* [PATCH v6 1/8] vhost-user: Add VirtIO Shared Memory map request
2025-08-14 8:37 [PATCH v6 0/8] vhost-user: Add SHMEM_MAP/UNMAP requests Albert Esteve
@ 2025-08-14 8:37 ` Albert Esteve
2025-08-18 7:05 ` Albert Esteve
2025-08-18 7:37 ` David Hildenbrand
2025-08-14 8:37 ` [PATCH v6 2/8] vhost_user.rst: Align VhostUserMsg excerpt members Albert Esteve
` (6 subsequent siblings)
7 siblings, 2 replies; 12+ messages in thread
From: Albert Esteve @ 2025-08-14 8:37 UTC (permalink / raw)
To: qemu-devel
Cc: Michael S. Tsirkin, Fabiano Rosas, hi, Alex Bennée,
Laurent Vivier, slp, Stefano Garzarella, Paolo Bonzini, david,
jasowang, stefanha, dbassey, stevensd, Albert Esteve
Add SHMEM_MAP/UNMAP requests to vhost-user for
dynamic management of VIRTIO Shared Memory mappings.
This implementation introduces VhostUserShmemObject
as an intermediate QOM parent for MemoryRegions
created for SHMEM_MAP requests. This object
provides reference-counted lifecycle management
with automatic cleanup.
This request allows backends to dynamically map
file descriptors into a VIRTIO Shared Memory
Regions identified by their shmid. Maps are created
using mmap() 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 associated VhostUserShmemObject,
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
respond to the backend to avoid deadlocks.
Signed-off-by: Albert Esteve <aesteve@redhat.com>
---
hw/virtio/meson.build | 1 +
hw/virtio/vhost-user-shmem.c | 166 +++++++++++++++++
hw/virtio/vhost-user.c | 207 +++++++++++++++++++++-
hw/virtio/virtio.c | 111 ++++++++++++
include/hw/virtio/vhost-user-shmem.h | 106 +++++++++++
include/hw/virtio/virtio.h | 93 ++++++++++
subprojects/libvhost-user/libvhost-user.c | 70 ++++++++
subprojects/libvhost-user/libvhost-user.h | 54 ++++++
8 files changed, 806 insertions(+), 2 deletions(-)
create mode 100644 hw/virtio/vhost-user-shmem.c
create mode 100644 include/hw/virtio/vhost-user-shmem.h
diff --git a/hw/virtio/meson.build b/hw/virtio/meson.build
index 3ea7b3cec8..5efcf70b75 100644
--- a/hw/virtio/meson.build
+++ b/hw/virtio/meson.build
@@ -20,6 +20,7 @@ if have_vhost
# fixme - this really should be generic
specific_virtio_ss.add(files('vhost-user.c'))
system_virtio_ss.add(files('vhost-user-base.c'))
+ system_virtio_ss.add(files('vhost-user-shmem.c'))
# MMIO Stubs
system_virtio_ss.add(files('vhost-user-device.c'))
diff --git a/hw/virtio/vhost-user-shmem.c b/hw/virtio/vhost-user-shmem.c
new file mode 100644
index 0000000000..ef231f5077
--- /dev/null
+++ b/hw/virtio/vhost-user-shmem.c
@@ -0,0 +1,166 @@
+/*
+ * VHost-user Shared Memory Object
+ *
+ * Copyright Red Hat, Inc. 2024
+ *
+ * Authors:
+ * Albert Esteve <aesteve@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "hw/virtio/vhost-user-shmem.h"
+#include "system/memory.h"
+#include "qapi/error.h"
+#include "qemu/error-report.h"
+#include "trace.h"
+#include <sys/mman.h>
+
+/**
+ * VhostUserShmemObject
+ *
+ * An intermediate QOM object that manages individual shared memory mappings
+ * created by VHOST_USER_BACKEND_SHMEM_MAP requests. It acts as a parent for
+ * MemoryRegion objects, providing proper lifecycle management with reference
+ * counting. When the object is unreferenced and its reference count drops
+ * to zero, it automatically cleans up the MemoryRegion and unmaps the memory.
+ */
+
+static void vhost_user_shmem_object_finalize(Object *obj);
+static void vhost_user_shmem_object_instance_init(Object *obj);
+
+static const TypeInfo vhost_user_shmem_object_info = {
+ .name = TYPE_VHOST_USER_SHMEM_OBJECT,
+ .parent = TYPE_OBJECT,
+ .instance_size = sizeof(VhostUserShmemObject),
+ .instance_init = vhost_user_shmem_object_instance_init,
+ .instance_finalize = vhost_user_shmem_object_finalize,
+};
+
+static void vhost_user_shmem_object_instance_init(Object *obj)
+{
+ VhostUserShmemObject *shmem_obj = VHOST_USER_SHMEM_OBJECT(obj);
+
+ shmem_obj->shmid = 0;
+ shmem_obj->fd = -1;
+ shmem_obj->fd_offset = 0;
+ shmem_obj->shm_offset = 0;
+ shmem_obj->len = 0;
+ shmem_obj->flags = 0;
+ shmem_obj->mapped_addr = NULL;
+ shmem_obj->mr = NULL;
+}
+
+static void vhost_user_shmem_object_finalize(Object *obj)
+{
+ VhostUserShmemObject *shmem_obj = VHOST_USER_SHMEM_OBJECT(obj);
+
+ /* Clean up MemoryRegion if it exists */
+ if (shmem_obj->mr) {
+ /* Unparent the MemoryRegion to trigger cleanup */
+ object_unparent(OBJECT(shmem_obj->mr));
+ shmem_obj->mr = NULL;
+ }
+
+ /* Clean up memory mapping */
+ if (shmem_obj->mapped_addr && shmem_obj->mapped_addr != MAP_FAILED) {
+ if (munmap(shmem_obj->mapped_addr, shmem_obj->len) < 0) {
+ warn_report("vhost-user-shmem: failed to unmap memory region");
+ }
+ shmem_obj->mapped_addr = NULL;
+ }
+
+ /* Close file descriptor */
+ if (shmem_obj->fd >= 0) {
+ close(shmem_obj->fd);
+ shmem_obj->fd = -1;
+ }
+}
+
+VhostUserShmemObject *vhost_user_shmem_object_new(uint8_t shmid,
+ int fd,
+ uint64_t fd_offset,
+ uint64_t shm_offset,
+ uint64_t len,
+ uint16_t flags)
+{
+ VhostUserShmemObject *shmem_obj;
+ void *mapped_addr;
+ MemoryRegion *mr;
+ g_autoptr(GString) mr_name = g_string_new(NULL);
+ int prot_flags;
+
+ if (fd < 0) {
+ error_report("Invalid file descriptor: %d", fd);
+ return NULL;
+ }
+
+ if (len == 0) {
+ error_report("Shared memory mapping size cannot be zero");
+ return NULL;
+ }
+
+ /* Determine memory protection flags */
+ prot_flags = PROT_READ;
+ if (flags & VHOST_USER_FLAG_MAP_RW) {
+ prot_flags |= PROT_WRITE;
+ }
+
+ /* Map the shared memory region */
+ mapped_addr = mmap(NULL, len, prot_flags, MAP_SHARED, fd, fd_offset);
+ if (mapped_addr == MAP_FAILED) {
+ error_report("Failed to map shared memory region: %s", strerror(errno));
+ return NULL;
+ }
+
+ /* Create the VhostUserShmemObject */
+ shmem_obj = VHOST_USER_SHMEM_OBJECT(
+ object_new(TYPE_VHOST_USER_SHMEM_OBJECT));
+
+ /* Set up object properties */
+ shmem_obj->shmid = shmid;
+ shmem_obj->fd = fd;
+ shmem_obj->fd_offset = fd_offset;
+ shmem_obj->shm_offset = shm_offset;
+ shmem_obj->len = len;
+ shmem_obj->flags = flags;
+ shmem_obj->mapped_addr = mapped_addr;
+
+ /* Create MemoryRegion as a child of this object */
+ mr = g_new0(MemoryRegion, 1);
+ g_string_printf(mr_name, "vhost-user-shmem-%d-%" PRIx64, shmid, shm_offset);
+
+ /* Initialize MemoryRegion with the mapped memory */
+ memory_region_init_ram_device_ptr(mr, OBJECT(shmem_obj), mr_name->str,
+ len, mapped_addr);
+
+ shmem_obj->mr = mr;
+ return shmem_obj;
+}
+
+MemoryRegion *vhost_user_shmem_object_get_mr(VhostUserShmemObject *shmem_obj)
+{
+ g_assert(shmem_obj);
+ return shmem_obj->mr;
+}
+
+int vhost_user_shmem_object_get_fd(VhostUserShmemObject *shmem_obj)
+{
+ g_assert(shmem_obj);
+ return shmem_obj->fd;
+}
+
+void *vhost_user_shmem_object_get_mapped_addr(VhostUserShmemObject *shmem_obj)
+{
+ g_assert(shmem_obj);
+ return shmem_obj->mapped_addr;
+}
+
+static void vhost_user_shmem_register_types(void)
+{
+ type_register_static(&vhost_user_shmem_object_info);
+}
+
+type_init(vhost_user_shmem_register_types)
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 1e1d6b0d6e..eb3ad728b0 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -11,6 +11,7 @@
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "hw/virtio/virtio-dmabuf.h"
+#include "hw/virtio/vhost-user-shmem.h"
#include "hw/virtio/vhost.h"
#include "hw/virtio/virtio-crypto.h"
#include "hw/virtio/vhost-user.h"
@@ -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;
@@ -192,6 +195,23 @@ 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_* */
+ uint16_t flags;
+} VhostUserMMap;
+
typedef struct {
VhostUserRequest request;
@@ -224,6 +244,7 @@ typedef union {
VhostUserInflight inflight;
VhostUserShared object;
VhostUserTransferDeviceState transfer_state;
+ VhostUserMMap mmap;
} VhostUserPayload;
typedef struct VhostUserMsg {
@@ -1768,6 +1789,172 @@ 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;
+ Error *local_err = NULL;
+ g_autoptr(GString) shm_name = g_string_new(NULL);
+
+ if (fd < 0) {
+ error_report("Bad fd for map");
+ return -EBADF;
+ }
+
+ if (QSIMPLEQ_EMPTY(&dev->vdev->shmem_list)) {
+ error_report("Device has no VIRTIO Shared Memory Regions. "
+ "Requested ID: %d", vu_mmap->shmid);
+ return -EFAULT;
+ }
+
+ shmem = virtio_find_shmem_region(dev->vdev, vu_mmap->shmid);
+ if (!shmem) {
+ error_report("VIRTIO Shared Memory Region at "
+ "ID %d not found or unitialized", vu_mmap->shmid);
+ return -EFAULT;
+ }
+
+ 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);
+ return -EFAULT;
+ }
+
+ g_string_printf(shm_name, "virtio-shm%i-%lu",
+ vu_mmap->shmid, vu_mmap->shm_offset);
+
+ memory_region_transaction_begin();
+
+ /* Create VhostUserShmemObject as intermediate parent for MemoryRegion */
