@@ -1859,6 +1859,33 @@ 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
+
+ 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``. A reply is generated indicating whether mapping
+ succeeded.
+
+ Mapping over an already existing map is not allowed and request shall fail.
+ Therefore, the memory range in the request must correspond with a valid,
+ free region of the VIRTIO Shared Memory Region.
+
+``VHOST_USER_BACKEND_SHMEM_UNMAP``
+ :id: 10
+ :equivalent ioctl: N/A
+ :request payload: ``struct VhostUserMMap``
+ :reply payload: N/A
+
+ This message can be submitted by the backends so that the front-end un-mmap
+ a given range (``offset``, ``len``) in the VIRTIO Shared Memory Region with
+ the requested ``shmid``.
+ A reply is generated indicating whether unmapping succeeded.
+
.. _reply_ack:
VHOST_USER_PROTOCOL_F_REPLY_ACK
@@ -115,6 +115,8 @@ typedef enum VhostUserBackendRequest {
VHOST_USER_BACKEND_SHARED_OBJECT_ADD = 6,
VHOST_USER_BACKEND_SHARED_OBJECT_REMOVE = 7,
VHOST_USER_BACKEND_SHARED_OBJECT_LOOKUP = 8,
+ VHOST_USER_BACKEND_SHMEM_MAP = 9,
+ VHOST_USER_BACKEND_SHMEM_UNMAP = 10,
VHOST_USER_BACKEND_MAX
} VhostUserBackendRequest;
@@ -192,6 +194,24 @@ typedef struct VhostUserShared {
unsigned char uuid[16];
} VhostUserShared;
+/* For the flags field of VhostUserMMap */
+#define VHOST_USER_FLAG_MAP_R (1u << 0)
+#define VHOST_USER_FLAG_MAP_W (1u << 1)
+
+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_* */
+ uint64_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 {
@@ -1748,6 +1769,100 @@ vhost_user_backend_handle_shared_object_lookup(struct vhost_user *u,
return 0;
}
+static int
+vhost_user_backend_handle_shmem_map(struct vhost_dev *dev,
+ VhostUserMMap *vu_mmap,
+ int fd)
+{
+ void *addr = 0;
+ MemoryRegion *mr = NULL;
+
+ if (fd < 0) {
+ error_report("Bad fd for map");
+ return -EBADF;
+ }
+
+ if (!dev->vdev->shmem_list ||
+ dev->vdev->n_shmem_regions <= vu_mmap->shmid) {
+ error_report("Device only has %d VIRTIO Shared Memory Regions. "
+ "Requested ID: %d",
+ dev->vdev->n_shmem_regions, vu_mmap->shmid);
+ return -EFAULT;
+ }
+
+ mr = &dev->vdev->shmem_list[vu_mmap->shmid];
+
+ if (!mr) {
+ error_report("VIRTIO Shared Memory Region at "
+ "ID %d unitialized", vu_mmap->shmid);
+ return -EFAULT;
+ }
+
+ if ((vu_mmap->shm_offset + vu_mmap->len) < vu_mmap->len ||
+ (vu_mmap->shm_offset + vu_mmap->len) > mr->size) {
+ error_report("Bad offset/len for mmap %" PRIx64 "+%" PRIx64,
+ vu_mmap->shm_offset, vu_mmap->len);
+ return -EFAULT;
+ }
+
+ void *shmem_ptr = memory_region_get_ram_ptr(mr);
+
+ addr = mmap(shmem_ptr + vu_mmap->shm_offset, vu_mmap->len,
+ ((vu_mmap->flags & VHOST_USER_FLAG_MAP_R) ? PROT_READ : 0) |
+ ((vu_mmap->flags & VHOST_USER_FLAG_MAP_W) ? PROT_WRITE : 0),
+ MAP_SHARED | MAP_FIXED, fd, vu_mmap->fd_offset);
+
+ if (addr == MAP_FAILED) {
+ error_report("Failed to mmap mem fd");
+ return -EFAULT;
+ }
+
+ return 0;
+}
+
+static int
+vhost_user_backend_handle_shmem_unmap(struct vhost_dev *dev,
+ VhostUserMMap *vu_mmap)
+{
+ void *addr = 0;
+ MemoryRegion *mr = NULL;
+
+ if (!dev->vdev->shmem_list ||
+ dev->vdev->n_shmem_regions <= vu_mmap->shmid) {
+ error_report("Device only has %d VIRTIO Shared Memory Regions. "
+ "Requested ID: %d",
+ dev->vdev->n_shmem_regions, vu_mmap->shmid);
+ return -EFAULT;
+ }
+
+ mr = &dev->vdev->shmem_list[vu_mmap->shmid];
+
+ if (!mr) {
+ error_report("VIRTIO Shared Memory Region at "
+ "ID %d unitialized", vu_mmap->shmid);
+ return -EFAULT;
+ }
+
+ if ((vu_mmap->shm_offset + vu_mmap->len) < vu_mmap->len ||
+ (vu_mmap->shm_offset + vu_mmap->len) > mr->size) {
+ error_report("Bad offset/len for mmap %" PRIx64 "+%" PRIx64,
+ vu_mmap->shm_offset, vu_mmap->len);
+ return -EFAULT;
+ }
+
+ void *shmem_ptr = memory_region_get_ram_ptr(mr);
+
+ addr = mmap(shmem_ptr + vu_mmap->shm_offset, vu_mmap->len,
+ PROT_NONE, MAP_PRIVATE | MAP_ANONYMOUS | MAP_FIXED, -1, 0);
+
+ if (addr == MAP_FAILED) {
+ error_report("Failed to unmap memory");
+ return -EFAULT;
+ }
+
+ return 0;
+}
+
static void close_backend_channel(struct vhost_user *u)
{
g_source_destroy(u->backend_src);
@@ -1816,6 +1931,13 @@ static gboolean backend_read(QIOChannel *ioc, GIOCondition condition,
ret = vhost_user_backend_handle_shared_object_lookup(dev->opaque, ioc,
&hdr, &payload);
break;
+ case VHOST_USER_BACKEND_SHMEM_MAP:
+ ret = vhost_user_backend_handle_shmem_map(dev, &payload.mmap,
