From: Oleksandr Andrushchenko oleksandr_andrushchenko@epam.com
Implement shared buffer handling according to the para-virtualized display device protocol at xen/interface/io/displif.h: - handle page directories according to displif protocol: - allocate and share page directories - grant references to the required set of pages for the page directory - allocate xen balllooned pages via Xen balloon driver with alloc_xenballooned_pages/free_xenballooned_pages - grant references to the required set of pages for the shared buffer itself - implement pages map/unmap for the buffers allocated by the backend (gnttab_map_refs/gnttab_unmap_refs)
Signed-off-by: Oleksandr Andrushchenko oleksandr_andrushchenko@epam.com --- drivers/gpu/drm/xen/Makefile | 1 + drivers/gpu/drm/xen/xen_drm_front.c | 8 + drivers/gpu/drm/xen/xen_drm_front_shbuf.c | 432 ++++++++++++++++++++++++++++++ drivers/gpu/drm/xen/xen_drm_front_shbuf.h | 72 +++++ 4 files changed, 513 insertions(+) create mode 100644 drivers/gpu/drm/xen/xen_drm_front_shbuf.c create mode 100644 drivers/gpu/drm/xen/xen_drm_front_shbuf.h
diff --git a/drivers/gpu/drm/xen/Makefile b/drivers/gpu/drm/xen/Makefile index 8417332f3b58..6c8c751f12ed 100644 --- a/drivers/gpu/drm/xen/Makefile +++ b/drivers/gpu/drm/xen/Makefile @@ -2,6 +2,7 @@
drm_xen_front-objs := xen_drm_front.o \ xen_drm_front_evtchnl.o \ + xen_drm_front_shbuf.o \ xen_drm_front_cfg.o
obj-$(CONFIG_DRM_XEN_FRONTEND) += drm_xen_front.o diff --git a/drivers/gpu/drm/xen/xen_drm_front.c b/drivers/gpu/drm/xen/xen_drm_front.c index 8312dab862e2..fae631067c31 100644 --- a/drivers/gpu/drm/xen/xen_drm_front.c +++ b/drivers/gpu/drm/xen/xen_drm_front.c @@ -18,6 +18,7 @@
#include "xen_drm_front.h" #include "xen_drm_front_evtchnl.h" +#include "xen_drm_front_shbuf.h"
static void xen_drv_remove_internal(struct xen_drm_front_info *front_info) { @@ -187,6 +188,13 @@ static struct xenbus_driver xen_driver = {
static int __init xen_drv_init(void) { + /* At the moment we only support case with XEN_PAGE_SIZE == PAGE_SIZE */ + if (XEN_PAGE_SIZE != PAGE_SIZE) { + DRM_ERROR(XENDISPL_DRIVER_NAME ": different kernel and Xen page sizes are not supported: XEN_PAGE_SIZE (%lu) != PAGE_SIZE (%lu)\n", + XEN_PAGE_SIZE, PAGE_SIZE); + return -ENODEV; + } + if (!xen_domain()) return -ENODEV;
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..0fde2d8f7706 --- /dev/null +++ b/drivers/gpu/drm/xen/xen_drm_front_shbuf.c @@ -0,0 +1,432 @@ +// 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); + if (buf->sgt) { + sg_free_table(buf->sgt); + kvfree(buf->pages); + } + 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) +{ + if (buf->sgt) { + buf->pages = kvmalloc_array(buf->num_pages, + sizeof(struct page *), GFP_KERNEL); + if (!buf->pages) + return -ENOMEM; + + if (drm_prime_sg_to_page_addr_arrays(buf->sgt, buf->pages, + NULL, buf->num_pages) < 0) + return -EINVAL; + } + + 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; + + /* either pages or sgt, not both */ + if (unlikely(cfg->pages && cfg->sgt)) { + DRM_ERROR("Cannot handle buffer allocation with both pages and sg table provided\n"); + return NULL; + } + + buf = kzalloc(sizeof(*buf), GFP_KERNEL); + if (!buf) + return NULL; + + 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->sgt = cfg->sgt; + 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); +} diff --git a/drivers/gpu/drm/xen/xen_drm_front_shbuf.h b/drivers/gpu/drm/xen/xen_drm_front_shbuf.h new file mode 100644 index 000000000000..6c4fbc68f328 --- /dev/null +++ b/drivers/gpu/drm/xen/xen_drm_front_shbuf.h @@ -0,0 +1,72 @@ +/* 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 + */ + +#ifndef __XEN_DRM_FRONT_SHBUF_H_ +#define __XEN_DRM_FRONT_SHBUF_H_ + +#include <linux/kernel.h> +#include <linux/scatterlist.h> + +#include <xen/grant_table.h> + +struct xen_drm_front_shbuf { + /* + * number of references granted for the backend use: + * - for allocated/imported dma-buf's this holds number of grant + * references for the page directory and pages of the buffer + * - for the buffer provided by the backend this holds number of + * grant references for the page directory as grant references for + * the buffer will be provided by the backend + */ + int num_grefs; + grant_ref_t *grefs; + unsigned char *directory; + + /* + * there are 2 ways to provide backing storage for this shared buffer: + * either pages or sgt. if buffer created from sgt then we own + * the pages and must free those ourselves on closure + */ + int num_pages; + struct page **pages; + + struct sg_table *sgt; + + struct xenbus_device *xb_dev; + + /* these are the ops used internally depending on be_alloc mode */ + const struct xen_drm_front_shbuf_ops *ops; + + /* Xen map handles for the buffer allocated by the backend */ + grant_handle_t *backend_map_handles; +}; + +struct xen_drm_front_shbuf_cfg { + struct xenbus_device *xb_dev; + size_t size; + struct page **pages; + struct sg_table *sgt; + bool be_alloc; +}; + +struct xen_drm_front_shbuf *xen_drm_front_shbuf_alloc( + struct xen_drm_front_shbuf_cfg *cfg); + +grant_ref_t xen_drm_front_shbuf_get_dir_start(struct xen_drm_front_shbuf *buf); + +int xen_drm_front_shbuf_map(struct xen_drm_front_shbuf *buf); + +int xen_drm_front_shbuf_unmap(struct xen_drm_front_shbuf *buf); + +void xen_drm_front_shbuf_flush(struct xen_drm_front_shbuf *buf); + +void xen_drm_front_shbuf_free(struct xen_drm_front_shbuf *buf); + +#endif /* __XEN_DRM_FRONT_SHBUF_H_ */