+ VhostUserShmemObject *shmem_obj = vhost_user_shmem_object_new(
+ vu_mmap->shmid, fd, vu_mmap->fd_offset, vu_mmap->shm_offset,
+ vu_mmap->len, vu_mmap->flags);
+
+ if (!shmem_obj) {
+ memory_region_transaction_commit();
+ return -EFAULT;
+ }
+
+ /* Add the mapping using our VhostUserShmemObject as the parent */
+ if (virtio_add_shmem_map(shmem, shmem_obj) != 0) {
+ error_report("Failed to add shared memory mapping");
+ object_unref(OBJECT(shmem_obj));
+ memory_region_transaction_commit();
+ return -EFAULT;
+ }
+
+ if (hdr->flags & VHOST_USER_NEED_REPLY_MASK) {
+ payload->u64 = 0;
+ hdr->size = sizeof(payload->u64);
+ vhost_user_send_resp(ioc, hdr, payload, &local_err);
+ if (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;
+
+ if (QSIMPLEQ_EMPTY(&dev->vdev->shmem_list)) {
+ error_report("Device has no VIRTIO Shared Memory Regions. "
+ "Requested ID: %d", vu_mmap->shmid);
+ return -EFAULT;
+ }
+
+ shmem = virtio_find_shmem_region(dev->vdev, vu_mmap->shmid);
+ if (!shmem) {
+ error_report("VIRTIO Shared Memory Region at "
+ "ID %d not found or unitialized", vu_mmap->shmid);
+ return -EFAULT;
+ }
+
+ 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);
+ return -EFAULT;
+ }
+
+ 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);
+ return -EFAULT;
+ }
+
+ memory_region_transaction_begin();
+ memory_region_del_subregion(&shmem->mr, mmap->mem);
+ if (hdr->flags & VHOST_USER_NEED_REPLY_MASK) {
+ payload->u64 = 0;
+ hdr->size = sizeof(payload->u64);
+ vhost_user_send_resp(ioc, hdr, payload, &local_err);
+ if (local_err) {
+ error_report_err(local_err);
+ memory_region_transaction_commit();
+ return -EFAULT;
+ }
+ }
+ memory_region_transaction_commit();
+
+ /* Free the MemoryRegion only after vhost_commit */
+ 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);
@@ -1833,8 +2020,24 @@ static gboolean backend_read(QIOChannel *ioc, GIOCondition condition,
&payload.object);
break;
case VHOST_USER_BACKEND_SHARED_OBJECT_LOOKUP:
- ret = vhost_user_backend_handle_shared_object_lookup(dev->opaque, ioc,
- &hdr, &payload);
+ /* Handler manages its own response, check error and close connection */
+ if (vhost_user_backend_handle_shared_object_lookup(dev->opaque, ioc,
+ &hdr, &payload) < 0) {
+ goto err;
+ }
+ 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);
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 9a81ad912e..28cefda255 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -14,6 +14,7 @@
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qapi/qapi-commands-virtio.h"
+#include "hw/virtio/vhost-user-shmem.h"
#include "trace.h"
#include "qemu/defer-call.h"
#include "qemu/error-report.h"
@@ -3045,6 +3046,102 @@ int virtio_save(VirtIODevice *vdev, QEMUFile *f)
return vmstate_save_state(f, &vmstate_virtio, vdev, NULL);
}
+VirtioSharedMemory *virtio_new_shmem_region(VirtIODevice *vdev, uint8_t shmid)
+{
+ 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, UINT64_MAX);
+ QTAILQ_INIT(&elem->mmaps);
+ QSIMPLEQ_INSERT_TAIL(&vdev->shmem_list, elem, entry);
+ return QSIMPLEQ_LAST(&vdev->shmem_list, VirtioSharedMemory, entry);
+}
+
+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;
+}
+
+int virtio_add_shmem_map(VirtioSharedMemory *shmem,
+ VhostUserShmemObject *shmem_obj)
+{
+ VirtioSharedMemoryMapping *mmap;
+ MemoryRegion *mr;
+ if (!shmem_obj) {
+ error_report("VhostUserShmemObject cannot be NULL");
+ return -1;
+ }
+ mr = vhost_user_shmem_object_get_mr(shmem_obj);
+ if (!mr) {
+ error_report("VhostUserShmemObject has no MemoryRegion");
+ return -1;
+ }
+
+ /* Validate boundaries against the VIRTIO shared memory region */
+ if (shmem_obj->shm_offset + shmem_obj->len > shmem->mr.size) {
+ error_report("Memory exceeds the shared memory boundaries");
+ return -1;
+ }
+
+ /* Create the VirtioSharedMemoryMapping wrapper */
+ mmap = g_new0(VirtioSharedMemoryMapping, 1);
+ mmap->mem = mr;
+ mmap->offset = shmem_obj->shm_offset;
+ mmap->shmem_obj = shmem_obj;
+
+ /* Take a reference on the VhostUserShmemObject */
+ object_ref(OBJECT(shmem_obj));
+
+ /* Add as subregion to the VIRTIO shared memory */
+ memory_region_add_subregion(&shmem->mr, mmap->offset, mmap->mem);
+
+ /* Add to the mapped regions list */
+ QTAILQ_INSERT_TAIL(&shmem->mmaps, mmap, link);
+
+ return 0;
+}
+
+VirtioSharedMemoryMapping *virtio_find_shmem_map(VirtioSharedMemory *shmem,
+ hwaddr offset, uint64_t size)
+{
+ VirtioSharedMemoryMapping *mmap;
+ QTAILQ_FOREACH(mmap, &shmem->mmaps, link) {
+ if (mmap->offset == offset && mmap->mem->size == size) {
+ return mmap;
+ }
+ }
+ return NULL;
+}
+
+void virtio_del_shmem_map(VirtioSharedMemory *shmem, hwaddr offset,
+ uint64_t size)
+{
+ VirtioSharedMemoryMapping *mmap = virtio_find_shmem_map(shmem, offset, size);
+ if (mmap == NULL) {
+ return;
+ }
+
+ /*
+ * Unref the VhostUserShmemObject which will trigger automatic cleanup
+ * when the reference count reaches zero.
+ */
+ object_unref(OBJECT(mmap->shmem_obj));
+
+ QTAILQ_REMOVE(&shmem->mmaps, mmap, link);
+ g_free(mmap);
+}
+
/* 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)
@@ -3521,6 +3618,7 @@ 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);
}
/*
@@ -4032,11 +4130,24 @@ 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 *mmap_reg = QTAILQ_FIRST(&shmem->mmaps);
+ virtio_del_shmem_map(shmem, mmap_reg->offset, mmap_reg->mem->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[] = {
diff --git a/include/hw/virtio/vhost-user-shmem.h b/include/hw/virtio/vhost-user-shmem.h
new file mode 100644
index 0000000000..ffbbea9c54
--- /dev/null
+++ b/include/hw/virtio/vhost-user-shmem.h
@@ -0,0 +1,106 @@
+/*
+ * VHost-user Shared Memory Object
+ *
+ * Copyright Red Hat, Inc. 2024
+ *
+ * Authors:
+ * Albert Esteve <aesteve@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#ifndef VHOST_USER_SHMEM_H
+#define VHOST_USER_SHMEM_H
+
+#include "qemu/osdep.h"
+#include "qom/object.h"
+#include "system/memory.h"
+#include "qapi/error.h"
+
+/* vhost-user memory mapping flags */
+#define VHOST_USER_FLAG_MAP_RW (1u << 0)
+
+#define TYPE_VHOST_USER_SHMEM_OBJECT "vhost-user-shmem"
+OBJECT_DECLARE_SIMPLE_TYPE(VhostUserShmemObject, VHOST_USER_SHMEM_OBJECT)
+
+/**
+ * VhostUserShmemObject:
+ * @parent: Parent object
+ * @shmid: VIRTIO Shared Memory Region ID
+ * @fd: File descriptor for the shared memory region
+ * @fd_offset: Offset within the file descriptor
+ * @shm_offset: Offset within the VIRTIO Shared Memory Region
+ * @len: Size of the mapping
+ * @flags: Mapping flags (read/write permissions)
+ * @mapped_addr: Pointer to the mapped memory region
+ * @mr: MemoryRegion associated with this shared memory mapping
+ *
+ * An intermediate QOM object that manages individual shared memory mappings
+ * created by VHOST_USER_BACKEND_SHMEM_MAP requests. It acts as a parent for
+ * MemoryRegion objects, providing proper lifecycle management with reference
+ * counting. When the object is unreferenced and its reference count drops
+ * to zero, it automatically cleans up the MemoryRegion and unmaps the memory.
+ */
+struct VhostUserShmemObject {
+ Object parent;
+
+ uint8_t shmid;
+ int fd;
+ uint64_t fd_offset;
+ uint64_t shm_offset;
+ uint64_t len;
+ uint16_t flags;
+ void *mapped_addr;
+ MemoryRegion *mr;
+};
+
+/**
+ * vhost_user_shmem_object_new() - Create a new VhostUserShmemObject
+ * @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
+ * @flags: Mapping flags (VHOST_USER_FLAG_MAP_*)
+ *
+ * Creates a new VhostUserShmemObject that manages a shared memory mapping.
+ * The object will automatically map the memory using mmap() and create
+ * a MemoryRegion as a child object. When the object is finalized, it will
+ * automatically unmap the memory and close the file descriptor.
+ * Errors are reported via error_report().
+ *
+ * Return: A new VhostUserShmemObject on success, NULL on error.
+ */
+VhostUserShmemObject *vhost_user_shmem_object_new(uint8_t shmid,
+ int fd,
+ uint64_t fd_offset,
+ uint64_t shm_offset,
+ uint64_t len,
+ uint16_t flags);
+
+/**
+ * vhost_user_shmem_object_get_mr() - Get the MemoryRegion
+ * @shmem_obj: VhostUserShmemObject instance
+ *
+ * Return: The MemoryRegion associated with this shared memory object.
+ */
+MemoryRegion *vhost_user_shmem_object_get_mr(VhostUserShmemObject *shmem_obj);
+
+/**
+ * vhost_user_shmem_object_get_fd() - Get the file descriptor
+ * @shmem_obj: VhostUserShmemObject instance
+ *
+ * Return: The file descriptor for the shared memory region.
+ */
+int vhost_user_shmem_object_get_fd(VhostUserShmemObject *shmem_obj);
+
+/**
+ * vhost_user_shmem_object_get_mapped_addr() - Get the mapped memory address
+ * @shmem_obj: VhostUserShmemObject instance
+ *
+ * Return: The mapped memory address.
