[Xen-devel][PATCH 3/3] ALSA: xen-front: Use Xen common shared buffer implementation

From: Oleksandr Andrushchenko
Date: Thu Nov 22 2018 - 05:02:47 EST

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>

Use page directory based shared buffer implementation
now available as common code for Xen frontend drivers.

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
---
sound/xen/Kconfig | 1 +
sound/xen/Makefile | 1 -
sound/xen/xen_snd_front.c | 7 +-
sound/xen/xen_snd_front.h | 4 +-
sound/xen/xen_snd_front_alsa.c | 101 +++++++++++++----
sound/xen/xen_snd_front_shbuf.c | 194 --------------------------------
sound/xen/xen_snd_front_shbuf.h | 36 ------
7 files changed, 83 insertions(+), 261 deletions(-)
delete mode 100644 sound/xen/xen_snd_front_shbuf.c
delete mode 100644 sound/xen/xen_snd_front_shbuf.h

diff --git a/sound/xen/Kconfig b/sound/xen/Kconfig
index 4f1fceea82d2..e4d7beb4df1c 100644
--- a/sound/xen/Kconfig
+++ b/sound/xen/Kconfig
@@ -5,6 +5,7 @@ config SND_XEN_FRONTEND
depends on XEN
select SND_PCM
select XEN_XENBUS_FRONTEND
+ select XEN_FRONT_PGDIR_SHBUF
help
Choose this option if you want to enable a para-virtualized
frontend sound driver for Xen guest OSes.
diff --git a/sound/xen/Makefile b/sound/xen/Makefile
index 1e6470ecc2f2..24031775b715 100644
--- a/sound/xen/Makefile
+++ b/sound/xen/Makefile
@@ -3,7 +3,6 @@
snd_xen_front-objs := xen_snd_front.o \
xen_snd_front_cfg.o \
xen_snd_front_evtchnl.o \
- xen_snd_front_shbuf.o \
xen_snd_front_alsa.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 b089b13b5160..a9e5c2cd7698 100644
--- a/sound/xen/xen_snd_front.c
+++ b/sound/xen/xen_snd_front.c
@@ -16,12 +16,12 @@
#include <xen/xen.h>
#include <xen/xenbus.h>

+#include <xen/xen-front-pgdir-shbuf.h>
#include <xen/interface/io/sndif.h>

#include "xen_snd_front.h"
#include "xen_snd_front_alsa.h"
#include "xen_snd_front_evtchnl.h"
-#include "xen_snd_front_shbuf.h"

static struct xensnd_req *
be_stream_prepare_req(struct xen_snd_front_evtchnl *evtchnl, u8 operation)
@@ -82,7 +82,7 @@ int xen_snd_front_stream_query_hw_param(struct xen_snd_front_evtchnl *evtchnl,
}

int xen_snd_front_stream_prepare(struct xen_snd_front_evtchnl *evtchnl,
- struct xen_snd_front_shbuf *sh_buf,
+ struct xen_front_pgdir_shbuf *shbuf,
u8 format, unsigned int channels,
unsigned int rate, u32 buffer_sz,
u32 period_sz)
@@ -99,7 +99,8 @@ int xen_snd_front_stream_prepare(struct xen_snd_front_evtchnl *evtchnl,
req->op.open.pcm_rate = rate;
req->op.open.buffer_sz = buffer_sz;
req->op.open.period_sz = period_sz;
- req->op.open.gref_directory = xen_snd_front_shbuf_get_dir_start(sh_buf);
+ req->op.open.gref_directory =
+ xen_front_pgdir_shbuf_get_dir_start(shbuf);
mutex_unlock(&evtchnl->ring_io_lock);

ret = be_stream_do_io(evtchnl);
diff --git a/sound/xen/xen_snd_front.h b/sound/xen/xen_snd_front.h
index a2ea2463bcc5..05611f113b94 100644
--- a/sound/xen/xen_snd_front.h
+++ b/sound/xen/xen_snd_front.h
@@ -16,7 +16,7 @@
struct xen_snd_front_card_info;
struct xen_snd_front_evtchnl;
struct xen_snd_front_evtchnl_pair;
-struct xen_snd_front_shbuf;
+struct xen_front_pgdir_shbuf;
struct xensnd_query_hw_param;

struct xen_snd_front_info {
@@ -35,7 +35,7 @@ int xen_snd_front_stream_query_hw_param(struct xen_snd_front_evtchnl *evtchnl,
struct xensnd_query_hw_param *hw_param_resp);

int xen_snd_front_stream_prepare(struct xen_snd_front_evtchnl *evtchnl,
- struct xen_snd_front_shbuf *sh_buf,
+ struct xen_front_pgdir_shbuf *shbuf,
u8 format, unsigned int channels,
unsigned int rate, u32 buffer_sz,
u32 period_sz);
diff --git a/sound/xen/xen_snd_front_alsa.c b/sound/xen/xen_snd_front_alsa.c
index 129180e17db1..5b874a7014e0 100644
--- a/sound/xen/xen_snd_front_alsa.c
+++ b/sound/xen/xen_snd_front_alsa.c
@@ -15,17 +15,24 @@
#include <sound/pcm_params.h>

