Release 4.10 drivers/hv/ring_buffer.c

Directory: drivers/hv
/*
 *
 * Copyright (c) 2009, Microsoft Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 * Authors:
 *   Haiyang Zhang <haiyangz@microsoft.com>
 *   Hank Janssen  <hjanssen@microsoft.com>
 *   K. Y. Srinivasan <kys@microsoft.com>
 *
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/hyperv.h>
#include <linux/uio.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>

#include "hyperv_vmbus.h"



void hv_begin_read(struct hv_ring_buffer_info *rbi)
{
	rbi->ring_buffer->interrupt_mask = 1;
	virt_mb();
}

Contributors
Person Tokens Prop Commits CommitProp
ky srinivasan ky srinivasan 21 100.00% 2 100.00%
Total 21 100.00% 2 100.00%



u32 hv_end_read(struct hv_ring_buffer_info *rbi)
{

	rbi->ring_buffer->interrupt_mask = 0;
	virt_mb();

	/*
         * Now check to see if the ring buffer is still empty.
         * If it is not, we raced and we need to process new
         * incoming messages.
         */
	return hv_get_bytes_to_read(rbi);
}

Contributors
Person Tokens Prop Commits CommitProp
ky srinivasan ky srinivasan 28 100.00% 3 100.00%
Total 28 100.00% 3 100.00%

/*
 * When we write to the ring buffer, check if the host needs to
 * be signaled. Here is the details of this protocol:
 *
 *      1. The host guarantees that while it is draining the
 *         ring buffer, it will set the interrupt_mask to
 *         indicate it does not need to be interrupted when
 *         new data is placed.
 *
 *      2. The host guarantees that it will completely drain
 *         the ring buffer before exiting the read loop. Further,
 *         once the ring buffer is empty, it will clear the
 *         interrupt_mask and re-check to see if new data has
 *         arrived.
 *
 * KYS: Oct. 30, 2016:
 * It looks like Windows hosts have logic to deal with DOS attacks that
 * can be triggered if it receives interrupts when it is not expecting
 * the interrupt. The host expects interrupts only when the ring
 * transitions from empty to non-empty (or full to non full on the guest
 * to host ring).
 * So, base the signaling decision solely on the ring state until the
 * host logic is fixed.
 */



static void hv_signal_on_write(u32 old_write, struct vmbus_channel *channel,
			       bool kick_q)
{
	struct hv_ring_buffer_info *rbi = &channel->outbound;

	virt_mb();
	if (READ_ONCE(rbi->ring_buffer->interrupt_mask))
		return;

	/* check interrupt_mask before read_index */
	virt_rmb();
	/*
         * This is the only case we need to signal when the
         * ring transitions from being empty to non-empty.
         */
	if (old_write == READ_ONCE(rbi->ring_buffer->read_index))
		vmbus_setevent(channel);

	return;
}

Contributors
Person Tokens Prop Commits CommitProp
ky srinivasan ky srinivasan 63 95.45% 6 85.71%
jason wang jason wang 3 4.55% 1 14.29%
Total 66 100.00% 7 100.00%

/* Get the next write location for the specified ring buffer. */

static inline u32

hv_get_next_write_location(struct hv_ring_buffer_info *ring_info)
{
	u32 next = ring_info->ring_buffer->write_index;

	return next;
}

Contributors
Person Tokens Prop Commits CommitProp
hank janssen hank janssen 15 62.50% 1 16.67%
greg kroah-hartman greg kroah-hartman 4 16.67% 2 33.33%
haiyang zhang haiyang zhang 4 16.67% 2 33.33%
ky srinivasan ky srinivasan 1 4.17% 1 16.67%
Total 24 100.00% 6 100.00%

/* Set the next write location for the specified ring buffer. */

static inline void

hv_set_next_write_location(struct hv_ring_buffer_info *ring_info,
		     u32 next_write_location)
{
	ring_info->ring_buffer->write_index = next_write_location;
}