+ */
+void *vhost_user_shmem_object_get_mapped_addr(VhostUserShmemObject *shmem_obj);
+
+#endif /* VHOST_USER_SHMEM_H */
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index c594764f23..a563bbac2c 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -98,6 +98,26 @@ enum virtio_device_endian {
VIRTIO_DEVICE_ENDIAN_BIG,
};
+struct VhostUserShmemObject;
+
+struct VirtioSharedMemoryMapping {
+ MemoryRegion *mem;
+ hwaddr offset;
+ QTAILQ_ENTRY(VirtioSharedMemoryMapping) link;
+ struct VhostUserShmemObject *shmem_obj; /* Intermediate parent object */
+};
+
+typedef struct VirtioSharedMemoryMapping VirtioSharedMemoryMapping;
+
+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
@@ -167,6 +187,8 @@ struct VirtIODevice
*/
EventNotifier config_notifier;
bool device_iotlb_enabled;
+ /* Shared memory region for mappings. */
+ QSIMPLEQ_HEAD(, VirtioSharedMemory) shmem_list;
};
struct VirtioDeviceClass {
@@ -295,6 +317,77 @@ 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
+ *
+ * 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);
+
+/**
+ * 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_add_shmem_map() - Add a memory mapping to a shared region
+ * @shmem: VirtioSharedMemory region
+ * @shmem_obj: VhostUserShmemObject to add (takes a reference)
+ *
+ * Adds a memory mapping to the shared memory region. The VhostUserShmemObject
+ * is added as a child of the mapping and will be automatically managed through
+ * QOM reference counting. The mapping will be removed 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,
+ struct VhostUserShmemObject *shmem_obj);
+
+/**
+ * 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..26b710c92d 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_* */
+ uint16_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
^ permalink raw reply related [flat|nested] 12+ messages in thread* Re: [PATCH v6 1/8] vhost-user: Add VirtIO Shared Memory map request
2025-08-14 8:37 ` [PATCH v6 1/8] vhost-user: Add VirtIO Shared Memory map request Albert Esteve
@ 2025-08-18 7:05 ` Albert Esteve
2025-08-18 7:37 ` David Hildenbrand
1 sibling, 0 replies; 12+ messages in thread
From: Albert Esteve @ 2025-08-18 7:05 UTC (permalink / raw)
To: qemu-devel
Cc: Michael S. Tsirkin, Fabiano Rosas, hi, Alex Bennée,
Laurent Vivier, slp, Stefano Garzarella, Paolo Bonzini, david,
jasowang, stefanha, dbassey, stevensd
On Thu, Aug 14, 2025 at 10:38 AM Albert Esteve <aesteve@redhat.com> wrote:
>
> Add SHMEM_MAP/UNMAP requests to vhost-user for
> dynamic management of VIRTIO Shared Memory mappings.
>
> This implementation introduces VhostUserShmemObject
> as an intermediate QOM parent for MemoryRegions
> created for SHMEM_MAP requests. This object
> provides reference-counted lifecycle management
> with automatic cleanup.
>
> This request allows backends to dynamically map
> file descriptors into a VIRTIO Shared Memory
> Regions identified by their shmid. Maps are created
> using mmap() 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 associated VhostUserShmemObject,
> 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
> respond to the backend to avoid deadlocks.
>
> Signed-off-by: Albert Esteve <aesteve@redhat.com>
> ---
> hw/virtio/meson.build | 1 +
> hw/virtio/vhost-user-shmem.c | 166 +++++++++++++++++
> hw/virtio/vhost-user.c | 207 +++++++++++++++++++++-
> hw/virtio/virtio.c | 111 ++++++++++++
> include/hw/virtio/vhost-user-shmem.h | 106 +++++++++++
> include/hw/virtio/virtio.h | 93 ++++++++++
> subprojects/libvhost-user/libvhost-user.c | 70 ++++++++
> subprojects/libvhost-user/libvhost-user.h | 54 ++++++
> 8 files changed, 806 insertions(+), 2 deletions(-)
> create mode 100644 hw/virtio/vhost-user-shmem.c
> create mode 100644 include/hw/virtio/vhost-user-shmem.h
>
> diff --git a/hw/virtio/meson.build b/hw/virtio/meson.build
> index 3ea7b3cec8..5efcf70b75 100644
> --- a/hw/virtio/meson.build
> +++ b/hw/virtio/meson.build
> @@ -20,6 +20,7 @@ if have_vhost
> # fixme - this really should be generic
> specific_virtio_ss.add(files('vhost-user.c'))
> system_virtio_ss.add(files('vhost-user-base.c'))
> + system_virtio_ss.add(files('vhost-user-shmem.c'))
>
> # MMIO Stubs
> system_virtio_ss.add(files('vhost-user-device.c'))
> diff --git a/hw/virtio/vhost-user-shmem.c b/hw/virtio/vhost-user-shmem.c
> new file mode 100644
> index 0000000000..ef231f5077
> --- /dev/null
> +++ b/hw/virtio/vhost-user-shmem.c
> @@ -0,0 +1,166 @@
> +/*
> + * VHost-user Shared Memory Object
> + *
> + * Copyright Red Hat, Inc. 2024
> + *
> + * Authors:
> + * Albert Esteve <aesteve@redhat.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + */
> +
> +#include "qemu/osdep.h"
> +#include "hw/virtio/vhost-user-shmem.h"
> +#include "system/memory.h"
> +#include "qapi/error.h"
> +#include "qemu/error-report.h"
> +#include "trace.h"
> +#include <sys/mman.h>
> +
> +/**
> + * VhostUserShmemObject
> + *
> + * An intermediate QOM object that manages individual shared memory mappings
> + * created by VHOST_USER_BACKEND_SHMEM_MAP requests. It acts as a parent for
> + * MemoryRegion objects, providing proper lifecycle management with reference
> + * counting. When the object is unreferenced and its reference count drops
> + * to zero, it automatically cleans up the MemoryRegion and unmaps the memory.
> + */
> +
> +static void vhost_user_shmem_object_finalize(Object *obj);
> +static void vhost_user_shmem_object_instance_init(Object *obj);
> +
> +static const TypeInfo vhost_user_shmem_object_info = {
> + .name = TYPE_VHOST_USER_SHMEM_OBJECT,
> + .parent = TYPE_OBJECT,
> + .instance_size = sizeof(VhostUserShmemObject),
> + .instance_init = vhost_user_shmem_object_instance_init,
> + .instance_finalize = vhost_user_shmem_object_finalize,
> +};
> +
> +static void vhost_user_shmem_object_instance_init(Object *obj)
> +{
> + VhostUserShmemObject *shmem_obj = VHOST_USER_SHMEM_OBJECT(obj);
> +
> + shmem_obj->shmid = 0;
> + shmem_obj->fd = -1;
> + shmem_obj->fd_offset = 0;
> + shmem_obj->shm_offset = 0;
> + shmem_obj->len = 0;
> + shmem_obj->flags = 0;
> + shmem_obj->mapped_addr = NULL;
> + shmem_obj->mr = NULL;
> +}
> +
> +static void vhost_user_shmem_object_finalize(Object *obj)
> +{
> + VhostUserShmemObject *shmem_obj = VHOST_USER_SHMEM_OBJECT(obj);
> +
> + /* Clean up MemoryRegion if it exists */
> + if (shmem_obj->mr) {
> + /* Unparent the MemoryRegion to trigger cleanup */
> + object_unparent(OBJECT(shmem_obj->mr));
> + shmem_obj->mr = NULL;
> + }
> +
> + /* Clean up memory mapping */
> + if (shmem_obj->mapped_addr && shmem_obj->mapped_addr != MAP_FAILED) {
> + if (munmap(shmem_obj->mapped_addr, shmem_obj->len) < 0) {
> + warn_report("vhost-user-shmem: failed to unmap memory region");
> + }
> + shmem_obj->mapped_addr = NULL;
> + }
> +
> + /* Close file descriptor */
> + if (shmem_obj->fd >= 0) {
> + close(shmem_obj->fd);
> + shmem_obj->fd = -1;
> + }
> +}
> +
> +VhostUserShmemObject *vhost_user_shmem_object_new(uint8_t shmid,
> + int fd,
> + uint64_t fd_offset,
> + uint64_t shm_offset,
> + uint64_t len,
> + uint16_t flags)
> +{
> + VhostUserShmemObject *shmem_obj;
> + void *mapped_addr;
> + MemoryRegion *mr;
> + g_autoptr(GString) mr_name = g_string_new(NULL);
> + int prot_flags;
> +
> + if (fd < 0) {
> + error_report("Invalid file descriptor: %d", fd);
> + return NULL;
> + }
> +
> + if (len == 0) {
> + error_report("Shared memory mapping size cannot be zero");
> + return NULL;
> + }
> +
> + /* Determine memory protection flags */
> + prot_flags = PROT_READ;
> + if (flags & VHOST_USER_FLAG_MAP_RW) {
> + prot_flags |= PROT_WRITE;
> + }
> +
> + /* Map the shared memory region */
> + mapped_addr = mmap(NULL, len, prot_flags, MAP_SHARED, fd, fd_offset);
> + if (mapped_addr == MAP_FAILED) {
> + error_report("Failed to map shared memory region: %s", strerror(errno));
> + return NULL;
> + }
> +
> + /* Create the VhostUserShmemObject */
> + shmem_obj = VHOST_USER_SHMEM_OBJECT(
> + object_new(TYPE_VHOST_USER_SHMEM_OBJECT));
> +
> + /* Set up object properties */
> + shmem_obj->shmid = shmid;
> + shmem_obj->fd = fd;
> + shmem_obj->fd_offset = fd_offset;
> + shmem_obj->shm_offset = shm_offset;
> + shmem_obj->len = len;
> + shmem_obj->flags = flags;
> + shmem_obj->mapped_addr = mapped_addr;
> +
> + /* Create MemoryRegion as a child of this object */
> + mr = g_new0(MemoryRegion, 1);
> + g_string_printf(mr_name, "vhost-user-shmem-%d-%" PRIx64, shmid, shm_offset);
> +
> + /* Initialize MemoryRegion with the mapped memory */
> + memory_region_init_ram_device_ptr(mr, OBJECT(shmem_obj), mr_name->str,
> + len, mapped_addr);
> +
> + shmem_obj->mr = mr;
> + return shmem_obj;
> +}
> +
> +MemoryRegion *vhost_user_shmem_object_get_mr(VhostUserShmemObject *shmem_obj)
> +{
> + g_assert(shmem_obj);
> + return shmem_obj->mr;
> +}
> +
> +int vhost_user_shmem_object_get_fd(VhostUserShmemObject *shmem_obj)
> +{
> + g_assert(shmem_obj);
> + return shmem_obj->fd;
> +}
> +
> +void *vhost_user_shmem_object_get_mapped_addr(VhostUserShmemObject *shmem_obj)
> +{
> + g_assert(shmem_obj);
> + return shmem_obj->mapped_addr;
> +}
Do not mind these getters for simple attributes, I thought I had removed them.
I'll do for the next version. I hope I can send one soonish.
