| Message ID | 20240912145335.129447-2-aesteve@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | vhost-user: Add SHMEM_MAP/UNMAP requests | expand |
On Thu, Sep 12, 2024 at 04:53:31PM +0200, Albert Esteve wrote: > 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> > --- > hw/virtio/vhost-user.c | 122 ++++++++++++++++++++++ > hw/virtio/virtio.c | 13 +++ > include/hw/virtio/virtio.h | 5 + > subprojects/libvhost-user/libvhost-user.c | 60 +++++++++++ > subprojects/libvhost-user/libvhost-user.h | 52 +++++++++ > 5 files changed, 252 insertions(+) > > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c > index 00561daa06..338cc942ec 100644 > --- a/hw/virtio/vhost-user.c > +++ b/hw/virtio/vhost-user.c > @@ -115,6 +115,8 @@ typedef enum VhostUserBackendRequest { > VHOST_USER_BACKEND_SHARED_OBJECT_ADD = 6, > VHOST_USER_BACKEND_SHARED_OBJECT_REMOVE = 7, > VHOST_USER_BACKEND_SHARED_OBJECT_LOOKUP = 8, > + VHOST_USER_BACKEND_SHMEM_MAP = 9, > + VHOST_USER_BACKEND_SHMEM_UNMAP = 10, > VHOST_USER_BACKEND_MAX > } VhostUserBackendRequest; > > @@ -192,6 +194,24 @@ 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 { > @@ -1749,6 +1770,100 @@ 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); > @@ -1817,6 +1932,13 @@ 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; > diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c > index 9e10cbc058..ccc4f2cd75 100644 > --- a/hw/virtio/virtio.c > +++ b/hw/virtio/virtio.c > @@ -3059,6 +3059,17 @@ 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; > + ++vdev->n_shmem_regions; > + vdev->shmem_list = g_renew(MemoryRegion, vdev->shmem_list, > + vdev->n_shmem_regions); > + mr = &vdev->shmem_list[vdev->n_shmem_regions - 1]; > + mr = g_new0(MemoryRegion, 1); > + return mr; > +} This function looks broken. shmem_list[] is reallocated so old MemoryRegion pointers will be dangling pointers. And then the MemoryRegion is allocated again using g_new0() but there is no way to retrieve that address again via shmem_list[]. I expected something like this: MemoryRegion *virtio_new_shmem_region(VirtIODevice *vdev) { MemoryRegion *mr; assert(vdev->n_shmem_regions < INT_MAX); ++vdev->n_shmem_regions; vdev->shmem_list = g_renew(MemoryRegion *, vdev->shmem_list, vdev->n_shmem_regions); mr = g_new0(MemoryRegion, 1); 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) > @@ -3481,6 +3492,8 @@ 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; shmem_list[] and each MemoryRegion needs to be free somewhere. virtio_device_instance_finalize()? > + vdev->n_shmem_regions = 0; > } > > /* > diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h > index 0fcbc5c0c6..d4a2f664d9 100644 > --- a/include/hw/virtio/virtio.h > +++ b/include/hw/virtio/virtio.h > @@ -167,6 +167,9 @@ 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 { > @@ -286,6 +289,8 @@ 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 \ > diff --git a/subprojects/libvhost-user/libvhost-user.c b/subprojects/libvhost-user/libvhost-user.c > index 9c630c2170..496268e12b 100644 > --- a/subprojects/libvhost-user/libvhost-user.c > +++ b/subprojects/libvhost-user/libvhost-user.c > @@ -1592,6 +1592,66 @@ 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) > +{ > + 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 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_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 deb40e77b3..ea4902e876 100644 > --- a/subprojects/libvhost-user/libvhost-user.h > +++ b/subprojects/libvhost-user/libvhost-user.h > @@ -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 +618,37 @@ 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); How is the fd passed to the front-end? > + > +/** > + * vu_shmem_map: "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 > -- > 2.45.2 >
