diff options
Diffstat (limited to 'include/linux/hyperv.h')
| -rw-r--r-- | include/linux/hyperv.h | 170 |
1 files changed, 169 insertions, 1 deletions
diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h index aa0fadce9..b10954a66 100644 --- a/include/linux/hyperv.h +++ b/include/linux/hyperv.h @@ -126,6 +126,8 @@ struct hv_ring_buffer_info { u32 ring_datasize; /* < ring_size */ u32 ring_data_startoffset; + u32 priv_write_index; + u32 priv_read_index; }; /* @@ -151,6 +153,33 @@ hv_get_ringbuffer_availbytes(struct hv_ring_buffer_info *rbi, *read = dsize - *write; } +static inline u32 hv_get_bytes_to_read(struct hv_ring_buffer_info *rbi) +{ + u32 read_loc, write_loc, dsize, read; + + dsize = rbi->ring_datasize; + read_loc = rbi->ring_buffer->read_index; + write_loc = READ_ONCE(rbi->ring_buffer->write_index); + + read = write_loc >= read_loc ? (write_loc - read_loc) : + (dsize - read_loc) + write_loc; + + return read; +} + +static inline u32 hv_get_bytes_to_write(struct hv_ring_buffer_info *rbi) +{ + u32 read_loc, write_loc, dsize, write; + + dsize = rbi->ring_datasize; + read_loc = READ_ONCE(rbi->ring_buffer->read_index); + write_loc = rbi->ring_buffer->write_index; + + write = write_loc >= read_loc ? dsize - (write_loc - read_loc) : + read_loc - write_loc; + return write; +} + /* * VMBUS version is 32 bit entity broken up into * two 16 bit quantities: major_number. minor_number. @@ -1091,7 +1120,7 @@ int vmbus_allocate_mmio(struct resource **new, struct hv_device *device_obj, resource_size_t min, resource_size_t max, resource_size_t size, resource_size_t align, bool fb_overlap_ok); - +void vmbus_free_mmio(resource_size_t start, resource_size_t size); int vmbus_cpu_number_to_vp_number(int cpu_number); u64 hv_do_hypercall(u64 control, void *input, void *output); @@ -1338,4 +1367,143 @@ extern __u32 vmbus_proto_version; int vmbus_send_tl_connect_request(const uuid_le *shv_guest_servie_id, const uuid_le *shv_host_servie_id); +void vmbus_set_event(struct vmbus_channel *channel); + +/* Get the start of the ring buffer. */ +static inline void * +hv_get_ring_buffer(struct hv_ring_buffer_info *ring_info) +{ + return (void *)ring_info->ring_buffer->buffer; +} + +/* + * To optimize the flow management on the send-side, + * when the sender is blocked because of lack of + * sufficient space in the ring buffer, potential the + * consumer of the ring buffer can signal the producer. + * This is controlled by the following parameters: + * + * 1. pending_send_sz: This is the size in bytes that the + * producer is trying to send. + * 2. The feature bit feat_pending_send_sz set to indicate if + * the consumer of the ring will signal when the ring + * state transitions from being full to a state where + * there is room for the producer to send the pending packet. + */ + +static inline bool hv_need_to_signal_on_read(struct hv_ring_buffer_info *rbi) +{ + u32 cur_write_sz; + u32 pending_sz; + + /* + * Issue a full memory barrier before making the signaling decision. + * Here is the reason for having this barrier: + * If the reading of the pend_sz (in this function) + * were to be reordered and read before we commit the new read + * index (in the calling function) we could + * have a problem. If the host were to set the pending_sz after we + * have sampled pending_sz and go to sleep before we commit the + * read index, we could miss sending the interrupt. Issue a full + * memory barrier to address this. + */ + virt_mb(); + + pending_sz = READ_ONCE(rbi->ring_buffer->pending_send_sz); + /* If the other end is not blocked on write don't bother. */ + if (pending_sz == 0) + return false; + + cur_write_sz = hv_get_bytes_to_write(rbi); + + if (cur_write_sz >= pending_sz) + return true; + + return false; +} + +/* + * An API to support in-place processing of incoming VMBUS packets. + */ +#define VMBUS_PKT_TRAILER 8 + +static inline struct vmpacket_descriptor * +get_next_pkt_raw(struct vmbus_channel *channel) +{ + struct hv_ring_buffer_info *ring_info = &channel->inbound; + u32 read_loc = ring_info->priv_read_index; + void *ring_buffer = hv_get_ring_buffer(ring_info); + struct vmpacket_descriptor *cur_desc; + u32 packetlen; + u32 dsize = ring_info->ring_datasize; + u32 delta = read_loc - ring_info->ring_buffer->read_index; + u32 bytes_avail_toread = (hv_get_bytes_to_read(ring_info) - delta); + + if (bytes_avail_toread < sizeof(struct vmpacket_descriptor)) + return NULL; + + if ((read_loc + sizeof(*cur_desc)) > dsize) + return NULL; + + cur_desc = ring_buffer + read_loc; + packetlen = cur_desc->len8 << 3; + + /* + * If the packet under consideration is wrapping around, + * return failure. + */ + if ((read_loc + packetlen + VMBUS_PKT_TRAILER) > (dsize - 1)) + return NULL; + + return cur_desc; +} + +/* + * A helper function to step through packets "in-place" + * This API is to be called after each successful call + * get_next_pkt_raw(). + */ +static inline void put_pkt_raw(struct vmbus_channel *channel, + struct vmpacket_descriptor *desc) +{ + struct hv_ring_buffer_info *ring_info = &channel->inbound; + u32 read_loc = ring_info->priv_read_index; + u32 packetlen = desc->len8 << 3; + u32 dsize = ring_info->ring_datasize; + + if ((read_loc + packetlen + VMBUS_PKT_TRAILER) > dsize) + BUG(); + /* + * Include the packet trailer. + */ + ring_info->priv_read_index += packetlen + VMBUS_PKT_TRAILER; +} + +/* + * This call commits the read index and potentially signals the host. + * Here is the pattern for using the "in-place" consumption APIs: + * + * while (get_next_pkt_raw() { + * process the packet "in-place"; + * put_pkt_raw(); + * } + * if (packets processed in place) + * commit_rd_index(); + */ +static inline void commit_rd_index(struct vmbus_channel *channel) +{ + struct hv_ring_buffer_info *ring_info = &channel->inbound; + /* + * Make sure all reads are done before we update the read index since + * the writer may start writing to the read area once the read index + * is updated. + */ + virt_rmb(); + ring_info->ring_buffer->read_index = ring_info->priv_read_index; + + if (hv_need_to_signal_on_read(ring_info)) + vmbus_set_event(channel); +} + + #endif /* _HYPERV_H */ |