> +
> +static void vhost_user_shmem_register_types(void)
> +{
> + type_register_static(&vhost_user_shmem_object_info);
> +}
> +
> +type_init(vhost_user_shmem_register_types)
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index 1e1d6b0d6e..eb3ad728b0 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -11,6 +11,7 @@
> #include "qemu/osdep.h"
> #include "qapi/error.h"
> #include "hw/virtio/virtio-dmabuf.h"
> +#include "hw/virtio/vhost-user-shmem.h"
> #include "hw/virtio/vhost.h"
> #include "hw/virtio/virtio-crypto.h"
> #include "hw/virtio/vhost-user.h"
> @@ -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;
>
> @@ -192,6 +195,23 @@ 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_* */
> + uint16_t flags;
> +} VhostUserMMap;
> +
> typedef struct {
> VhostUserRequest request;
>
> @@ -224,6 +244,7 @@ typedef union {
> VhostUserInflight inflight;
> VhostUserShared object;
> VhostUserTransferDeviceState transfer_state;
> + VhostUserMMap mmap;
> } VhostUserPayload;
>
> typedef struct VhostUserMsg {
> @@ -1768,6 +1789,172 @@ 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;
> + Error *local_err = NULL;
> + g_autoptr(GString) shm_name = g_string_new(NULL);
> +
> + if (fd < 0) {
> + error_report("Bad fd for map");
> + return -EBADF;
> + }
> +
> + if (QSIMPLEQ_EMPTY(&dev->vdev->shmem_list)) {
> + error_report("Device has no VIRTIO Shared Memory Regions. "
> + "Requested ID: %d", vu_mmap->shmid);
> + return -EFAULT;
> + }
> +
> + shmem = virtio_find_shmem_region(dev->vdev, vu_mmap->shmid);
> + if (!shmem) {
> + error_report("VIRTIO Shared Memory Region at "
> + "ID %d not found or unitialized", vu_mmap->shmid);
> + return -EFAULT;
> + }
> +
> + 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);
> + return -EFAULT;
> + }
> +
> + g_string_printf(shm_name, "virtio-shm%i-%lu",
> + vu_mmap->shmid, vu_mmap->shm_offset);
> +
> + memory_region_transaction_begin();
> +
> + /* Create VhostUserShmemObject as intermediate parent for MemoryRegion */
> + VhostUserShmemObject *shmem_obj = vhost_user_shmem_object_new(
> + vu_mmap->shmid, fd, vu_mmap->fd_offset, vu_mmap->shm_offset,
> + vu_mmap->len, vu_mmap->flags);
> +
> + if (!shmem_obj) {
> + memory_region_transaction_commit();
> + return -EFAULT;
> + }
> +
> + /* Add the mapping using our VhostUserShmemObject as the parent */
> + if (virtio_add_shmem_map(shmem, shmem_obj) != 0) {
> + error_report("Failed to add shared memory mapping");
> + object_unref(OBJECT(shmem_obj));
> + memory_region_transaction_commit();
> + return -EFAULT;
> + }
> +
> + if (hdr->flags & VHOST_USER_NEED_REPLY_MASK) {
> + payload->u64 = 0;
> + hdr->size = sizeof(payload->u64);
> + vhost_user_send_resp(ioc, hdr, payload, &local_err);
> + if (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;
> +
> + if (QSIMPLEQ_EMPTY(&dev->vdev->shmem_list)) {
> + error_report("Device has no VIRTIO Shared Memory Regions. "
> + "Requested ID: %d", vu_mmap->shmid);
> + return -EFAULT;
> + }
> +
> + shmem = virtio_find_shmem_region(dev->vdev, vu_mmap->shmid);
> + if (!shmem) {
> + error_report("VIRTIO Shared Memory Region at "
> + "ID %d not found or unitialized", vu_mmap->shmid);
> + return -EFAULT;
> + }
> +
> + 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);
> + return -EFAULT;
> + }
> +
> + 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);
> + return -EFAULT;
> + }
> +
> + memory_region_transaction_begin();
> + memory_region_del_subregion(&shmem->mr, mmap->mem);
> + if (hdr->flags & VHOST_USER_NEED_REPLY_MASK) {
> + payload->u64 = 0;
> + hdr->size = sizeof(payload->u64);
> + vhost_user_send_resp(ioc, hdr, payload, &local_err);
> + if (local_err) {
> + error_report_err(local_err);
> + memory_region_transaction_commit();
> + return -EFAULT;
> + }
> + }
> + memory_region_transaction_commit();
> +
> + /* Free the MemoryRegion only after vhost_commit */
> + 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);
> @@ -1833,8 +2020,24 @@ static gboolean backend_read(QIOChannel *ioc, GIOCondition condition,
> &payload.object);
> break;
> case VHOST_USER_BACKEND_SHARED_OBJECT_LOOKUP:
> - ret = vhost_user_backend_handle_shared_object_lookup(dev->opaque, ioc,
> - &hdr, &payload);
> + /* Handler manages its own response, check error and close connection */
> + if (vhost_user_backend_handle_shared_object_lookup(dev->opaque, ioc,
> + &hdr, &payload) < 0) {
> + goto err;
> + }
> + 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);
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 9a81ad912e..28cefda255 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -14,6 +14,7 @@
> #include "qemu/osdep.h"
> #include "qapi/error.h"
> #include "qapi/qapi-commands-virtio.h"
> +#include "hw/virtio/vhost-user-shmem.h"
> #include "trace.h"
> #include "qemu/defer-call.h"
> #include "qemu/error-report.h"
> @@ -3045,6 +3046,102 @@ int virtio_save(VirtIODevice *vdev, QEMUFile *f)
> return vmstate_save_state(f, &vmstate_virtio, vdev, NULL);
> }
>
> +VirtioSharedMemory *virtio_new_shmem_region(VirtIODevice *vdev, uint8_t shmid)
> +{
> + 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, UINT64_MAX);
> + QTAILQ_INIT(&elem->mmaps);
> + QSIMPLEQ_INSERT_TAIL(&vdev->shmem_list, elem, entry);
> + return QSIMPLEQ_LAST(&vdev->shmem_list, VirtioSharedMemory, entry);
> +}
> +
> +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;
> +}
> +
> +int virtio_add_shmem_map(VirtioSharedMemory *shmem,
> + VhostUserShmemObject *shmem_obj)
> +{
> + VirtioSharedMemoryMapping *mmap;
> + MemoryRegion *mr;
> + if (!shmem_obj) {
> + error_report("VhostUserShmemObject cannot be NULL");
> + return -1;
> + }
> + mr = vhost_user_shmem_object_get_mr(shmem_obj);
> + if (!mr) {
> + error_report("VhostUserShmemObject has no MemoryRegion");
> + return -1;
> + }
> +
> + /* Validate boundaries against the VIRTIO shared memory region */
> + if (shmem_obj->shm_offset + shmem_obj->len > shmem->mr.size) {
> + error_report("Memory exceeds the shared memory boundaries");
> + return -1;
> + }
> +
> + /* Create the VirtioSharedMemoryMapping wrapper */
> + mmap = g_new0(VirtioSharedMemoryMapping, 1);
> + mmap->mem = mr;
> + mmap->offset = shmem_obj->shm_offset;
> + mmap->shmem_obj = shmem_obj;
> +
> + /* Take a reference on the VhostUserShmemObject */
> + object_ref(OBJECT(shmem_obj));
> +
> + /* Add as subregion to the VIRTIO shared memory */
> + memory_region_add_subregion(&shmem->mr, mmap->offset, mmap->mem);
> +
> + /* Add to the mapped regions list */
> + QTAILQ_INSERT_TAIL(&shmem->mmaps, mmap, link);
> +
> + return 0;
> +}
> +
> +VirtioSharedMemoryMapping *virtio_find_shmem_map(VirtioSharedMemory *shmem,
> + hwaddr offset, uint64_t size)
> +{
> + VirtioSharedMemoryMapping *mmap;
> + QTAILQ_FOREACH(mmap, &shmem->mmaps, link) {
> + if (mmap->offset == offset && mmap->mem->size == size) {
> + return mmap;
> + }
> + }
> + return NULL;
> +}
> +
> +void virtio_del_shmem_map(VirtioSharedMemory *shmem, hwaddr offset,
> + uint64_t size)
> +{
> + VirtioSharedMemoryMapping *mmap = virtio_find_shmem_map(shmem, offset, size);
> + if (mmap == NULL) {
> + return;
> + }
> +
> + /*
> + * Unref the VhostUserShmemObject which will trigger automatic cleanup
> + * when the reference count reaches zero.
> + */
> + object_unref(OBJECT(mmap->shmem_obj));
> +
> + QTAILQ_REMOVE(&shmem->mmaps, mmap, link);
> + g_free(mmap);
> +}
> +
> /* 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)
> @@ -3521,6 +3618,7 @@ 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);
> }
>
> /*
> @@ -4032,11 +4130,24 @@ 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 *mmap_reg = QTAILQ_FIRST(&shmem->mmaps);
> + virtio_del_shmem_map(shmem, mmap_reg->offset, mmap_reg->mem->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[] = {
> diff --git a/include/hw/virtio/vhost-user-shmem.h b/include/hw/virtio/vhost-user-shmem.h
> new file mode 100644
> index 0000000000..ffbbea9c54
> --- /dev/null
> +++ b/include/hw/virtio/vhost-user-shmem.h
> @@ -0,0 +1,106 @@
> +/*
> + * VHost-user Shared Memory Object
> + *
> + * Copyright Red Hat, Inc. 2024
> + *
> + * Authors:
> + * Albert Esteve <aesteve@redhat.com>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or later.
> + * See the COPYING file in the top-level directory.
> + */
> +
> +#ifndef VHOST_USER_SHMEM_H
> +#define VHOST_USER_SHMEM_H
> +
> +#include "qemu/osdep.h"
> +#include "qom/object.h"
> +#include "system/memory.h"
> +#include "qapi/error.h"
> +
> +/* vhost-user memory mapping flags */
> +#define VHOST_USER_FLAG_MAP_RW (1u << 0)
> +
> +#define TYPE_VHOST_USER_SHMEM_OBJECT "vhost-user-shmem"
> +OBJECT_DECLARE_SIMPLE_TYPE(VhostUserShmemObject, VHOST_USER_SHMEM_OBJECT)
> +
> +/**
> + * VhostUserShmemObject:
> + * @parent: Parent object
> + * @shmid: VIRTIO Shared Memory Region ID
> + * @fd: File descriptor for the shared memory region
> + * @fd_offset: Offset within the file descriptor
> + * @shm_offset: Offset within the VIRTIO Shared Memory Region
> + * @len: Size of the mapping
> + * @flags: Mapping flags (read/write permissions)
> + * @mapped_addr: Pointer to the mapped memory region
> + * @mr: MemoryRegion associated with this shared memory mapping
> + *
> + * An intermediate QOM object that manages individual shared memory mappings
> + * created by VHOST_USER_BACKEND_SHMEM_MAP requests. It acts as a parent for
> + * MemoryRegion objects, providing proper lifecycle management with reference
> + * counting. When the object is unreferenced and its reference count drops
> + * to zero, it automatically cleans up the MemoryRegion and unmaps the memory.
