[PATCH v3 00/21] xen: simplify frontend side ring setup

[PATCH v3 00/21] xen: simplify frontend side ring setup

[Juergen Gross]

Many Xen PV frontends share similar code for setting up a ring page
(allocating and granting access for the backend) and for tearing it
down.

Create new service functions doing all needed steps in one go.

This requires all frontends to use a common value for an invalid
grant reference in order to make the functions idempotent.

Changes in V3:
- new patches 1 and 2, comments addressed

Changes in V2:
- new patch 9 and related changes in patches 10-18

Juergen Gross (21):
  xen: update grant_table.h
  xen/grant-table: never put a reserved grant on the free list
  xen/blkfront: switch blkfront to use INVALID_GRANT_REF
  xen/netfront: switch netfront to use INVALID_GRANT_REF
  xen/scsifront: remove unused GRANT_INVALID_REF definition
  xen/usb: switch xen-hcd to use INVALID_GRANT_REF
  xen/drm: switch xen_drm_front to use INVALID_GRANT_REF
  xen/sound: switch xen_snd_front to use INVALID_GRANT_REF
  xen/dmabuf: switch gntdev-dmabuf to use INVALID_GRANT_REF
  xen/shbuf: switch xen-front-pgdir-shbuf to use INVALID_GRANT_REF
  xen: update ring.h
  xen/xenbus: add xenbus_setup_ring() service function
  xen/blkfront: use xenbus_setup_ring() and xenbus_teardown_ring()
  xen/netfront: use xenbus_setup_ring() and xenbus_teardown_ring()
  xen/tpmfront: use xenbus_setup_ring() and xenbus_teardown_ring()
  xen/drmfront: use xenbus_setup_ring() and xenbus_teardown_ring()
  xen/pcifront: use xenbus_setup_ring() and xenbus_teardown_ring()
  xen/scsifront: use xenbus_setup_ring() and xenbus_teardown_ring()
  xen/usbfront: use xenbus_setup_ring() and xenbus_teardown_ring()
  xen/sndfront: use xenbus_setup_ring() and xenbus_teardown_ring()
  xen/xenbus: eliminate xenbus_grant_ring()

 drivers/block/xen-blkfront.c                |  57 +++----
 drivers/char/tpm/xen-tpmfront.c             |  18 +--
 drivers/gpu/drm/xen/xen_drm_front.h         |   9 --
 drivers/gpu/drm/xen/xen_drm_front_evtchnl.c |  43 ++----
 drivers/net/xen-netfront.c                  |  85 ++++-------
 drivers/pci/xen-pcifront.c                  |  19 +--
 drivers/scsi/xen-scsifront.c                |  31 +---
 drivers/usb/host/xen-hcd.c                  |  65 ++------
 drivers/xen/gntdev-dmabuf.c                 |  13 +-
 drivers/xen/grant-table.c                   |  12 +-
 drivers/xen/xen-front-pgdir-shbuf.c         |  18 +--
 drivers/xen/xenbus/xenbus_client.c          |  82 +++++++---
 include/xen/grant_table.h                   |   2 -
 include/xen/interface/grant_table.h         | 161 ++++++++++++--------
 include/xen/interface/io/ring.h             |  19 ++-
 include/xen/xenbus.h                        |   4 +-
 sound/xen/xen_snd_front_evtchnl.c           |  44 ++----
 sound/xen/xen_snd_front_evtchnl.h           |   9 --
 18 files changed, 287 insertions(+), 404 deletions(-)

-- 
2.35.3

[PATCH v3 01/21] xen: update grant_table.h

[Juergen Gross]

Update include/xen/interface/grant_table.h to its newest version.

This allows to drop some private definitions in grant-table.c and
include/xen/grant_table.h.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
V3:
- new patch
---
 drivers/xen/grant-table.c           |   8 +-
 include/xen/grant_table.h           |   2 -
 include/xen/interface/grant_table.h | 161 +++++++++++++++++-----------
 3 files changed, 103 insertions(+), 68 deletions(-)

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 8ccccace2a4f..6ea31ea26008 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -66,8 +66,6 @@
 
 #include <asm/sync_bitops.h>
 
-/* External tools reserve first few grant table entries. */
-#define NR_RESERVED_ENTRIES 8
 #define GNTTAB_LIST_END 0xffffffff
 
 static grant_ref_t **gnttab_list;
@@ -1465,12 +1463,12 @@ int gnttab_init(void)
 	nr_init_grefs = nr_grant_frames *
 			gnttab_interface->grefs_per_grant_frame;
 
-	for (i = NR_RESERVED_ENTRIES; i < nr_init_grefs - 1; i++)
+	for (i = GNTTAB_NR_RESERVED_ENTRIES; i < nr_init_grefs - 1; i++)
 		gnttab_entry(i) = i + 1;
 
 	gnttab_entry(nr_init_grefs - 1) = GNTTAB_LIST_END;
-	gnttab_free_count = nr_init_grefs - NR_RESERVED_ENTRIES;
-	gnttab_free_head  = NR_RESERVED_ENTRIES;
+	gnttab_free_count = nr_init_grefs - GNTTAB_NR_RESERVED_ENTRIES;
+	gnttab_free_head  = GNTTAB_NR_RESERVED_ENTRIES;
 
 	printk("Grant table initialized\n");
 	return 0;
diff --git a/include/xen/grant_table.h b/include/xen/grant_table.h
index dfd5bf31cfb9..7d0f2f0037b8 100644
--- a/include/xen/grant_table.h
+++ b/include/xen/grant_table.h
@@ -57,8 +57,6 @@
 #define INVALID_GRANT_REF          ((grant_ref_t)-1)
 #define INVALID_GRANT_HANDLE       ((grant_handle_t)-1)
 
-#define GNTTAB_RESERVED_XENSTORE 1
-
 /* NR_GRANT_FRAMES must be less than or equal to that configured in Xen */
 #define NR_GRANT_FRAMES 4
 
diff --git a/include/xen/interface/grant_table.h b/include/xen/interface/grant_table.h
index 3eeabbc7ee09..cebbd99f1f84 100644
--- a/include/xen/interface/grant_table.h
+++ b/include/xen/interface/grant_table.h
@@ -19,7 +19,8 @@
 
 /* Some rough guidelines on accessing and updating grant-table entries
  * in a concurrency-safe manner. For more information, Linux contains a
- * reference implementation for guest OSes (arch/xen/kernel/grant_table.c).
+ * reference implementation for guest OSes (drivers/xen/grant_table.c, see
+ * http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=drivers/xen/grant-table.c;hb=HEAD
  *
  * NB. WMB is a no-op on current-generation x86 processors. However, a
  *     compiler barrier will still be required.
@@ -80,8 +81,9 @@ typedef uint32_t grant_ref_t;
  */
 
 /*
- * Version 1 of the grant table entry structure is maintained purely
- * for backwards compatibility.  New guests should use version 2.
+ * Version 1 of the grant table entry structure is maintained largely for
+ * backwards compatibility.  New guests are recommended to support using
+ * version 2 to overcome version 1 limitations, but to default to version 1.
  */
 struct grant_entry_v1 {
     /* GTF_xxx: various type and flag information.  [XEN,GST] */
@@ -89,12 +91,21 @@ struct grant_entry_v1 {
     /* The domain being granted foreign privileges. [GST] */
     domid_t  domid;
     /*
-     * GTF_permit_access: Frame that @domid is allowed to map and access. [GST]
-     * GTF_accept_transfer: Frame whose ownership transferred by @domid. [XEN]
+     * GTF_permit_access: GFN that @domid is allowed to map and access. [GST]
+     * GTF_accept_transfer: GFN that @domid is allowed to transfer into. [GST]
+     * GTF_transfer_completed: MFN whose ownership transferred by @domid
+     *                         (non-translated guests only). [XEN]
      */
     uint32_t frame;
 };
 
+/* The first few grant table entries will be preserved across grant table
+ * version changes and may be pre-populated at domain creation by tools.
+ */
+#define GNTTAB_NR_RESERVED_ENTRIES     8
+#define GNTTAB_RESERVED_CONSOLE        0
+#define GNTTAB_RESERVED_XENSTORE       1
+
 /*
  * Type of grant entry.
  *  GTF_invalid: This grant entry grants no privileges.
@@ -111,10 +122,13 @@ struct grant_entry_v1 {
 #define GTF_type_mask       (3U<<0)
 
 /*
- * Subflags for GTF_permit_access.
+ * Subflags for GTF_permit_access and GTF_transitive.
  *  GTF_readonly: Restrict @domid to read-only mappings and accesses. [GST]
  *  GTF_reading: Grant entry is currently mapped for reading by @domid. [XEN]
  *  GTF_writing: Grant entry is currently mapped for writing by @domid. [XEN]
+ * Further subflags for GTF_permit_access only.
+ *  GTF_PAT, GTF_PWT, GTF_PCD: (x86) cache attribute flags to be used for
+ *                             mappings of the grant [GST]
  *  GTF_sub_page: Grant access to only a subrange of the page.  @domid
  *                will only be allowed to copy from the grant, and not
  *                map it. [GST]
@@ -125,6 +139,12 @@ struct grant_entry_v1 {
 #define GTF_reading         (1U<<_GTF_reading)
 #define _GTF_writing        (4)
 #define GTF_writing         (1U<<_GTF_writing)
+#define _GTF_PWT            (5)
+#define GTF_PWT             (1U<<_GTF_PWT)
+#define _GTF_PCD            (6)
+#define GTF_PCD             (1U<<_GTF_PCD)
+#define _GTF_PAT            (7)
+#define GTF_PAT             (1U<<_GTF_PAT)
 #define _GTF_sub_page       (8)
 #define GTF_sub_page        (1U<<_GTF_sub_page)
 
