ALSA: xen-front: Use Xen common shared buffer implementation

Use page directory based shared buffer implementation
now available as common code for Xen frontend drivers.
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

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.

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

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);

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);

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 +221,20 @@ 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);
+	if (stream->buffer)
+		free_pages_exact(stream->buffer, stream->buffer_sz);
+	kfree(stream->pages);
 	stream_clear(stream);
 }
 
@@ -421,10 +436,34 @@ 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 = alloc_pages_exact(stream->buffer_sz, GFP_KERNEL);
+	if (!stream->buffer)
+		return -ENOMEM;
+
+	stream->buffer_sz = buffer_sz;
+	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 +471,32 @@ 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 +528,7 @@ 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 +608,10 @@ 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 +623,10 @@ 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 +638,14 @@ 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 +656,14 @@ 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 +674,10 @@ 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);
 }

sound/xen/xen_snd_front_shbuf.c

-// 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;
-}

sound/xen/xen_snd_front_shbuf.h

-/* 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 */