> + */
> +struct VhostUserShmemObject {
> + Object parent;
> +
> + uint8_t shmid;
> + int fd;
> + uint64_t fd_offset;
> + uint64_t shm_offset;
> + uint64_t len;
> + uint16_t flags;
> + void *mapped_addr;
> + MemoryRegion *mr;
> +};
> +
> +/**
> + * vhost_user_shmem_object_new() - Create a new VhostUserShmemObject
> + * @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
> + * @flags: Mapping flags (VHOST_USER_FLAG_MAP_*)
> + *
> + * Creates a new VhostUserShmemObject that manages a shared memory mapping.
> + * The object will automatically map the memory using mmap() and create
> + * a MemoryRegion as a child object. When the object is finalized, it will
> + * automatically unmap the memory and close the file descriptor.
> + * Errors are reported via error_report().
> + *
> + * Return: A new VhostUserShmemObject on success, NULL on error.
> + */
> +VhostUserShmemObject *vhost_user_shmem_object_new(uint8_t shmid,
> + int fd,
> + uint64_t fd_offset,
> + uint64_t shm_offset,
> + uint64_t len,
> + uint16_t flags);
> +
> +/**
> + * vhost_user_shmem_object_get_mr() - Get the MemoryRegion
> + * @shmem_obj: VhostUserShmemObject instance
> + *
> + * Return: The MemoryRegion associated with this shared memory object.
> + */
> +MemoryRegion *vhost_user_shmem_object_get_mr(VhostUserShmemObject *shmem_obj);
> +
> +/**
> + * vhost_user_shmem_object_get_fd() - Get the file descriptor
> + * @shmem_obj: VhostUserShmemObject instance
> + *
> + * Return: The file descriptor for the shared memory region.
> + */
> +int vhost_user_shmem_object_get_fd(VhostUserShmemObject *shmem_obj);
> +
> +/**
> + * vhost_user_shmem_object_get_mapped_addr() - Get the mapped memory address
> + * @shmem_obj: VhostUserShmemObject instance
> + *
> + * Return: The mapped memory address.
> + */
> +void *vhost_user_shmem_object_get_mapped_addr(VhostUserShmemObject *shmem_obj);
> +
> +#endif /* VHOST_USER_SHMEM_H */
> diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
> index c594764f23..a563bbac2c 100644
> --- a/include/hw/virtio/virtio.h
> +++ b/include/hw/virtio/virtio.h
> @@ -98,6 +98,26 @@ enum virtio_device_endian {
> VIRTIO_DEVICE_ENDIAN_BIG,
> };
>
> +struct VhostUserShmemObject;
> +
> +struct VirtioSharedMemoryMapping {
> + MemoryRegion *mem;
> + hwaddr offset;
> + QTAILQ_ENTRY(VirtioSharedMemoryMapping) link;
> + struct VhostUserShmemObject *shmem_obj; /* Intermediate parent object */
> +};
> +
> +typedef struct VirtioSharedMemoryMapping VirtioSharedMemoryMapping;
> +
> +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
> @@ -167,6 +187,8 @@ struct VirtIODevice
> */
> EventNotifier config_notifier;
> bool device_iotlb_enabled;
> + /* Shared memory region for mappings. */
> + QSIMPLEQ_HEAD(, VirtioSharedMemory) shmem_list;
> };
>
> struct VirtioDeviceClass {
> @@ -295,6 +317,77 @@ 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
> + *
> + * 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);
> +
> +/**
> + * 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_add_shmem_map() - Add a memory mapping to a shared region
> + * @shmem: VirtioSharedMemory region
> + * @shmem_obj: VhostUserShmemObject to add (takes a reference)
> + *
> + * Adds a memory mapping to the shared memory region. The VhostUserShmemObject
> + * is added as a child of the mapping and will be automatically managed through
> + * QOM reference counting. The mapping will be removed 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,
> + struct VhostUserShmemObject *shmem_obj);
> +
> +/**
> + * 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..26b710c92d 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_* */
> + uint16_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
>
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [PATCH v6 1/8] vhost-user: Add VirtIO Shared Memory map request
2025-08-14 8:37 ` [PATCH v6 1/8] vhost-user: Add VirtIO Shared Memory map request Albert Esteve
2025-08-18 7:05 ` Albert Esteve
@ 2025-08-18 7:37 ` David Hildenbrand
2025-08-18 8:51 ` Albert Esteve
1 sibling, 1 reply; 12+ messages in thread
From: David Hildenbrand @ 2025-08-18 7:37 UTC (permalink / raw)
To: Albert Esteve, qemu-devel
Cc: Michael S. Tsirkin, Fabiano Rosas, hi, Alex Bennée,
Laurent Vivier, slp, Stefano Garzarella, Paolo Bonzini, jasowang,
stefanha, dbassey, stevensd
> + /* Map the shared memory region */
> + mapped_addr = mmap(NULL, len, prot_flags, MAP_SHARED, fd, fd_offset);
> + if (mapped_addr == MAP_FAILED) {
> + error_report("Failed to map shared memory region: %s", strerror(errno));
> + return NULL;
> + }
> +
> + /* Create the VhostUserShmemObject */
> + shmem_obj = VHOST_USER_SHMEM_OBJECT(
> + object_new(TYPE_VHOST_USER_SHMEM_OBJECT));
> +
> + /* Set up object properties */
> + shmem_obj->shmid = shmid;
> + shmem_obj->fd = fd;
> + shmem_obj->fd_offset = fd_offset;
> + shmem_obj->shm_offset = shm_offset;
> + shmem_obj->len = len;
> + shmem_obj->flags = flags;
> + shmem_obj->mapped_addr = mapped_addr;
> +
> + /* Create MemoryRegion as a child of this object */
> + mr = g_new0(MemoryRegion, 1);
> + g_string_printf(mr_name, "vhost-user-shmem-%d-%" PRIx64, shmid, shm_offset);
> +
> + /* Initialize MemoryRegion with the mapped memory */
> + memory_region_init_ram_device_ptr(mr, OBJECT(shmem_obj), mr_name->str,
> + len, mapped_addr);
Oh, why did we go from memory_region_init_ram_from_fd() back to
memory_region_init_ram_device_ptr() in this series?
I thought having a wrapper object around the memory region would have
been sufficient to handle the race?
--
Cheers
David / dhildenb
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [PATCH v6 1/8] vhost-user: Add VirtIO Shared Memory map request
2025-08-18 7:37 ` David Hildenbrand
@ 2025-08-18 8:51 ` Albert Esteve
0 siblings, 0 replies; 12+ messages in thread
From: Albert Esteve @ 2025-08-18 8:51 UTC (permalink / raw)
To: David Hildenbrand
Cc: qemu-devel, Michael S. Tsirkin, Fabiano Rosas, hi,
Alex Bennée, Laurent Vivier, slp, Stefano Garzarella,
Paolo Bonzini, jasowang, stefanha, dbassey, stevensd
On Mon, Aug 18, 2025 at 9:37 AM David Hildenbrand <david@redhat.com> wrote:
>
>
> > + /* Map the shared memory region */
> > + mapped_addr = mmap(NULL, len, prot_flags, MAP_SHARED, fd, fd_offset);
> > + if (mapped_addr == MAP_FAILED) {
> > + error_report("Failed to map shared memory region: %s", strerror(errno));
> > + return NULL;
> > + }
> > +
> > + /* Create the VhostUserShmemObject */
> > + shmem_obj = VHOST_USER_SHMEM_OBJECT(
> > + object_new(TYPE_VHOST_USER_SHMEM_OBJECT));
> > +
> > + /* Set up object properties */
> > + shmem_obj->shmid = shmid;
> > + shmem_obj->fd = fd;
> > + shmem_obj->fd_offset = fd_offset;
> > + shmem_obj->shm_offset = shm_offset;
> > + shmem_obj->len = len;
> > + shmem_obj->flags = flags;
> > + shmem_obj->mapped_addr = mapped_addr;
> > +
> > + /* Create MemoryRegion as a child of this object */
> > + mr = g_new0(MemoryRegion, 1);
> > + g_string_printf(mr_name, "vhost-user-shmem-%d-%" PRIx64, shmid, shm_offset);
> > +
> > + /* Initialize MemoryRegion with the mapped memory */
> > + memory_region_init_ram_device_ptr(mr, OBJECT(shmem_obj), mr_name->str,
> > + len, mapped_addr);
>
> Oh, why did we go from memory_region_init_ram_from_fd() back to
> memory_region_init_ram_device_ptr() in this series?
>
> I thought having a wrapper object around the memory region would have
> been sufficient to handle the race?
Ah true :facepalm: I was under the impression that I needed mmap for
the read-write
flags, as I went a bit of back and forth for the last version. I was wrong, as
from_fd allows flags as an argument.
Let me send a new quick iteration for this patch with this fixed (and
other small things I saw
myself). Thanks for checking.
>
> --
> Cheers
>
> David / dhildenb
>
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH v6 2/8] vhost_user.rst: Align VhostUserMsg excerpt members
2025-08-14 8:37 [PATCH v6 0/8] vhost-user: Add SHMEM_MAP/UNMAP requests Albert Esteve
2025-08-14 8:37 ` [PATCH v6 1/8] vhost-user: Add VirtIO Shared Memory map request Albert Esteve
@ 2025-08-14 8:37 ` Albert Esteve
2025-08-14 8:37 ` [PATCH v6 3/8] vhost_user.rst: Add SHMEM_MAP/_UNMAP to spec Albert Esteve
` (5 subsequent siblings)
7 siblings, 0 replies; 12+ messages in thread
From: Albert Esteve @ 2025-08-14 8:37 UTC (permalink / raw)
To: qemu-devel
Cc: Michael S. Tsirkin, Fabiano Rosas, hi, Alex Bennée,
Laurent Vivier, slp, Stefano Garzarella, Paolo Bonzini, david,
jasowang, stefanha, dbassey, stevensd, Albert Esteve
Add missing members to the VhostUserMsg excerpt in
the vhost-user spec documentation.
