diff options
Diffstat (limited to 'sound/xen/xen_snd_front_shbuf.c')
| -rw-r--r-- | sound/xen/xen_snd_front_shbuf.c | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/sound/xen/xen_snd_front_shbuf.c b/sound/xen/xen_snd_front_shbuf.c new file mode 100644 index 000000000..07ac176a4 --- /dev/null +++ b/sound/xen/xen_snd_front_shbuf.c @@ -0,0 +1,194 @@ +// 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; +} |