diff options
Diffstat (limited to 'drivers/gpu/drm/xen/xen_drm_front_shbuf.c')
| -rw-r--r-- | drivers/gpu/drm/xen/xen_drm_front_shbuf.c | 414 |
1 files changed, 414 insertions, 0 deletions
diff --git a/drivers/gpu/drm/xen/xen_drm_front_shbuf.c b/drivers/gpu/drm/xen/xen_drm_front_shbuf.c new file mode 100644 index 000000000000..8099cb343ae3 --- /dev/null +++ b/drivers/gpu/drm/xen/xen_drm_front_shbuf.c @@ -0,0 +1,414 @@ +// 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) \ + ((phys_addr_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; + + if (grefs_left <= XEN_DRM_NUM_GREFS_PER_PAGE) { + to_copy = grefs_left; + page_dir->gref_dir_next_page = GRANT_INVALID_REF; + } else { + to_copy = XEN_DRM_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 += PAGE_SIZE; + grefs_left -= to_copy; + cur_gref += to_copy; + } +} + +static int guest_grant_refs_for_buffer(struct xen_drm_front_shbuf *buf, + grant_ref_t *priv_gref_head, + int gref_idx) +{ + int i, cur_ref, otherend_id; + + otherend_id = buf->xb_dev->otherend_id; + for (i = 0; i < buf->num_pages; i++) { + cur_ref = gnttab_claim_grant_reference(priv_gref_head); + if (cur_ref < 0) + return cur_ref; + + gnttab_grant_foreign_access_ref(cur_ref, otherend_id, + xen_page_to_gfn(buf->pages[i]), + 0); + buf->grefs[gref_idx++] = cur_ref; + } + return 0; +} + +static int grant_references(struct xen_drm_front_shbuf *buf) +{ + grant_ref_t priv_gref_head; + int ret, i, j, cur_ref; + int otherend_id, num_pages_dir; + + ret = gnttab_alloc_grant_references(buf->num_grefs, &priv_gref_head); + if (ret < 0) { + DRM_ERROR("Cannot allocate grant references\n"); + return ret; + } + + otherend_id = buf->xb_dev->otherend_id; + j = 0; + num_pages_dir = get_num_pages_dir(buf); + for (i = 0; i < num_pages_dir; i++) { + unsigned long frame; + + cur_ref = gnttab_claim_grant_reference(&priv_gref_head); + if (cur_ref < 0) + return cur_ref; + + frame = xen_page_to_gfn(virt_to_page(buf->directory + + PAGE_SIZE * i)); + gnttab_grant_foreign_access_ref(cur_ref, otherend_id, frame, 0); + buf->grefs[j++] = cur_ref; + } + + if (buf->ops->grant_refs_for_buffer) { + ret = buf->ops->grant_refs_for_buffer(buf, &priv_gref_head, j); + if (ret) + return ret; + } + + gnttab_free_grant_references(priv_gref_head); + return 0; +} + +static int alloc_storage(struct xen_drm_front_shbuf *buf) +{ + buf->grefs = kcalloc(buf->num_grefs, sizeof(*buf->grefs), GFP_KERNEL); + if (!buf->grefs) + return -ENOMEM; + + buf->directory = kcalloc(get_num_pages_dir(buf), PAGE_SIZE, GFP_KERNEL); + if (!buf->directory) + return -ENOMEM; + + return 0; +} + +/* + * For be allocated buffers we don't need grant_refs_for_buffer as those + * grant references are allocated at backend side + */ +static const struct xen_drm_front_shbuf_ops backend_ops = { + .calc_num_grefs = backend_calc_num_grefs, + .fill_page_dir = backend_fill_page_dir, + .map = backend_map, + .unmap = backend_unmap +}; + +/* For locally granted references we do not need to map/unmap the references */ +static const struct xen_drm_front_shbuf_ops local_ops = { + .calc_num_grefs = guest_calc_num_grefs, + .fill_page_dir = guest_fill_page_dir, + .grant_refs_for_buffer = guest_grant_refs_for_buffer, +}; + +struct xen_drm_front_shbuf * +xen_drm_front_shbuf_alloc(struct xen_drm_front_shbuf_cfg *cfg) +{ + struct xen_drm_front_shbuf *buf; + int ret; + + buf = kzalloc(sizeof(*buf), GFP_KERNEL); + if (!buf) + return ERR_PTR(-ENOMEM); + + if (cfg->be_alloc) + buf->ops = &backend_ops; + else + buf->ops = &local_ops; + + buf->xb_dev = cfg->xb_dev; + buf->num_pages = DIV_ROUND_UP(cfg->size, PAGE_SIZE); + buf->pages = cfg->pages; + + buf->ops->calc_num_grefs(buf); + + ret = alloc_storage(buf); + if (ret) + goto fail; + + ret = grant_references(buf); + if (ret) + goto fail; + + buf->ops->fill_page_dir(buf); + + return buf; + +fail: + xen_drm_front_shbuf_free(buf); + return ERR_PTR(ret); +} |