With SHMEM_MAP messages, sharing descriptors between devices will cause that these devices do not see the mappings, and fail to access these memory regions.
To solve this, introduce MEM_READ/WRITE requests that will get triggered as a fallback when vhost-user memory translation fails. Signed-off-by: Albert Esteve <aest...@redhat.com> --- hw/virtio/vhost-user.c | 31 +++++++++ subprojects/libvhost-user/libvhost-user.c | 84 +++++++++++++++++++++++ subprojects/libvhost-user/libvhost-user.h | 38 ++++++++++ 3 files changed, 153 insertions(+) diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index 57406dc8b4..18cacb2d68 100644 --- a/hw/virtio/vhost-user.c +++ b/hw/virtio/vhost-user.c @@ -118,6 +118,8 @@ typedef enum VhostUserBackendRequest { VHOST_USER_BACKEND_SHARED_OBJECT_LOOKUP = 8, VHOST_USER_BACKEND_SHMEM_MAP = 9, VHOST_USER_BACKEND_SHMEM_UNMAP = 10, + VHOST_USER_BACKEND_MEM_READ = 11, + VHOST_USER_BACKEND_MEM_WRITE = 12, VHOST_USER_BACKEND_MAX } VhostUserBackendRequest; @@ -145,6 +147,12 @@ typedef struct VhostUserShMemConfig { uint64_t memory_sizes[VHOST_MEMORY_BASELINE_NREGIONS]; } VhostUserShMemConfig; +typedef struct VhostUserMemRWMsg { + uint64_t guest_address; + uint32_t size; + uint8_t data[]; +} VhostUserMemRWMsg; + typedef struct VhostUserLog { uint64_t mmap_size; uint64_t mmap_offset; @@ -253,6 +261,7 @@ typedef union { VhostUserTransferDeviceState transfer_state; VhostUserMMap mmap; VhostUserShMemConfig shmem; + VhostUserMemRWMsg mem_rw; } VhostUserPayload; typedef struct VhostUserMsg { @@ -1871,6 +1880,22 @@ vhost_user_backend_handle_shmem_unmap(struct vhost_dev *dev, return 0; } +static int +vhost_user_backend_handle_mem_read(struct vhost_dev *dev, + VhostUserMemRWMsg *mem_rw) +{ + /* TODO */ + return -EPERM; +} + +static int +vhost_user_backend_handle_mem_write(struct vhost_dev *dev, + VhostUserMemRWMsg *mem_rw) +{ + /* TODO */ + return -EPERM; +} + static void close_backend_channel(struct vhost_user *u) { g_source_destroy(u->backend_src); @@ -1946,6 +1971,12 @@ static gboolean backend_read(QIOChannel *ioc, GIOCondition condition, case VHOST_USER_BACKEND_SHMEM_UNMAP: ret = vhost_user_backend_handle_shmem_unmap(dev, &payload.mmap); break; + case VHOST_USER_BACKEND_MEM_READ: + ret = vhost_user_backend_handle_mem_read(dev, &payload.mem_rw); + break; + case VHOST_USER_BACKEND_MEM_WRITE: + ret = vhost_user_backend_handle_mem_write(dev, &payload.mem_rw); + break; default: error_report("Received unexpected msg type: %d.", hdr.request); ret = -EINVAL; diff --git a/subprojects/libvhost-user/libvhost-user.c b/subprojects/libvhost-user/libvhost-user.c index 28556d183a..b5184064b5 100644 --- a/subprojects/libvhost-user/libvhost-user.c +++ b/subprojects/libvhost-user/libvhost-user.c @@ -1651,6 +1651,90 @@ vu_shmem_unmap(VuDev *dev, uint8_t shmid, uint64_t fd_offset, return vu_process_message_reply(dev, &vmsg); } +bool +vu_send_mem_read(VuDev *dev, uint64_t guest_addr, uint32_t size, + uint8_t *data) +{ + VhostUserMsg msg_reply; + VhostUserMsg msg = { + .request = VHOST_USER_BACKEND_MEM_READ, + .size = sizeof(msg.payload.mem_rw), + .flags = VHOST_USER_VERSION | VHOST_USER_NEED_REPLY_MASK, + .payload = { + .mem_rw = { + .guest_address = guest_addr, + .size = size, + } + } + }; + + pthread_mutex_lock(&dev->backend_mutex); + if (!vu_message_write(dev, dev->backend_fd, &msg)) { + goto out_err; + } + + if (!vu_message_read_default(dev, dev->backend_fd, &msg_reply)) { + goto out_err; + } + + if (msg_reply.request != msg.request) { + DPRINT("Received unexpected msg type. Expected %d, received %d", + msg.request, msg_reply.request); + goto out_err; + } + + if (msg_reply.payload.mem_rw.size != size) { + DPRINT("Received unexpected number of bytes in the response. " + "Expected %d, received %d", + size, msg_reply.payload.mem_rw.size); + goto out_err; + } + + data = malloc(msg_reply.payload.mem_rw.size); + if (!data) { + DPRINT("Failed to malloc read memory data"); + goto out_err; + } + + memcpy(data, msg_reply.payload.mem_rw.data, size); + pthread_mutex_unlock(&dev->backend_mutex); + return true; + +out_err: + pthread_mutex_unlock(&dev->backend_mutex); + return false; +} + +bool +vu_send_mem_write(VuDev *dev, uint64_t guest_addr, uint32_t size, + uint8_t *data) +{ + VhostUserMsg msg = { + .request = VHOST_USER_BACKEND_MEM_WRITE, + .size = sizeof(msg.payload.mem_rw), + .flags = VHOST_USER_VERSION, + .payload = { + .mem_rw = { + .guest_address = guest_addr, + .size = size, + } + } + }; + memcpy(msg.payload.mem_rw.data, data, size); + + if (vu_has_protocol_feature(dev, VHOST_USER_PROTOCOL_F_REPLY_ACK)) { + msg.flags |= VHOST_USER_NEED_REPLY_MASK; + } + + if (!vu_message_write(dev, dev->backend_fd, &msg)) { + pthread_mutex_unlock(&dev->backend_mutex); + return false; + } + + /* Also unlocks the backend_mutex */ + return vu_process_message_reply(dev, &msg); +} + 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 7f6c22cc1a..8ef794870d 100644 --- a/subprojects/libvhost-user/libvhost-user.h +++ b/subprojects/libvhost-user/libvhost-user.h @@ -129,6 +129,8 @@ typedef enum VhostUserBackendRequest { VHOST_USER_BACKEND_SHARED_OBJECT_LOOKUP = 8, VHOST_USER_BACKEND_SHMEM_MAP = 9, VHOST_USER_BACKEND_SHMEM_UNMAP = 10, + VHOST_USER_BACKEND_MEM_READ = 11, + VHOST_USER_BACKEND_MEM_WRITE = 12, VHOST_USER_BACKEND_MAX } VhostUserBackendRequest; @@ -152,6 +154,12 @@ typedef struct VhostUserMemRegMsg { VhostUserMemoryRegion region; } VhostUserMemRegMsg; +typedef struct VhostUserMemRWMsg { + uint64_t guest_address; + uint32_t size; + uint8_t data[]; +} VhostUserMemRWMsg; + typedef struct VhostUserLog { uint64_t mmap_size; uint64_t mmap_offset; @@ -235,6 +243,7 @@ typedef struct VhostUserMsg { VhostUserInflight inflight; VhostUserShared object; VhostUserMMap mmap; + VhostUserMemRWMsg mem_rw; } payload; int fds[VHOST_MEMORY_BASELINE_NREGIONS]; @@ -650,6 +659,35 @@ bool vu_shmem_map(VuDev *dev, uint8_t shmid, uint64_t fd_offset, bool vu_shmem_unmap(VuDev *dev, uint8_t shmid, uint64_t fd_offset, uint64_t shm_offset, uint64_t len); +/** + * vu_send_mem_read: + * @dev: a VuDev context + * @guest_addr: guest physical address to read + * @size: number of bytes to read + * @data: head of an unitialized bytes array + * + * Reads `size` bytes of `guest_addr` in the frontend and stores + * them in `data`. + * + * Returns: TRUE on success, FALSE on failure. + */ +bool vu_send_mem_read(VuDev *dev, uint64_t guest_addr, uint32_t size, + uint8_t *data); + +/** + * vu_send_mem_write: + * @dev: a VuDev context + * @guest_addr: guest physical address to write + * @size: number of bytes to write + * @data: head of an array with `size` bytes to write + * + * Writes `size` bytes from `data` into `guest_addr` in the frontend. + * + * Returns: TRUE on success, FALSE on failure. + */ +bool vu_send_mem_write(VuDev *dev, uint64_t guest_addr, uint32_t size, + uint8_t *data); + /** * vu_queue_set_notification: * @dev: a VuDev context -- 2.45.2