On Wed, Mar 4, 2026 at 2:08 PM Stefano Garzarella <[email protected]> wrote:
>
> On Thu, Feb 19, 2026 at 02:03:28PM +0100, 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 <[email protected]>
> >Signed-off-by: Albert Esteve <[email protected]>
> >---
> > hw/virtio/vhost-user.c | 269 ++++++++++++++++++++++
> > hw/virtio/virtio.c | 201 ++++++++++++++++
> > include/hw/virtio/virtio.h | 135 +++++++++++
> > include/system/memory.h | 13 ++
> > subprojects/libvhost-user/libvhost-user.c | 70 ++++++
> > subprojects/libvhost-user/libvhost-user.h | 54 +++++
> > 6 files changed, 742 insertions(+)
> >
> >diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> >index 63fa9a1b4b..5d3841d58b 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 = 41,
> > VHOST_USER_SET_DEVICE_STATE_FD = 42,
> > VHOST_USER_CHECK_DEVICE_STATE = 43,
> >+ VHOST_USER_GET_SHMEM_CONFIG = 44,
> > VHOST_USER_MAX
> > } VhostUserRequest;
> >
> >@@ -115,6 +116,8 @@ 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;
> >
> >@@ -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 {
> >@@ -1771,6 +1799,196 @@
> >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;
> >+ }
> >+
> >+ 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) {
>
> Any reason about not using `memory_region_size(&shmem->mr)` ?
Nope, that would be better, I will change it.
>
> >+ 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_commit;
> >+ }
> >+
> >+ /* 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_commit;
> >+ }
> >+
> >+send_reply_commit:
> >+ /* Send reply and commit after transaction started */
> >+ 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;
> >+
> >+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;
> >+ }
> >+ }
> >+ 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 = NULL;
> >+ 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 && shmem && 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);
> >@@ -1844,6 +2062,21 @@ static gboolean backend_read(QIOChannel *ioc,
> >GIOCondition condition,
> > ret = vhost_user_backend_handle_shared_object_lookup(dev->opaque,
> >
> > &payload.object);
> > break;
> >+ case VHOST_USER_BACKEND_SHMEM_MAP:
> >+ /* Handler manages its own response, check error and close
> >connection */
> >+ reply_ack = false;
> >+ 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 */
> >+ reply_ack = false;
> >+ 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;
> >@@ -3021,6 +3254,41 @@ static int vhost_user_check_device_state(struct
> >vhost_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 = {
> >+ .hdr.request = VHOST_USER_GET_SHMEM_CONFIG,
> >+ .hdr.flags = VHOST_USER_VERSION,
> >+ };
> >+
> >+ if (!virtio_has_feature(dev->protocol_features,
> >+ VHOST_USER_PROTOCOL_F_SHMEM)) {
> >+ *nregions = 0;
> >+ return 0;
> >+ }
> >+
> >+ ret = vhost_user_write(dev, &msg, NULL, 0);
> >+ if (ret < 0) {
> >+ return ret;
> >+ }
> >+
> >+ ret = vhost_user_read(dev, &msg);
> >+ if (ret < 0) {
> >+ return ret;
> >+ }
> >+
> >+ assert(msg.payload.shmem.nregions <= VIRTIO_MAX_SHMEM_REGIONS);
>
> Is this `assert()` too much?
> This means that a bad vhost-user backend can crash QEMU, so not sure
> it's really what we want, I'd return an error.
I guess I was doing the same as in `vhost_user_get_config`, which also
asserts the max size. But I agree, returning an error is reasonable in
this case.
>
> >+ *nregions = 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 = {
> > .backend_type = VHOST_BACKEND_TYPE_USER,
> > .vhost_backend_init = vhost_user_backend_init,
> >@@ -3059,4 +3327,5 @@ const VhostOps user_ops = {
> > .vhost_supports_device_state = vhost_user_supports_device_state,
> > .vhost_set_device_state_fd = vhost_user_set_device_state_fd,
> > .vhost_check_device_state = vhost_user_check_device_state,
> >+ .vhost_get_shmem_config = vhost_user_get_shmem_config,
> > };
> >diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> >index 3dc9423eae..2f608f33ae 100644
> >--- a/hw/virtio/virtio.c
> >+++ b/hw/virtio/virtio.c
> >@@ -3111,6 +3111,173 @@ int virtio_save(VirtIODevice *vdev, QEMUFile *f)
> > return ret;
> > }
> >
> >+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->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;
> >+ }
> >+}
> >+
> >+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->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 > memory_region_size(&shmem->mr)) {
> >+ 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->len == 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)
> >@@ -3237,6 +3404,7 @@ 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;
> >
> >@@ -3276,6 +3444,15 @@ 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,
> >+ memory_region_size(mapping->mr));
> >+ }
> >+ }
> > }
> >
> > static void virtio_device_check_notification_compatibility(VirtIODevice
> > *vdev,
> >@@ -3599,6 +3776,7 @@ 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);
> > }
> >
> > /*
> >@@ -4110,11 +4288,25 @@ 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,
> >+ memory_region_size(mapping->mr));
> >+ }
> >+
> >+ /* 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[] = {
> >@@ -4480,9 +4672,18 @@ 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 27cd98d2fe..40d881ca09 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_MEMORY_MAPPING)
> >+
> >+/**
> >+ * VirtioSharedMemoryMapping:
> >+ * @parent: Parent QOM object
> >+ * @shmid: VIRTIO Shared Memory Region ID
> >+ * @fd: File descriptor for the shared memory region
>
> `fd` is not there anymore.
True. Thanks!
>
> The rest LGTM. I think we can eventually fix them later, so don't want
> to block this, but if you need to resend, please fix them.
Since I will send a follow up to fix the feature ID, I will update
with your comments. Thanks for reviewing!
>
> Reviewed-by: Stefano Garzarella <[email protected]>
>