@@ -164,8 +184,7 @@ struct grant_entry_header {
 };
 
 /*
- * Version 2 of the grant entry structure, here is a union because three
- * different types are suppotted: full_page, sub_page and transitive.
+ * Version 2 of the grant entry structure.
  */
 union grant_entry_v2 {
     struct grant_entry_header hdr;
@@ -180,9 +199,9 @@ union grant_entry_v2 {
      * field of the same name in the V1 entry structure.
      */
     struct {
-	struct grant_entry_header hdr;
-	uint32_t pad0;
-	uint64_t frame;
+        struct grant_entry_header hdr;
+        uint32_t pad0;
+        uint64_t frame;
     } full_page;
 
     /*
@@ -191,10 +210,10 @@ union grant_entry_v2 {
      * in frame @frame.
      */
     struct {
-	struct grant_entry_header hdr;
-	uint16_t page_off;
-	uint16_t length;
-	uint64_t frame;
+        struct grant_entry_header hdr;
+        uint16_t page_off;
+        uint16_t length;
+        uint64_t frame;
     } sub_page;
 
     /*
@@ -202,12 +221,15 @@ union grant_entry_v2 {
      * grant @gref in domain @trans_domid, as if it was the local
      * domain.  Obviously, the transitive access must be compatible
      * with the original grant.
+     *
+     * The current version of Xen does not allow transitive grants
+     * to be mapped.
      */
     struct {
-	struct grant_entry_header hdr;
-	domid_t trans_domid;
-	uint16_t pad0;
-	grant_ref_t gref;
+        struct grant_entry_header hdr;
+        domid_t trans_domid;
+        uint16_t pad0;
+        grant_ref_t gref;
     } transitive;
 
     uint32_t __spacer[4]; /* Pad to a power of two */
@@ -219,6 +241,21 @@ typedef uint16_t grant_status_t;
  * GRANT TABLE QUERIES AND USES
  */
 
+#define GNTTABOP_map_grant_ref        0
+#define GNTTABOP_unmap_grant_ref      1
+#define GNTTABOP_setup_table          2
+#define GNTTABOP_dump_table           3
+#define GNTTABOP_transfer             4
+#define GNTTABOP_copy                 5
+#define GNTTABOP_query_size           6
+#define GNTTABOP_unmap_and_replace    7
+#define GNTTABOP_set_version          8
+#define GNTTABOP_get_status_frames    9
+#define GNTTABOP_get_version          10
+#define GNTTABOP_swap_grant_ref	      11
+#define GNTTABOP_cache_flush	      12
+/* ` } */
+
 /*
  * Handle to track a mapping created via a grant reference.
  */
@@ -227,7 +264,7 @@ typedef uint32_t grant_handle_t;
 /*
  * GNTTABOP_map_grant_ref: Map the grant entry (<dom>,<ref>) for access
  * by devices and/or host CPUs. If successful, <handle> is a tracking number
- * that must be presented later to destroy the mapping(s). On error, <handle>
+ * that must be presented later to destroy the mapping(s). On error, <status>
  * is a negative status code.
  * NOTES:
  *  1. If GNTMAP_device_map is specified then <dev_bus_addr> is the address
@@ -241,7 +278,6 @@ typedef uint32_t grant_handle_t;
  *     host mapping is destroyed by other means then it is *NOT* guaranteed
  *     to be accounted to the correct grant reference!
  */
-#define GNTTABOP_map_grant_ref        0
 struct gnttab_map_grant_ref {
     /* IN parameters. */
     uint64_t host_addr;
@@ -266,7 +302,6 @@ DEFINE_GUEST_HANDLE_STRUCT(gnttab_map_grant_ref);
  *  3. After executing a batch of unmaps, it is guaranteed that no stale
  *     mappings will remain in the device or host TLBs.
  */
-#define GNTTABOP_unmap_grant_ref      1
 struct gnttab_unmap_grant_ref {
     /* IN parameters. */
     uint64_t host_addr;
@@ -286,7 +321,6 @@ DEFINE_GUEST_HANDLE_STRUCT(gnttab_unmap_grant_ref);
  *  2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF.
  *  3. Xen may not support more than a single grant-table page per domain.
  */
-#define GNTTABOP_setup_table          2
 struct gnttab_setup_table {
     /* IN parameters. */
     domid_t  dom;
@@ -301,7 +335,6 @@ DEFINE_GUEST_HANDLE_STRUCT(gnttab_setup_table);
  * GNTTABOP_dump_table: Dump the contents of the grant table to the
  * xen console. Debugging use only.
  */
-#define GNTTABOP_dump_table           3
 struct gnttab_dump_table {
     /* IN parameters. */
     domid_t dom;
@@ -311,17 +344,17 @@ struct gnttab_dump_table {
 DEFINE_GUEST_HANDLE_STRUCT(gnttab_dump_table);
 
 /*
- * GNTTABOP_transfer_grant_ref: Transfer <frame> to a foreign domain. The
- * foreign domain has previously registered its interest in the transfer via
- * <domid, ref>.
+ * GNTTABOP_transfer: Transfer <frame> to a foreign domain. The foreign domain
+ * has previously registered its interest in the transfer via <domid, ref>.
  *
  * Note that, even if the transfer fails, the specified page no longer belongs
  * to the calling domain *unless* the error is GNTST_bad_page.
+ *
+ * Note further that only PV guests can use this operation.
  */
-#define GNTTABOP_transfer                4
 struct gnttab_transfer {
     /* IN parameters. */
-    xen_pfn_t mfn;
+    xen_pfn_t     mfn;
     domid_t       domid;
     grant_ref_t   ref;
     /* OUT parameters. */
@@ -352,21 +385,20 @@ DEFINE_GUEST_HANDLE_STRUCT(gnttab_transfer);
 #define _GNTCOPY_dest_gref        (1)
 #define GNTCOPY_dest_gref         (1<<_GNTCOPY_dest_gref)
 
-#define GNTTABOP_copy                 5
 struct gnttab_copy {
-	/* IN parameters. */
-	struct {
-		union {
-			grant_ref_t ref;
-			xen_pfn_t   gmfn;
-		} u;
-		domid_t  domid;
-		uint16_t offset;
-	} source, dest;
-	uint16_t      len;
-	uint16_t      flags;          /* GNTCOPY_* */
-	/* OUT parameters. */
-	int16_t       status;
+    /* IN parameters. */
+    struct gnttab_copy_ptr {
+        union {
+            grant_ref_t ref;
+            xen_pfn_t   gmfn;
+        } u;
+        domid_t  domid;
+        uint16_t offset;
+    } source, dest;
+    uint16_t      len;
+    uint16_t      flags;          /* GNTCOPY_* */
+    /* OUT parameters. */
+    int16_t       status;
 };
 DEFINE_GUEST_HANDLE_STRUCT(gnttab_copy);
 
@@ -377,7 +409,6 @@ DEFINE_GUEST_HANDLE_STRUCT(gnttab_copy);
  *  1. <dom> may be specified as DOMID_SELF.
  *  2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF.
  */
-#define GNTTABOP_query_size           6
 struct gnttab_query_size {
     /* IN parameters. */
     domid_t  dom;
@@ -399,7 +430,6 @@ DEFINE_GUEST_HANDLE_STRUCT(gnttab_query_size);
  *  2. After executing a batch of unmaps, it is guaranteed that no stale
  *     mappings will remain in the device or host TLBs.
  */
-#define GNTTABOP_unmap_and_replace    7
 struct gnttab_unmap_and_replace {
     /* IN parameters. */
     uint64_t host_addr;
@@ -412,14 +442,12 @@ DEFINE_GUEST_HANDLE_STRUCT(gnttab_unmap_and_replace);
 
 /*
  * GNTTABOP_set_version: Request a particular version of the grant
- * table shared table structure.  This operation can only be performed
- * once in any given domain.  It must be performed before any grants
- * are activated; otherwise, the domain will be stuck with version 1.
- * The only defined versions are 1 and 2.
+ * table shared table structure.  This operation may be used to toggle
+ * between different versions, but must be performed while no grants
+ * are active.  The only defined versions are 1 and 2.
  */
-#define GNTTABOP_set_version          8
 struct gnttab_set_version {
-    /* IN parameters */
+    /* IN/OUT parameters */
     uint32_t version;
 };
 DEFINE_GUEST_HANDLE_STRUCT(gnttab_set_version);
@@ -436,7 +464,6 @@ DEFINE_GUEST_HANDLE_STRUCT(gnttab_set_version);
  *  1. <dom> may be specified as DOMID_SELF.
  *  2. Only a sufficiently-privileged domain may specify <dom> != DOMID_SELF.
  */
-#define GNTTABOP_get_status_frames     9
 struct gnttab_get_status_frames {
     /* IN parameters. */
     uint32_t nr_frames;
@@ -451,7 +478,6 @@ DEFINE_GUEST_HANDLE_STRUCT(gnttab_get_status_frames);
  * GNTTABOP_get_version: Get the grant table version which is in
  * effect for domain <dom>.
  */
-#define GNTTABOP_get_version          10
 struct gnttab_get_version {
     /* IN parameters */
     domid_t dom;
@@ -461,27 +487,38 @@ struct gnttab_get_version {
 };
 DEFINE_GUEST_HANDLE_STRUCT(gnttab_get_version);
 