Contributors
Person Tokens Prop Commits CommitProp
hank janssen hank janssen 13 56.52% 1 16.67%
haiyang zhang haiyang zhang 6 26.09% 2 33.33%
greg kroah-hartman greg kroah-hartman 3 13.04% 2 33.33%
ky srinivasan ky srinivasan 1 4.35% 1 16.67%
Total 23 100.00% 6 100.00%

/* Get the next read location for the specified ring buffer. */

static inline u32

hv_get_next_read_location(struct hv_ring_buffer_info *ring_info)
{
	u32 next = ring_info->ring_buffer->read_index;

	return next;
}

Contributors
Person Tokens Prop Commits CommitProp
hank janssen hank janssen 15 62.50% 1 16.67%
haiyang zhang haiyang zhang 4 16.67% 2 33.33%
greg kroah-hartman greg kroah-hartman 4 16.67% 2 33.33%
ky srinivasan ky srinivasan 1 4.17% 1 16.67%
Total 24 100.00% 6 100.00%

/*
 * Get the next read location + offset for the specified ring buffer.
 * This allows the caller to skip.
 */

static inline u32

hv_get_next_readlocation_withoffset(struct hv_ring_buffer_info *ring_info,
				 u32 offset)
{
	u32 next = ring_info->ring_buffer->read_index;

	next += offset;
	next %= ring_info->ring_datasize;

	return next;
}

Contributors
Person Tokens Prop Commits CommitProp
hank janssen hank janssen 23 62.16% 1 16.67%
haiyang zhang haiyang zhang 8 21.62% 2 33.33%
greg kroah-hartman greg kroah-hartman 5 13.51% 2 33.33%
ky srinivasan ky srinivasan 1 2.70% 1 16.67%
Total 37 100.00% 6 100.00%

/* Set the next read location for the specified ring buffer. */

static inline void

hv_set_next_read_location(struct hv_ring_buffer_info *ring_info,
		    u32 next_read_location)
{
	ring_info->ring_buffer->read_index = next_read_location;
	ring_info->priv_read_index = next_read_location;
}

Contributors
Person Tokens Prop Commits CommitProp
hank janssen hank janssen 13 44.83% 1 14.29%
ky srinivasan ky srinivasan 7 24.14% 2 28.57%
haiyang zhang haiyang zhang 6 20.69% 2 28.57%
greg kroah-hartman greg kroah-hartman 3 10.34% 2 28.57%
Total 29 100.00% 7 100.00%

/* Get the size of the ring buffer. */

static inline u32

hv_get_ring_buffersize(struct hv_ring_buffer_info *ring_info)
{
	return ring_info->ring_datasize;
}

Contributors
Person Tokens Prop Commits CommitProp
hank janssen hank janssen 10 58.82% 1 16.67%
greg kroah-hartman greg kroah-hartman 3 17.65% 2 33.33%
haiyang zhang haiyang zhang 3 17.65% 2 33.33%
ky srinivasan ky srinivasan 1 5.88% 1 16.67%
Total 17 100.00% 6 100.00%

/* Get the read and write indices as u64 of the specified ring buffer. */

static inline u64

hv_get_ring_bufferindices(struct hv_ring_buffer_info *ring_info)
{
	return (u64)ring_info->ring_buffer->write_index << 32;
}

Contributors
Person Tokens Prop Commits CommitProp
hank janssen hank janssen 15 62.50% 1 16.67%
greg kroah-hartman greg kroah-hartman 4 16.67% 2 33.33%
haiyang zhang haiyang zhang 4 16.67% 2 33.33%
ky srinivasan ky srinivasan 1 4.17% 1 16.67%
Total 24 100.00% 6 100.00%

