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// SPDX-License-Identifier: GPL-2.0 OR MIT
/*
* Xen para-virtual DRM device
*
* Copyright (C) 2016-2018 EPAM Systems Inc.
*
* Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
*/
#include <drm/drmP.h>
#if defined(CONFIG_X86)
#include <drm/drm_cache.h>
#endif
#include <linux/errno.h>
#include <linux/mm.h>
#include <asm/xen/hypervisor.h>
#include <xen/balloon.h>
#include <xen/xen.h>
#include <xen/xenbus.h>
#include <xen/interface/io/ring.h>
#include <xen/interface/io/displif.h>
#include "xen_drm_front.h"
#include "xen_drm_front_shbuf.h"
struct xen_drm_front_shbuf_ops {
/*
* Calculate number of grefs required to handle this buffer,
* e.g. if grefs are required for page directory only or the buffer
* pages as well.
*/
void (*calc_num_grefs)(struct xen_drm_front_shbuf *buf);
/* Fill page directory according to para-virtual display protocol. */
void (*fill_page_dir)(struct xen_drm_front_shbuf *buf);
/* Claim grant references for the pages of the buffer. */
int (*grant_refs_for_buffer)(struct xen_drm_front_shbuf *buf,
grant_ref_t *priv_gref_head, int gref_idx);
/* Map grant references of the buffer. */
int (*map)(struct xen_drm_front_shbuf *buf);
/* Unmap grant references of the buffer. */
int (*unmap)(struct xen_drm_front_shbuf *buf);
};
grant_ref_t xen_drm_front_shbuf_get_dir_start(struct xen_drm_front_shbuf *buf)
{
if (!buf->grefs)
return GRANT_INVALID_REF;
return buf->grefs[0];
}
int xen_drm_front_shbuf_map(struct xen_drm_front_shbuf *buf)
{
if (buf->ops->map)
return buf->ops->map(buf);
/* no need to map own grant references */
return 0;
}
int xen_drm_front_shbuf_unmap(struct xen_drm_front_shbuf *buf)
{
if (buf->ops->unmap)
return buf->ops->unmap(buf);
/* no need to unmap own grant references */
return 0;
}
void xen_drm_front_shbuf_flush(struct xen_drm_front_shbuf *buf)
{
#if defined(CONFIG_X86)
drm_clflush_pages(buf->pages, buf->num_pages);
#endif
}
void xen_drm_front_shbuf_free(struct xen_drm_front_shbuf *buf)
{
if (buf->grefs) {
int i;
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);
kfree(buf);
}
/*
* number of grefs a page can hold with respect to the
* struct xendispl_page_directory header
*/
#define XEN_DRM_NUM_GREFS_PER_PAGE ((PAGE_SIZE - \
offsetof(struct xendispl_page_directory, gref)) / \
sizeof(grant_ref_t))
static int get_num_pages_dir(struct xen_drm_front_shbuf *buf)
{
/* number of pages the page directory consumes itself */
return DIV_ROUND_UP(buf->num_pages, XEN_DRM_NUM_GREFS_PER_PAGE);
}
static void backend_calc_num_grefs(struct xen_drm_front_shbuf *buf)
{
/* only for pages the page directory consumes itself */
buf->num_grefs = get_num_pages_dir(buf);
}
static void guest_calc_num_grefs(struct xen_drm_front_shbuf *buf)
{
/*
* number of pages the page directory consumes itself
* plus grefs for the buffer pages
*/
buf->num_grefs = get_num_pages_dir(buf) + buf->num_pages;
}
#define xen_page_to_vaddr(page) \
((uintptr_t)pfn_to_kaddr(page_to_xen_pfn(page)))
static int backend_unmap(struct xen_drm_front_shbuf *buf)
{
struct gnttab_unmap_grant_ref *unmap_ops;
int i, ret;
if (!buf->pages || !buf->backend_map_handles || !buf->grefs)
return 0;
unmap_ops = kcalloc(buf->num_pages, sizeof(*unmap_ops),
GFP_KERNEL);
if (!unmap_ops) {
DRM_ERROR("Failed to get memory while unmapping\n");
return -ENOMEM;
}
for (i = 0; i < buf->num_pages; i++) {
phys_addr_t addr;