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Albert Esteve <aesteve@redhat.com>
---
docs/interop/vhost-user.rst | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst
index 2e50f2ddfa..436a94c0ee 100644
--- a/docs/interop/vhost-user.rst
+++ b/docs/interop/vhost-user.rst
@@ -366,11 +366,15 @@ In QEMU the vhost-user message is implemented with the following struct:
struct vhost_vring_state state;
struct vhost_vring_addr addr;
VhostUserMemory memory;
+ VhostUserMemRegMsg mem_reg;
VhostUserLog log;
struct vhost_iotlb_msg iotlb;
VhostUserConfig config;
+ VhostUserCryptoSession session;
VhostUserVringArea area;
VhostUserInflight inflight;
+ VhostUserShared object;
+ VhostUserTransferDeviceState transfer_state;
};
} QEMU_PACKED VhostUserMsg;
--
2.49.0
^ permalink raw reply related [flat|nested] 12+ messages in thread* [PATCH v6 3/8] vhost_user.rst: Add SHMEM_MAP/_UNMAP to spec
2025-08-14 8:37 [PATCH v6 0/8] vhost-user: Add SHMEM_MAP/UNMAP requests Albert Esteve
2025-08-14 8:37 ` [PATCH v6 1/8] vhost-user: Add VirtIO Shared Memory map request Albert Esteve
2025-08-14 8:37 ` [PATCH v6 2/8] vhost_user.rst: Align VhostUserMsg excerpt members Albert Esteve
@ 2025-08-14 8:37 ` Albert Esteve
2025-08-14 8:37 ` [PATCH v6 4/8] vhost_user: Add frontend get_shmem_config command Albert Esteve
` (4 subsequent siblings)
7 siblings, 0 replies; 12+ messages in thread
From: Albert Esteve @ 2025-08-14 8:37 UTC (permalink / raw)
To: qemu-devel
Cc: Michael S. Tsirkin, Fabiano Rosas, hi, Alex Bennée,
Laurent Vivier, slp, Stefano Garzarella, Paolo Bonzini, david,
jasowang, stefanha, dbassey, stevensd, Albert Esteve
Add SHMEM_MAP/_UNMAP request to the vhost-user
spec documentation.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Albert Esteve <aesteve@redhat.com>
---
docs/interop/vhost-user.rst | 58 +++++++++++++++++++++++++++++++++++++
1 file changed, 58 insertions(+)
diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst
index 436a94c0ee..dab9f3af42 100644
--- a/docs/interop/vhost-user.rst
+++ b/docs/interop/vhost-user.rst
@@ -350,6 +350,27 @@ Device state transfer parameters
In the future, additional phases might be added e.g. to allow
iterative migration while the device is running.
+MMAP request
+^^^^^^^^^^^^
+
++-------+---------+-----------+------------+-----+-------+
+| shmid | padding | fd_offset | shm_offset | len | flags |
++-------+---------+-----------+------------+-----+-------+
+
+:shmid: a 8-bit shared memory region identifier
+
+:fd_offset: a 64-bit offset of this area from the start
+ of the supplied file descriptor
+
+:shm_offset: a 64-bit offset from the start of the
+ pointed shared memory region
+
+:len: a 64-bit size of the memory to map
+
+:flags: a 64-bit value:
+ - 0: Pages are mapped read-only
+ - 1: Pages are mapped read-write
+
C structure
-----------
@@ -375,6 +396,7 @@ In QEMU the vhost-user message is implemented with the following struct:
VhostUserInflight inflight;
VhostUserShared object;
VhostUserTransferDeviceState transfer_state;
+ VhostUserMMap mmap;
};
} QEMU_PACKED VhostUserMsg;
@@ -1057,6 +1079,7 @@ Protocol features
#define VHOST_USER_PROTOCOL_F_XEN_MMAP 17
#define VHOST_USER_PROTOCOL_F_SHARED_OBJECT 18
#define VHOST_USER_PROTOCOL_F_DEVICE_STATE 19
+ #define VHOST_USER_PROTOCOL_F_SHMEM 20
Front-end message types
-----------------------
@@ -1865,6 +1888,41 @@ is sent by the front-end.
when the operation is successful, or non-zero otherwise. Note that if the
operation fails, no fd is sent to the backend.
+``VHOST_USER_BACKEND_SHMEM_MAP``
+ :id: 9
+ :equivalent ioctl: N/A
+ :request payload: fd and ``struct VhostUserMMap``
+ :reply payload: N/A
+
+ When the ``VHOST_USER_PROTOCOL_F_SHMEM`` protocol feature has been
+ successfully negotiated, this message can be submitted by the backends to
+ advertise a new mapping to be made in a given VIRTIO Shared Memory Region.
+ Upon receiving the message, the front-end will mmap the given fd into the
+ VIRTIO Shared Memory Region with the requested ``shmid``.
+ If``VHOST_USER_PROTOCOL_F_REPLY_ACK`` is negotiated, and
+ back-end set the ``VHOST_USER_NEED_REPLY`` flag, the front-end
+ must respond with zero when operation is successfully completed,
+ or non-zero otherwise.
+
+ Mapping over an already existing map is not allowed and requests shall fail.
+ Therefore, the memory range in the request must correspond with a valid,
+ free region of the VIRTIO Shared Memory Region. Also, note that mappings
+ consume resources and that the request can fail when there are no resources
+ available.
+
+``VHOST_USER_BACKEND_SHMEM_UNMAP``
+ :id: 10
+ :equivalent ioctl: N/A
+ :request payload: ``struct VhostUserMMap``
+ :reply payload: N/A
+
+ When the ``VHOST_USER_PROTOCOL_F_SHMEM`` protocol feature has been
+ successfully negotiated, this message can be submitted by the backends so
+ that the front-end un-mmaps a given range (``shm_offset``, ``len``) in the
+ VIRTIO Shared Memory Region with the requested ``shmid``. Note that the
+ given range shall correspond to the entirety of a valid mapped region.
+ A reply is generated indicating whether unmapping succeeded.
+
.. _reply_ack:
VHOST_USER_PROTOCOL_F_REPLY_ACK
--
2.49.0
^ permalink raw reply related [flat|nested] 12+ messages in thread* [PATCH v6 4/8] vhost_user: Add frontend get_shmem_config command
2025-08-14 8:37 [PATCH v6 0/8] vhost-user: Add SHMEM_MAP/UNMAP requests Albert Esteve
` (2 preceding siblings ...)
2025-08-14 8:37 ` [PATCH v6 3/8] vhost_user.rst: Add SHMEM_MAP/_UNMAP to spec Albert Esteve
@ 2025-08-14 8:37 ` Albert Esteve
2025-08-14 8:37 ` [PATCH v6 5/8] vhost_user.rst: Add GET_SHMEM_CONFIG message Albert Esteve
` (3 subsequent siblings)
7 siblings, 0 replies; 12+ messages in thread
From: Albert Esteve @ 2025-08-14 8:37 UTC (permalink / raw)
To: qemu-devel
Cc: Michael S. Tsirkin, Fabiano Rosas, hi, Alex Bennée,
Laurent Vivier, slp, Stefano Garzarella, Paolo Bonzini, david,
jasowang, stefanha, dbassey, stevensd, Albert Esteve
The frontend can use this command to retrieve
VirtIO Shared Memory Regions configuration from
the backend. The response contains the number of
shared memory regions, their size, and shmid.
This is useful when the frontend is unaware of
specific backend type and configuration,
for example, in the `vhost-user-device` case.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Albert Esteve <aesteve@redhat.com>
---
hw/virtio/vhost-user.c | 43 +++++++++++++++++++++++++++++++
include/hw/virtio/vhost-backend.h | 10 +++++++
include/hw/virtio/vhost-user.h | 1 +
include/hw/virtio/virtio.h | 2 ++
4 files changed, 56 insertions(+)
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index eb3ad728b0..d1bf162497 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -105,6 +105,7 @@ 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;
@@ -139,6 +140,12 @@ 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;
@@ -245,6 +252,7 @@ typedef union {
VhostUserShared object;
VhostUserTransferDeviceState transfer_state;
VhostUserMMap mmap;
+ VhostUserShMemConfig shmem;
} VhostUserPayload;
typedef struct VhostUserMsg {
@@ -3213,6 +3221,40 @@ 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)) {
+ 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);
+ *nregions = msg.payload.shmem.nregions;
+ memcpy(memory_sizes,
+ &msg.payload.shmem.memory_sizes,
+ sizeof(uint64_t) * msg.payload.shmem.nregions);
+ return 0;
+}
+
const VhostOps user_ops = {
.backend_type = VHOST_BACKEND_TYPE_USER,
.vhost_backend_init = vhost_user_backend_init,
@@ -3251,4 +3293,5 @@ 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/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h
index d6df209a2f..42400b276e 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -159,6 +159,15 @@ typedef int (*vhost_set_device_state_fd_op)(struct vhost_dev *dev,
int *reply_fd,
Error **errp);
typedef int (*vhost_check_device_state_op)(struct vhost_dev *dev, Error **errp);
+/*
+ * Max regions is VIRTIO_MAX_SHMEM_REGIONS, so that is the maximum
+ * number of memory_sizes that will be accepted.
+ */
+typedef int (*vhost_get_shmem_config_op)(struct vhost_dev *dev,
+ int *nregions,
+ uint64_t *memory_sizes,
+ Error **errp);
+
typedef struct VhostOps {
VhostBackendType backend_type;
@@ -214,6 +223,7 @@ typedef struct VhostOps {
vhost_supports_device_state_op vhost_supports_device_state;
vhost_set_device_state_fd_op vhost_set_device_state_fd;
vhost_check_device_state_op vhost_check_device_state;
+ vhost_get_shmem_config_op vhost_get_shmem_config;
} VhostOps;
int vhost_backend_update_device_iotlb(struct vhost_dev *dev,
diff --git a/include/hw/virtio/vhost-user.h b/include/hw/virtio/vhost-user.h
index 9a3f238b43..bacc7d184c 100644
--- a/include/hw/virtio/vhost-user.h
+++ b/include/hw/virtio/vhost-user.h
@@ -32,6 +32,7 @@ enum VhostUserProtocolFeature {
/* Feature 17 reserved for VHOST_USER_PROTOCOL_F_XEN_MMAP. */
VHOST_USER_PROTOCOL_F_SHARED_OBJECT = 18,
VHOST_USER_PROTOCOL_F_DEVICE_STATE = 19,
+ VHOST_USER_PROTOCOL_F_SHMEM = 20,
VHOST_USER_PROTOCOL_F_MAX
};
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index a563bbac2c..2109186d7d 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -81,6 +81,8 @@ typedef struct VirtQueueElement
#define VIRTIO_NO_VECTOR 0xffff
+#define VIRTIO_MAX_SHMEM_REGIONS 256
+
/* special index value used internally for config irqs */
#define VIRTIO_CONFIG_IRQ_IDX -1
--
2.49.0
^ permalink raw reply related [flat|nested] 12+ messages in thread* [PATCH v6 5/8] vhost_user.rst: Add GET_SHMEM_CONFIG message
2025-08-14 8:37 [PATCH v6 0/8] vhost-user: Add SHMEM_MAP/UNMAP requests Albert Esteve
` (3 preceding siblings ...)
