path: root/include/linux/hyperv.h

/*
 *
 * Copyright (c) 2011, 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>
 *
 */

#ifndef _HYPERV_H
#define _HYPERV_H

#include <uapi/linux/hyperv.h>

#include <linux/types.h>
#include <linux/scatterlist.h>
#include <linux/list.h>
#include <linux/timer.h>
#include <linux/completion.h>
#include <linux/device.h>
#include <linux/mod_devicetable.h>
#include <linux/interrupt.h>
#include <linux/reciprocal_div.h>

#define MAX_PAGE_BUFFER_COUNT				32
#define MAX_MULTIPAGE_BUFFER_COUNT			32 /* 128K */

#pragma pack(push, 1)

/* Single-page buffer */
struct hv_page_buffer {
	u32 len;
	u32 offset;
	u64 pfn;
};

/* Multiple-page buffer */
struct hv_multipage_buffer {
	/* Length and Offset determines the # of pfns in the array */
	u32 len;
	u32 offset;
	u64 pfn_array[MAX_MULTIPAGE_BUFFER_COUNT];
};

/*
 * Multiple-page buffer array; the pfn array is variable size:
 * The number of entries in the PFN array is determined by
 * "len" and "offset".
 */
struct hv_mpb_array {
	/* Length and Offset determines the # of pfns in the array */
	u32 len;
	u32 offset;
	u64 pfn_array[];
};

/* 0x18 includes the proprietary packet header */
#define MAX_PAGE_BUFFER_PACKET		(0x18 +			\
					(sizeof(struct hv_page_buffer) * \
					 MAX_PAGE_BUFFER_COUNT))
#define MAX_MULTIPAGE_BUFFER_PACKET	(0x18 +			\
					 sizeof(struct hv_multipage_buffer))


#pragma pack(pop)

struct hv_ring_buffer {
	/* Offset in bytes from the start of ring data below */
	u32 write_index;

	/* Offset in bytes from the start of ring data below */
	u32 read_index;

	u32 interrupt_mask;

	/*
	 * WS2012/Win8 and later versions of Hyper-V implement interrupt
	 * driven flow management. The feature bit feat_pending_send_sz
	 * is set by the host on the host->guest ring buffer, and by the
	 * guest on the guest->host ring buffer.
	 *
	 * The meaning of the feature bit is a bit complex in that it has
	 * semantics that apply to both ring buffers.  If the guest sets
	 * the feature bit in the guest->host ring buffer, the guest is
	 * telling the host that:
	 * 1) It will set the pending_send_sz field in the guest->host ring
	 *    buffer when it is waiting for space to become available, and
	 * 2) It will read the pending_send_sz field in the host->guest
	 *    ring buffer and interrupt the host when it frees enough space
	 *
	 * Similarly, if the host sets the feature bit in the host->guest
	 * ring buffer, the host is telling the guest that:
	 * 1) It will set the pending_send_sz field in the host->guest ring
	 *    buffer when it is waiting for space to become available, and
	 * 2) It will read the pending_send_sz field in the guest->host
	 *    ring buffer and interrupt the guest when it frees enough space
	 *
	 * If either the guest or host does not set the feature bit that it
	 * owns, that guest or host must do polling if it encounters a full
	 * ring buffer, and not signal the other end with an interrupt.
	 */
	u32 pending_send_sz;
	u32 reserved1[12];
	union {
		struct {
			u32 feat_pending_send_sz:1;
		};
		u32 value;
	} feature_bits;

	/* Pad it to PAGE_SIZE so that data starts on page boundary */
	u8	reserved2[4028];

	/*
	 * Ring data starts here + RingDataStartOffset
	 * !!! DO NOT place any fields below this !!!
	 */
	u8 buffer[0];
} __packed;

struct hv_ring_buffer_info {
	struct hv_ring_buffer *ring_buffer;
	u32 ring_size;			/* Include the shared header */
	struct reciprocal_value ring_size_div10_reciprocal;
	spinlock_t ring_lock;

	u32 ring_datasize;		/* < ring_size */
	u32 priv_read_index;
	/*
	 * The ring buffer mutex lock. This lock prevents the ring buffer from
	 * being freed while the ring buffer is being accessed.
	 */
	struct mutex ring_buffer_mutex;
};


static inline u32 hv_get_bytes_to_read(const 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(const 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 - rea