567 строки
13 KiB
C
567 строки
13 KiB
C
/*
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*
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* Copyright (c) 2009, Microsoft Corporation.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 59 Temple
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* Place - Suite 330, Boston, MA 02111-1307 USA.
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*
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* Authors:
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* Haiyang Zhang <haiyangz@microsoft.com>
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* Hank Janssen <hjanssen@microsoft.com>
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* K. Y. Srinivasan <kys@microsoft.com>
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*
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/hyperv.h>
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#include <linux/uio.h>
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#include "hyperv_vmbus.h"
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void hv_begin_read(struct hv_ring_buffer_info *rbi)
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{
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rbi->ring_buffer->interrupt_mask = 1;
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mb();
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}
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u32 hv_end_read(struct hv_ring_buffer_info *rbi)
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{
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u32 read;
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u32 write;
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rbi->ring_buffer->interrupt_mask = 0;
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mb();
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/*
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* Now check to see if the ring buffer is still empty.
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* If it is not, we raced and we need to process new
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* incoming messages.
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*/
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hv_get_ringbuffer_availbytes(rbi, &read, &write);
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return read;
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}
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/*
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* When we write to the ring buffer, check if the host needs to
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* be signaled. Here is the details of this protocol:
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*
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* 1. The host guarantees that while it is draining the
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* ring buffer, it will set the interrupt_mask to
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* indicate it does not need to be interrupted when
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* new data is placed.
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*
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* 2. The host guarantees that it will completely drain
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* the ring buffer before exiting the read loop. Further,
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* once the ring buffer is empty, it will clear the
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* interrupt_mask and re-check to see if new data has
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* arrived.
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*/
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static bool hv_need_to_signal(u32 old_write, struct hv_ring_buffer_info *rbi)
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{
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mb();
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if (rbi->ring_buffer->interrupt_mask)
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return false;
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/* check interrupt_mask before read_index */
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rmb();
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/*
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* This is the only case we need to signal when the
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* ring transitions from being empty to non-empty.
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*/
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if (old_write == rbi->ring_buffer->read_index)
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return true;
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return false;
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}
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/*
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* To optimize the flow management on the send-side,
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* when the sender is blocked because of lack of
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* sufficient space in the ring buffer, potential the
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* consumer of the ring buffer can signal the producer.
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* This is controlled by the following parameters:
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*
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* 1. pending_send_sz: This is the size in bytes that the
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* producer is trying to send.
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* 2. The feature bit feat_pending_send_sz set to indicate if
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* the consumer of the ring will signal when the ring
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* state transitions from being full to a state where
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* there is room for the producer to send the pending packet.
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*/
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static bool hv_need_to_signal_on_read(u32 old_rd,
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struct hv_ring_buffer_info *rbi)
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{
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u32 prev_write_sz;
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u32 cur_write_sz;
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u32 r_size;
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u32 write_loc = rbi->ring_buffer->write_index;
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u32 read_loc = rbi->ring_buffer->read_index;
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u32 pending_sz = rbi->ring_buffer->pending_send_sz;
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/*
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* If the other end is not blocked on write don't bother.
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*/
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if (pending_sz == 0)
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return false;
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r_size = rbi->ring_datasize;
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cur_write_sz = write_loc >= read_loc ? r_size - (write_loc - read_loc) :
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read_loc - write_loc;
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prev_write_sz = write_loc >= old_rd ? r_size - (write_loc - old_rd) :
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old_rd - write_loc;
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if ((prev_write_sz < pending_sz) && (cur_write_sz >= pending_sz))
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return true;
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return false;
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}
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/*
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* hv_get_next_write_location()
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*
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* Get the next write location for the specified ring buffer
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*
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*/
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static inline u32
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hv_get_next_write_location(struct hv_ring_buffer_info *ring_info)
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{
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u32 next = ring_info->ring_buffer->write_index;
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return next;
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}
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/*
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* hv_set_next_write_location()
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*
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* Set the next write location for the specified ring buffer
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*
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*/
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static inline void
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hv_set_next_write_location(struct hv_ring_buffer_info *ring_info,
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u32 next_write_location)
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{
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ring_info->ring_buffer->write_index = next_write_location;
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}
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/*
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* hv_get_next_read_location()
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*
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* Get the next read location for the specified ring buffer
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*/
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static inline u32
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hv_get_next_read_location(struct hv_ring_buffer_info *ring_info)
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{
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u32 next = ring_info->ring_buffer->read_index;
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return next;
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}
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/*
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* hv_get_next_readlocation_withoffset()
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*
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* Get the next read location + offset for the specified ring buffer.
