diff options
| -rw-r--r-- | docs/interop/vhost-user.txt | 285 | ||||
| -rw-r--r-- | hw/virtio/vhost-user.c | 107 | ||||
| -rw-r--r-- | hw/virtio/vhost.c | 96 | ||||
| -rw-r--r-- | include/hw/virtio/vhost-backend.h | 10 | ||||
| -rw-r--r-- | include/hw/virtio/vhost.h | 18 |
5 files changed, 516 insertions, 0 deletions
diff --git a/docs/interop/vhost-user.txt b/docs/interop/vhost-user.txt index 9ee2a60cfb..4dbd530cb9 100644 --- a/docs/interop/vhost-user.txt +++ b/docs/interop/vhost-user.txt @@ -147,6 +147,17 @@ Depending on the request type, payload can be: Offset: a 64-bit offset of this area from the start of the supplied file descriptor + * Inflight description + ----------------------------------------------------- + | mmap size | mmap offset | num queues | queue size | + ----------------------------------------------------- + + mmap size: a 64-bit size of area to track inflight I/O + mmap offset: a 64-bit offset of this area from the start + of the supplied file descriptor + num queues: a 16-bit number of virtqueues + queue size: a 16-bit size of virtqueues + In QEMU the vhost-user message is implemented with the following struct: typedef struct VhostUserMsg { @@ -162,6 +173,7 @@ typedef struct VhostUserMsg { struct vhost_iotlb_msg iotlb; VhostUserConfig config; VhostUserVringArea area; + VhostUserInflight inflight; }; } QEMU_PACKED VhostUserMsg; @@ -180,6 +192,7 @@ the ones that do: * VHOST_USER_GET_PROTOCOL_FEATURES * VHOST_USER_GET_VRING_BASE * VHOST_USER_SET_LOG_BASE (if VHOST_USER_PROTOCOL_F_LOG_SHMFD) + * VHOST_USER_GET_INFLIGHT_FD (if VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD) [ Also see the section on REPLY_ACK protocol extension. ] @@ -193,6 +206,7 @@ in the ancillary data: * VHOST_USER_SET_VRING_CALL * VHOST_USER_SET_VRING_ERR * VHOST_USER_SET_SLAVE_REQ_FD + * VHOST_USER_SET_INFLIGHT_FD (if VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD) If Master is unable to send the full message or receives a wrong reply it will close the connection. An optional reconnection mechanism can be implemented. @@ -387,6 +401,256 @@ If VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD protocol feature is negotiated, slave can send file descriptors (at most 8 descriptors in each message) to master via ancillary data using this fd communication channel. +Inflight I/O tracking +--------------------- + +To support reconnecting after restart or crash, slave may need to resubmit +inflight I/Os. If virtqueue is processed in order, we can easily achieve +that by getting the inflight descriptors from descriptor table (split virtqueue) +or descriptor ring (packed virtqueue). However, it can't work when we process +descriptors out-of-order because some entries which store the information of +inflight descriptors in available ring (split virtqueue) or descriptor +ring (packed virtqueue) might be overrided by new entries. To solve this +problem, slave need to allocate an extra buffer to store this information of inflight +descriptors and share it with master for persistent. VHOST_USER_GET_INFLIGHT_FD and +VHOST_USER_SET_INFLIGHT_FD are used to transfer this buffer between master +and slave. And the format of this buffer is described below: + +------------------------------------------------------- +| queue0 region | queue1 region | ... | queueN region | +------------------------------------------------------- + +N is the number of available virtqueues. Slave could get it from num queues +field of VhostUserInflight. + +For split virtqueue, queue region can be implemented as: + +typedef struct DescStateSplit { + /* Indicate whether this descriptor is inflight or not. + * Only available for head-descriptor. */ + uint8_t inflight; + + /* Padding */ + uint8_t padding[5]; + + /* Maintain a list for the last batch of used descriptors. + * Only available when batching is used for submitting */ + uint16_t next; + + /* Used to preserve the order of fetching available descriptors. + * Only available for head-descriptor. */ + uint64_t counter; +} DescStateSplit; + +typedef struct