+/*
+ * GNTTABOP_swap_grant_ref: Swap the contents of two grant entries.
+ */
+struct gnttab_swap_grant_ref {
+    /* IN parameters */
+    grant_ref_t ref_a;
+    grant_ref_t ref_b;
+    /* OUT parameters */
+    int16_t status;             /* GNTST_* */
+};
+DEFINE_GUEST_HANDLE_STRUCT(gnttab_swap_grant_ref);
+
 /*
  * Issue one or more cache maintenance operations on a portion of a
  * page granted to the calling domain by a foreign domain.
  */
-#define GNTTABOP_cache_flush          12
 struct gnttab_cache_flush {
     union {
         uint64_t dev_bus_addr;
         grant_ref_t ref;
     } a;
-    uint16_t offset;   /* offset from start of grant */
-    uint16_t length;   /* size within the grant */
-#define GNTTAB_CACHE_CLEAN          (1<<0)
-#define GNTTAB_CACHE_INVAL          (1<<1)
-#define GNTTAB_CACHE_SOURCE_GREF    (1<<31)
+    uint16_t offset; /* offset from start of grant */
+    uint16_t length; /* size within the grant */
+#define GNTTAB_CACHE_CLEAN          (1u<<0)
+#define GNTTAB_CACHE_INVAL          (1u<<1)
+#define GNTTAB_CACHE_SOURCE_GREF    (1u<<31)
     uint32_t op;
 };
 DEFINE_GUEST_HANDLE_STRUCT(gnttab_cache_flush);
 
 /*
- * Bitfield values for update_pin_status.flags.
+ * Bitfield values for gnttab_map_grant_ref.flags.
  */
  /* Map the grant entry for access by I/O devices. */
 #define _GNTMAP_device_map      (0)
@@ -531,6 +568,7 @@ DEFINE_GUEST_HANDLE_STRUCT(gnttab_cache_flush);
 #define GNTST_bad_copy_arg    (-10) /* copy arguments cross page boundary.   */
 #define GNTST_address_too_big (-11) /* transfer page address too large.      */
 #define GNTST_eagain          (-12) /* Operation not done; try again.        */
+#define GNTST_no_space        (-13) /* Out of space (handles etc).           */
 
 #define GNTTABOP_error_msgs {                   \
     "okay",                                     \
@@ -545,7 +583,8 @@ DEFINE_GUEST_HANDLE_STRUCT(gnttab_cache_flush);
     "bad page",                                 \
     "copy arguments cross page boundary",       \
     "page address size too large",              \
-    "operation not done; try again"             \
+    "operation not done; try again",            \
+    "out of space",                             \
 }
 
 #endif /* __XEN_PUBLIC_GRANT_TABLE_H__ */
-- 
2.35.3

[PATCH v3 02/21] xen/grant-table: never put a reserved grant on the free list

[Juergen Gross]

Make sure a reserved grant is never put on the free list, as this could
cause hard to debug errors.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
V3:
- new patch
---
 drivers/xen/grant-table.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
index 6ea31ea26008..1a1aec0a88a1 100644
--- a/drivers/xen/grant-table.c
+++ b/drivers/xen/grant-table.c
@@ -207,6 +207,10 @@ static inline void check_free_callbacks(void)
 static void put_free_entry(grant_ref_t ref)
 {
 	unsigned long flags;
+
+	if (unlikely(ref < GNTTAB_NR_RESERVED_ENTRIES))
+		return;
+
 	spin_lock_irqsave(&gnttab_list_lock, flags);
 	gnttab_entry(ref) = gnttab_free_head;
 	gnttab_free_head = ref;
-- 
2.35.3

[PATCH v3 03/21] xen/blkfront: switch blkfront to use INVALID_GRANT_REF

[Juergen Gross]

Instead of using a private macro for an invalid grant reference use
the common one.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/block/xen-blkfront.c | 26 ++++++++++++--------------
 1 file changed, 12 insertions(+), 14 deletions(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 003056d4f7f5..7f35e30e626a 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -229,8 +229,6 @@ static unsigned int nr_minors;
 static unsigned long *minors;
 static DEFINE_SPINLOCK(minor_lock);
 
-#define GRANT_INVALID_REF	0
-
 #define PARTS_PER_DISK		16
 #define PARTS_PER_EXT_DISK      256
 
@@ -321,7 +319,7 @@ static int fill_grant_buffer(struct blkfront_ring_info *rinfo, int num)
 			gnt_list_entry->page = granted_page;
 		}
 
-		gnt_list_entry->gref = GRANT_INVALID_REF;
+		gnt_list_entry->gref = INVALID_GRANT_REF;
 		list_add(&gnt_list_entry->node, &rinfo->grants);
 		i++;
 	}
@@ -350,7 +348,7 @@ static struct grant *get_free_grant(struct blkfront_ring_info *rinfo)
 					  node);
 	list_del(&gnt_list_entry->node);
 
-	if (gnt_list_entry->gref != GRANT_INVALID_REF)
+	if (gnt_list_entry->gref != INVALID_GRANT_REF)
 		rinfo->persistent_gnts_c--;
 
 	return gnt_list_entry;
@@ -372,7 +370,7 @@ static struct grant *get_grant(grant_ref_t *gref_head,
 	struct grant *gnt_list_entry = get_free_grant(rinfo);
 	struct blkfront_info *info = rinfo->dev_info;
 
-	if (gnt_list_entry->gref != GRANT_INVALID_REF)
+	if (gnt_list_entry->gref != INVALID_GRANT_REF)
 		return gnt_list_entry;
 
 	/* Assign a gref to this page */
@@ -396,7 +394,7 @@ static struct grant *get_indirect_grant(grant_ref_t *gref_head,
 	struct grant *gnt_list_entry = get_free_grant(rinfo);
 	struct blkfront_info *info = rinfo->dev_info;
 
-	if (gnt_list_entry->gref != GRANT_INVALID_REF)
+	if (gnt_list_entry->gref != INVALID_GRANT_REF)
 		return gnt_list_entry;
 
 	/* Assign a gref to this page */
@@ -1221,7 +1219,7 @@ static void blkif_free_ring(struct blkfront_ring_info *rinfo)
 		list_for_each_entry_safe(persistent_gnt, n,
 					 &rinfo->grants, node) {
 			list_del(&persistent_gnt->node);
-			if (persistent_gnt->gref != GRANT_INVALID_REF) {
+			if (persistent_gnt->gref != INVALID_GRANT_REF) {
 				gnttab_end_foreign_access(persistent_gnt->gref,
 							  0UL);
 				rinfo->persistent_gnts_c--;
@@ -1283,9 +1281,9 @@ static void blkif_free_ring(struct blkfront_ring_info *rinfo)
 
 	/* Free resources associated with old device channel. */
 	for (i = 0; i < info->nr_ring_pages; i++) {
-		if (rinfo->ring_ref[i] != GRANT_INVALID_REF) {
+		if (rinfo->ring_ref[i] != INVALID_GRANT_REF) {
 			gnttab_end_foreign_access(rinfo->ring_ref[i], 0);
-			rinfo->ring_ref[i] = GRANT_INVALID_REF;
+			rinfo->ring_ref[i] = INVALID_GRANT_REF;
 		}
 	}
 	free_pages_exact(rinfo->ring.sring,
@@ -1475,7 +1473,7 @@ static int blkif_completion(unsigned long *id,
 			 * to the tail of the list, so it will not be picked
 			 * again unless we run out of persistent grants.
 			 */
-			s->grants_used[i]->gref = GRANT_INVALID_REF;
+			s->grants_used[i]->gref = INVALID_GRANT_REF;
 			list_add_tail(&s->grants_used[i]->node, &rinfo->grants);
 		}
 	}
@@ -1500,7 +1498,7 @@ static int blkif_completion(unsigned long *id,
 					indirect_page = s->indirect_grants[i]->page;
 					list_add(&indirect_page->lru, &rinfo->indirect_pages);
 				}
-				s->indirect_grants[i]->gref = GRANT_INVALID_REF;
+				s->indirect_grants[i]->gref = INVALID_GRANT_REF;
 				list_add_tail(&s->indirect_grants[i]->node, &rinfo->grants);
 			}
 		}
@@ -1687,7 +1685,7 @@ static int setup_blkring(struct xenbus_device *dev,
 	grant_ref_t gref[XENBUS_MAX_RING_GRANTS];
 
 	for (i = 0; i < info->nr_ring_pages; i++)
-		rinfo->ring_ref[i] = GRANT_INVALID_REF;
+		rinfo->ring_ref[i] = INVALID_GRANT_REF;
 
 	sring = alloc_pages_exact(ring_size, GFP_NOIO);
 	if (!sring) {
@@ -2544,13 +2542,13 @@ static void purge_persistent_grants(struct blkfront_info *info)
 
 		list_for_each_entry_safe(gnt_list_entry, tmp, &rinfo->grants,
 					 node) {
-			if (gnt_list_entry->gref == GRANT_INVALID_REF ||
+			if (gnt_list_entry->gref == INVALID_GRANT_REF ||
 			    !gnttab_try_end_foreign_access(gnt_list_entry->gref))
 				continue;
 
 			list_del(&gnt_list_entry->node);
 			rinfo->persistent_gnts_c--;
-			gnt_list_entry->gref = GRANT_INVALID_REF;
+			gnt_list_entry->gref = INVALID_GRANT_REF;
 			list_add_tail(&gnt_list_entry->node, &grants);
 		}
 
-- 
2.35.3

Re: [PATCH v3 03/21] xen/blkfront: switch blkfront to use INVALID_GRANT_REF

[Roger Pau Monné]

On Thu, May 05, 2022 at 10:16:22AM +0200, Juergen Gross wrote:
> Instead of using a private macro for an invalid grant reference use
> the common one.
> 
> Signed-off-by: Juergen Gross <jgross@suse.com>

Acked-by: Roger Pau Monné <roger.pau@citrix.com>

Thanks, Roger.

