From: Oleksandr Andrushchenko oleksandr_andrushchenko@epam.com
Implement shared buffer handling according to the para-virtualized sound device protocol at xen/interface/io/sndif.h: - manage buffer memory - handle granted references - handle page directories
Signed-off-by: Oleksandr Andrushchenko oleksandr_andrushchenko@epam.com --- sound/drivers/xen-front.c | 178 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 178 insertions(+)
diff --git a/sound/drivers/xen-front.c b/sound/drivers/xen-front.c index a92459b2737e..04ebc15757f4 100644 --- a/sound/drivers/xen-front.c +++ b/sound/drivers/xen-front.c @@ -58,6 +58,14 @@ struct xdrv_evtchnl_info { uint16_t resp_id; };
+struct sh_buf_info { + int num_grefs; + grant_ref_t *grefs; + uint8_t *vdirectory; + uint8_t *vbuffer; + size_t vbuffer_sz; +}; + struct cfg_stream { int unique_id; char *xenstore_path; @@ -825,6 +833,176 @@ static void xdrv_remove_internal(struct xdrv_info *drv_info) xdrv_evtchnl_free_all(drv_info); }
+static inline grant_ref_t sh_buf_get_dir_start(struct sh_buf_info *buf) +{ + if (!buf->grefs) + return GRANT_INVALID_REF; + return buf->grefs[0]; +} + +static inline void sh_buf_clear(struct sh_buf_info *buf) +{ + memset(buf, 0, sizeof(*buf)); +} + +static void sh_buf_free(struct sh_buf_info *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->vdirectory); + free_pages_exact(buf->vbuffer, buf->vbuffer_sz); + sh_buf_clear(buf); +} + +/* + * number of grant references a page can hold with respect to the + * xendispl_page_directory header + */ +#define XENSND_NUM_GREFS_PER_PAGE ((XEN_PAGE_SIZE - \ + offsetof(struct xensnd_page_directory, gref)) / \ + sizeof(grant_ref_t)) + +static void sh_buf_fill_page_dir(struct sh_buf_info *buf, int num_pages_dir) +{ + struct xensnd_page_directory *page_dir; + unsigned char *ptr; + int i, cur_gref, grefs_left, to_copy; + + ptr = buf->vdirectory; + 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 sh_buf_grant_refs(struct xenbus_device *xb_dev, + struct sh_buf_info *buf, + int num_pages_dir, int num_pages_vbuffer, int num_grefs) +{ + grant_ref_t priv_gref_head; + 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; + } + + gnttab_grant_foreign_access_ref(cur_ref, otherend_id, + xen_page_to_gfn(virt_to_page(buf->vdirectory + + XEN_PAGE_SIZE * i)), 0); + buf->grefs[j++] = cur_ref; + } + + for (i = 0; i < num_pages_vbuffer; i++) { + cur_ref = gnttab_claim_grant_reference(&priv_gref_head); + if (cur_ref < 0) { + ret = cur_ref; + goto fail; + } + + gnttab_grant_foreign_access_ref(cur_ref, otherend_id, + xen_page_to_gfn(virt_to_page(buf->vbuffer + + XEN_PAGE_SIZE * i)), 0); + buf->grefs[j++] = cur_ref; + } + + gnttab_free_grant_references(priv_gref_head); + sh_buf_fill_page_dir(buf, num_pages_dir); + return 0; + +fail: + gnttab_free_grant_references(priv_gref_head); + return ret; +} + +static int sh_buf_alloc_int_buffers(struct sh_buf_info *buf, + int num_pages_dir, int num_pages_vbuffer, int num_grefs) +{ + buf->grefs = kcalloc(num_grefs, sizeof(*buf->grefs), GFP_KERNEL); + if (!buf->grefs) + return -ENOMEM; + + buf->vdirectory = kcalloc(num_pages_dir, XEN_PAGE_SIZE, GFP_KERNEL); + if (!buf->vdirectory) + goto fail; + + buf->vbuffer_sz = num_pages_vbuffer * XEN_PAGE_SIZE; + buf->vbuffer = alloc_pages_exact(buf->vbuffer_sz, GFP_KERNEL); + if (!buf->vbuffer) + goto fail; + return 0; + +fail: + kfree(buf->grefs); + buf->grefs = NULL; + kfree(buf->vdirectory); + buf->vdirectory = NULL; + return -ENOMEM; +} + +static int sh_buf_alloc(struct xenbus_device *xb_dev, + struct sh_buf_info *buf, unsigned int buffer_size) +{ + int num_pages_vbuffer, num_pages_dir, num_grefs; + int ret; + + sh_buf_clear(buf); + + num_pages_vbuffer = DIV_ROUND_UP(buffer_size, XEN_PAGE_SIZE); + /* number of pages the page directory consumes itself */ + num_pages_dir = DIV_ROUND_UP(num_pages_vbuffer, + XENSND_NUM_GREFS_PER_PAGE); + num_grefs = num_pages_vbuffer + num_pages_dir; + + ret = sh_buf_alloc_int_buffers(buf, num_pages_dir, + num_pages_vbuffer, num_grefs); + if (ret < 0) + return ret; + + ret = sh_buf_grant_refs(xb_dev, buf, + num_pages_dir, num_pages_vbuffer, num_grefs); + if (ret < 0) + return ret; + + sh_buf_fill_page_dir(buf, num_pages_dir); + return 0; +} + static int xdrv_be_on_initwait(struct xdrv_info *drv_info) { int stream_idx;