QueueRegionSplit { + /* The feature flags of this region. Now it's initialized to 0. */ + uint64_t features; + + /* The version of this region. It's 1 currently. + * Zero value indicates an uninitialized buffer */ + uint16_t version; + + /* The size of DescStateSplit array. It's equal to the virtqueue + * size. Slave could get it from queue size field of VhostUserInflight. */ + uint16_t desc_num; + + /* The head of list that track the last batch of used descriptors. */ + uint16_t last_batch_head; + + /* Store the idx value of used ring */ + uint16_t used_idx; + + /* Used to track the state of each descriptor in descriptor table */ + DescStateSplit desc[0]; +} QueueRegionSplit; + +To track inflight I/O, the queue region should be processed as follows: + +When receiving available buffers from the driver: + + 1. Get the next available head-descriptor index from available ring, i + + 2. Set desc[i].counter to the value of global counter + + 3. Increase global counter by 1 + + 4. Set desc[i].inflight to 1 + +When supplying used buffers to the driver: + + 1. Get corresponding used head-descriptor index, i + + 2. Set desc[i].next to last_batch_head + + 3. Set last_batch_head to i + + 4. Steps 1,2,3 may be performed repeatedly if batching is possible + + 5. Increase the idx value of used ring by the size of the batch + + 6. Set the inflight field of each DescStateSplit entry in the batch to 0 + + 7. Set used_idx to the idx value of used ring + +When reconnecting: + + 1. If the value of used_idx does not match the idx value of used ring (means + the inflight field of DescStateSplit entries in last batch may be incorrect), + + (a) Subtract the value of used_idx from the idx value of used ring to get + last batch size of DescStateSplit entries + + (b) Set the inflight field of each DescStateSplit entry to 0 in last batch + list which starts from last_batch_head + + (c) Set used_idx to the idx value of used ring + + 2. Resubmit inflight DescStateSplit entries in order of their counter value + +For packed virtqueue, queue region can be implemented as: + +typedef struct DescStatePacked { + /* Indicate whether this descriptor is inflight or not. + * Only available for head-descriptor. */ + uint8_t inflight; + + /* Padding */ + uint8_t padding; + + /* Link to the next free entry */ + uint16_t next; + + /* Link to the last entry of descriptor list. + * Only available for head-descriptor. */ + uint16_t last; + + /* The length of descriptor list. + * Only available for head-descriptor. */ + uint16_t num; + + /* Used to preserve the order of fetching available descriptors. + * Only available for head-descriptor. */ + uint64_t counter; + + /* The buffer id */ + uint16_t id; + + /* The descriptor flags */ + uint16_t flags; + + /* The buffer length */ + uint32_t len; + + /* The buffer address */ + uint64_t addr; +} DescStatePacked; + +typedef struct QueueRegionPacked { + /* The feature flags of this region. Now it's initialized to 0. */ + uint64_t features; + + /* The version of this region. It's 1 currently. + * Zero value indicates an uninitialized buffer */ + uint16_t version; + + /* The size of DescStatePacked array. It's equal to the virtqueue + * size. Slave could get it from queue size field of VhostUserInflight. */ + uint16_t desc_num; + + /* The head of free DescStatePacked entry list */ + uint16_t free_head; + + /* The old head of free DescStatePacked entry list */ + uint16_t old_free_head; + + /* The used index of descriptor ring */ + uint16_t used_idx; + + /* The old used index of descriptor ring */ + uint16_t old_used_idx; + + /* Device ring wrap counter */ + uint8_t used_wrap_counter; + + /* The old device ring wrap counter */ + uint8_t old_used_wrap_counter; + + /* Padding */ + uint8_t padding[7]; + + /* Used to track the state of each descriptor fetched from descriptor ring */ + DescStatePacked desc[0]; +} QueueRegionPacked; + +To track inflight I/O, the queue region should be processed as follows: + +When receiving available buffers from the driver: + + 1. Get the next available