On 12.09.24 16:53, Albert Esteve wrote: > 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> > --- > hw/virtio/vhost-user.c | 122 ++++++++++++++++++++++ > hw/virtio/virtio.c | 13 +++ > include/hw/virtio/virtio.h | 5 + > subprojects/libvhost-user/libvhost-user.c | 60 +++++++++++ > subprojects/libvhost-user/libvhost-user.h | 52 +++++++++ > 5 files changed, 252 insertions(+) > > diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c > index 00561daa06..338cc942ec 100644 > --- a/hw/virtio/vhost-user.c > +++ b/hw/virtio/vhost-user.c > @@ -115,6 +115,8 @@ typedef enum VhostUserBackendRequest { > VHOST_USER_BACKEND_SHARED_OBJECT_ADD = 6, > VHOST_USER_BACKEND_SHARED_OBJECT_REMOVE = 7, > VHOST_USER_BACKEND_SHARED_OBJECT_LOOKUP = 8, > + VHOST_USER_BACKEND_SHMEM_MAP = 9, > + VHOST_USER_BACKEND_SHMEM_UNMAP = 10, > VHOST_USER_BACKEND_MAX > } VhostUserBackendRequest; > > @@ -192,6 +194,24 @@ 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 { > @@ -1749,6 +1770,100 @@ 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); > + I'm sorry, but that looks completely wrong. You cannot just take some RAM memory region/ RAMBlock that has properly set flags/fd/whatssoever and map whatever you want in there. Likely you would need a distinct RAMBlock/RAM memory region per mmap(), and would end up mmaping implicitly via qemu_ram_mmap(). Then, your shared region would simply be an empty container into which you map these RAM memory regions.
diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index 00561daa06..338cc942ec 100644 --- a/hw/virtio/vhost-user.c +++ b/hw/virtio/vhost-user.c @@ -115,6 +115,8 @@ typedef enum VhostUserBackendRequest { VHOST_USER_BACKEND_SHARED_OBJECT_ADD = 6, VHOST_USER_BACKEND_SHARED_OBJECT_REMOVE = 7, VHOST_USER_BACKEND_SHARED_OBJECT_LOOKUP = 8, + VHOST_USER_BACKEND_SHMEM_MAP = 9, + VHOST_USER_BACKEND_SHMEM_UNMAP = 10, VHOST_USER_BACKEND_MAX } VhostUserBackendRequest; @@ -192,6 +194,24 @@ 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 { @@ -1749,6 +1770,100 @@ 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); @@ -1817,6 +1932,13 @@ 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; diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 9e10cbc058..ccc4f2cd75 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -3059,6 +3059,17 @@ 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; + ++vdev->n_shmem_regions; + vdev->shmem_list = g_renew(MemoryRegion, vdev->shmem_list, + vdev->n_shmem_regions); + mr = &vdev->shmem_list[vdev->n_shmem_regions - 1]; + mr = g_new0(MemoryRegion, 1); + 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) @@ -3481,6 +3492,8 @@ 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; } /* diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h index 0fcbc5c0c6..d4a2f664d9 100644 --- a/include/hw/virtio/virtio.h +++ b/include/hw/virtio/virtio.h @@ -167,6 +167,9 @@ 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 { @@ -286,6 +289,8 @@ 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 \ diff --git a/subprojects/libvhost-user/libvhost-user.c b/subprojects/libvhost-user/libvhost-user.c index 9c630c2170..496268e12b 100644 --- a/subprojects/libvhost-user/libvhost-user.c +++ b/subprojects/libvhost-user/libvhost-user.c @@ -1592,6 +1592,66 @@ 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) +{ + 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 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_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 deb40e77b3..ea4902e876 100644 --- a/subprojects/libvhost-user/libvhost-user.h +++ b/subprojects/libvhost-user/libvhost-user.h @@ -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 +618,37 @@ 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 + * @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
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> --- hw/virtio/vhost-user.c | 122 ++++++++++++++++++++++ hw/virtio/virtio.c | 13 +++ include/hw/virtio/virtio.h | 5 + subprojects/libvhost-user/libvhost-user.c | 60 +++++++++++ subprojects/libvhost-user/libvhost-user.h | 52 +++++++++ 5 files changed, 252 insertions(+)