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>

7 files changed, 84 insertions, 261 deletions

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 2cbd9679aca1..a7f413cb704d 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 +221,20 @@ 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);
 }
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@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;
-}
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@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 */