2025-08-14 8:37 ` [PATCH v6 4/8] vhost_user: Add frontend get_shmem_config command Albert Esteve
@ 2025-08-14 8:37 ` Albert Esteve
2025-08-14 8:37 ` [PATCH v6 6/8] tests/qtest: Add GET_SHMEM validation test Albert Esteve
` (2 subsequent siblings)
7 siblings, 0 replies; 12+ messages in thread
From: Albert Esteve @ 2025-08-14 8:37 UTC (permalink / raw)
To: qemu-devel
Cc: Michael S. Tsirkin, Fabiano Rosas, hi, Alex Bennée,
Laurent Vivier, slp, Stefano Garzarella, Paolo Bonzini, david,
jasowang, stefanha, dbassey, stevensd, Albert Esteve
Add GET_SHMEM_CONFIG vhost-user frontend
message to the spec documentation.
Reviewed-by: Alyssa Ross <hi@alyssa.is>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Albert Esteve <aesteve@redhat.com>
---
docs/interop/vhost-user.rst | 39 +++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)
diff --git a/docs/interop/vhost-user.rst b/docs/interop/vhost-user.rst
index dab9f3af42..54d64ae75f 100644
--- a/docs/interop/vhost-user.rst
+++ b/docs/interop/vhost-user.rst
@@ -371,6 +371,20 @@ MMAP request
- 0: Pages are mapped read-only
- 1: Pages are mapped read-write
+VIRTIO Shared Memory Region configuration
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
++-------------+---------+------------+----+--------------+
+| num regions | padding | mem size 0 | .. | mem size 255 |
++-------------+---------+------------+----+--------------+
+
+:num regions: a 32-bit number of regions
+
+:padding: 32-bit
+
+:mem size: contains ``num regions`` 64-bit fields representing the size of each
+ VIRTIO Shared Memory Region
+
C structure
-----------
@@ -397,6 +411,7 @@ In QEMU the vhost-user message is implemented with the following struct:
VhostUserShared object;
VhostUserTransferDeviceState transfer_state;
VhostUserMMap mmap;
+ VhostUserShMemConfig shmem;
};
} QEMU_PACKED VhostUserMsg;
@@ -1754,6 +1769,30 @@ Front-end message types
Using this function requires prior negotiation of the
``VHOST_USER_PROTOCOL_F_DEVICE_STATE`` feature.
+``VHOST_USER_GET_SHMEM_CONFIG``
+ :id: 44
+ :equivalent ioctl: N/A
+ :request payload: N/A
+ :reply payload: ``struct VhostUserShMemConfig``
+
+ When the ``VHOST_USER_PROTOCOL_F_SHMEM`` protocol feature has been
+ successfully negotiated, this message can be submitted by the front-end
+ to gather the VIRTIO Shared Memory Region configuration. The back-end will
+ respond with the number of VIRTIO Shared Memory Regions it requires, and
+ each shared memory region size in an array. The shared memory IDs are
+ represented by the array index. The information returned shall comply
+ with the following rules:
+
+ * The shared information will remain valid and unchanged for the entire
+ lifetime of the connection.
+
+ * The Shared Memory Region size must be a multiple of the page size
+ supported by mmap(2).
+
+ * The size may be 0 if the region is unused. This can happen when the
+ device does not support an optional feature but does support a feature
+ that uses a higher shmid.
+
Back-end message types
----------------------
--
2.49.0
^ permalink raw reply related [flat|nested] 12+ messages in thread* [PATCH v6 6/8] tests/qtest: Add GET_SHMEM validation test
2025-08-14 8:37 [PATCH v6 0/8] vhost-user: Add SHMEM_MAP/UNMAP requests Albert Esteve
` (4 preceding siblings ...)
2025-08-14 8:37 ` [PATCH v6 5/8] vhost_user.rst: Add GET_SHMEM_CONFIG message Albert Esteve
@ 2025-08-14 8:37 ` Albert Esteve
2025-08-14 8:37 ` [PATCH v6 7/8] qmp: add shmem feature map Albert Esteve
2025-08-14 8:37 ` [PATCH v6 8/8] vhost-user-device: Add shared memory BAR Albert Esteve
7 siblings, 0 replies; 12+ messages in thread
From: Albert Esteve @ 2025-08-14 8:37 UTC (permalink / raw)
To: qemu-devel
Cc: Michael S. Tsirkin, Fabiano Rosas, hi, Alex Bennée,
Laurent Vivier, slp, Stefano Garzarella, Paolo Bonzini, david,
jasowang, stefanha, dbassey, stevensd, Albert Esteve
Improve vhost-user-test to properly validate
VHOST_USER_GET_SHMEM_CONFIG message handling by
directly simulating the message exchange.
The test manually triggers the
VHOST_USER_GET_SHMEM_CONFIG message by calling
chr_read() with a crafted VhostUserMsg, allowing direct
validation of the shmem configuration response handler.
Added TestServerShmem structure to track shmem
configuration state, including nregions_sent and
sizes_sent arrays for comprehensive validation.
The test verifies that the response contains the expected
number of shared memory regions and their corresponding
sizes.
Signed-off-by: Albert Esteve <aesteve@redhat.com>
---
tests/qtest/vhost-user-test.c | 91 +++++++++++++++++++++++++++++++++++
1 file changed, 91 insertions(+)
diff --git a/tests/qtest/vhost-user-test.c b/tests/qtest/vhost-user-test.c
index 75cb3e44b2..44a5e90b2e 100644
--- a/tests/qtest/vhost-user-test.c
+++ b/tests/qtest/vhost-user-test.c
@@ -88,6 +88,7 @@ typedef enum VhostUserRequest {
VHOST_USER_SET_VRING_ENABLE = 18,
VHOST_USER_GET_CONFIG = 24,
VHOST_USER_SET_CONFIG = 25,
+ VHOST_USER_GET_SHMEM_CONFIG = 44,
VHOST_USER_MAX
} VhostUserRequest;
@@ -109,6 +110,20 @@ typedef struct VhostUserLog {
uint64_t mmap_offset;
} VhostUserLog;
+#define VIRTIO_MAX_SHMEM_REGIONS 256
+
+typedef struct VhostUserShMemConfig {
+ uint32_t nregions;
+ uint32_t padding;
+ uint64_t memory_sizes[VIRTIO_MAX_SHMEM_REGIONS];
+} VhostUserShMemConfig;
+
+typedef struct TestServerShmem {
+ bool test_enabled;
+ uint32_t nregions_sent;
+ uint64_t sizes_sent[VIRTIO_MAX_SHMEM_REGIONS];
+} TestServerShmem;
+
typedef struct VhostUserMsg {
VhostUserRequest request;
@@ -124,6 +139,7 @@ typedef struct VhostUserMsg {
struct vhost_vring_addr addr;
VhostUserMemory memory;
VhostUserLog log;
+ VhostUserShMemConfig shmem;
} payload;
} QEMU_PACKED VhostUserMsg;
@@ -170,6 +186,7 @@ typedef struct TestServer {
bool test_fail;
int test_flags;
int queues;
+ TestServerShmem shmem;
struct vhost_user_ops *vu_ops;
} TestServer;
@@ -513,6 +530,31 @@ static void chr_read(void *opaque, const uint8_t *buf, int size)
qos_printf("set_vring(%d)=%s\n", msg.payload.state.index,
msg.payload.state.num ? "enabled" : "disabled");
break;
+
+ case VHOST_USER_GET_SHMEM_CONFIG:
+ if (!s->shmem.test_enabled) {
+ /* Reply with error if shmem feature not enabled */
+ msg.flags |= VHOST_USER_REPLY_MASK;
+ msg.size = sizeof(uint64_t);
+ msg.payload.u64 = -1; /* Error */
+ qemu_chr_fe_write_all(chr, (uint8_t *) &msg, VHOST_USER_HDR_SIZE + msg.size);
+ } else {
+ /* Reply with test shmem configuration */
+ msg.flags |= VHOST_USER_REPLY_MASK;
+ msg.size = sizeof(VhostUserShMemConfig);
+ msg.payload.shmem.nregions = 2; /* Test with 2 regions */
+ msg.payload.shmem.padding = 0;
+ msg.payload.shmem.memory_sizes[0] = 0x100000; /* 1MB */
+ msg.payload.shmem.memory_sizes[1] = 0x200000; /* 2MB */
+
+ /* Record what we're sending for test validation */
+ s->shmem.nregions_sent = msg.payload.shmem.nregions;
+ s->shmem.sizes_sent[0] = msg.payload.shmem.memory_sizes[0];
+ s->shmem.sizes_sent[1] = msg.payload.shmem.memory_sizes[1];
+
+ qemu_chr_fe_write_all(chr, (uint8_t *) &msg, VHOST_USER_HDR_SIZE + msg.size);
+ }
+ break;
default:
qos_printf("vhost-user: un-handled message: %d\n", msg.request);
@@ -809,6 +851,22 @@ static void *vhost_user_test_setup_shm(GString *cmd_line, void *arg)
return server;
}
+static void *vhost_user_test_setup_shmem_config(GString *cmd_line, void *arg)
+{
+ TestServer *server = test_server_new("vhost-user-test", arg);
+ test_server_listen(server);
+
+ /* Enable shmem testing for this server */
+ server->shmem.test_enabled = true;
+
+ append_mem_opts(server, cmd_line, 256, TEST_MEMFD_SHM);
+ server->vu_ops->append_opts(server, cmd_line, "");
+
+ g_test_queue_destroy(vhost_user_test_cleanup, server);
+
+ return server;
+}
+
static void test_read_guest_mem(void *obj, void *arg, QGuestAllocator *alloc)
{
TestServer *server = arg;
@@ -1089,6 +1147,33 @@ static struct vhost_user_ops g_vu_net_ops = {
.get_protocol_features = vu_net_get_protocol_features,
};
+/* Test function for VHOST_USER_GET_SHMEM_CONFIG message */
+static void test_shmem_config(void *obj, void *arg, QGuestAllocator *alloc)
+{
+ TestServer *s = arg;
+
+ g_assert_true(s->shmem.test_enabled);
+
+ g_mutex_lock(&s->data_mutex);
+ s->shmem.nregions_sent = 0;
+ s->shmem.sizes_sent[0] = 0;
+ s->shmem.sizes_sent[1] = 0;
+ g_mutex_unlock(&s->data_mutex);
+
+ VhostUserMsg msg = {
+ .request = VHOST_USER_GET_SHMEM_CONFIG,
+ .flags = VHOST_USER_VERSION,
+ .size = 0,
+ };
+ chr_read(s, (uint8_t *) &msg, VHOST_USER_HDR_SIZE);
+
+ g_mutex_lock(&s->data_mutex);
+ g_assert_cmpint(s->shmem.nregions_sent, ==, 2);
+ g_assert_cmpint(s->shmem.sizes_sent[0], ==, 0x100000); /* 1MB */
+ g_assert_cmpint(s->shmem.sizes_sent[1], ==, 0x200000); /* 2MB */
+ g_mutex_unlock(&s->data_mutex);
+}
+
static void register_vhost_user_test(void)
{
QOSGraphTestOptions opts = {
@@ -1136,6 +1221,12 @@ static void register_vhost_user_test(void)
qos_add_test("vhost-user/multiqueue",
"virtio-net",
test_multiqueue, &opts);
+
+ opts.before = vhost_user_test_setup_shmem_config;
+ opts.edge.extra_device_opts = "";
+ qos_add_test("vhost-user/shmem-config",
+ "virtio-net",
+ test_shmem_config, &opts);
}
libqos_init(register_vhost_user_test);
--
2.49.0
^ permalink raw reply related [flat|nested] 12+ messages in thread* [PATCH v6 7/8] qmp: add shmem feature map
2025-08-14 8:37 [PATCH v6 0/8] vhost-user: Add SHMEM_MAP/UNMAP requests Albert Esteve
` (5 preceding siblings ...)