[PATCH v3 04/21] xen/netfront: switch netfront to use INVALID_GRANT_REF

[Juergen Gross]

Instead of using a private macro for an invalid grant reference use
the common one.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/net/xen-netfront.c | 36 +++++++++++++++++-------------------
 1 file changed, 17 insertions(+), 19 deletions(-)

diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index e2b4a1893a13..af3d3de7d9fa 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -78,8 +78,6 @@ struct netfront_cb {
 
 #define RX_COPY_THRESHOLD 256
 
-#define GRANT_INVALID_REF	0
-
 #define NET_TX_RING_SIZE __CONST_RING_SIZE(xen_netif_tx, XEN_PAGE_SIZE)
 #define NET_RX_RING_SIZE __CONST_RING_SIZE(xen_netif_rx, XEN_PAGE_SIZE)
 
@@ -224,7 +222,7 @@ static grant_ref_t xennet_get_rx_ref(struct netfront_queue *queue,
 {
 	int i = xennet_rxidx(ri);
 	grant_ref_t ref = queue->grant_rx_ref[i];
-	queue->grant_rx_ref[i] = GRANT_INVALID_REF;
+	queue->grant_rx_ref[i] = INVALID_GRANT_REF;
 	return ref;
 }
 
@@ -432,7 +430,7 @@ static bool xennet_tx_buf_gc(struct netfront_queue *queue)
 			}
 			gnttab_release_grant_reference(
 				&queue->gref_tx_head, queue->grant_tx_ref[id]);
-			queue->grant_tx_ref[id] = GRANT_INVALID_REF;
+			queue->grant_tx_ref[id] = INVALID_GRANT_REF;
 			queue->grant_tx_page[id] = NULL;
 			add_id_to_list(&queue->tx_skb_freelist, queue->tx_link, id);
 			dev_kfree_skb_irq(skb);
@@ -1021,7 +1019,7 @@ static int xennet_get_responses(struct netfront_queue *queue,
 		 * the backend driver. In future this should flag the bad
 		 * situation to the system controller to reboot the backend.
 		 */
-		if (ref == GRANT_INVALID_REF) {
+		if (ref == INVALID_GRANT_REF) {
 			if (net_ratelimit())
 				dev_warn(dev, "Bad rx response id %d.\n",
 					 rx->id);
@@ -1390,7 +1388,7 @@ static void xennet_release_tx_bufs(struct netfront_queue *queue)
 		gnttab_end_foreign_access(queue->grant_tx_ref[i],
 					  (unsigned long)page_address(queue->grant_tx_page[i]));
 		queue->grant_tx_page[i] = NULL;
-		queue->grant_tx_ref[i] = GRANT_INVALID_REF;
+		queue->grant_tx_ref[i] = INVALID_GRANT_REF;
 		add_id_to_list(&queue->tx_skb_freelist, queue->tx_link, i);
 		dev_kfree_skb_irq(skb);
 	}
@@ -1411,7 +1409,7 @@ static void xennet_release_rx_bufs(struct netfront_queue *queue)
 			continue;
 
 		ref = queue->grant_rx_ref[id];
-		if (ref == GRANT_INVALID_REF)
+		if (ref == INVALID_GRANT_REF)
 			continue;
 
 		page = skb_frag_page(&skb_shinfo(skb)->frags[0]);
@@ -1422,7 +1420,7 @@ static void xennet_release_rx_bufs(struct netfront_queue *queue)
 		get_page(page);
 		gnttab_end_foreign_access(ref,
 					  (unsigned long)page_address(page));
-		queue->grant_rx_ref[id] = GRANT_INVALID_REF;
+		queue->grant_rx_ref[id] = INVALID_GRANT_REF;
 
 		kfree_skb(skb);
 	}
@@ -1761,7 +1759,7 @@ static int netfront_probe(struct xenbus_device *dev,
 static void xennet_end_access(int ref, void *page)
 {
 	/* This frees the page as a side-effect */
-	if (ref != GRANT_INVALID_REF)
+	if (ref != INVALID_GRANT_REF)
 		gnttab_end_foreign_access(ref, (unsigned long)page);
 }
 
@@ -1798,8 +1796,8 @@ static void xennet_disconnect_backend(struct netfront_info *info)
 		xennet_end_access(queue->tx_ring_ref, queue->tx.sring);
 		xennet_end_access(queue->rx_ring_ref, queue->rx.sring);
 
-		queue->tx_ring_ref = GRANT_INVALID_REF;
-		queue->rx_ring_ref = GRANT_INVALID_REF;
+		queue->tx_ring_ref = INVALID_GRANT_REF;
+		queue->rx_ring_ref = INVALID_GRANT_REF;
 		queue->tx.sring = NULL;
 		queue->rx.sring = NULL;
 
@@ -1927,8 +1925,8 @@ static int setup_netfront(struct xenbus_device *dev,
 	grant_ref_t gref;
 	int err;
 
-	queue->tx_ring_ref = GRANT_INVALID_REF;
-	queue->rx_ring_ref = GRANT_INVALID_REF;
+	queue->tx_ring_ref = INVALID_GRANT_REF;
+	queue->rx_ring_ref = INVALID_GRANT_REF;
 	queue->rx.sring = NULL;
 	queue->tx.sring = NULL;
 
@@ -1978,17 +1976,17 @@ static int setup_netfront(struct xenbus_device *dev,
 	 * granted pages because backend is not accessing it at this point.
 	 */
  fail:
-	if (queue->rx_ring_ref != GRANT_INVALID_REF) {
+	if (queue->rx_ring_ref != INVALID_GRANT_REF) {
 		gnttab_end_foreign_access(queue->rx_ring_ref,
 					  (unsigned long)rxs);
-		queue->rx_ring_ref = GRANT_INVALID_REF;
+		queue->rx_ring_ref = INVALID_GRANT_REF;
 	} else {
 		free_page((unsigned long)rxs);
 	}
-	if (queue->tx_ring_ref != GRANT_INVALID_REF) {
+	if (queue->tx_ring_ref != INVALID_GRANT_REF) {
 		gnttab_end_foreign_access(queue->tx_ring_ref,
 					  (unsigned long)txs);
-		queue->tx_ring_ref = GRANT_INVALID_REF;
+		queue->tx_ring_ref = INVALID_GRANT_REF;
 	} else {
 		free_page((unsigned long)txs);
 	}
@@ -2020,7 +2018,7 @@ static int xennet_init_queue(struct netfront_queue *queue)
 	queue->tx_pend_queue = TX_LINK_NONE;
 	for (i = 0; i < NET_TX_RING_SIZE; i++) {
 		queue->tx_link[i] = i + 1;
-		queue->grant_tx_ref[i] = GRANT_INVALID_REF;
+		queue->grant_tx_ref[i] = INVALID_GRANT_REF;
 		queue->grant_tx_page[i] = NULL;
 	}
 	queue->tx_link[NET_TX_RING_SIZE - 1] = TX_LINK_NONE;
@@ -2028,7 +2026,7 @@ static int xennet_init_queue(struct netfront_queue *queue)
 	/* Clear out rx_skbs */
 	for (i = 0; i < NET_RX_RING_SIZE; i++) {
 		queue->rx_skbs[i] = NULL;
-		queue->grant_rx_ref[i] = GRANT_INVALID_REF;
+		queue->grant_rx_ref[i] = INVALID_GRANT_REF;
 	}
 
 	/* A grant for every tx ring slot */
-- 
2.35.3

[PATCH v3 05/21] xen/scsifront: remove unused GRANT_INVALID_REF definition

[Juergen Gross]

GRANT_INVALID_REF isn't used in scsifront, so remove it.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/scsi/xen-scsifront.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/scsi/xen-scsifront.c b/drivers/scsi/xen-scsifront.c
index 56173beecbc6..4c55e479fc36 100644
--- a/drivers/scsi/xen-scsifront.c
+++ b/drivers/scsi/xen-scsifront.c
@@ -58,9 +58,6 @@
 
 #include <asm/xen/hypervisor.h>
 
-
-#define GRANT_INVALID_REF	0
-
 #define VSCSIFRONT_OP_ADD_LUN	1
 #define VSCSIFRONT_OP_DEL_LUN	2
 #define VSCSIFRONT_OP_READD_LUN	3
-- 
2.35.3

[PATCH v3 06/21] xen/usb: switch xen-hcd to use INVALID_GRANT_REF

[Juergen Gross]

Instead of using a private macro for an invalid grant reference use
the common one.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/host/xen-hcd.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/drivers/usb/host/xen-hcd.c b/drivers/usb/host/xen-hcd.c
index 3e487baf8422..9cbc7c2dab02 100644
--- a/drivers/usb/host/xen-hcd.c
+++ b/drivers/usb/host/xen-hcd.c
@@ -87,8 +87,6 @@ struct xenhcd_info {
 	bool error;
 };
 
-#define GRANT_INVALID_REF 0
-
 #define XENHCD_RING_JIFFIES (HZ/200)
 #define XENHCD_SCAN_JIFFIES 1
 
@@ -1100,17 +1098,17 @@ static void xenhcd_destroy_rings(struct xenhcd_info *info)
 		unbind_from_irqhandler(info->irq, info);
 	info->irq = 0;
 
-	if (info->urb_ring_ref != GRANT_INVALID_REF) {
+	if (info->urb_ring_ref != INVALID_GRANT_REF) {
 		gnttab_end_foreign_access(info->urb_ring_ref,
 					  (unsigned long)info->urb_ring.sring);
-		info->urb_ring_ref = GRANT_INVALID_REF;
+		info->urb_ring_ref = INVALID_GRANT_REF;
 	}
 	info->urb_ring.sring = NULL;
 
