_XEN_MMAP. */ > VHOST_USER_PROTOCOL_F_SHARED_OBJECT =3D 18, > + /* Feature 19 is reserved for VHOST_USER_PROTOCOL_F_DEVICE_STATE */ > + VHOST_USER_PROTOCOL_F_SHMEM =3D 20, > VHOST_USER_PROTOCOL_F_MAX > }; > > @@ -127,6 +129,8 @@ typedef enum VhostUserBackendRequest { > VHOST_USER_BACKEND_SHARED_OBJECT_ADD =3D 6, > VHOST_USER_BACKEND_SHARED_OBJECT_REMOVE =3D 7, > VHOST_USER_BACKEND_SHARED_OBJECT_LOOKUP =3D 8, > + VHOST_USER_BACKEND_SHMEM_MAP =3D 9, > + VHOST_USER_BACKEND_SHMEM_UNMAP =3D 10, > VHOST_USER_BACKEND_MAX > } VhostUserBackendRequest; > > @@ -186,6 +190,23 @@ typedef struct VhostUserShared { > unsigned char uuid[UUID_LEN]; > } VhostUserShared; > > +/* For the flags field of VhostUserMMap */ > +#define VHOST_USER_FLAG_MAP_RW (1u << 0) > + > +typedef struct { > + /* VIRTIO Shared Memory Region ID */ > + uint8_t shmid; > + uint8_t padding[7]; > + /* File offset */ > + uint64_t fd_offset; > + /* Offset within the VIRTIO Shared Memory Region */ > + uint64_t shm_offset; > + /* Size of the mapping */ > + uint64_t len; > + /* Flags for the mmap operation, from VHOST_USER_FLAG_MAP_* */ > + uint64_t flags; > +} VhostUserMMap; > + > #define VU_PACKED __attribute__((packed)) > > typedef struct VhostUserMsg { > @@ -210,6 +231,7 @@ typedef struct VhostUserMsg { > VhostUserVringArea area; > VhostUserInflight inflight; > VhostUserShared object; > + VhostUserMMap mmap; > } payload; > > int fds[VHOST_MEMORY_BASELINE_NREGIONS]; > @@ -593,6 +615,38 @@ bool vu_add_shared_object(VuDev *dev, unsigned char = uuid[UUID_LEN]); > */ > bool vu_rm_shared_object(VuDev *dev, unsigned char uuid[UUID_LEN]); > > +/** > + * vu_shmem_map: > + * @dev: a VuDev context > + * @shmid: VIRTIO Shared Memory Region ID > + * @fd_offset: File offset > + * @shm_offset: Offset within the VIRTIO Shared Memory Region > + * @len: Size of the mapping > + * @flags: Flags for the mmap operation > + * @fd: A file descriptor > + * > + * Advertises a new mapping to be made in a given VIRTIO Shared Memory R= egion. > + * > + * Returns: TRUE on success, FALSE on failure. > + */ > +bool vu_shmem_map(VuDev *dev, uint8_t shmid, uint64_t fd_offset, > + uint64_t shm_offset, uint64_t len, uint64_t flags, int= fd); > + > +/** > + * vu_shmem_unmap: > + * @dev: a VuDev context > + * @shmid: VIRTIO Shared Memory Region ID > + * @fd_offset: File offset > + * @len: Size of the mapping > + * > + * The front-end un-mmaps a given range in the VIRTIO Shared Memory Regi= on > + * with the requested `shmid`. > + * > + * Returns: TRUE on success, FALSE on failure. > + */ > +bool vu_shmem_unmap(VuDev *dev, uint8_t shmid, uint64_t shm_offset, > + uint64_t len); > + > /** > * vu_queue_set_notification: > * @dev: a VuDev context > -- > 2.49.0 >