descriptor entry from descriptor ring, d + + 2. If d is head descriptor, + + (a) Set desc[old_free_head].num to 0 + + (b) Set desc[old_free_head].counter to the value of global counter + + (c) Increase global counter by 1 + + (d) Set desc[old_free_head].inflight to 1 + + 3. If d is last descriptor, set desc[old_free_head].last to free_head + + 4. Increase desc[old_free_head].num by 1 + + 5. Set desc[free_head].addr, desc[free_head].len, desc[free_head].flags, + desc[free_head].id to d.addr, d.len, d.flags, d.id + + 6. Set free_head to desc[free_head].next + + 7. If d is last descriptor, set old_free_head to free_head + +When supplying used buffers to the driver: + + 1. Get corresponding used head-descriptor entry from descriptor ring, d + + 2. Get corresponding DescStatePacked entry, e + + 3. Set desc[e.last].next to free_head + + 4. Set free_head to the index of e + + 5. Steps 1,2,3,4 may be performed repeatedly if batching is possible + + 6. Increase used_idx by the size of the batch and update used_wrap_counter if needed + + 7. Update d.flags + + 8. Set the inflight field of each head DescStatePacked entry in the batch to 0 + + 9. Set old_free_head, old_used_idx, old_used_wrap_counter to free_head, used_idx, + used_wrap_counter + +When reconnecting: + + 1. If used_idx does not match old_used_idx (means the inflight field of DescStatePacked + entries in last batch may be incorrect), + + (a) Get the next descriptor ring entry through old_used_idx, d + + (b) Use old_used_wrap_counter to calculate the available flags + + (c) If d.flags is not equal to the calculated flags value (means slave has + submitted the buffer to guest driver before crash, so it has to commit the + in-progres update), set old_free_head, old_used_idx, old_used_wrap_counter + to free_head, used_idx, used_wrap_counter + + 2. Set free_head, used_idx, used_wrap_counter to old_free_head, old_used_idx, + old_used_wrap_counter (roll back any in-progress update) + + 3. Set the inflight field of each DescStatePacked entry in free list to 0 + + 4. Resubmit inflight DescStatePacked entries in order of their counter value + Protocol features ----------------- @@ -402,6 +666,7 @@ Protocol features #define VHOST_USER_PROTOCOL_F_CONFIG 9 #define VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD 10 #define VHOST_USER_PROTOCOL_F_HOST_NOTIFIER 11 +#define VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD 12 Master message types -------------------- @@ -766,6 +1031,26 @@ Master message types was previously sent. The value returned is an error indication; 0 is success. + * VHOST_USER_GET_INFLIGHT_FD + Id: 31 + Equivalent ioctl: N/A + Master payload: inflight description + + When VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD protocol feature has been + successfully negotiated, this message is submitted by master to get + a shared buffer from slave. The shared buffer will be used to track + inflight I/O by slave. QEMU should retrieve a new one when vm reset. + + * VHOST_USER_SET_INFLIGHT_FD + Id: 32 + Equivalent ioctl: N/A + Master payload: inflight description + + When VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD protocol feature has been + successfully negotiated, this message is submitted by master to send + the shared inflight buffer back to slave so that slave could get + inflight I/O after a crash or restart. + Slave message types ------------------- diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index 5df73405bc..553319c7ac 100644 --- a/hw/virtio/vhost-user.c +++ b/hw/virtio/vhost-user.c @@ -56,6 +56,7 @@ enum VhostUserProtocolFeature { VHOST_USER_PROTOCOL_F_CONFIG = 9, VHOST_USER_PROTOCOL_F_SLAVE_SEND_FD = 10, VHOST_USER_PROTOCOL_F_HOST_NOTIFIER = 11, + VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD = 12, VHOST_USER_PROTOCOL_F_MAX }; @@ -93,6 +94,8 @@ typedef enum VhostUserRequest { VHOST_USER_POSTCOPY_ADVISE = 28, VHOST_USER_POSTCOPY_LISTEN = 29, VHOST_USER_POSTCOPY_END = 30, + VHOST_USER_GET_INFLIGHT_FD = 31, + VHOST_USER_SET_INFLIGHT_FD = 32, VHOST_USER_MAX } VhostUserRequest; @@ -151,6 +154,13 @@ typedef struct VhostUserVringArea { uint64_t offset; } VhostUserVringArea; +typedef struct VhostUserInflight { + uint64_t mmap_size; + uint64_t mmap_offset; + uint16_t num_queues; + uint16_t queue_size; +} VhostUserInflight; + typedef struct { VhostUserRequest request; @@ -173,6 +183,7 @@ typedef union { VhostUserConfig config; VhostUserCryptoSession session; VhostUserVringArea area; + VhostUserInflight inflight; } VhostUserPayload; typedef struct VhostUserMsg { @@ -1770,6 +1781,100 @@ static bool vhost_user_mem_section_filter(struct vhost_dev *dev, return result; } +static int vhost_user_get_inflight_fd(struct vhost_dev *dev, + uint16_t queue_size, + struct vhost_inflight *inflight) +{ + void *addr; + int fd; + struct vhost_user *u = dev->opaque; + CharBackend *chr = u->user->chr; + VhostUserMsg msg = { + .hdr.request = VHOST_USER_GET_INFLIGHT_FD, + .hdr.flags = VHOST_USER_VERSION, + .payload.inflight.num_queues = dev->nvqs, + .payload.inflight.queue_size = queue_size, + .hdr.size = sizeof(msg.payload.inflight), + }; + + if (!virtio_has_feature(dev->protocol_features, + VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD)) { + return 0; + } + + if (vhost_user_write(dev, &msg, NULL, 0) < 0) { + return -1; + } + + if (vhost_user_read(dev, &msg) < 0) { + return -1; + } + + if (msg.hdr.request != VHOST_USER_GET_INFLIGHT_FD) { + error_report("Received unexpected msg type. " + "Expected %d received %d", + VHOST_USER_GET_INFLIGHT_FD, msg.hdr.request); + return -1; + } + + if (msg.hdr.size != sizeof(msg.payload.inflight)) { + error_report("Received bad msg size."); + return -1; + } + + if (!msg.payload.inflight.mmap_size) { + return 0; + } + + fd = qemu_chr_fe_get_msgfd(chr); + if (fd < 0) { + error_report("Failed to get mem fd"); + return -1; + } + + addr = mmap(0, msg.payload.inflight.mmap_size, PROT_READ | PROT_WRITE, + MAP_SHARED, fd, msg.payload.inflight.mmap_offset); + + if (addr == MAP_FAILED) { + error_report("Failed to mmap mem fd"); + close(fd); + return -1; + } + + inflight->addr = addr; + inflight->fd = fd; + inflight->size = msg.payload.inflight.mmap_size; + inflight->offset = msg.payload.inflight.mmap_offset; + inflight->queue_size = queue_size; + + return 0; +} + +static int vhost_user_set_inflight_fd(struct vhost_dev *dev, + struct vhost_inflight *inflight) +{ + VhostUserMsg msg = { + .hdr.request = VHOST_USER_SET_INFLIGHT_FD, + .hdr.flags = VHOST_USER_VERSION, + .payload.inflight.mmap_size = inflight->size, + .payload.inflight.mmap_offset = inflight->offset, + .payload.inflight.num_queues = dev->nvqs, + .payload.inflight.queue_size = inflight->queue_size, + .hdr.size = sizeof(msg.payload.inflight), + }; + + if (!virtio_has_feature(dev->protocol_features, + VHOST_USER_PROTOCOL_F_INFLIGHT_SHMFD)) { + return 0; + } + + if (vhost_user_write(dev, &msg, &inflight->fd, 1) < 0) { + return -1; + } + + return 0; +} + bool vhost_user_init(VhostUserState *user, CharBackend *chr, Error **errp) { if (user->chr) { @@ -1829,4 +1934,6 @@ const VhostOps user_ops = { .vhost_crypto_create_session = vhost_user_crypto_create_session, .vhost_crypto_close_session = vhost_user_crypto_close_session, .vhost_backend_mem_section_filter = vhost_user_mem_section_filter, + .vhost_get_inflight_fd = vhost_user_get_inflight_fd, + .vhost_set_inflight_fd = vhost_user_set_inflight_fd, }; diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c index 311432f190..7f61018f2a 100644 --- a/hw/virtio/vhost.c +++ b/hw/virtio/vhost.c @@ -1481,6 +1481,102 @@ void vhost_dev_set_config_notifier(struct vhost_dev *hdev, hdev->config_ops = ops; } +void vhost_dev_free_inflight(struct vhost_inflight *inflight) +{ + if (inflight->addr) { + qemu_memfd_free(inflight->addr, inflight->size, inflight->fd); + inflight->addr = NULL; + inflight->fd = -1; + } +} + +static int vhost_dev_resize_inflight(struct vhost_inflight *inflight, + uint64_t new_size) +{ + Error *err = NULL; + int fd = -1; + void *addr = qemu_memfd_alloc("vhost-inflight", new_size, + F_SEAL_GROW | F_SEAL_SHRINK | F_SEAL_SEAL, + &fd, &err); + + if (err) { + error_report_err(err); + return -1; + } + + vhost_dev_free_inflight(inflight); + inflight->offset = 0; + inflight->addr = addr; + inflight->fd = fd; + inflight->size = new_size; + + return 0; +} + +void vhost_dev_save_inflight(struct vhost_inflight *inflight, QEMUFile *f) +{ + if (inflight->addr) { + qemu_put_be64(f, inflight->size); + qemu_put_be16(f, inflight->queue_size); + qemu_put_buffer(f, inflight->addr, inflight->size); + } else { + qemu_put_be64(f, 0); + } +} + +int vhost_dev_load_inflight(struct vhost_inflight *inflight, QEMUFile *f) +{ + uint64_t size; + + size = qemu_get_be64(f); + if (!size) { + return 0; + } + + if (inflight->size != size) { + if (vhost_dev_resize_inflight(inflight, size)) { + return -1; + } + } + inflight->queue_size = qemu_get_be16(f); + + qemu_get_buffer(f, inflight->addr, size); + + return 0; +} + +int vhost_dev_set_inflight(struct vhost_dev *dev, + struct vhost_inflight *inflight) +{ + int r; + + if (dev->vhost_ops->vhost_set_inflight_fd && inflight->addr) { + r = dev->vhost_ops->vhost_set_inflight_fd(dev, inflight); + if (r) { + VHOST_OPS_DEBUG("vhost_set_inflight_fd failed"); + return -errno; + } + } + + return 0; +} + +int vhost_dev_get_inflight(struct vhost_dev *dev, uint16_t queue_size, + struct vhost_inflight *inflight) +{ + int r; + + if (dev->vhost_ops->vhost_get_inflight_fd) { + r = dev->vhost_ops->vhost_get_inflight_fd(dev, queue_size, inflight); + if (r) { + VHOST_OPS_DEBUG("vhost_get_inflight_fd failed"); + return -errno; + } + } + + return 0; +} + /* Host notifiers must be enabled at this point. */ int vhost_dev_start(struct vhost_dev *hdev, VirtIODevice *vdev) { diff --git a/include/hw/virtio/vhost-backend.h b/include/hw/virtio/vhost-backend.h index 81283ec50f..d6632a18e6 100644 --- a/include/hw/virtio/vhost-backend.h +++ b/include/hw/virtio/vhost-backend.h @@ -25,6 +25,7 @@ typedef enum VhostSetConfigType { VHOST_SET_CONFIG_TYPE_MIGRATION = 1, } VhostSetConfigType; +struct vhost_inflight; struct vhost_dev; struct vhost_log; struct vhost_memory; @@ -104,6 +105,13 @@ typedef int (*vhost_crypto_close_session_op)(struct vhost_dev *dev, typedef bool (*vhost_backend_mem_section_filter_op)(struct vhost_dev *dev, MemoryRegionSection *section); +typedef int (*vhost_get_inflight_fd_op)(struct vhost_dev *dev, + uint16_t queue_size, + struct vhost_inflight *inflight); + +typedef int (*vhost_set_inflight_fd_op)(struct vhost_dev *dev, + struct vhost_inflight *inflight); + typedef struct VhostOps { VhostBackendType backend_type; vhost_backend_init vhost_backend_init; @@ -142,6 +150,8 @@ typedef struct VhostOps { vhost_crypto_create_session_op vhost_crypto_create_session; vhost_crypto_close_session_op vhost_crypto_close_session; vhost_backend_mem_section_filter_op vhost_backend_mem_section_filter; + vhost_get_inflight_fd_op vhost_get_inflight_fd; + vhost_set_inflight_fd_op vhost_set_inflight_fd; } VhostOps; extern const VhostOps user_ops; diff --git a/include/hw/virtio/vhost.h b/include/hw/virtio/vhost.h index a7f449fa87..619498c8f4 100644 --- a/include/hw/virtio/vhost.h +++ b/include/hw/virtio/vhost.h @@ -7,6 +7,15 @@ #include "exec/memory.h" /* Generic structures common for any vhost based device. */ + +struct vhost_inflight { + int fd; + void *addr; + uint64_t size; + uint64_t offset; + uint16_t queue_size; +}; + struct vhost_virtqueue { int kick; int call; @@ -120,4 +129,13 @@ int vhost_dev_set_config(struct vhost_dev *dev, const uint8_t *data, */ void vhost_dev_set_config_notifier(struct vhost_dev *dev, const VhostDevConfigOps *ops); + +void vhost_dev_reset_inflight(struct vhost_inflight *inflight); +void vhost_dev_free_inflight(struct vhost_inflight *inflight); +void vhost_dev_save_inflight(struct vhost_inflight *inflight, QEMUFile *f); +int vhost_dev_load_inflight(struct vhost_inflight *inflight, QEMUFile *f); +int vhost_dev_set_inflight(struct vhost_dev *dev, + struct vhost_inflight *inflight); +int vhost_dev_get_inflight(struct vhost_dev *dev, uint16_t queue_size, + struct vhost_inflight *inflight); #endif |