+ fd ? fd[0] : -1);
+ break;
+ case VHOST_USER_BACKEND_SHMEM_UNMAP:
+ ret = vhost_user_backend_handle_shmem_unmap(dev, &payload.mmap);
+ break;
default:
error_report("Received unexpected msg type: %d.", hdr.request);
ret = -EINVAL;
@@ -2856,6 +2856,16 @@ int virtio_save(VirtIODevice *vdev, QEMUFile *f)
return vmstate_save_state(f, &vmstate_virtio, vdev, NULL);
}
+MemoryRegion *virtio_new_shmem_region(VirtIODevice *vdev)
+{
+ MemoryRegion *mr = g_new0(MemoryRegion, 1);
+ ++vdev->n_shmem_regions;
+ vdev->shmem_list = g_renew(MemoryRegion, vdev->shmem_list,
+ vdev->n_shmem_regions);
+ vdev->shmem_list[vdev->n_shmem_regions - 1] = *mr;
+ return mr;
+}
+
/* 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)
@@ -3264,6 +3274,8 @@ void virtio_init(VirtIODevice *vdev, uint16_t device_id, size_t config_size)
virtio_vmstate_change, vdev);
vdev->device_endian = virtio_default_endian();
vdev->use_guest_notifier_mask = true;
+ vdev->shmem_list = NULL;
+ vdev->n_shmem_regions = 0;
}
/*
@@ -165,6 +165,9 @@ struct VirtIODevice
*/
EventNotifier config_notifier;
bool device_iotlb_enabled;
+ /* Shared memory region for vhost-user mappings. */
+ MemoryRegion *shmem_list;
+ int n_shmem_regions;
};
struct VirtioDeviceClass {
@@ -280,6 +283,8 @@ void virtio_notify(VirtIODevice *vdev, VirtQueue *vq);
int virtio_save(VirtIODevice *vdev, QEMUFile *f);
+MemoryRegion *virtio_new_shmem_region(VirtIODevice *vdev);
+
extern const VMStateInfo virtio_vmstate_info;
#define VMSTATE_VIRTIO_DEVICE \
@@ -1586,6 +1586,71 @@ 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)
+{
+ bool result = false;
+ VhostUserMsg msg_reply;
+ 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,
+ },
+ };
+
+ 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 fd_offset,
+ uint64_t shm_offset, uint64_t len)
+{
+ bool result = false;
+ VhostUserMsg msg_reply;
+ VhostUserMsg vmsg = {
+ .request = VHOST_USER_BACKEND_SHMEM_UNMAP,
+ .size = sizeof(vmsg.payload.mmap),
+ .flags = VHOST_USER_VERSION,
+ .payload.mmap = {
+ .shmid = shmid,
+ .fd_offset = fd_offset,
+ .shm_offset = shm_offset,
+ .len = len,
+ },
+ };
+
+ 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)
{
@@ -127,6 +127,8 @@ 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 +188,24 @@ typedef struct VhostUserShared {
unsigned char uuid[UUID_LEN];
} VhostUserShared;
+/* For the flags field of VhostUserMMap */
+#define VHOST_USER_FLAG_MAP_R (1u << 0)
+#define VHOST_USER_FLAG_MAP_W (1u << 1)
+
+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_* */
+ uint64_t flags;
+} VhostUserMMap;
+
#if defined(_WIN32) && (defined(__x86_64__) || defined(__i386__))
# define VU_PACKED __attribute__((gcc_struct, packed))
#else
@@ -214,6 +234,7 @@ typedef struct VhostUserMsg {
VhostUserVringArea area;
VhostUserInflight inflight;
VhostUserShared object;
+ VhostUserMMap mmap;
} payload;
int fds[VHOST_MEMORY_BASELINE_NREGIONS];
@@ -597,6 +618,38 @@ 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
+ *
+ * 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);
+
+/**
+ * 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
+ *
+ * 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 fd_offset,
+ uint64_t shm_offset, uint64_t len);
+
/**
* vu_queue_set_notification:
* @dev: a VuDev context
Add SHMEM_MAP/UNMAP requests to vhost-user to handle VIRTIO Shared Memory mappings. This request allows backends to dynamically map fds into a VIRTIO Shared Memory Region indentified by its `shmid`. Then, the fd memory is advertised to the driver as a base addres + offset, so it can be read/written (depending on the mmap flags requested) while its valid. The backend can munmap the memory range in a given VIRTIO Shared Memory Region (again, identified by its `shmid`), to free it. Upon receiving this message, the front-end must mmap the regions with PROT_NONE to reserve the virtual memory space. The device model needs to create MemoryRegion instances for the VIRTIO Shared Memory Regions and add them to the `VirtIODevice` instance. Signed-off-by: Albert Esteve <aesteve@redhat.com> --- docs/interop/vhost-user.rst | 27 +++++ hw/virtio/vhost-user.c | 122 ++++++++++++++++++++++ hw/virtio/virtio.c | 12 +++ include/hw/virtio/virtio.h | 5 + subprojects/libvhost-user/libvhost-user.c | 65 ++++++++++++ subprojects/libvhost-user/libvhost-user.h | 53 ++++++++++ 6 files changed, 284 insertions(+)