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Commit 9988ce68 authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Greg Kroah-Hartman
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Drivers: hv: ring_buffer: wrap around mappings for ring buffers 



Make it possible to always use a single memcpy() or to provide a direct
link to a packet on the ring buffer by creating virtual mapping for two
copies of the ring buffer with vmap(). Utilize currently empty
hv_ringbuffer_cleanup() to do the unmap.

While on it, replace sizeof(struct hv_ring_buffer) check
in hv_ringbuffer_init() with BUILD_BUG_ON() as it is a compile time check.

Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Tested-by: default avatarDexuan Cui <decui@microsoft.com>
Signed-off-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 98f531b1

drivers/hv/channel.c

+14 −15
Original line number Diff line number Diff line
@@ -75,7 +75,6 @@ int vmbus_open(struct vmbus_channel *newchannel, u32 send_ringbuffer_size, 
{

	struct vmbus_channel_open_channel *open_msg;

	struct vmbus_channel_msginfo *open_info = NULL;

	void *in, *out;

	unsigned long flags;

	int ret, err = 0;

	struct page *page;
@@ -112,23 +111,21 @@ int vmbus_open(struct vmbus_channel *newchannel, u32 send_ringbuffer_size, 
		goto error_set_chnstate;

	}



	out = page_address(page);

	in = (void *)((unsigned long)out + send_ringbuffer_size);



	newchannel->ringbuffer_pages = out;

	newchannel->ringbuffer_pages = page_address(page);

	newchannel->ringbuffer_pagecount = (send_ringbuffer_size +

					   recv_ringbuffer_size) >> PAGE_SHIFT;



	ret = hv_ringbuffer_init(

		&newchannel->outbound, out, send_ringbuffer_size);

	ret = hv_ringbuffer_init(&newchannel->outbound, page,

				 send_ringbuffer_size >> PAGE_SHIFT);



	if (ret != 0) {

		err = ret;

		goto error_free_pages;

	}



	ret = hv_ringbuffer_init(

		&newchannel->inbound, in, recv_ringbuffer_size);

	ret = hv_ringbuffer_init(&newchannel->inbound,

				 &page[send_ringbuffer_size >> PAGE_SHIFT],

				 recv_ringbuffer_size >> PAGE_SHIFT);

	if (ret != 0) {

		err = ret;

		goto error_free_pages;
@@ -139,7 +136,7 @@ int vmbus_open(struct vmbus_channel *newchannel, u32 send_ringbuffer_size, 
	newchannel->ringbuffer_gpadlhandle = 0;



	ret = vmbus_establish_gpadl(newchannel,

					 newchannel->outbound.ring_buffer,

				    page_address(page),

				    send_ringbuffer_size +

				    recv_ringbuffer_size,

				    &newchannel->ringbuffer_gpadlhandle);
@@ -214,7 +211,9 @@ int vmbus_open(struct vmbus_channel *newchannel, u32 send_ringbuffer_size, 
	vmbus_teardown_gpadl(newchannel, newchannel->ringbuffer_gpadlhandle);

	kfree(open_info);

error_free_pages:

	free_pages((unsigned long)out,

	hv_ringbuffer_cleanup(&newchannel->outbound);

	hv_ringbuffer_cleanup(&newchannel->inbound);

	__free_pages(page,

		     get_order(send_ringbuffer_size + recv_ringbuffer_size));

error_set_chnstate:

	newchannel->state = CHANNEL_OPEN_STATE;

drivers/hv/hyperv_vmbus.h

+2 −2
Original line number Diff line number Diff line
@@ -522,8 +522,8 @@ extern unsigned int host_info_edx; 
/* Interface */





int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info, void *buffer,

		   u32 buflen);

int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,

		       struct page *pages, u32 pagecnt);



void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info);

drivers/hv/ring_buffer.c

+33 −6
Original line number Diff line number Diff line
@@ -27,6 +27,8 @@ 
#include <linux/mm.h>

#include <linux/hyperv.h>

#include <linux/uio.h>

#include <linux/vmalloc.h>

#include <linux/slab.h>



#include "hyperv_vmbus.h"
@@ -243,22 +245,46 @@ void hv_ringbuffer_get_debuginfo(struct hv_ring_buffer_info *ring_info, 


/* Initialize the ring buffer. */

int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info,

		   void *buffer, u32 buflen)

		       struct page *pages, u32 page_cnt)

{

	if (sizeof(struct hv_ring_buffer) != PAGE_SIZE)

		return -EINVAL;

	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));



	ring_info->ring_buffer = (struct hv_ring_buffer *)buffer;

	/*

	 * 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 = buflen;

	ring_info->ring_datasize = buflen - sizeof(struct hv_ring_buffer);

	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);
@@ -268,6 +294,7 @@ int hv_ringbuffer_init(struct hv_ring_buffer_info *ring_info, 
/* Cleanup the ring buffer. */

void hv_ringbuffer_cleanup(struct hv_ring_buffer_info *ring_info)

{

	vunmap(ring_info->ring_buffer);

}



/* Write to the ring buffer. */