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[2.86.215.65]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-426ce589a21sm28901137f8f.23.2025.10.15.02.52.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Oct 2025 02:52:46 -0700 (PDT) Date: Wed, 15 Oct 2025 12:47:18 +0300 From: Manos Pitsidianakis To: Albert Esteve , qemu-devel@nongnu.org Cc: stevensd@chromium.org, jasowang@redhat.com, Paolo Bonzini , hi@alyssa.is, Laurent Vivier , Alex Benn=?UTF-8?B?w6k=?=e , david@redhat.com, manos.pitsidianakis@linaro.org, Fabiano Rosas , Michael S. Tsirkin , stefanha@redhat.com, Stefano Garzarella , slp@redhat.com, dbassey@redhat.com, Albert Esteve Subject: Re: [PATCH v9 1/7] vhost-user: Add VirtIO Shared Memory map request User-Agent: meli/0.8.12 References: <20251015085930.1517330-1-aesteve@redhat.com> <20251015085930.1517330-2-aesteve@redhat.com> In-Reply-To: <20251015085930.1517330-2-aesteve@redhat.com> Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Received-SPF: pass client-ip=2a00:1450:4864:20::334; envelope-from=manos.pitsidianakis@linaro.org; helo=mail-wm1-x334.google.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, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=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 Wed, 15 Oct 2025 11:59, 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. > >Signed-off-by: Albert Esteve >--- > hw/virtio/vhost-user.c | 213 ++++++++++++++++++++++ > hw/virtio/virtio.c | 207 +++++++++++++++++++++ > include/hw/virtio/virtio.h | 136 ++++++++++++++ > subprojects/libvhost-user/libvhost-user.c | 70 +++++++ > subprojects/libvhost-user/libvhost-user.h | 54 ++++++ > 5 files changed, 680 insertions(+) > >diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c >index 36c9c2e04d..8a4385a5ad 100644 >--- a/hw/virtio/vhost-user.c >+++ b/hw/virtio/vhost-user.c >@@ -115,6 +115,8 @@ typedef enum VhostUserBackendRequest { > VHOST_USER_BACKEND_SHARED_OBJECT_ADD = 6, > VHOST_USER_BACKEND_SHARED_OBJECT_REMOVE = 7, > VHOST_USER_BACKEND_SHARED_OBJECT_LOOKUP = 8, >+ VHOST_USER_BACKEND_SHMEM_MAP = 9, >+ VHOST_USER_BACKEND_SHMEM_UNMAP = 10, > VHOST_USER_BACKEND_MAX > } VhostUserBackendRequest; > >@@ -192,6 +194,23 @@ 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 +243,7 @@ typedef union { > VhostUserInflight inflight; > VhostUserShared object; > VhostUserTransferDeviceState transfer_state; >+ VhostUserMMap mmap; > } VhostUserPayload; > > typedef struct VhostUserMsg { >@@ -1768,6 +1788,186 @@ vhost_user_backend_handle_shared_object_lookup(struct vhost_user *u, > return 0; > } > >+/** >+ * vhost_user_backend_handle_shmem_map() - Handle SHMEM_MAP backend request >+ * @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. Creates >+ * a VhostUserShmemObject to manage the shared memory mapping and adds it >+ * to the appropriate VirtIO shared memory region. The VhostUserShmemObject >+ * serves as an intermediate parent for the MemoryRegion, ensuring proper >+ * 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 = &payload->mmap; >+ VirtioSharedMemoryMapping *existing; >+ Error *local_err = NULL; >+ int ret = 0; >+ >+ if (fd < 0) { >+ error_report("Bad fd for map"); >+ ret = -EBADF; >+ goto send_reply; Apologies if I missed something obvious, but won't going to send_reply at this point cause memory_region_transaction_commit() to be called? Maybe we should have two cleanup labels, depending on whether memory_region_transaction_begin() has been called yet? >+ } >+ >+ if (QSIMPLEQ_EMPTY(&dev->vdev->shmem_list)) { >+ error_report("Device has no VIRTIO Shared Memory Regions. " >+ "Requested ID: %d", vu_mmap->shmid); >+ ret = -EFAULT; >+ goto send_reply; >+ } >+ >+ shmem = 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 = -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 = -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 = -EFAULT; >+ goto send_reply; >+ } >+ } >+ >+ memory_region_transaction_begin(); >+ >+ /* Create VirtioSharedMemoryMapping object */ >+ VirtioSharedMemoryMapping *mapping = 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 = -EFAULT; >+ goto send_reply; >+ } >+ >+ /* Add the mapping to the shared memory region */ >+ if (virtio_add_shmem_map(shmem, mapping) != 0) { >+ error_report("Failed to add shared memory mapping"); >+ object_unref(OBJECT(mapping)); >+ ret = -EFAULT; >+ goto send_reply; >+ } >+ >+send_reply: >+ if (hdr->flags & VHOST_USER_NEED_REPLY_MASK) { >+ payload->u64 = !!ret; >+ hdr->size = 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; >+} >+ >+/** >+ * 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. Removes >+ * the specified memory mapping from the VirtIO shared memory region. This >+ * 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 = NULL; >+ VhostUserMMap *vu_mmap = &payload->mmap; >+ Error *local_err = NULL; >+ int ret = 0; >+ >+ if (QSIMPLEQ_EMPTY(&dev->vdev->shmem_list)) { >+ error_report("Device has no VIRTIO Shared Memory Regions. " >+ "Requested ID: %d", vu_mmap->shmid); >+ ret = -EFAULT; >+ goto send_reply; >+ } >+ >+ shmem = 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 = -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 = -EFAULT; >+ goto send_reply; >+ } >+ >+ mmap = virtio_find_shmem_map(shmem, vu_mmap->shm_offset, vu_mmap->len); >+ if (!mmap) { >+ error_report("Shared memory mapping not found at offset %" PRIx64 >+ " with length %" PRIx64, >+ vu_mmap->shm_offset, vu_mmap->len); >+ ret = -EFAULT; >+ goto send_reply; >+ } >+ >+send_reply: >+ if (hdr->flags & VHOST_USER_NEED_REPLY_MASK) { >+ payload->u64 = !!ret; >+ hdr->size = 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 +2036,19 @@ static gboolean backend_read(QIOChannel *ioc, GIOCondition condition, > ret = vhost_user_backend_handle_shared_object_lookup(dev->opaque, ioc, > &hdr, &payload); > break; >+ case VHOST_USER_BACKEND_SHMEM_MAP: >+ /* Handler manages its own response, check error and close connection */ >+ 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 connection */ >+ if (vhost_user_backend_handle_shmem_unmap(dev, ioc, &hdr, &payload) < 0) { >+ goto err; >+ } >+ break; > default: > error_report("Received unexpected msg type: %d.", hdr.request); > ret = -EINVAL; >diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c >index 153ee0a0cf..37070e7951 100644 >--- a/hw/virtio/virtio.c >+++ b/hw/virtio/virtio.c >@@ -3086,6 +3086,181 @@ int virtio_save(VirtIODevice *vdev, QEMUFile *f) > return vmstate_save_state(f, &vmstate_virtio, vdev, NULL, &error_fatal); > } > >+VirtioSharedMemory *virtio_new_shmem_region(VirtIODevice *vdev, uint8_t shmid, uint64_t size) >+{ >+ VirtioSharedMemory *elem; >+ g_autofree char *name = NULL; >+ >+ elem = g_new0(VirtioSharedMemory, 1); >+ elem->shmid = shmid; >+ >+ /* Initialize embedded MemoryRegion as container for shmem mappings */ >+ name = 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 == shmid) { >+ return shmem; >+ } >+ } >+ return NULL; >+} >+ >+static void virtio_shared_memory_mapping_instance_init(Object *obj) >+{ >+ VirtioSharedMemoryMapping *mapping = VIRTIO_SHARED_MEMORY_MAPPING(obj); >+ >+ mapping->shmid = 0; >+ mapping->fd = -1; >+ mapping->offset = 0; >+ mapping->len = 0; >+ mapping->mr = NULL; >+} >+ >+static void virtio_shared_memory_mapping_instance_finalize(Object *obj) >+{ >+ VirtioSharedMemoryMapping *mapping = 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 = NULL; >+ } >+ >+ /* Close file descriptor */ >+ if (mapping->fd >= 0) { >+ close(mapping->fd); >+ mapping->fd = -1; >+ } >+} >+ >+VirtioSharedMemoryMapping *virtio_shared_memory_mapping_new(uint8_t shmid, >+ int fd, >+ uint64_t fd_offset, >+ uint64_t shm_offset, >+ uint64_t len, >+ bool allow_write) >+{ >+ VirtioSharedMemoryMapping *mapping; >+ MemoryRegion *mr; >+ g_autoptr(GString) mr_name = g_string_new(NULL); >+ uint32_t ram_flags; >+ Error *local_err = NULL; >+ >+ if (len == 0) { >+ error_report("Shared memory mapping size cannot be zero"); >+ return NULL; >+ } >+ >+ fd = dup(fd); >+ if (fd < 0) { >+ error_report("Failed to duplicate fd: %s", strerror(errno)); >+ return NULL; >+ } >+ >+ /* Determine RAM flags */ >+ ram_flags = RAM_SHARED; >+ if (!allow_write) { >+ ram_flags |= RAM_READONLY_FD; >+ } >+ >+ /* Create the VirtioSharedMemoryMapping */ >+ mapping = VIRTIO_SHARED_MEMORY_MAPPING( >+ object_new(TYPE_VIRTIO_SHARED_MEMORY_MAPPING)); >+ >+ /* Set up object properties */ >+ mapping->shmid = shmid; >+ mapping->fd = fd; >+ mapping->offset = shm_offset; >+ mapping->len = len; >+ >+ /* Create MemoryRegion as a child of this object */ >+ mr = g_new0(MemoryRegion, 1); >+ g_string_printf(mr_name, "virtio-shmem-%d-%" PRIx64, shmid, shm_offset); >+ >+ /* Initialize MemoryRegion with file descriptor */ >+ if (!memory_region_init_ram_from_fd(mr, OBJECT(mapping), mr_name->str, >+ 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 = 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 *shmem, >+ hwaddr offset, uint64_t size) >+{ >+ VirtioSharedMemoryMapping *mapping; >+ QTAILQ_FOREACH(mapping, &shmem->mmaps, link) { >+ if (mapping->offset == offset && mapping->mr->size == size) { >+ return mapping; >+ } >+ } >+ return NULL; >+} >+ >+void virtio_del_shmem_map(VirtioSharedMemory *shmem, hwaddr offset, >+ uint64_t size) >+{ >+ VirtioSharedMemoryMapping *mapping = virtio_find_shmem_map(shmem, offset, size); >+ if (mapping == 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 automatic 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 *vmdesc) >@@ -3212,6 +3387,7 @@ void virtio_reset(void *opaque) > { > VirtIODevice *vdev = opaque; > VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev); >+ VirtioSharedMemory *shmem; > uint64_t features[VIRTIO_FEATURES_NU64S]; > int i; > >@@ -3251,6 +3427,14 @@ void virtio_reset(void *opaque) > for (i = 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 = QTAILQ_FIRST(&shmem->mmaps); >+ virtio_del_shmem_map(shmem, mapping->offset, mapping->mr->size); >+ } >+ } > } > > static void virtio_device_check_notification_compatibility(VirtIODevice *vdev, >@@ -3574,6 +3758,7 @@ void virtio_init(VirtIODevice *vdev, uint16_t device_id, size_t config_size) > NULL, virtio_vmstate_change, vdev); > vdev->device_endian = virtio_default_endian(); > vdev->use_guest_notifier_mask = true; >+ QSIMPLEQ_INIT(&vdev->shmem_list); > } > > /* >@@ -4085,11 +4270,24 @@ static void virtio_device_free_virtqueues(VirtIODevice *vdev) > static void virtio_device_instance_finalize(Object *obj) > { > VirtIODevice *vdev = 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 = QSIMPLEQ_FIRST(&vdev->shmem_list); >+ while (!QTAILQ_EMPTY(&shmem->mmaps)) { >+ VirtioSharedMemoryMapping *mapping = QTAILQ_FIRST(&shmem->mmaps); >+ virtio_del_shmem_map(shmem, mapping->offset, mapping->mr->size); >+ } >+ >+ /* 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[] = { >@@ -4455,9 +4653,18 @@ static const TypeInfo virtio_device_info = { > .class_size = sizeof(VirtioDeviceClass), > }; > >+static const TypeInfo virtio_shared_memory_mapping_info = { >+ .name = TYPE_VIRTIO_SHARED_MEMORY_MAPPING, >+ .parent = TYPE_OBJECT, >+ .instance_size = sizeof(VirtioSharedMemoryMapping), >+ .instance_init = virtio_shared_memory_mapping_instance_init, >+ .instance_finalize = virtio_shared_memory_mapping_instance_finalize, >+}; >+ > 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..cee807e236 