-	if (info->conn_ring_ref != GRANT_INVALID_REF) {
+	if (info->conn_ring_ref != INVALID_GRANT_REF) {
 		gnttab_end_foreign_access(info->conn_ring_ref,
 					  (unsigned long)info->conn_ring.sring);
-		info->conn_ring_ref = GRANT_INVALID_REF;
+		info->conn_ring_ref = INVALID_GRANT_REF;
 	}
 	info->conn_ring.sring = NULL;
 }
@@ -1123,8 +1121,8 @@ static int xenhcd_setup_rings(struct xenbus_device *dev,
 	grant_ref_t gref;
 	int err;
 
-	info->urb_ring_ref = GRANT_INVALID_REF;
-	info->conn_ring_ref = GRANT_INVALID_REF;
+	info->urb_ring_ref = INVALID_GRANT_REF;
+	info->conn_ring_ref = INVALID_GRANT_REF;
 
 	urb_sring = (struct xenusb_urb_sring *)get_zeroed_page(
 							GFP_NOIO | __GFP_HIGH);
-- 
2.35.3

[PATCH v3 07/21] xen/drm: switch xen_drm_front to use INVALID_GRANT_REF

[Juergen Gross]

Instead of using a private macro for an invalid grant reference use
the common one.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/gpu/drm/xen/xen_drm_front.h         | 9 ---------
 drivers/gpu/drm/xen/xen_drm_front_evtchnl.c | 4 ++--
 2 files changed, 2 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/xen/xen_drm_front.h b/drivers/gpu/drm/xen/xen_drm_front.h
index cefafe859aba..a987c78abe41 100644
--- a/drivers/gpu/drm/xen/xen_drm_front.h
+++ b/drivers/gpu/drm/xen/xen_drm_front.h
@@ -80,15 +80,6 @@ struct drm_pending_vblank_event;
 /* timeout in ms to wait for backend to respond */
 #define XEN_DRM_FRONT_WAIT_BACK_MS	3000
 
-#ifndef GRANT_INVALID_REF
-/*
- * Note on usage of grant reference 0 as invalid grant reference:
- * grant reference 0 is valid, but never exposed to a PV driver,
- * because of the fact it is already in use/reserved by the PV console.
- */
-#define GRANT_INVALID_REF	0
-#endif
-
 struct xen_drm_front_info {
 	struct xenbus_device *xb_dev;
 	struct xen_drm_front_drm_info *drm_info;
diff --git a/drivers/gpu/drm/xen/xen_drm_front_evtchnl.c b/drivers/gpu/drm/xen/xen_drm_front_evtchnl.c
index 08b526eeec16..4006568b9e32 100644
--- a/drivers/gpu/drm/xen/xen_drm_front_evtchnl.c
+++ b/drivers/gpu/drm/xen/xen_drm_front_evtchnl.c
@@ -147,7 +147,7 @@ static void evtchnl_free(struct xen_drm_front_info *front_info,
 		xenbus_free_evtchn(front_info->xb_dev, evtchnl->port);
 
 	/* end access and free the page */
-	if (evtchnl->gref != GRANT_INVALID_REF)
+	if (evtchnl->gref != INVALID_GRANT_REF)
 		gnttab_end_foreign_access(evtchnl->gref, page);
 
 	memset(evtchnl, 0, sizeof(*evtchnl));
@@ -168,7 +168,7 @@ static int evtchnl_alloc(struct xen_drm_front_info *front_info, int index,
 	evtchnl->index = index;
 	evtchnl->front_info = front_info;
 	evtchnl->state = EVTCHNL_STATE_DISCONNECTED;
-	evtchnl->gref = GRANT_INVALID_REF;
+	evtchnl->gref = INVALID_GRANT_REF;
 
 	page = get_zeroed_page(GFP_NOIO | __GFP_HIGH);
 	if (!page) {
-- 
2.35.3

[PATCH v3 08/21] xen/sound: switch xen_snd_front to use INVALID_GRANT_REF

[Juergen Gross]

Instead of using a private macro for an invalid grant reference use
the common one.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 sound/xen/xen_snd_front_evtchnl.c | 4 ++--
 sound/xen/xen_snd_front_evtchnl.h | 9 ---------
 2 files changed, 2 insertions(+), 11 deletions(-)

diff --git a/sound/xen/xen_snd_front_evtchnl.c b/sound/xen/xen_snd_front_evtchnl.c
index ecbc294fc59a..3e21369c8216 100644
--- a/sound/xen/xen_snd_front_evtchnl.c
+++ b/sound/xen/xen_snd_front_evtchnl.c
@@ -167,7 +167,7 @@ static void evtchnl_free(struct xen_snd_front_info *front_info,
 		xenbus_free_evtchn(front_info->xb_dev, channel->port);
 
 	/* End access and free the page. */
-	if (channel->gref != GRANT_INVALID_REF)
+	if (channel->gref != INVALID_GRANT_REF)
 		gnttab_end_foreign_access(channel->gref, page);
 	else
 		free_page(page);
@@ -207,7 +207,7 @@ static int evtchnl_alloc(struct xen_snd_front_info *front_info, int index,
 	channel->index = index;
 	channel->front_info = front_info;
 	channel->state = EVTCHNL_STATE_DISCONNECTED;
-	channel->gref = GRANT_INVALID_REF;
+	channel->gref = INVALID_GRANT_REF;
 	page = get_zeroed_page(GFP_KERNEL);
 	if (!page) {
 		ret = -ENOMEM;
diff --git a/sound/xen/xen_snd_front_evtchnl.h b/sound/xen/xen_snd_front_evtchnl.h
index cbe51fd1ec15..3675fba70564 100644
--- a/sound/xen/xen_snd_front_evtchnl.h
+++ b/sound/xen/xen_snd_front_evtchnl.h
@@ -15,15 +15,6 @@
 
 struct xen_snd_front_info;
 
-#ifndef GRANT_INVALID_REF
-/*
- * FIXME: usage of grant reference 0 as invalid grant reference:
- * grant reference 0 is valid, but never exposed to a PV driver,
- * because of the fact it is already in use/reserved by the PV console.
- */
-#define GRANT_INVALID_REF	0
-#endif
-
 /* Timeout in ms to wait for backend to respond. */
 #define VSND_WAIT_BACK_MS	3000
 
-- 
2.35.3

[PATCH v3 09/21] xen/dmabuf: switch gntdev-dmabuf to use INVALID_GRANT_REF

[Juergen Gross]

Instead of using a private macro for an invalid grant reference use
the common one.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/xen/gntdev-dmabuf.c | 13 ++-----------
 1 file changed, 2 insertions(+), 11 deletions(-)

diff --git a/drivers/xen/gntdev-dmabuf.c b/drivers/xen/gntdev-dmabuf.c
index d5bfd7b867fc..91073b4e4a20 100644
--- a/drivers/xen/gntdev-dmabuf.c
+++ b/drivers/xen/gntdev-dmabuf.c
@@ -24,15 +24,6 @@
 
 MODULE_IMPORT_NS(DMA_BUF);
 
-#ifndef GRANT_INVALID_REF
-/*
- * Note on usage of grant reference 0 as invalid grant reference:
- * grant reference 0 is valid, but never exposed to a driver,
- * because of the fact it is already in use/reserved by the PV console.
- */
-#define GRANT_INVALID_REF	0
-#endif
-
 struct gntdev_dmabuf {
 	struct gntdev_dmabuf_priv *priv;
 	struct dma_buf *dmabuf;
@@ -532,7 +523,7 @@ static void dmabuf_imp_end_foreign_access(u32 *refs, int count)
 	int i;
 
 	for (i = 0; i < count; i++)
-		if (refs[i] != GRANT_INVALID_REF)
+		if (refs[i] != INVALID_GRANT_REF)
 			gnttab_end_foreign_access(refs[i], 0UL);
 }
 
@@ -567,7 +558,7 @@ static struct gntdev_dmabuf *dmabuf_imp_alloc_storage(int count)
 	gntdev_dmabuf->nr_pages = count;
 
 	for (i = 0; i < count; i++)
-		gntdev_dmabuf->u.imp.refs[i] = GRANT_INVALID_REF;
+		gntdev_dmabuf->u.imp.refs[i] = INVALID_GRANT_REF;
 
 	return gntdev_dmabuf;
 
-- 
2.35.3

[PATCH v3 10/21] xen/shbuf: switch xen-front-pgdir-shbuf to use INVALID_GRANT_REF

[Juergen Gross]

Instead of using a private macro for an invalid grant reference use
the common one.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
V3:
- terminate grant ref list with 0 (Oleksandr Tyshchenko)
---
 drivers/xen/xen-front-pgdir-shbuf.c | 18 +++++-------------
 1 file changed, 5 insertions(+), 13 deletions(-)

diff --git a/drivers/xen/xen-front-pgdir-shbuf.c b/drivers/xen/xen-front-pgdir-shbuf.c
index a959dee21134..b6433761d42c 100644
--- a/drivers/xen/xen-front-pgdir-shbuf.c
+++ b/drivers/xen/xen-front-pgdir-shbuf.c
@@ -21,15 +21,6 @@
 
 #include <xen/xen-front-pgdir-shbuf.h>
 
-#ifndef GRANT_INVALID_REF
-/*
- * FIXME: usage of grant reference 0 as invalid grant reference:
- * grant reference 0 is valid, but never exposed to a PV driver,
- * because of the fact it is already in use/reserved by the PV console.
- */
-#define GRANT_INVALID_REF	0
-#endif
-
 /**
  * This structure represents the structure of a shared page
  * that contains grant references to the pages of the shared
@@ -38,6 +29,7 @@
  */
 struct xen_page_directory {
 	grant_ref_t gref_dir_next_page;
+#define XEN_GREF_LIST_END	0
 	grant_ref_t gref[1]; /* Variable length */
 };
 
