[PATCH RESEND 05/11] ALSA: vsnd: Implement handling of shared buffers

[Oleksandr Andrushchenko]

From: Oleksandr Andrushchenko 

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 
---
 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(_dir->gref, >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, _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(_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(_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 

[PATCH RESEND 05/11] ALSA: vsnd: Implement handling of shared buffers

[Oleksandr Andrushchenko]

From: Oleksandr Andrushchenko 

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 
---
 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(_dir->gref, >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, _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(_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(_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