100644 >--- a/include/hw/virtio/virtio.h >+++ b/include/hw/virtio/virtio.h >@@ -99,6 +99,46 @@ 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_MEMORY_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 shared >+ * memory mapping within a VIRTIO Shared Memory Region. It manages the >+ * MemoryRegion lifecycle and file descriptor cleanup through QOM reference >+ * counting. When the object is unreferenced and its reference count drops >+ * to zero, it automatically cleans up the MemoryRegion and closes the file >+ * descriptor. >+ */ >+struct VirtioSharedMemoryMapping { >+ Object parent; >+ >+ uint8_t shmid; >+ int fd; >+ 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 +208,8 @@ struct VirtIODevice > */ > EventNotifier config_notifier; > bool device_iotlb_enabled; >+ /* Shared memory region for mappings. */ >+ QSIMPLEQ_HEAD(, VirtioSharedMemory) shmem_list; > }; > > struct VirtioDeviceClass { >@@ -298,6 +340,100 @@ void virtio_notify(VirtIODevice *vdev, VirtQueue *vq); > > 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 failure >+ */ >+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 pointer >+ * is owned by the VirtIODevice and should not be freed by the caller. >+ * >+ * Returns: Pointer to the VirtioSharedMemory region, or NULL if not found >+ */ >+VirtioSharedMemory *virtio_find_shmem_region(VirtIODevice *vdev, uint8_t shmid); >+ >+/** >+ * virtio_shared_memory_mapping_new() - Create a new VirtioSharedMemoryMapping >+ * @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_from_fd() >+ * as a child object. When the object is finalized, it will automatically >+ * 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 shmid, >+ int fd, >+ uint64_t fd_offset, >+ uint64_t shm_offset, >+ uint64_t len, >+ bool allow_write); >+ >+/** >+ * 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 VirtioSharedMemoryMapping >+ * ownership is transferred to the shared memory region and will be automatically >+ * 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 VirtioSharedMemory >+ * region and should not be freed by the caller. >+ * >+ * Returns: Pointer to the VirtioSharedMemoryMapping, or NULL if not found >+ */ >+VirtioSharedMemoryMapping *virtio_find_shmem_map(VirtioSharedMemory *shmem, >+ 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/libvhost-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 = { >+ .request = VHOST_USER_BACKEND_SHMEM_MAP, >+ .size = sizeof(vmsg.payload.mmap), >+ .flags = VHOST_USER_VERSION, >+ .payload.mmap = { >+ .shmid = shmid, >+ .fd_offset = fd_offset, >+ .shm_offset = shm_offset, >+ .len = len, >+ .flags = flags, >+ }, >+ .fd_num = 1, >+ .fds[0] = 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 |= 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 = { >+ .request = VHOST_USER_BACKEND_SHMEM_UNMAP, >+ .size = sizeof(vmsg.payload.mmap), >+ .flags = VHOST_USER_VERSION, >+ .payload.mmap = { >+ .shmid = shmid, >+ .fd_offset = 0, >+ .shm_offset = shm_offset, >+ .len = 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 |= 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/libvhost-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 = 18, >+ /* Feature 19 is reserved for VHOST_USER_PROTOCOL_F_DEVICE_STATE */ >+ VHOST_USER_PROTOCOL_F_SHMEM = 20, > VHOST_USER_PROTOCOL_F_MAX > }; > >@@ -127,6 +129,8 @@ typedef enum VhostUserBackendRequest { > VHOST_USER_BACKEND_SHARED_OBJECT_ADD = 6, > VHOST_USER_BACKEND_SHARED_OBJECT_REMOVE = 7, > VHOST_USER_BACKEND_SHARED_OBJECT_LOOKUP = 8, >+ VHOST_USER_BACKEND_SHMEM_MAP = 9, >+ VHOST_USER_BACKEND_SHMEM_UNMAP = 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 Region. >+ * >+ * 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 Region >+ * 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 >