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* This allows the caller to skip
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*/
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static inline u32
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hv_get_next_readlocation_withoffset(struct hv_ring_buffer_info *ring_info,
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u32 offset)
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{
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u32 next = ring_info->ring_buffer->read_index;
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next += offset;
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next %= ring_info->ring_datasize;
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return next;
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}
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/*
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*
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* hv_set_next_read_location()
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*
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* Set the next read location for the specified ring buffer
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*
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*/
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static inline void
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hv_set_next_read_location(struct hv_ring_buffer_info *ring_info,
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u32 next_read_location)
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{
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ring_info->ring_buffer->read_index = next_read_location;
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}
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/*
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*
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* hv_get_ring_buffer()
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*
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* Get the start of the ring buffer
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*/
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static inline void *
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hv_get_ring_buffer(struct hv_ring_buffer_info *ring_info)
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{
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return (void *)ring_info->ring_buffer->buffer;
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}
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/*
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*
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* hv_get_ring_buffersize()
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*
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* Get the size of the ring buffer
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*/
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static inline u32
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hv_get_ring_buffersize(struct hv_ring_buffer_info *ring_info)
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{
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return ring_info->ring_datasize;
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}
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/*
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*
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* hv_get_ring_bufferindices()
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*
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* Get the read and write indices as u64 of the specified ring buffer
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*
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*/
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static inline u64
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hv_get_ring_bufferindices(struct hv_ring_buffer_info *ring_info)
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{
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return (u64)ring_info->ring_buffer->write_index << 32;
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}
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/*
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*
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* hv_copyfrom_ringbuffer()
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*
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* Helper routine to copy to source from ring buffer.
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* Assume there is enough room. Handles wrap-around in src case only!!
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*
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*/
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static u32 hv_copyfrom_ringbuffer(
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struct hv_ring_buffer_info *ring_info,
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void *dest,
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u32 destlen,
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u32 start_read_offset)
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{
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void *ring_buffer = hv_get_ring_buffer(ring_info);
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u32 ring_buffer_size = hv_get_ring_buffersize(ring_info);
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u32 frag_len;
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/* wrap-around detected at the src */
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if (destlen > ring_buffer_size - start_read_offset) {
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frag_len = ring_buffer_size - start_read_offset;
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memcpy(dest, ring_buffer + start_read_offset, frag_len);
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memcpy(dest + frag_len, ring_buffer, destlen - frag_len);
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} else
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memcpy(dest, ring_buffer + start_read_offset, destlen);
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start_read_offset += destlen;
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start_read_offset %= ring_buffer_size;
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return start_read_offset;
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}
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/*
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*
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* hv_copyto_ringbuffer()
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*
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* Helper routine to copy from source to ring buffer.
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* Assume there is enough room. Handles wrap-around in dest case only!!
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*
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*/
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static u32 hv_copyto_ringbuffer(
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struct hv_ring_buffer_info *ring_info,
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u32 start_write_offset,
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void *src,
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u32 srclen)
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{
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void *ring_buffer = hv_get_ring_buffer(ring_info);
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u32 ring_buffer_size = hv_get_ring_buffersize(ring_info);
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u32 frag_len;
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/* wrap-around detected! */
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if (srclen > ring_buffer_size - start_write_offset) {
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frag_len = ring_buffer_size - start_write_offset;
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memcpy(ring_buffer + start_write_offset, src, frag_len);
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memcpy(ring_buffer, src + frag_len, srclen - frag_len);
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} else
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memcpy(ring_buffer + start_write_offset, src, srclen);
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start_write_offset += srclen;
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start_write_offset %= ring_buffer_size;
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return start_write_offset;
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}
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/*
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*
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* hv_ringbuffer_get_debuginfo()
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*
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* Get various debug metrics for the specified ring buffer
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*
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*/
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void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info,
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struct hv_ring_buffer_debug_info *debug_info)
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{
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u32 bytes_avail_towrite;
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u32 bytes_avail_toread;
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if (ring_info->ring_buffer) {
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hv_get_ringbuffer_availbytes(ring_info,
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&bytes_avail_toread,
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&bytes_avail_towrite);
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debug_info->bytes_avail_toread = bytes_avail_toread;
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debug_info->bytes_avail_towrite = bytes_avail_towrite;
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debug_info->current_read_index =
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ring_info->ring_buffer->read_index;
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debug_info->current_write_index =
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ring_info->ring_buffer->write_index;
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debug_info->current_interrupt_mask =
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ring_info->ring_buffer->interrupt_mask;
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}
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}
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/*
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*
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* hv_ringbuffer_init()
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*
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*Initialize the ring buffer
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*
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*/
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int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
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void *buffer, u32 buflen)
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{
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if (sizeof(struct hv_ring_buffer) != PAGE_SIZE)
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return -EINVAL;
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memset(ring_info, 0, sizeof(struct hv_ring_buffer_info));
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ring_info->ring_buffer = (struct hv_ring_buffer *)buffer;
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ring_info->ring_buffer->read_index =
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ring_info->ring_buffer->write_index = 0;
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/*
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* Set the feature bit for enabling flow control.
