forked from Minki/linux
18f20bc530
The xen_drm_front_shbuf_alloc() function was returning a mix of error
pointers and NULL and the the caller wasn't checking correctly. I've
changed it to always return error pointer consistently.
Fixes: c575b7eeb8
("drm/xen-front: Add support for Xen PV display frontend")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180508092739.GB661@mwanda
415 lines
10 KiB
C
415 lines
10 KiB
C
// SPDX-License-Identifier: GPL-2.0 OR MIT
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/*
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* Xen para-virtual DRM device
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*
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* Copyright (C) 2016-2018 EPAM Systems Inc.
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*
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* Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
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*/
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#include <drm/drmP.h>
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#if defined(CONFIG_X86)
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#include <drm/drm_cache.h>
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#endif
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#include <linux/errno.h>
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#include <linux/mm.h>
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#include <asm/xen/hypervisor.h>
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#include <xen/balloon.h>
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#include <xen/xen.h>
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#include <xen/xenbus.h>
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#include <xen/interface/io/ring.h>
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#include <xen/interface/io/displif.h>
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#include "xen_drm_front.h"
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#include "xen_drm_front_shbuf.h"
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struct xen_drm_front_shbuf_ops {
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/*
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* Calculate number of grefs required to handle this buffer,
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* e.g. if grefs are required for page directory only or the buffer
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* pages as well.
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*/
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void (*calc_num_grefs)(struct xen_drm_front_shbuf *buf);
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/* Fill page directory according to para-virtual display protocol. */
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void (*fill_page_dir)(struct xen_drm_front_shbuf *buf);
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/* Claim grant references for the pages of the buffer. */
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int (*grant_refs_for_buffer)(struct xen_drm_front_shbuf *buf,
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grant_ref_t *priv_gref_head, int gref_idx);
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/* Map grant references of the buffer. */
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int (*map)(struct xen_drm_front_shbuf *buf);
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/* Unmap grant references of the buffer. */
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int (*unmap)(struct xen_drm_front_shbuf *buf);
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};
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grant_ref_t xen_drm_front_shbuf_get_dir_start(struct xen_drm_front_shbuf *buf)
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{
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if (!buf->grefs)
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return GRANT_INVALID_REF;
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return buf->grefs[0];
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}
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int xen_drm_front_shbuf_map(struct xen_drm_front_shbuf *buf)
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{
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if (buf->ops->map)
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return buf->ops->map(buf);
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/* no need to map own grant references */
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return 0;
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}
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int xen_drm_front_shbuf_unmap(struct xen_drm_front_shbuf *buf)
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{
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if (buf->ops->unmap)
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return buf->ops->unmap(buf);
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/* no need to unmap own grant references */
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return 0;
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}
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void xen_drm_front_shbuf_flush(struct xen_drm_front_shbuf *buf)
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{
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#if defined(CONFIG_X86)
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drm_clflush_pages(buf->pages, buf->num_pages);
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#endif
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}
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void xen_drm_front_shbuf_free(struct xen_drm_front_shbuf *buf)
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{
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if (buf->grefs) {
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int i;
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for (i = 0; i < buf->num_grefs; i++)
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if (buf->grefs[i] != GRANT_INVALID_REF)
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gnttab_end_foreign_access(buf->grefs[i],
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0, 0UL);
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}
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kfree(buf->grefs);
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kfree(buf->directory);
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kfree(buf);
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}
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/*
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* number of grefs a page can hold with respect to the
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* struct xendispl_page_directory header
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*/
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#define XEN_DRM_NUM_GREFS_PER_PAGE ((PAGE_SIZE - \
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offsetof(struct xendispl_page_directory, gref)) / \
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sizeof(grant_ref_t))
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static int get_num_pages_dir(struct xen_drm_front_shbuf *buf)
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{
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/* number of pages the page directory consumes itself */
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return DIV_ROUND_UP(buf->num_pages, XEN_DRM_NUM_GREFS_PER_PAGE);
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}
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static void backend_calc_num_grefs(struct xen_drm_front_shbuf *buf)
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{
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/* only for pages the page directory consumes itself */
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buf->num_grefs = get_num_pages_dir(buf);
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}
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static void guest_calc_num_grefs(struct xen_drm_front_shbuf *buf)
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{
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/*
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* number of pages the page directory consumes itself
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* plus grefs for the buffer pages
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*/
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buf->num_grefs = get_num_pages_dir(buf) + buf->num_pages;
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}
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#define xen_page_to_vaddr(page) \
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((phys_addr_t)pfn_to_kaddr(page_to_xen_pfn(page)))
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static int backend_unmap(struct xen_drm_front_shbuf *buf)
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{
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struct gnttab_unmap_grant_ref *unmap_ops;
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int i, ret;
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if (!buf->pages || !buf->backend_map_handles || !buf->grefs)
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return 0;