/*
 * Helper routine to copy to source from ring buffer.
 * Assume there is enough room. Handles wrap-around in src case only!!
 */


static u32 hv_copyfrom_ringbuffer(
	struct hv_ring_buffer_info	*ring_info,
	void				*dest,
	u32				destlen,
	u32				start_read_offset)
{
	void *ring_buffer = hv_get_ring_buffer(ring_info);
	u32 ring_buffer_size = hv_get_ring_buffersize(ring_info);

	memcpy(dest, ring_buffer + start_read_offset, destlen);

	start_read_offset += destlen;
	start_read_offset %= ring_buffer_size;

	return start_read_offset;
}


Contributors
Person Tokens Prop Commits CommitProp
ky srinivasan ky srinivasan 47 78.33% 1 16.67%
greg kroah-hartman greg kroah-hartman 6 10.00% 3 50.00%
hank janssen hank janssen 6 10.00% 1 16.67%
haiyang zhang haiyang zhang 1 1.67% 1 16.67%
Total 60 100.00% 6 100.00%

/*
 * Helper routine to copy from source to ring buffer.
 * Assume there is enough room. Handles wrap-around in dest case only!!
 */


static u32 hv_copyto_ringbuffer(
	struct hv_ring_buffer_info	*ring_info,
	u32				start_write_offset,
	void				*src,
	u32				srclen)
{
	void *ring_buffer = hv_get_ring_buffer(ring_info);
	u32 ring_buffer_size = hv_get_ring_buffersize(ring_info);

	memcpy(ring_buffer + start_write_offset, src, srclen);

	start_write_offset += srclen;
	start_write_offset %= ring_buffer_size;

	return start_write_offset;
}

Contributors
Person Tokens Prop Commits CommitProp
ky srinivasan ky srinivasan 47 78.33% 2 28.57%
hank janssen hank janssen 6 10.00% 1 14.29%
greg kroah-hartman greg kroah-hartman 6 10.00% 3 42.86%
haiyang zhang haiyang zhang 1 1.67% 1 14.29%
Total 60 100.00% 7 100.00%

/* Get various debug metrics for the specified ring buffer. */


void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info,
			    struct hv_ring_buffer_debug_info *debug_info)
{
	u32 bytes_avail_towrite;
	u32 bytes_avail_toread;

	if (ring_info->ring_buffer) {
		hv_get_ringbuffer_availbytes(ring_info,
					&bytes_avail_toread,
					&bytes_avail_towrite);

		debug_info->bytes_avail_toread = bytes_avail_toread;
		debug_info->bytes_avail_towrite = bytes_avail_towrite;
		debug_info->current_read_index =
			ring_info->ring_buffer->read_index;
		debug_info->current_write_index =
			ring_info->ring_buffer->write_index;
		debug_info->current_interrupt_mask =
			ring_info->ring_buffer->interrupt_mask;
	}
}

Contributors
Person Tokens Prop Commits CommitProp
hank janssen hank janssen 43 52.44% 1 11.11%
haiyang zhang haiyang zhang 24 29.27% 2 22.22%
greg kroah-hartman greg kroah-hartman 13 15.85% 4 44.44%
ky srinivasan ky srinivasan 2 2.44% 2 22.22%
Total 82 100.00% 9 100.00%

/* Initialize the ring buffer. */


int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,
		       struct page *pages, u32 page_cnt)
{
	int i;
	struct page **pages_wraparound;

	BUILD_BUG_ON((sizeof(struct hv_ring_buffer) != PAGE_SIZE));

	memset(ring_info, 0, sizeof(struct hv_ring_buffer_info));

	/*
         * First page holds struct hv_ring_buffer, do wraparound mapping for
         * the rest.
         */
	pages_wraparound = kzalloc(sizeof(struct page *) * (page_cnt * 2 - 1),
				   GFP_KERNEL);
	if (!pages_wraparound)
		return -ENOMEM;

	pages_wraparound[0] = pages;
	for (i = 0; i < 2 * (page_cnt - 1); i++)
		pages_wraparound[i + 1] = &pages[i % (page_cnt - 1) + 1];

	ring_info->ring_buffer = (struct hv_ring_buffer *)
		vmap(pages_wraparound, page_cnt * 2 - 1, VM_MAP, PAGE_KERNEL);

	kfree(pages_wraparound);


	if (!ring_info->ring_buffer)
		return -ENOMEM;

	ring_info->ring_buffer->read_index =
		ring_info->ring_buffer->write_index = 0;