@@ -83,7 +75,7 @@ grant_ref_t
 xen_front_pgdir_shbuf_get_dir_start(struct xen_front_pgdir_shbuf *buf)
 {
 	if (!buf->grefs)
-		return GRANT_INVALID_REF;
+		return INVALID_GRANT_REF;
 
 	return buf->grefs[0];
 }
@@ -142,7 +134,7 @@ void xen_front_pgdir_shbuf_free(struct xen_front_pgdir_shbuf *buf)
 		int i;
 
 		for (i = 0; i < buf->num_grefs; i++)
-			if (buf->grefs[i] != GRANT_INVALID_REF)
+			if (buf->grefs[i] != INVALID_GRANT_REF)
 				gnttab_end_foreign_access(buf->grefs[i], 0UL);
 	}
 	kfree(buf->grefs);
@@ -355,7 +347,7 @@ static void backend_fill_page_dir(struct xen_front_pgdir_shbuf *buf)
 	}
 	/* Last page must say there is no more pages. */
 	page_dir = (struct xen_page_directory *)ptr;
-	page_dir->gref_dir_next_page = GRANT_INVALID_REF;
+	page_dir->gref_dir_next_page = XEN_GREF_LIST_END;
 }
 
 /**
@@ -384,7 +376,7 @@ static void guest_fill_page_dir(struct xen_front_pgdir_shbuf *buf)
 
 		if (grefs_left <= XEN_NUM_GREFS_PER_PAGE) {
 			to_copy = grefs_left;
-			page_dir->gref_dir_next_page = GRANT_INVALID_REF;
+			page_dir->gref_dir_next_page = XEN_GREF_LIST_END;
 		} else {
 			to_copy = XEN_NUM_GREFS_PER_PAGE;
 			page_dir->gref_dir_next_page = buf->grefs[i + 1];
-- 
2.35.3

Re: [PATCH v3 10/21] xen/shbuf: switch xen-front-pgdir-shbuf to use INVALID_GRANT_REF

[Oleksandr]

On 05.05.22 11:16, Juergen Gross wrote:


Hello Juergen


> Instead of using a private macro for an invalid grant reference use
> the common one.
>
> Signed-off-by: Juergen Gross <jgross@suse.com>
> ---
> V3:
> - terminate grant ref list with 0 (Oleksandr Tyshchenko)


Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>


> ---
>   drivers/xen/xen-front-pgdir-shbuf.c | 18 +++++-------------
>   1 file changed, 5 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/xen/xen-front-pgdir-shbuf.c b/drivers/xen/xen-front-pgdir-shbuf.c
> index a959dee21134..b6433761d42c 100644
> --- a/drivers/xen/xen-front-pgdir-shbuf.c
> +++ b/drivers/xen/xen-front-pgdir-shbuf.c
> @@ -21,15 +21,6 @@
>   
>   #include <xen/xen-front-pgdir-shbuf.h>
>   
> -#ifndef GRANT_INVALID_REF
> -/*
> - * FIXME: usage of grant reference 0 as invalid grant reference:
> - * grant reference 0 is valid, but never exposed to a PV driver,
> - * because of the fact it is already in use/reserved by the PV console.
> - */
> -#define GRANT_INVALID_REF	0
> -#endif
> -
>   /**
>    * This structure represents the structure of a shared page
>    * that contains grant references to the pages of the shared
> @@ -38,6 +29,7 @@
>    */
>   struct xen_page_directory {
>   	grant_ref_t gref_dir_next_page;
> +#define XEN_GREF_LIST_END	0
>   	grant_ref_t gref[1]; /* Variable length */
>   };
>   
> @@ -83,7 +75,7 @@ grant_ref_t
>   xen_front_pgdir_shbuf_get_dir_start(struct xen_front_pgdir_shbuf *buf)
>   {
>   	if (!buf->grefs)
> -		return GRANT_INVALID_REF;
> +		return INVALID_GRANT_REF;
>   
>   	return buf->grefs[0];
>   }
> @@ -142,7 +134,7 @@ void xen_front_pgdir_shbuf_free(struct xen_front_pgdir_shbuf *buf)
>   		int i;
>   
>   		for (i = 0; i < buf->num_grefs; i++)
> -			if (buf->grefs[i] != GRANT_INVALID_REF)
> +			if (buf->grefs[i] != INVALID_GRANT_REF)
>   				gnttab_end_foreign_access(buf->grefs[i], 0UL);
>   	}
>   	kfree(buf->grefs);
> @@ -355,7 +347,7 @@ static void backend_fill_page_dir(struct xen_front_pgdir_shbuf *buf)
>   	}
>   	/* Last page must say there is no more pages. */
>   	page_dir = (struct xen_page_directory *)ptr;
> -	page_dir->gref_dir_next_page = GRANT_INVALID_REF;
> +	page_dir->gref_dir_next_page = XEN_GREF_LIST_END;
>   }
>   
>   /**
> @@ -384,7 +376,7 @@ static void guest_fill_page_dir(struct xen_front_pgdir_shbuf *buf)
>   
>   		if (grefs_left <= XEN_NUM_GREFS_PER_PAGE) {
>   			to_copy = grefs_left;
> -			page_dir->gref_dir_next_page = GRANT_INVALID_REF;
> +			page_dir->gref_dir_next_page = XEN_GREF_LIST_END;
>   		} else {
>   			to_copy = XEN_NUM_GREFS_PER_PAGE;
>   			page_dir->gref_dir_next_page = buf->grefs[i + 1];

-- 
Regards,

Oleksandr Tyshchenko

[PATCH v3 11/21] xen: update ring.h

[Juergen Gross]

Update include/xen/interface/io/ring.h to its newest version.

Switch the two improper use cases of RING_HAS_UNCONSUMED_RESPONSES() to
XEN_RING_NR_UNCONSUMED_RESPONSES() in order to avoid the nasty
XEN_RING_HAS_UNCONSUMED_IS_BOOL #define.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
V2:
- new patch
---
 drivers/net/xen-netfront.c      |  4 ++--
 include/xen/interface/io/ring.h | 19 ++++++++++++++-----
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index af3d3de7d9fa..966bee2a6902 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -866,7 +866,7 @@ static void xennet_set_rx_rsp_cons(struct netfront_queue *queue, RING_IDX val)
 
 	spin_lock_irqsave(&queue->rx_cons_lock, flags);
 	queue->rx.rsp_cons = val;
-	queue->rx_rsp_unconsumed = RING_HAS_UNCONSUMED_RESPONSES(&queue->rx);
+	queue->rx_rsp_unconsumed = XEN_RING_NR_UNCONSUMED_RESPONSES(&queue->rx);
 	spin_unlock_irqrestore(&queue->rx_cons_lock, flags);
 }
 
@@ -1498,7 +1498,7 @@ static bool xennet_handle_rx(struct netfront_queue *queue, unsigned int *eoi)
 		return false;
 
 	spin_lock_irqsave(&queue->rx_cons_lock, flags);
-	work_queued = RING_HAS_UNCONSUMED_RESPONSES(&queue->rx);
+	work_queued = XEN_RING_NR_UNCONSUMED_RESPONSES(&queue->rx);
 	if (work_queued > queue->rx_rsp_unconsumed) {
 		queue->rx_rsp_unconsumed = work_queued;
 		*eoi = 0;
diff --git a/include/xen/interface/io/ring.h b/include/xen/interface/io/ring.h
index 2470ec45ebb2..ba4c4274b714 100644
--- a/include/xen/interface/io/ring.h
+++ b/include/xen/interface/io/ring.h
@@ -72,9 +72,8 @@ typedef unsigned int RING_IDX;
  * of the shared memory area (PAGE_SIZE, for instance). To initialise
  * the front half:
  *
- *     mytag_front_ring_t front_ring;
- *     SHARED_RING_INIT((mytag_sring_t *)shared_page);
- *     FRONT_RING_INIT(&front_ring, (mytag_sring_t *)shared_page, PAGE_SIZE);
+ *     mytag_front_ring_t ring;
+ *     XEN_FRONT_RING_INIT(&ring, (mytag_sring_t *)shared_page, PAGE_SIZE);
  *
  * Initializing the back follows similarly (note that only the front
  * initializes the shared ring):
@@ -146,6 +145,11 @@ struct __name##_back_ring {                                             \
 
 #define FRONT_RING_INIT(_r, _s, __size) FRONT_RING_ATTACH(_r, _s, 0, __size)
 
+#define XEN_FRONT_RING_INIT(r, s, size) do {                            \
+    SHARED_RING_INIT(s);                                                \
+    FRONT_RING_INIT(r, s, size);                                        \
+} while (0)
+
 #define BACK_RING_ATTACH(_r, _s, _i, __size) do {                       \
     (_r)->rsp_prod_pvt = (_i);                                          \
     (_r)->req_cons = (_i);                                              \
@@ -170,16 +174,21 @@ struct __name##_back_ring {                                             \
     (RING_FREE_REQUESTS(_r) == 0)
 
 /* Test if there are outstanding messages to be processed on a ring. */
-#define RING_HAS_UNCONSUMED_RESPONSES(_r)                               \
+#define XEN_RING_NR_UNCONSUMED_RESPONSES(_r)                            \
     ((_r)->sring->rsp_prod - (_r)->rsp_cons)
 
-#define RING_HAS_UNCONSUMED_REQUESTS(_r) ({                             \
+#define XEN_RING_NR_UNCONSUMED_REQUESTS(_r) ({                          \
     unsigned int req = (_r)->sring->req_prod - (_r)->req_cons;          \
     unsigned int rsp = RING_SIZE(_r) -                                  \
         ((_r)->req_cons - (_r)->rsp_prod_pvt);                          \
     req < rsp ? req : rsp;                                              \
 })
 
