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// SPDX-License-Identifier: GPL-2.0 OR MIT
/*
* Xen para-virtual sound device
*
* Copyright (C) 2016-2018 EPAM Systems Inc.
*
* Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
*/
#include <linux/kernel.h>
#include <xen/xen.h>
#include <xen/xenbus.h>
#include "xen_snd_front_shbuf.h"
grant_ref_t xen_snd_front_shbuf_get_dir_start(struct xen_snd_front_shbuf *buf)
{
if (!buf->grefs)
return GRANT_INVALID_REF;
return buf->grefs[0];
}
void xen_snd_front_shbuf_clear(struct xen_snd_front_shbuf *buf)
{
memset(buf, 0, sizeof(*buf));
}
void xen_snd_front_shbuf_free(struct xen_snd_front_shbuf *buf)
{
int i;
if (buf->grefs) {
for (i = 0; i < buf->num_grefs; i++)
if (buf->grefs[i] != GRANT_INVALID_REF)
gnttab_end_foreign_access(buf->grefs[i],
0, 0UL);
kfree(buf->grefs);
}
kfree(buf->directory);
free_pages_exact(buf->buffer, buf->buffer_sz);
xen_snd_front_shbuf_clear(buf);
}
/*
* number of grant references a page can hold with respect to the
* xensnd_page_directory header
*/
#define XENSND_NUM_GREFS_PER_PAGE ((XEN_PAGE_SIZE - \
offsetof(struct xensnd_page_directory, gref)) / \
sizeof(grant_ref_t))
static void fill_page_dir(struct xen_snd_front_shbuf *buf,
int num_pages_dir)
{
struct xensnd_page_directory *page_dir;
unsigned char *ptr;
int i, cur_gref, grefs_left, to_copy;
ptr = buf->directory;
grefs_left = buf->num_grefs - num_pages_dir;
/*
* skip grant references at the beginning, they are for pages granted
* for the page directory itself
*/
cur_gref = num_pages_dir;
for (i = 0; i < num_pages_dir; i++) {
page_dir = (struct xensnd_page_directory *)ptr;
if (grefs_left <= XENSND_NUM_GREFS_PER_PAGE) {
to_copy = grefs_left;
page_dir->gref_dir_next_page = GRANT_INVALID_REF;
} else {
to_copy = XENSND_NUM_GREFS_PER_PAGE;
page_dir->gref_dir_next_page = buf->grefs[i + 1];
}
memcpy(&page_dir->gref, &buf->grefs[cur_gref],
to_copy * sizeof(grant_ref_t));
ptr += XEN_PAGE_SIZE;
grefs_left -= to_copy;
cur_gref += to_copy;
}
}
static int grant_references(struct xenbus_device *xb_dev,
struct xen_snd_front_shbuf *buf,
int num_pages_dir, int num_pages_buffer,
int num_grefs)
{
grant_ref_t priv_gref_head;
unsigned long frame;
int ret, i, j, cur_ref;
int otherend_id;
ret = gnttab_alloc_grant_references(num_grefs, &priv_gref_head);
if (ret)
return ret;
buf->num_grefs = num_grefs;
otherend_id = xb_dev->otherend_id;
j = 0;
for (i = 0; i < num_pages_dir; i++) {
cur_ref = gnttab_claim_grant_reference(&priv_gref_head);
if (cur_ref < 0) {
ret = cur_ref;
goto fail;
}
frame = xen_page_to_gfn(virt_to_page(buf->directory +
XEN_PAGE_SIZE * i));
gnttab_grant_foreign_access_ref(cur_ref, otherend_id, frame, 0);
buf->grefs[j++] = cur_ref;
}
for (i = 0; i < num_pages_buffer; i++) {
cur_ref = gnttab_claim_grant_reference(&priv_gref_head);
if (cur_ref < 0) {
ret = cur_ref;
goto fail;
}
frame = xen_page_to_gfn(virt_to_page(buf->buffer +
XEN_PAGE_SIZE * i));
gnttab_grant_foreign_access_ref(cur_ref, otherend_id, frame, 0);
buf->grefs[j++] = cur_ref;
}
gnttab_free_grant_references(priv_gref_head);
fill_page_dir(buf, num_pages_dir);
return 0;
fail:
gnttab_free_grant_references(priv_gref_head);
return ret;
}
static int alloc_int_buffers(struct xen_snd_front_shbuf *buf,
int num_pages_dir, int num_pages_buffer,
int num_grefs)
{
buf->grefs = kcalloc(num_grefs, sizeof(*buf->grefs), GFP_KERNEL);
if (!buf->grefs)
return -ENOMEM;
buf->directory = kcalloc(num_pages_dir, XEN_PAGE_SIZE, GFP_KERNEL);
if (!buf->directory)
goto fail;
buf->buffer_sz = num_pages_buffer * XEN_PAGE_SIZE;
buf->buffer = alloc_pages_exact(buf->buffer_sz, GFP_KERNEL);
if (!buf->buffer)
goto fail;
return 0;
fail:
kfree(buf->grefs);
buf->grefs = NULL;
kfree(buf->directory);
buf->directory = NULL;
return -ENOMEM;
}
int xen_snd_front_shbuf_alloc(struct xenbus_device *xb_dev,
struct xen_snd_front_shbuf *buf,
unsigned int buffer_sz)
{
int num_pages_buffer, num_pages_dir, num_grefs;
int ret;
xen_snd_front_shbuf_clear(buf);
num_pages_buffer = DIV_ROUND_UP(buffer_sz, XEN_PAGE_SIZE);
/* number of pages the page directory consumes itself */
num_pages_dir = DIV_ROUND_UP(num_pages_buffer,
XENSND_NUM_GREFS_PER_PAGE);
num_grefs = num_pages_buffer + num_pages_dir;
ret = alloc_int_buffers(buf, num_pages_dir,
num_pages_buffer, num_grefs);
if (ret < 0)
return ret;
ret = grant_references(xb_dev, buf, num_pages_dir, num_pages_buffer,
num_grefs);
if (ret < 0)
return ret;
fill_page_dir(buf, num_pages_dir);
return 0;
}
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