#include <xen/xenbus.h>
+#include <xen/xen-front-pgdir-shbuf.h>

#include "xen_snd_front.h"
#include "xen_snd_front_alsa.h"
#include "xen_snd_front_cfg.h"
#include "xen_snd_front_evtchnl.h"
-#include "xen_snd_front_shbuf.h"

struct xen_snd_front_pcm_stream_info {
struct xen_snd_front_info *front_info;
struct xen_snd_front_evtchnl_pair *evt_pair;
- struct xen_snd_front_shbuf sh_buf;
+
+ /* This is the shared buffer with its backing storage. */
+ struct xen_front_pgdir_shbuf shbuf;
+ u8 *buffer;
+ size_t buffer_sz;
+ int num_pages;
+ struct page **pages;
+
int index;

bool is_open;
@@ -214,12 +221,19 @@ static void stream_clear(struct xen_snd_front_pcm_stream_info *stream)
stream->out_frames = 0;
atomic_set(&stream->hw_ptr, 0);
xen_snd_front_evtchnl_pair_clear(stream->evt_pair);
- xen_snd_front_shbuf_clear(&stream->sh_buf);
+ memset(&stream->shbuf, 0, sizeof(stream->shbuf));
+ stream->buffer = NULL;
+ stream->buffer_sz = 0;
+ stream->pages = NULL;
+ stream->num_pages = 0;
}

static void stream_free(struct xen_snd_front_pcm_stream_info *stream)
{
- xen_snd_front_shbuf_free(&stream->sh_buf);
+ xen_front_pgdir_shbuf_unmap(&stream->shbuf);
+ xen_front_pgdir_shbuf_free(&stream->shbuf);
+ free_pages_exact(stream->buffer, stream->buffer_sz);
+ kfree(stream->pages);
stream_clear(stream);
}

@@ -421,10 +435,34 @@ static int alsa_close(struct snd_pcm_substream *substream)
return 0;
}

+static int shbuf_setup_backstore(struct xen_snd_front_pcm_stream_info *stream,
+ size_t buffer_sz)
+{
+ int i;
+
+ stream->buffer_sz = buffer_sz;
+ stream->buffer = alloc_pages_exact(stream->buffer_sz, GFP_KERNEL);
+ if (!stream->buffer)
+ return -ENOMEM;
+
+ stream->num_pages = DIV_ROUND_UP(stream->buffer_sz, PAGE_SIZE);
+ stream->pages = kcalloc(stream->num_pages, sizeof(struct page *),
+ GFP_KERNEL);
+ if (!stream->pages)
+ return -ENOMEM;
+
+ for (i = 0; i < stream->num_pages; i++)
+ stream->pages[i] = virt_to_page(stream->buffer + i * PAGE_SIZE);
+
+ return 0;
+}
+
static int alsa_hw_params(struct snd_pcm_substream *substream,
struct snd_pcm_hw_params *params)
{
struct xen_snd_front_pcm_stream_info *stream = stream_get(substream);
+ struct xen_snd_front_info *front_info = stream->front_info;
+ struct xen_front_pgdir_shbuf_cfg buf_cfg;
int ret;

/*
@@ -432,19 +470,32 @@ static int alsa_hw_params(struct snd_pcm_substream *substream,
* so free the previously allocated shared buffer if any.
*/
stream_free(stream);
+ ret = shbuf_setup_backstore(stream, params_buffer_bytes(params));
+ if (ret < 0)
+ goto fail;

- ret = xen_snd_front_shbuf_alloc(stream->front_info->xb_dev,
- &stream->sh_buf,
- params_buffer_bytes(params));
- if (ret < 0) {
- stream_free(stream);
- dev_err(&stream->front_info->xb_dev->dev,
- "Failed to allocate buffers for stream with index %d\n",
- stream->index);
- return ret;
- }
+ memset(&buf_cfg, 0, sizeof(buf_cfg));
+ buf_cfg.xb_dev = front_info->xb_dev;
+ buf_cfg.pgdir = &stream->shbuf;
+ buf_cfg.num_pages = stream->num_pages;
+ buf_cfg.pages = stream->pages;
+
+ ret = xen_front_pgdir_shbuf_alloc(&buf_cfg);
+ if (ret < 0)
+ goto fail;
+
+ ret = xen_front_pgdir_shbuf_map(&stream->shbuf);
+ if (ret < 0)
+ goto fail;