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unmap_ops = kcalloc(buf->num_pages, sizeof(*unmap_ops),
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GFP_KERNEL);
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if (!unmap_ops) {
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DRM_ERROR("Failed to get memory while unmapping\n");
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return -ENOMEM;
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}
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for (i = 0; i < buf->num_pages; i++) {
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phys_addr_t addr;
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addr = xen_page_to_vaddr(buf->pages[i]);
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gnttab_set_unmap_op(&unmap_ops[i], addr, GNTMAP_host_map,
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buf->backend_map_handles[i]);
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}
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ret = gnttab_unmap_refs(unmap_ops, NULL, buf->pages,
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buf->num_pages);
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for (i = 0; i < buf->num_pages; i++) {
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if (unlikely(unmap_ops[i].status != GNTST_okay))
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DRM_ERROR("Failed to unmap page %d: %d\n",
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i, unmap_ops[i].status);
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}
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if (ret)
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DRM_ERROR("Failed to unmap grant references, ret %d", ret);
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kfree(unmap_ops);
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kfree(buf->backend_map_handles);
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buf->backend_map_handles = NULL;
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return ret;
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}
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static int backend_map(struct xen_drm_front_shbuf *buf)
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{
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struct gnttab_map_grant_ref *map_ops = NULL;
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unsigned char *ptr;
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int ret, cur_gref, cur_dir_page, cur_page, grefs_left;
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map_ops = kcalloc(buf->num_pages, sizeof(*map_ops), GFP_KERNEL);
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if (!map_ops)
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return -ENOMEM;
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buf->backend_map_handles = kcalloc(buf->num_pages,
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sizeof(*buf->backend_map_handles),
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GFP_KERNEL);
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if (!buf->backend_map_handles) {
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kfree(map_ops);
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return -ENOMEM;
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}
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/*
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* read page directory to get grefs from the backend: for external
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* buffer we only allocate buf->grefs for the page directory,
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* so buf->num_grefs has number of pages in the page directory itself
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*/
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ptr = buf->directory;
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grefs_left = buf->num_pages;
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cur_page = 0;
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for (cur_dir_page = 0; cur_dir_page < buf->num_grefs; cur_dir_page++) {
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struct xendispl_page_directory *page_dir =
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(struct xendispl_page_directory *)ptr;
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int to_copy = XEN_DRM_NUM_GREFS_PER_PAGE;
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if (to_copy > grefs_left)
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to_copy = grefs_left;
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for (cur_gref = 0; cur_gref < to_copy; cur_gref++) {
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phys_addr_t addr;
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addr = xen_page_to_vaddr(buf->pages[cur_page]);
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gnttab_set_map_op(&map_ops[cur_page], addr,
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GNTMAP_host_map,
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page_dir->gref[cur_gref],
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buf->xb_dev->otherend_id);
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cur_page++;
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}
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grefs_left -= to_copy;
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ptr += PAGE_SIZE;
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}
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ret = gnttab_map_refs(map_ops, NULL, buf->pages, buf->num_pages);
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/* save handles even if error, so we can unmap */
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for (cur_page = 0; cur_page < buf->num_pages; cur_page++) {
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buf->backend_map_handles[cur_page] = map_ops[cur_page].handle;
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if (unlikely(map_ops[cur_page].status != GNTST_okay))
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DRM_ERROR("Failed to map page %d: %d\n",
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cur_page, map_ops[cur_page].status);
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}
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if (ret) {
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DRM_ERROR("Failed to map grant references, ret %d", ret);
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backend_unmap(buf);
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}
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kfree(map_ops);
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return ret;
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}
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static void backend_fill_page_dir(struct xen_drm_front_shbuf *buf)
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{
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struct xendispl_page_directory *page_dir;
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unsigned char *ptr;
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int i, num_pages_dir;
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ptr = buf->directory;
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num_pages_dir = get_num_pages_dir(buf);
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/* fill only grefs for the page directory itself */
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for (i = 0; i < num_pages_dir - 1; i++) {
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page_dir = (struct xendispl_page_directory *)ptr;
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page_dir->gref_dir_next_page = buf->grefs[i + 1];
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ptr += PAGE_SIZE;
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}
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/* last page must say there is no more pages */
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page_dir = (struct xendispl_page_directory *)ptr;
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page_dir->gref_dir_next_page = GRANT_INVALID_REF;
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}
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static void guest_fill_page_dir(struct xen_drm_front_shbuf *buf)
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{
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unsigned char *ptr;
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int cur_gref, grefs_left, to_copy, i, num_pages_dir;
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ptr = buf->directory;
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num_pages_dir = get_num_pages_dir(buf);
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/*
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* while copying, skip grefs at start, they are for pages
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* granted for the page directory itself
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*/
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cur_gref = num_pages_dir;
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grefs_left = buf->num_pages;
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for (i = 0; i < num_pages_dir; i++) {
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struct xendispl_page_directory *page_dir =
