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/xen/Makefile | 3 +- sound/xen/xen_snd_front.c | 8 ++ sound/xen/xen_snd_front_shbuf.c | 193 ++++++++++++++++++++++++++++++++ sound/xen/xen_snd_front_shbuf.h | 36 ++++++ 4 files changed, 239 insertions(+), 1 deletion(-) create mode 100644 sound/xen/xen_snd_front_shbuf.c create mode 100644 sound/xen/xen_snd_front_shbuf.h
diff --git a/sound/xen/Makefile b/sound/xen/Makefile index 03c669984000..f028bc30af5d 100644 --- a/sound/xen/Makefile +++ b/sound/xen/Makefile @@ -2,6 +2,7 @@
snd_xen_front-objs := xen_snd_front.o \ xen_snd_front_cfg.o \ - xen_snd_front_evtchnl.o + xen_snd_front_evtchnl.o \ + xen_snd_front_shbuf.o
obj-$(CONFIG_SND_XEN_FRONTEND) += snd_xen_front.o diff --git a/sound/xen/xen_snd_front.c b/sound/xen/xen_snd_front.c index 277214d4fd0a..cdf66ea516c4 100644 --- a/sound/xen/xen_snd_front.c +++ b/sound/xen/xen_snd_front.c @@ -11,6 +11,7 @@ #include <linux/delay.h> #include <linux/module.h>
+#include <xen/page.h> #include <xen/platform_pci.h> #include <xen/xen.h> #include <xen/xenbus.h> @@ -191,6 +192,13 @@ static int __init xen_drv_init(void) if (!xen_has_pv_devices()) return -ENODEV;
+ /* At the moment we only support case with XEN_PAGE_SIZE == PAGE_SIZE */ + if (XEN_PAGE_SIZE != PAGE_SIZE) { + pr_err(XENSND_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; + } + pr_info("Initialising Xen " XENSND_DRIVER_NAME " frontend driver\n"); return xenbus_register_frontend(&xen_driver); } diff --git a/sound/xen/xen_snd_front_shbuf.c b/sound/xen/xen_snd_front_shbuf.c new file mode 100644 index 000000000000..6845dbc7fdf5 --- /dev/null +++ b/sound/xen/xen_snd_front_shbuf.c @@ -0,0 +1,193 @@ +// 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 <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; +} diff --git a/sound/xen/xen_snd_front_shbuf.h b/sound/xen/xen_snd_front_shbuf.h new file mode 100644 index 000000000000..d28e97c47b2c --- /dev/null +++ b/sound/xen/xen_snd_front_shbuf.h @@ -0,0 +1,36 @@ +/* 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 + */ + +#ifndef __XEN_SND_FRONT_SHBUF_H +#define __XEN_SND_FRONT_SHBUF_H + +#include <xen/grant_table.h> + +#include "xen_snd_front_evtchnl.h" + +struct xen_snd_front_shbuf { + int num_grefs; + grant_ref_t *grefs; + u8 *directory; + u8 *buffer; + size_t buffer_sz; +}; + +grant_ref_t xen_snd_front_shbuf_get_dir_start(struct xen_snd_front_shbuf *buf); + +int xen_snd_front_shbuf_alloc(struct xenbus_device *xb_dev, + struct xen_snd_front_shbuf *buf, + unsigned int buffer_sz); + +void xen_snd_front_shbuf_clear(struct xen_snd_front_shbuf *buf); + +void xen_snd_front_shbuf_free(struct xen_snd_front_shbuf *buf); + +#endif /* __XEN_SND_FRONT_SHBUF_H */