2025-08-14 8:37 ` [PATCH v6 6/8] tests/qtest: Add GET_SHMEM validation test Albert Esteve
@ 2025-08-14 8:37 ` Albert Esteve
2025-08-14 8:37 ` [PATCH v6 8/8] vhost-user-device: Add shared memory BAR Albert Esteve
7 siblings, 0 replies; 12+ messages in thread
From: Albert Esteve @ 2025-08-14 8:37 UTC (permalink / raw)
To: qemu-devel
Cc: Michael S. Tsirkin, Fabiano Rosas, hi, Alex Bennée,
Laurent Vivier, slp, Stefano Garzarella, Paolo Bonzini, david,
jasowang, stefanha, dbassey, stevensd, Albert Esteve
Add new vhost-user protocol
VHOST_USER_PROTOCOL_F_SHMEM feature to
feature map.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Albert Esteve <aesteve@redhat.com>
---
hw/virtio/virtio-qmp.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/hw/virtio/virtio-qmp.c b/hw/virtio/virtio-qmp.c
index 3b6377cf0d..8c2cfd0916 100644
--- a/hw/virtio/virtio-qmp.c
+++ b/hw/virtio/virtio-qmp.c
@@ -127,6 +127,9 @@ static const qmp_virtio_feature_map_t vhost_user_protocol_map[] = {
FEATURE_ENTRY(VHOST_USER_PROTOCOL_F_DEVICE_STATE, \
"VHOST_USER_PROTOCOL_F_DEVICE_STATE: Backend device state transfer "
"supported"),
+ FEATURE_ENTRY(VHOST_USER_PROTOCOL_F_SHMEM, \
+ "VHOST_USER_PROTOCOL_F_SHMEM: Backend shared memory mapping "
+ "supported"),
{ -1, "" }
};
--
2.49.0
^ permalink raw reply related [flat|nested] 12+ messages in thread* [PATCH v6 8/8] vhost-user-device: Add shared memory BAR
2025-08-14 8:37 [PATCH v6 0/8] vhost-user: Add SHMEM_MAP/UNMAP requests Albert Esteve
` (6 preceding siblings ...)
2025-08-14 8:37 ` [PATCH v6 7/8] qmp: add shmem feature map Albert Esteve
@ 2025-08-14 8:37 ` Albert Esteve
7 siblings, 0 replies; 12+ messages in thread
From: Albert Esteve @ 2025-08-14 8:37 UTC (permalink / raw)
To: qemu-devel
Cc: Michael S. Tsirkin, Fabiano Rosas, hi, Alex Bennée,
Laurent Vivier, slp, Stefano Garzarella, Paolo Bonzini, david,
jasowang, stefanha, dbassey, stevensd, Albert Esteve
Add shared memory BAR support to vhost-user-device-pci
to enable direct file mapping for VIRTIO Shared
Memory Regions.
The implementation creates a consolidated shared
memory BAR that contains all VIRTIO Shared
Memory Regions as subregions. Each region is
configured with its proper shmid, size, and
offset within the BAR. The number and size of
regions are retrieved via VHOST_USER_GET_SHMEM_CONFIG
message sent by vhost-user-base during realization
after virtio_init().
Specifiically, it uses BAR 3 to avoid conflicts, as
it is currently unused.
The shared memory BAR is only created when the
backend supports VHOST_USER_PROTOCOL_F_SHMEM and
has configured shared memory regions. This maintains
backward compatibility with backends that do not
support shared memory functionality.
Signed-off-by: Albert Esteve <aesteve@redhat.com>
---
hw/virtio/vhost-user-base.c | 49 +++++++++++++++++++++++++++++--
hw/virtio/vhost-user-device-pci.c | 34 +++++++++++++++++++--
2 files changed, 78 insertions(+), 5 deletions(-)
diff --git a/hw/virtio/vhost-user-base.c b/hw/virtio/vhost-user-base.c
index ff67a020b4..932f9b5596 100644
--- a/hw/virtio/vhost-user-base.c
+++ b/hw/virtio/vhost-user-base.c
@@ -16,6 +16,7 @@
#include "hw/virtio/virtio-bus.h"
#include "hw/virtio/vhost-user-base.h"
#include "qemu/error-report.h"
+#include "migration/blocker.h"
static void vub_start(VirtIODevice *vdev)
{
@@ -276,7 +277,9 @@ static void vub_device_realize(DeviceState *dev, Error **errp)
{
VirtIODevice *vdev = VIRTIO_DEVICE(dev);
VHostUserBase *vub = VHOST_USER_BASE(dev);
- int ret;
+ uint64_t memory_sizes[VIRTIO_MAX_SHMEM_REGIONS];
+ g_autofree char *name = NULL;
+ int i, ret, nregions;
if (!vub->chardev.chr) {
error_setg(errp, "vhost-user-base: missing chardev");
@@ -319,7 +322,7 @@ static void vub_device_realize(DeviceState *dev, Error **errp)
/* Allocate queues */
vub->vqs = g_ptr_array_sized_new(vub->num_vqs);
- for (int i = 0; i < vub->num_vqs; i++) {
+ for (i = 0; i < vub->num_vqs; i++) {
g_ptr_array_add(vub->vqs,
virtio_add_queue(vdev, vub->vq_size,
vub_handle_output));
@@ -333,11 +336,51 @@ static void vub_device_realize(DeviceState *dev, Error **errp)
VHOST_BACKEND_TYPE_USER, 0, errp);
if (ret < 0) {
- do_vhost_user_cleanup(vdev, vub);
+ goto err;
+ }
+
+ ret = vub->vhost_dev.vhost_ops->vhost_get_shmem_config(&vub->vhost_dev,
+ &nregions,
+ memory_sizes,
+ errp);
+
+ if (ret < 0) {
+ goto err;
+ }
+
+ for (i = 0; i < nregions; i++) {
+ if (memory_sizes[i]) {
+ if (vub->vhost_dev.migration_blocker == NULL) {
+ error_setg(&vub->vhost_dev.migration_blocker,
+ "Migration disabled: devices with VIRTIO Shared Memory "
+ "Regions do not support migration yet.");
+ ret = migrate_add_blocker_normal(
+ &vub->vhost_dev.migration_blocker,
+ errp);
+
+ if (ret < 0) {
+ goto err;
+ }
+ }
+
+ if (memory_sizes[i] % qemu_real_host_page_size() != 0) {
+ error_setg(errp, "Shared memory %d size must be a power of 2 "
+ "no smaller than the page size", i);
+ goto err;
+ }
+
+ name = g_strdup_printf("vub-shm-%d", i);
+ memory_region_init(&virtio_new_shmem_region(vdev, i)->mr,
+ OBJECT(vdev), name,
+ memory_sizes[i]);
+ }
}
qemu_chr_fe_set_handlers(&vub->chardev, NULL, NULL, vub_event, NULL,
dev, NULL, true);
+ return;
+err:
+ do_vhost_user_cleanup(vdev, vub);
}
static void vub_device_unrealize(DeviceState *dev)
diff --git a/hw/virtio/vhost-user-device-pci.c b/hw/virtio/vhost-user-device-pci.c
index f10bac874e..bac99e7c60 100644
--- a/hw/virtio/vhost-user-device-pci.c
+++ b/hw/virtio/vhost-user-device-pci.c
@@ -8,14 +8,18 @@
*/
#include "qemu/osdep.h"
+#include "qapi/error.h"
#include "hw/qdev-properties.h"
#include "hw/virtio/vhost-user-base.h"
#include "hw/virtio/virtio-pci.h"
+#define VIRTIO_DEVICE_PCI_SHMEM_BAR 3
+
struct VHostUserDevicePCI {
VirtIOPCIProxy parent_obj;
VHostUserBase vub;
+ MemoryRegion shmembar;
};
#define TYPE_VHOST_USER_DEVICE_PCI "vhost-user-device-pci-base"
@@ -25,10 +29,36 @@ OBJECT_DECLARE_SIMPLE_TYPE(VHostUserDevicePCI, VHOST_USER_DEVICE_PCI)
static void vhost_user_device_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
{
VHostUserDevicePCI *dev = VHOST_USER_DEVICE_PCI(vpci_dev);
- DeviceState *vdev = DEVICE(&dev->vub);
+ DeviceState *dev_state = DEVICE(&dev->vub);
+ VirtIODevice *vdev = VIRTIO_DEVICE(dev_state);
+ VirtioSharedMemory *shmem, *next;
+ uint64_t offset = 0, shmem_size = 0;
vpci_dev->nvectors = 1;
- qdev_realize(vdev, BUS(&vpci_dev->bus), errp);
+ qdev_realize(dev_state, BUS(&vpci_dev->bus), errp);
+
+ QSIMPLEQ_FOREACH_SAFE(shmem, &vdev->shmem_list, entry, next) {
+ if (shmem->mr.size > UINT64_MAX - shmem_size) {
+ error_setg(errp, "Total shared memory required overflow");
+ return;
+ }
+ shmem_size = shmem_size + shmem->mr.size;
+ }
+ if (shmem_size) {
+ memory_region_init(&dev->shmembar, OBJECT(vpci_dev),
+ "vhost-device-pci-shmembar", shmem_size);
+ QSIMPLEQ_FOREACH_SAFE(shmem, &vdev->shmem_list, entry, next) {
+ memory_region_add_subregion(&dev->shmembar, offset, &shmem->mr);
+ virtio_pci_add_shm_cap(vpci_dev, VIRTIO_DEVICE_PCI_SHMEM_BAR,
+ offset, shmem->mr.size, shmem->shmid);
+ offset = offset + shmem->mr.size;
+ }
+ pci_register_bar(&vpci_dev->pci_dev, VIRTIO_DEVICE_PCI_SHMEM_BAR,
+ PCI_BASE_ADDRESS_SPACE_MEMORY |
+ PCI_BASE_ADDRESS_MEM_PREFETCH |
+ PCI_BASE_ADDRESS_MEM_TYPE_64,
+ &dev->shmembar);
+ }
}
static void vhost_user_device_pci_class_init(ObjectClass *klass,
--
2.49.0
^ permalink raw reply related [flat|nested] 12+ messages in thread