	/* Set the feature bit for enabling flow control. */
	ring_info->ring_buffer->feature_bits.value = 1;

	ring_info->ring_size = page_cnt << PAGE_SHIFT;
	ring_info->ring_datasize = ring_info->ring_size -
		sizeof(struct hv_ring_buffer);

	spin_lock_init(&ring_info->ring_lock);

	return 0;
}

Contributors
Person Tokens Prop Commits CommitProp
vitaly kuznetsov vitaly kuznetsov 135 58.70% 2 15.38%
hank janssen hank janssen 51 22.17% 1 7.69%
greg kroah-hartman greg kroah-hartman 17 7.39% 5 38.46%
haiyang zhang haiyang zhang 15 6.52% 2 15.38%
ky srinivasan ky srinivasan 11 4.78% 2 15.38%
bill pemberton bill pemberton 1 0.43% 1 7.69%
Total 230 100.00% 13 100.00%

/* Cleanup the ring buffer. */


void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)
{
	vunmap(ring_info->ring_buffer);
}

Contributors
Person Tokens Prop Commits CommitProp
vitaly kuznetsov vitaly kuznetsov 9 52.94% 1 16.67%
hank janssen hank janssen 3 17.65% 1 16.67%
greg kroah-hartman greg kroah-hartman 3 17.65% 2 33.33%
haiyang zhang haiyang zhang 1 5.88% 1 16.67%
ky srinivasan ky srinivasan 1 5.88% 1 16.67%
Total 17 100.00% 6 100.00%

/* Write to the ring buffer. */


int hv_ringbuffer_write(struct vmbus_channel *channel,
		    struct kvec *kv_list, u32 kv_count, bool lock,
		    bool kick_q)
{
	int i = 0;
	u32 bytes_avail_towrite;
	u32 totalbytes_towrite = 0;

	u32 next_write_location;
	u32 old_write;
	u64 prev_indices = 0;
	unsigned long flags = 0;
	struct hv_ring_buffer_info *outring_info = &channel->outbound;

	for (i = 0; i < kv_count; i++)
		totalbytes_towrite += kv_list[i].iov_len;

	totalbytes_towrite += sizeof(u64);

	if (lock)
		spin_lock_irqsave(&outring_info->ring_lock, flags);

	bytes_avail_towrite = hv_get_bytes_to_write(outring_info);

	/*
         * If there is only room for the packet, assume it is full.
         * Otherwise, the next time around, we think the ring buffer
         * is empty since the read index == write index.
         */
	if (bytes_avail_towrite <= totalbytes_towrite) {
		if (lock)
			spin_unlock_irqrestore(&outring_info->ring_lock, flags);
		return -EAGAIN;
	}

	/* Write to the ring buffer */
	next_write_location = hv_get_next_write_location(outring_info);

	old_write = next_write_location;

	for (i = 0; i < kv_count; i++) {
		next_write_location = hv_copyto_ringbuffer(outring_info,
						     next_write_location,
						     kv_list[i].iov_base,
						     kv_list[i].iov_len);
	}

	/* Set previous packet start */
	prev_indices = hv_get_ring_bufferindices(outring_info);

	next_write_location = hv_copyto_ringbuffer(outring_info,
					     next_write_location,
					     &prev_indices,
					     sizeof(u64));

	/* Issue a full memory barrier before updating the write index */
	virt_mb();