addr = xen_page_to_vaddr(buf->pages[i]);
gnttab_set_unmap_op(&unmap_ops[i], addr, GNTMAP_host_map,
buf->backend_map_handles[i]);
}
ret = gnttab_unmap_refs(unmap_ops, NULL, buf->pages,
buf->num_pages);
for (i = 0; i < buf->num_pages; i++) {
if (unlikely(unmap_ops[i].status != GNTST_okay))
DRM_ERROR("Failed to unmap page %d: %d\n",
i, unmap_ops[i].status);
}
if (ret)
DRM_ERROR("Failed to unmap grant references, ret %d", ret);
kfree(unmap_ops);
kfree(buf->backend_map_handles);
buf->backend_map_handles = NULL;
return ret;
}
static int backend_map(struct xen_drm_front_shbuf *buf)
{
struct gnttab_map_grant_ref *map_ops = NULL;
unsigned char *ptr;
int ret, cur_gref, cur_dir_page, cur_page, grefs_left;
map_ops = kcalloc(buf->num_pages, sizeof(*map_ops), GFP_KERNEL);
if (!map_ops)
return -ENOMEM;
buf->backend_map_handles = kcalloc(buf->num_pages,
sizeof(*buf->backend_map_handles),
GFP_KERNEL);
if (!buf->backend_map_handles) {
kfree(map_ops);
return -ENOMEM;
}
/*
* read page directory to get grefs from the backend: for external
* buffer we only allocate buf->grefs for the page directory,
* so buf->num_grefs has number of pages in the page directory itself
*/
ptr = buf->directory;
grefs_left = buf->num_pages;
cur_page = 0;
for (cur_dir_page = 0; cur_dir_page < buf->num_grefs; cur_dir_page++) {
struct xendispl_page_directory *page_dir =
(struct xendispl_page_directory *)ptr;
int to_copy = XEN_DRM_NUM_GREFS_PER_PAGE;
if (to_copy > grefs_left)
to_copy = grefs_left;
for (cur_gref = 0; cur_gref < to_copy; cur_gref++) {
phys_addr_t addr;
addr = xen_page_to_vaddr(buf->pages[cur_page]);
gnttab_set_map_op(&map_ops[cur_page], addr,
GNTMAP_host_map,
page_dir->gref[cur_gref],
buf->xb_dev->otherend_id);
cur_page++;
}
grefs_left -= to_copy;
ptr += PAGE_SIZE;
}
ret = gnttab_map_refs(map_ops, NULL, buf->pages, buf->num_pages);
/* save handles even if error, so we can unmap */
for (cur_page = 0; cur_page < buf->num_pages; cur_page++) {
buf->backend_map_handles[cur_page] = map_ops[cur_page].handle;
if (unlikely(map_ops[cur_page].status != GNTST_okay))
DRM_ERROR("Failed to map page %d: %d\n",
cur_page, map_ops[cur_page].status);
}
if (ret) {
DRM_ERROR("Failed to map grant references, ret %d", ret);
backend_unmap(buf);
}
kfree(map_ops);
return ret;
}
static void backend_fill_page_dir(struct xen_drm_front_shbuf *buf)
{
struct xendispl_page_directory *page_dir;
unsigned char *ptr;
int i, num_pages_dir;
ptr = buf->directory;
num_pages_dir = get_num_pages_dir(buf);
/* fill only grefs for the page directory itself */
for (i = 0; i < num_pages_dir - 1; i++) {
page_dir = (struct xendispl_page_directory *)ptr;
page_dir->gref_dir_next_page = buf->grefs[i + 1];
ptr += PAGE_SIZE;
}
/* last page must say there is no more pages */
page_dir = (struct xendispl_page_directory *)ptr;
page_dir->gref_dir_next_page = GRANT_INVALID_REF;
}
static void guest_fill_page_dir(struct xen_drm_front_shbuf *buf)
{
unsigned char *ptr;
int cur_gref, grefs_left, to_copy, i, num_pages_dir;
ptr = buf->directory;
num_pages_dir = get_num_pages_dir(buf);
/*
* while copying, skip grefs at start, they are for pages
* granted for the page directory itself
*/
cur_gref = num_pages_dir;
grefs_left = buf->num_pages;
for (i = 0; i < num_pages_dir; i++) {
struct xendispl_page_directory *page_dir =
(struct xendispl_page_directory *)ptr;
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