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(struct xendispl_page_directory *)ptr;
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if (grefs_left <= XEN_DRM_NUM_GREFS_PER_PAGE) {
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to_copy = grefs_left;
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page_dir->gref_dir_next_page = GRANT_INVALID_REF;
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} else {
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to_copy = XEN_DRM_NUM_GREFS_PER_PAGE;
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page_dir->gref_dir_next_page = buf->grefs[i + 1];
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}
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memcpy(&page_dir->gref, &buf->grefs[cur_gref],
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to_copy * sizeof(grant_ref_t));
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ptr += PAGE_SIZE;
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grefs_left -= to_copy;
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cur_gref += to_copy;
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}
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}
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static int guest_grant_refs_for_buffer(struct xen_drm_front_shbuf *buf,
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grant_ref_t *priv_gref_head,
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int gref_idx)
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{
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int i, cur_ref, otherend_id;
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otherend_id = buf->xb_dev->otherend_id;
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for (i = 0; i < buf->num_pages; i++) {
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cur_ref = gnttab_claim_grant_reference(priv_gref_head);
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if (cur_ref < 0)
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return cur_ref;
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gnttab_grant_foreign_access_ref(cur_ref, otherend_id,
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xen_page_to_gfn(buf->pages[i]),
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0);
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buf->grefs[gref_idx++] = cur_ref;
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}
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return 0;
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}
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static int grant_references(struct xen_drm_front_shbuf *buf)
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{
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grant_ref_t priv_gref_head;
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int ret, i, j, cur_ref;
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int otherend_id, num_pages_dir;
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ret = gnttab_alloc_grant_references(buf->num_grefs, &priv_gref_head);
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if (ret < 0) {
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DRM_ERROR("Cannot allocate grant references\n");
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return ret;
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}
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otherend_id = buf->xb_dev->otherend_id;
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j = 0;
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num_pages_dir = get_num_pages_dir(buf);
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for (i = 0; i < num_pages_dir; i++) {
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unsigned long frame;
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cur_ref = gnttab_claim_grant_reference(&priv_gref_head);
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if (cur_ref < 0)
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return cur_ref;
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frame = xen_page_to_gfn(virt_to_page(buf->directory +
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PAGE_SIZE * i));
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gnttab_grant_foreign_access_ref(cur_ref, otherend_id, frame, 0);
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buf->grefs[j++] = cur_ref;
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}
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if (buf->ops->grant_refs_for_buffer) {
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ret = buf->ops->grant_refs_for_buffer(buf, &priv_gref_head, j);
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if (ret)
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return ret;
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}
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gnttab_free_grant_references(priv_gref_head);
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return 0;
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}
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static int alloc_storage(struct xen_drm_front_shbuf *buf)
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{
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buf->grefs = kcalloc(buf->num_grefs, sizeof(*buf->grefs), GFP_KERNEL);
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if (!buf->grefs)
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return -ENOMEM;
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buf->directory = kcalloc(get_num_pages_dir(buf), PAGE_SIZE, GFP_KERNEL);
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if (!buf->directory)
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return -ENOMEM;
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return 0;
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}
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/*
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* For be allocated buffers we don't need grant_refs_for_buffer as those
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* grant references are allocated at backend side
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*/
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static const struct xen_drm_front_shbuf_ops backend_ops = {
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.calc_num_grefs = backend_calc_num_grefs,
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.fill_page_dir = backend_fill_page_dir,
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.map = backend_map,
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.unmap = backend_unmap
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};
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/* For locally granted references we do not need to map/unmap the references */
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static const struct xen_drm_front_shbuf_ops local_ops = {
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.calc_num_grefs = guest_calc_num_grefs,
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.fill_page_dir = guest_fill_page_dir,
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.grant_refs_for_buffer = guest_grant_refs_for_buffer,
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};
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struct xen_drm_front_shbuf *
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xen_drm_front_shbuf_alloc(struct xen_drm_front_shbuf_cfg *cfg)
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{
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struct xen_drm_front_shbuf *buf;
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int ret;
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buf = kzalloc(sizeof(*buf), GFP_KERNEL);
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if (!buf)
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return ERR_PTR(-ENOMEM);
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if (cfg->be_alloc)
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buf->ops = &backend_ops;
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else
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buf->ops = &local_ops;
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buf->xb_dev = cfg->xb_dev;
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buf->num_pages = DIV_ROUND_UP(cfg->size, PAGE_SIZE);
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buf->pages = cfg->pages;
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buf->ops->calc_num_grefs(buf);
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ret = alloc_storage(buf);
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if (ret)
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goto fail;
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ret = grant_references(buf);
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if (ret)
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goto fail;
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buf->ops->fill_page_dir(buf);
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return buf;
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fail:
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xen_drm_front_shbuf_free(buf);
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return ERR_PTR(ret);
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}
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