+#define RING_HAS_UNCONSUMED_RESPONSES(_r) \
+    (!!XEN_RING_NR_UNCONSUMED_RESPONSES(_r))
+#define RING_HAS_UNCONSUMED_REQUESTS(_r)  \
+    (!!XEN_RING_NR_UNCONSUMED_REQUESTS(_r))
+
 /* Direct access to individual ring elements, by index. */
 #define RING_GET_REQUEST(_r, _idx)                                      \
     (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req))
-- 
2.35.3

[PATCH v3 12/21] xen/xenbus: add xenbus_setup_ring() service function

[Juergen Gross]

Most PV device frontends share very similar code for setting up shared
ring buffers:

- allocate page(s)
- init the ring admin data
- give the backend access to the ring via grants

Tearing down the ring requires similar actions in all frontends again:

- remove grants
- free the page(s)

Provide service functions xenbus_setup_ring() and xenbus_teardown_ring()
for that purpose.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/xen/xenbus/xenbus_client.c | 69 ++++++++++++++++++++++++++++++
 include/xen/xenbus.h               |  4 ++
 2 files changed, 73 insertions(+)

diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index df6890681231..1a2e0d94ccd1 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -407,6 +407,75 @@ int xenbus_grant_ring(struct xenbus_device *dev, void *vaddr,
 }
 EXPORT_SYMBOL_GPL(xenbus_grant_ring);
 
+/*
+ * xenbus_setup_ring
+ * @dev: xenbus device
+ * @vaddr: pointer to starting virtual address of the ring
+ * @nr_pages: number of pages to be granted
+ * @grefs: grant reference array to be filled in
+ *
+ * Allocate physically contiguous pages for a shared ring buffer and grant it
+ * to the peer of the given device. The ring buffer is initially filled with
+ * zeroes. The virtual address of the ring is stored at @vaddr and the
+ * grant references are stored in the @grefs array. In case of error @vaddr
+ * will be set to NULL and @grefs will be filled with INVALID_GRANT_REF.
+ */
+int xenbus_setup_ring(struct xenbus_device *dev, gfp_t gfp, void **vaddr,
+		      unsigned int nr_pages, grant_ref_t *grefs)
+{
+	unsigned long ring_size = nr_pages * XEN_PAGE_SIZE;
+	unsigned int i;
+	int ret;
+
+	*vaddr = alloc_pages_exact(ring_size, gfp | __GFP_ZERO);
+	if (!*vaddr) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	ret = xenbus_grant_ring(dev, *vaddr, nr_pages, grefs);
+	if (ret)
+		goto err;
+
+	return 0;
+
+ err:
+	if (*vaddr)
+		free_pages_exact(*vaddr, ring_size);
+	for (i = 0; i < nr_pages; i++)
+		grefs[i] = INVALID_GRANT_REF;
+	*vaddr = NULL;
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(xenbus_setup_ring);
+
+/*
+ * xenbus_teardown_ring
+ * @vaddr: starting virtual address of the ring
+ * @nr_pages: number of pages
+ * @grefs: grant reference array
+ *
+ * Remove grants for the shared ring buffer and free the associated memory.
+ * On return the grant reference array is filled with INVALID_GRANT_REF.
+ */
+void xenbus_teardown_ring(void **vaddr, unsigned int nr_pages,
+			  grant_ref_t *grefs)
+{
+	unsigned int i;
+
+	for (i = 0; i < nr_pages; i++) {
+		if (grefs[i] != INVALID_GRANT_REF) {
+			gnttab_end_foreign_access(grefs[i], 0);
+			grefs[i] = INVALID_GRANT_REF;
+		}
+	}
+
+	if (*vaddr)
+		free_pages_exact(*vaddr, nr_pages * XEN_PAGE_SIZE);
+	*vaddr = NULL;
+}
+EXPORT_SYMBOL_GPL(xenbus_teardown_ring);
 
 /**
  * Allocate an event channel for the given xenbus_device, assigning the newly
diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h
index b13eb86395e0..b533b4adc835 100644
--- a/include/xen/xenbus.h
+++ b/include/xen/xenbus.h
@@ -226,6 +226,10 @@ int xenbus_watch_pathfmt(struct xenbus_device *dev, struct xenbus_watch *watch,
 int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state new_state);
 int xenbus_grant_ring(struct xenbus_device *dev, void *vaddr,
 		      unsigned int nr_pages, grant_ref_t *grefs);
+int xenbus_setup_ring(struct xenbus_device *dev, gfp_t gfp, void **vaddr,
+		      unsigned int nr_pages, grant_ref_t *grefs);
+void xenbus_teardown_ring(void **vaddr, unsigned int nr_pages,
+			  grant_ref_t *grefs);
 int xenbus_map_ring_valloc(struct xenbus_device *dev, grant_ref_t *gnt_refs,
 			   unsigned int nr_grefs, void **vaddr);
 
-- 
2.35.3

[PATCH v3 13/21] xen/blkfront: use xenbus_setup_ring() and xenbus_teardown_ring()

[Juergen Gross]

Simplify blkfront's ring creation and removal via xenbus_setup_ring()
and xenbus_teardown_ring().

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/block/xen-blkfront.c | 37 ++++++++----------------------------
 1 file changed, 8 insertions(+), 29 deletions(-)

diff --git a/drivers/block/xen-blkfront.c b/drivers/block/xen-blkfront.c
index 7f35e30e626a..bd7b34f29193 100644
--- a/drivers/block/xen-blkfront.c
+++ b/drivers/block/xen-blkfront.c
@@ -1280,15 +1280,8 @@ static void blkif_free_ring(struct blkfront_ring_info *rinfo)
 	flush_work(&rinfo->work);
 
 	/* Free resources associated with old device channel. */
-	for (i = 0; i < info->nr_ring_pages; i++) {
-		if (rinfo->ring_ref[i] != INVALID_GRANT_REF) {
-			gnttab_end_foreign_access(rinfo->ring_ref[i], 0);
-			rinfo->ring_ref[i] = INVALID_GRANT_REF;
-		}
-	}
-	free_pages_exact(rinfo->ring.sring,
-			 info->nr_ring_pages * XEN_PAGE_SIZE);
-	rinfo->ring.sring = NULL;
+	xenbus_teardown_ring((void **)&rinfo->ring.sring, info->nr_ring_pages,
+			     rinfo->ring_ref);
 
 	if (rinfo->irq)
 		unbind_from_irqhandler(rinfo->irq, rinfo);
@@ -1679,30 +1672,16 @@ static int setup_blkring(struct xenbus_device *dev,
 			 struct blkfront_ring_info *rinfo)
 {
 	struct blkif_sring *sring;
-	int err, i;
+	int err;
 	struct blkfront_info *info = rinfo->dev_info;
 	unsigned long ring_size = info->nr_ring_pages * XEN_PAGE_SIZE;
-	grant_ref_t gref[XENBUS_MAX_RING_GRANTS];
-
-	for (i = 0; i < info->nr_ring_pages; i++)
-		rinfo->ring_ref[i] = INVALID_GRANT_REF;
 
-	sring = alloc_pages_exact(ring_size, GFP_NOIO);
-	if (!sring) {
-		xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
-		return -ENOMEM;
-	}
-	SHARED_RING_INIT(sring);
-	FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
-
-	err = xenbus_grant_ring(dev, rinfo->ring.sring, info->nr_ring_pages, gref);
-	if (err < 0) {
-		free_pages_exact(sring, ring_size);
-		rinfo->ring.sring = NULL;
+	err = xenbus_setup_ring(dev, GFP_NOIO, (void **)&sring,
+				info->nr_ring_pages, rinfo->ring_ref);
+	if (err)
 		goto fail;
-	}
-	for (i = 0; i < info->nr_ring_pages; i++)
-		rinfo->ring_ref[i] = gref[i];
+
+	XEN_FRONT_RING_INIT(&rinfo->ring, sring, ring_size);
 
 	err = xenbus_alloc_evtchn(dev, &rinfo->evtchn);
 	if (err)
-- 
2.35.3

Re: [PATCH v3 13/21] xen/blkfront: use xenbus_setup_ring() and xenbus_teardown_ring()

[Roger Pau Monné]

On Thu, May 05, 2022 at 10:16:32AM +0200, Juergen Gross wrote:
> Simplify blkfront's ring creation and removal via xenbus_setup_ring()
> and xenbus_teardown_ring().
> 
> Signed-off-by: Juergen Gross <jgross@suse.com>

Acked-by: Roger Pau Monné <roger.pau@citrix.com>

Thanks, Roger.

[PATCH v3 14/21] xen/netfront: use xenbus_setup_ring() and xenbus_teardown_ring()

[Juergen Gross]

Simplify netfront's ring creation and removal via xenbus_setup_ring()
and xenbus_teardown_ring().