	/* Now, update the write location */
	hv_set_next_write_location(outring_info, next_write_location);


	if (lock)
		spin_unlock_irqrestore(&outring_info->ring_lock, flags);

	hv_signal_on_write(old_write, channel, kick_q);
	return 0;
}

Contributors
Person Tokens Prop Commits CommitProp
ky srinivasan ky srinivasan 107 42.13% 10 50.00%
hank janssen hank janssen 88 34.65% 1 5.00%
greg kroah-hartman greg kroah-hartman 28 11.02% 5 25.00%
haiyang zhang haiyang zhang 25 9.84% 1 5.00%
bill pemberton bill pemberton 3 1.18% 1 5.00%
nicolas palix nicolas palix 2 0.79% 1 5.00%
vitaly kuznetsov vitaly kuznetsov 1 0.39% 1 5.00%
Total 254 100.00% 20 100.00%



int hv_ringbuffer_read(struct vmbus_channel *channel,
		       void *buffer, u32 buflen, u32 *buffer_actual_len,
		       u64 *requestid, bool raw)
{
	u32 bytes_avail_toread;
	u32 next_read_location = 0;
	u64 prev_indices = 0;
	struct vmpacket_descriptor desc;
	u32 offset;
	u32 packetlen;
	int ret = 0;
	struct hv_ring_buffer_info *inring_info = &channel->inbound;

	if (buflen <= 0)
		return -EINVAL;


	*buffer_actual_len = 0;
	*requestid = 0;

	bytes_avail_toread = hv_get_bytes_to_read(inring_info);
	/* Make sure there is something to read */
	if (bytes_avail_toread < sizeof(desc)) {
		/*
                 * No error is set when there is even no header, drivers are
                 * supposed to analyze buffer_actual_len.
                 */
		return ret;
	}

	init_cached_read_index(channel);
	next_read_location = hv_get_next_read_location(inring_info);
	next_read_location = hv_copyfrom_ringbuffer(inring_info, &desc,
						    sizeof(desc),
						    next_read_location);

	offset = raw ? 0 : (desc.offset8 << 3);
	packetlen = (desc.len8 << 3) - offset;
	*buffer_actual_len = packetlen;
	*requestid = desc.trans_id;

	if (bytes_avail_toread < packetlen + offset)
		return -EAGAIN;

	if (packetlen > buflen)
		return -ENOBUFS;

	next_read_location =
		hv_get_next_readlocation_withoffset(inring_info, offset);

	next_read_location = hv_copyfrom_ringbuffer(inring_info,
						buffer,
						packetlen,
						next_read_location);

	next_read_location = hv_copyfrom_ringbuffer(inring_info,
						&prev_indices,
						sizeof(u64),
						next_read_location);

	/*
         * 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_mb();

	/* Update the read index */
	hv_set_next_read_location(inring_info, next_read_location);

	hv_signal_on_read(channel);

	return ret;
}
Contributors
Person Tokens Prop Commits CommitProp
vitaly kuznetsov vitaly kuznetsov 119 46.30% 3 14.29%
hank janssen hank janssen 58 22.57% 1 4.76%
ky srinivasan ky srinivasan 32 12.45% 7 33.33%
haiyang zhang haiyang zhang 22 8.56% 1 4.76%
greg kroah-hartman greg kroah-hartman 11 4.28% 6 28.57%
bill pemberton bill pemberton 10 3.89% 2 9.52%
dexuan cui dexuan cui 5 1.95% 1 4.76%
Total 257 100.00% 21 100.00%

Overall Contributors
Person Tokens Prop Commits CommitProp
ky srinivasan ky srinivasan 380 29.32% 26 52.00%
hank janssen hank janssen 368 28.40% 2 4.00%
vitaly kuznetsov vitaly kuznetsov 283 21.84% 4 8.00%
haiyang zhang haiyang zhang 124 9.57% 2 4.00%
greg kroah-hartman greg kroah-hartman 117 9.03% 10 20.00%
bill pemberton bill pemberton 14 1.08% 3 6.00%
dexuan cui dexuan cui 5 0.39% 1 2.00%
jason wang jason wang 3 0.23% 1 2.00%
nicolas palix nicolas palix 2 0.15% 1 2.00%
Total 1296 100.00% 50 100.00%
Directory: drivers/hv

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	Person	Tokens	Prop	Commits	CommitProp
ky srinivasan	ky srinivasan	21	100.00%	2	100.00%
	Total	21	100.00%	2	100.00%
cregit-Linux how code gets into the kernel

Release 4.10 drivers/hv/ring_buffer.c

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