return 0;
+
+fail:
+ stream_free(stream);
+ dev_err(&front_info->xb_dev->dev,
+ "Failed to allocate buffers for stream with index %d\n",
+ stream->index);
+ return ret;
}

static int alsa_hw_free(struct snd_pcm_substream *substream)
@@ -476,7 +527,7 @@ static int alsa_prepare(struct snd_pcm_substream *substream)
sndif_format = ret;

ret = xen_snd_front_stream_prepare(&stream->evt_pair->req,
- &stream->sh_buf,
+ &stream->shbuf,
sndif_format,
runtime->channels,
runtime->rate,
@@ -556,10 +607,10 @@ static int alsa_pb_copy_user(struct snd_pcm_substream *substream,
{
struct xen_snd_front_pcm_stream_info *stream = stream_get(substream);

- if (unlikely(pos + count > stream->sh_buf.buffer_sz))
+ if (unlikely(pos + count > stream->buffer_sz))
return -EINVAL;

- if (copy_from_user(stream->sh_buf.buffer + pos, src, count))
+ if (copy_from_user(stream->buffer + pos, src, count))
return -EFAULT;

return xen_snd_front_stream_write(&stream->evt_pair->req, pos, count);
@@ -571,10 +622,10 @@ static int alsa_pb_copy_kernel(struct snd_pcm_substream *substream,
{
struct xen_snd_front_pcm_stream_info *stream = stream_get(substream);

- if (unlikely(pos + count > stream->sh_buf.buffer_sz))
+ if (unlikely(pos + count > stream->buffer_sz))
return -EINVAL;

- memcpy(stream->sh_buf.buffer + pos, src, count);
+ memcpy(stream->buffer + pos, src, count);

return xen_snd_front_stream_write(&stream->evt_pair->req, pos, count);
}
@@ -586,14 +637,14 @@ static int alsa_cap_copy_user(struct snd_pcm_substream *substream,
struct xen_snd_front_pcm_stream_info *stream = stream_get(substream);
int ret;

- if (unlikely(pos + count > stream->sh_buf.buffer_sz))
+ if (unlikely(pos + count > stream->buffer_sz))
return -EINVAL;

ret = xen_snd_front_stream_read(&stream->evt_pair->req, pos, count);
if (ret < 0)
return ret;

- return copy_to_user(dst, stream->sh_buf.buffer + pos, count) ?
+ return copy_to_user(dst, stream->buffer + pos, count) ?
-EFAULT : 0;
}

@@ -604,14 +655,14 @@ static int alsa_cap_copy_kernel(struct snd_pcm_substream *substream,
struct xen_snd_front_pcm_stream_info *stream = stream_get(substream);
int ret;

- if (unlikely(pos + count > stream->sh_buf.buffer_sz))
+ if (unlikely(pos + count > stream->buffer_sz))
return -EINVAL;

ret = xen_snd_front_stream_read(&stream->evt_pair->req, pos, count);
if (ret < 0)
return ret;

- memcpy(dst, stream->sh_buf.buffer + pos, count);
+ memcpy(dst, stream->buffer + pos, count);

return 0;
}
@@ -622,10 +673,10 @@ static int alsa_pb_fill_silence(struct snd_pcm_substream *substream,
{
struct xen_snd_front_pcm_stream_info *stream = stream_get(substream);

- if (unlikely(pos + count > stream->sh_buf.buffer_sz))
+ if (unlikely(pos + count > stream->buffer_sz))
return -EINVAL;

- memset(stream->sh_buf.buffer + pos, 0, count);
+ memset(stream->buffer + pos, 0, count);

return xen_snd_front_stream_write(&stream->evt_pair->req, pos, count);
}
diff --git a/sound/xen/xen_snd_front_shbuf.c b/sound/xen/xen_snd_front_shbuf.c
deleted file mode 100644
index 07ac176a41ba..000000000000
--- a/sound/xen/xen_snd_front_shbuf.c
+++ /dev/null
@@ -1,194 +0,0 @@
-// 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@xxxxxxxx>
- */
-
-#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;
-}
diff --git a/sound/xen/xen_snd_front_shbuf.h b/sound/xen/xen_snd_front_shbuf.h
deleted file mode 100644
index d28e97c47b2c..000000000000
--- a/sound/xen/xen_snd_front_shbuf.h
+++ /dev/null
@@ -1,36 +0,0 @@
-/* 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@xxxxxxxx>
- */
-
-#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 */
--
2.19.1