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*/
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ring_info->ring_buffer->feature_bits.value = 1;
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ring_info->ring_size = buflen;
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ring_info->ring_datasize = buflen - sizeof(struct hv_ring_buffer);
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spin_lock_init(&ring_info->ring_lock);
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return 0;
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}
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/*
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*
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* hv_ringbuffer_cleanup()
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*
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* Cleanup the ring buffer
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*
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*/
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void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
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{
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}
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/*
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*
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* hv_ringbuffer_write()
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*
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* Write to the ring buffer
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*
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*/
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int hv_ringbuffer_write(struct hv_ring_buffer_info *outring_info,
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struct kvec *kv_list, u32 kv_count, bool *signal)
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{
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int i = 0;
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u32 bytes_avail_towrite;
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u32 bytes_avail_toread;
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u32 totalbytes_towrite = 0;
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u32 next_write_location;
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u32 old_write;
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u64 prev_indices = 0;
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unsigned long flags;
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for (i = 0; i < kv_count; i++)
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totalbytes_towrite += kv_list[i].iov_len;
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totalbytes_towrite += sizeof(u64);
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spin_lock_irqsave(&outring_info->ring_lock, flags);
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hv_get_ringbuffer_availbytes(outring_info,
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&bytes_avail_toread,
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&bytes_avail_towrite);
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/* If there is only room for the packet, assume it is full. */
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/* Otherwise, the next time around, we think the ring buffer */
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/* is empty since the read index == write index */
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if (bytes_avail_towrite <= totalbytes_towrite) {
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spin_unlock_irqrestore(&outring_info->ring_lock, flags);
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return -EAGAIN;
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}
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/* Write to the ring buffer */
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next_write_location = hv_get_next_write_location(outring_info);
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old_write = next_write_location;
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for (i = 0; i < kv_count; i++) {
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next_write_location = hv_copyto_ringbuffer(outring_info,
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next_write_location,
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kv_list[i].iov_base,
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kv_list[i].iov_len);
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}
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/* Set previous packet start */
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prev_indices = hv_get_ring_bufferindices(outring_info);
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next_write_location = hv_copyto_ringbuffer(outring_info,
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next_write_location,
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&prev_indices,
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sizeof(u64));
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/* Issue a full memory barrier before updating the write index */
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mb();
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/* Now, update the write location */
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hv_set_next_write_location(outring_info, next_write_location);
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spin_unlock_irqrestore(&outring_info->ring_lock, flags);
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*signal = hv_need_to_signal(old_write, outring_info);
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return 0;
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}
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/*
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*
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* hv_ringbuffer_peek()
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*
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* Read without advancing the read index
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*
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*/
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int hv_ringbuffer_peek(struct hv_ring_buffer_info *Inring_info,
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void *Buffer, u32 buflen)
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{
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u32 bytes_avail_towrite;
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u32 bytes_avail_toread;
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u32 next_read_location = 0;
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unsigned long flags;
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spin_lock_irqsave(&Inring_info->ring_lock, flags);
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hv_get_ringbuffer_availbytes(Inring_info,
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&bytes_avail_toread,
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&bytes_avail_towrite);
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/* Make sure there is something to read */
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if (bytes_avail_toread < buflen) {
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spin_unlock_irqrestore(&Inring_info->ring_lock, flags);
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return -EAGAIN;
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}
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/* Convert to byte offset */
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next_read_location = hv_get_next_read_location(Inring_info);
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next_read_location = hv_copyfrom_ringbuffer(Inring_info,
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Buffer,
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buflen,
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next_read_location);
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spin_unlock_irqrestore(&Inring_info->ring_lock, flags);
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return 0;
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}
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/*
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*
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* hv_ringbuffer_read()
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*
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* Read and advance the read index
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*
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*/
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int hv_ringbuffer_read(struct hv_ring_buffer_info *inring_info, void *buffer,
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u32 buflen, u32 offset, bool *signal)
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{
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u32 bytes_avail_towrite;
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u32 bytes_avail_toread;
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u32 next_read_location = 0;
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u64 prev_indices = 0;
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unsigned long flags;
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u32 old_read;
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if (buflen <= 0)
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return -EINVAL;
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spin_lock_irqsave(&inring_info->ring_lock, flags);
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hv_get_ringbuffer_availbytes(inring_info,
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&bytes_avail_toread,
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&bytes_avail_towrite);
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old_read = bytes_avail_toread;
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/* Make sure there is something to read */
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if (bytes_avail_toread < buflen) {
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spin_unlock_irqrestore(&inring_info->ring_lock, flags);
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return -EAGAIN;
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}
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next_read_location =
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hv_get_next_readlocation_withoffset(inring_info, offset);
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next_read_location = hv_copyfrom_ringbuffer(inring_info,
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buffer,
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buflen,
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next_read_location);
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next_read_location = hv_copyfrom_ringbuffer(inring_info,
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&prev_indices,
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sizeof(u64),
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next_read_location);
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/* Make sure all reads are done before we update the read index since */
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/* the writer may start writing to the read area once the read index */
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/*is updated */
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mb();
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/* Update the read index */
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hv_set_next_read_location(inring_info, next_read_location);
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|
|
spin_unlock_irqrestore(&inring_info->ring_lock, flags);
|
|
|
|
*signal = hv_need_to_signal_on_read(old_read, inring_info);
|
|
|
|
return 0;
|
|
}
|