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/net/xen-netfront.c | 53 +++++++++-----------------------------
 1 file changed, 12 insertions(+), 41 deletions(-)

diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c
index 966bee2a6902..65ab907aca5a 100644
--- a/drivers/net/xen-netfront.c
+++ b/drivers/net/xen-netfront.c
@@ -1921,8 +1921,7 @@ static int setup_netfront(struct xenbus_device *dev,
 			struct netfront_queue *queue, unsigned int feature_split_evtchn)
 {
 	struct xen_netif_tx_sring *txs;
-	struct xen_netif_rx_sring *rxs = NULL;
-	grant_ref_t gref;
+	struct xen_netif_rx_sring *rxs;
 	int err;
 
 	queue->tx_ring_ref = INVALID_GRANT_REF;
@@ -1930,33 +1929,19 @@ static int setup_netfront(struct xenbus_device *dev,
 	queue->rx.sring = NULL;
 	queue->tx.sring = NULL;
 
-	txs = (struct xen_netif_tx_sring *)get_zeroed_page(GFP_NOIO | __GFP_HIGH);
-	if (!txs) {
-		err = -ENOMEM;
-		xenbus_dev_fatal(dev, err, "allocating tx ring page");
+	err = xenbus_setup_ring(dev, GFP_NOIO | __GFP_HIGH, (void **)&txs,
+				1, &queue->tx_ring_ref);
+	if (err)
 		goto fail;
-	}
-	SHARED_RING_INIT(txs);
-	FRONT_RING_INIT(&queue->tx, txs, XEN_PAGE_SIZE);
 
-	err = xenbus_grant_ring(dev, txs, 1, &gref);
-	if (err < 0)
-		goto fail;
-	queue->tx_ring_ref = gref;
+	XEN_FRONT_RING_INIT(&queue->tx, txs, XEN_PAGE_SIZE);
 
-	rxs = (struct xen_netif_rx_sring *)get_zeroed_page(GFP_NOIO | __GFP_HIGH);
-	if (!rxs) {
-		err = -ENOMEM;
-		xenbus_dev_fatal(dev, err, "allocating rx ring page");
+	err = xenbus_setup_ring(dev, GFP_NOIO | __GFP_HIGH, (void **)&rxs,
+				1, &queue->rx_ring_ref);
+	if (err)
 		goto fail;
-	}
-	SHARED_RING_INIT(rxs);
-	FRONT_RING_INIT(&queue->rx, rxs, XEN_PAGE_SIZE);
 
-	err = xenbus_grant_ring(dev, rxs, 1, &gref);
-	if (err < 0)
-		goto fail;
-	queue->rx_ring_ref = gref;
+	XEN_FRONT_RING_INIT(&queue->rx, rxs, XEN_PAGE_SIZE);
 
 	if (feature_split_evtchn)
 		err = setup_netfront_split(queue);
@@ -1972,24 +1957,10 @@ static int setup_netfront(struct xenbus_device *dev,
 
 	return 0;
 
-	/* If we fail to setup netfront, it is safe to just revoke access to
-	 * granted pages because backend is not accessing it at this point.
-	 */
  fail:
-	if (queue->rx_ring_ref != INVALID_GRANT_REF) {
-		gnttab_end_foreign_access(queue->rx_ring_ref,
-					  (unsigned long)rxs);
-		queue->rx_ring_ref = INVALID_GRANT_REF;
-	} else {
-		free_page((unsigned long)rxs);
-	}
-	if (queue->tx_ring_ref != INVALID_GRANT_REF) {
-		gnttab_end_foreign_access(queue->tx_ring_ref,
-					  (unsigned long)txs);
-		queue->tx_ring_ref = INVALID_GRANT_REF;
-	} else {
-		free_page((unsigned long)txs);
-	}
+	xenbus_teardown_ring((void **)&queue->rx.sring, 1, &queue->rx_ring_ref);
+	xenbus_teardown_ring((void **)&queue->tx.sring, 1, &queue->tx_ring_ref);
+
 	return err;
 }
 
-- 
2.35.3

[PATCH v3 15/21] xen/tpmfront: use xenbus_setup_ring() and xenbus_teardown_ring()

[Juergen Gross]

Simplify tpmfront's ring creation and removal via xenbus_setup_ring()
and xenbus_teardown_ring().

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/char/tpm/xen-tpmfront.c | 18 +++---------------
 1 file changed, 3 insertions(+), 15 deletions(-)

diff --git a/drivers/char/tpm/xen-tpmfront.c b/drivers/char/tpm/xen-tpmfront.c
index 69df04ae2401..379291826261 100644
--- a/drivers/char/tpm/xen-tpmfront.c
+++ b/drivers/char/tpm/xen-tpmfront.c
@@ -253,20 +253,12 @@ static int setup_ring(struct xenbus_device *dev, struct tpm_private *priv)
 	struct xenbus_transaction xbt;
 	const char *message = NULL;
 	int rv;
-	grant_ref_t gref;
 
-	priv->shr = (void *)__get_free_page(GFP_KERNEL|__GFP_ZERO);
-	if (!priv->shr) {
-		xenbus_dev_fatal(dev, -ENOMEM, "allocating shared ring");
-		return -ENOMEM;
-	}
-
-	rv = xenbus_grant_ring(dev, priv->shr, 1, &gref);
+	rv = xenbus_setup_ring(dev, GFP_KERNEL, (void **)&priv->shr, 1,
+			       &priv->ring_ref);
 	if (rv < 0)
 		return rv;
 
-	priv->ring_ref = gref;
-
 	rv = xenbus_alloc_evtchn(dev, &priv->evtchn);
 	if (rv)
 		return rv;
@@ -331,11 +323,7 @@ static void ring_free(struct tpm_private *priv)
 	if (!priv)
 		return;
 
-	if (priv->ring_ref)
-		gnttab_end_foreign_access(priv->ring_ref,
-				(unsigned long)priv->shr);
-	else
-		free_page((unsigned long)priv->shr);
+	xenbus_teardown_ring((void **)&priv->shr, 1, &priv->ring_ref);
 
 	if (priv->irq)
 		unbind_from_irqhandler(priv->irq, priv);
-- 
2.35.3

Re: [PATCH v3 15/21] xen/tpmfront: use xenbus_setup_ring() and xenbus_teardown_ring()

[Jarkko Sakkinen]

On Thu, May 05, 2022 at 10:16:34AM +0200, Juergen Gross wrote:
> Simplify tpmfront's ring creation and removal via xenbus_setup_ring()
> and xenbus_teardown_ring().
> 
> Signed-off-by: Juergen Gross <jgross@suse.com>

Please add to the commit message why these provide an equivalent
functionality.

BR, Jarkko

Re: [PATCH v3 15/21] xen/tpmfront: use xenbus_setup_ring() and xenbus_teardown_ring()

[Juergen Gross]

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On 07.05.22 00:32, Jarkko Sakkinen wrote:
> On Thu, May 05, 2022 at 10:16:34AM +0200, Juergen Gross wrote:
>> Simplify tpmfront's ring creation and removal via xenbus_setup_ring()
>> and xenbus_teardown_ring().
>>
>> Signed-off-by: Juergen Gross <jgross@suse.com>
> 
> Please add to the commit message why these provide an equivalent
> functionality.

Would you be fine with:

   Simplify tpmfront's ring creation and removal via xenbus_setup_ring()
   and xenbus_teardown_ring(), which are provided exactly for the use
   pattern as seen in this driver.


Juergen

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Re: [PATCH v3 15/21] xen/tpmfront: use xenbus_setup_ring() and xenbus_teardown_ring()

[Jarkko Sakkinen]

On Wed, May 18, 2022 at 11:41:51AM +0200, Juergen Gross wrote:
> On 07.05.22 00:32, Jarkko Sakkinen wrote:
> > On Thu, May 05, 2022 at 10:16:34AM +0200, Juergen Gross wrote:
> > > Simplify tpmfront's ring creation and removal via xenbus_setup_ring()
> > > and xenbus_teardown_ring().
> > > 
> > > Signed-off-by: Juergen Gross <jgross@suse.com>
> > 
> > Please add to the commit message why these provide an equivalent
> > functionality.
> 
> Would you be fine with:
> 
>   Simplify tpmfront's ring creation and removal via xenbus_setup_ring()
>   and xenbus_teardown_ring(), which are provided exactly for the use
>   pattern as seen in this driver.
> 
> 
> Juergen

Looks fine to me!

BR, Jarkko

[PATCH v3 16/21] xen/drmfront: use xenbus_setup_ring() and xenbus_teardown_ring()

[Juergen Gross]

Simplify drmfront's ring creation and removal via xenbus_setup_ring()
and xenbus_teardown_ring().

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/gpu/drm/xen/xen_drm_front_evtchnl.c | 43 ++++++---------------
 1 file changed, 11 insertions(+), 32 deletions(-)

diff --git a/drivers/gpu/drm/xen/xen_drm_front_evtchnl.c b/drivers/gpu/drm/xen/xen_drm_front_evtchnl.c
index 4006568b9e32..e52afd792346 100644
--- a/drivers/gpu/drm/xen/xen_drm_front_evtchnl.c
+++ b/drivers/gpu/drm/xen/xen_drm_front_evtchnl.c
@@ -123,12 +123,12 @@ static irqreturn_t evtchnl_interrupt_evt(int irq, void *dev_id)
 static void evtchnl_free(struct xen_drm_front_info *front_info,
 			 struct xen_drm_front_evtchnl *evtchnl)
 {
-	unsigned long page = 0;
+	void *page = NULL;
 
 	if (evtchnl->type == EVTCHNL_TYPE_REQ)
-		page = (unsigned long)evtchnl->u.req.ring.sring;
+		page = evtchnl->u.req.ring.sring;
 	else if (evtchnl->type == EVTCHNL_TYPE_EVT)
-		page = (unsigned long)evtchnl->u.evt.page;
+		page = evtchnl->u.evt.page;
 	if (!page)
 		return;
 
@@ -147,8 +147,7 @@ static void evtchnl_free(struct xen_drm_front_info *front_info,
 		xenbus_free_evtchn(front_info->xb_dev, evtchnl->port);
 
 	/* end access and free the page */
-	if (evtchnl->gref != INVALID_GRANT_REF)
-		gnttab_end_foreign_access(evtchnl->gref, page);
+	xenbus_teardown_ring(&page, 1, &evtchnl->gref);
 
 	memset(evtchnl, 0, sizeof(*evtchnl));
 }
@@ -158,8 +157,7 @@ static int evtchnl_alloc(struct xen_drm_front_info *front_info, int index,
 			 enum xen_drm_front_evtchnl_type type)
 {
 	struct xenbus_device *xb_dev = front_info->xb_dev;
-	unsigned long page;
-	grant_ref_t gref;
+	void *page;
 	irq_handler_t handler;
 	int ret;
 
@@ -168,44 +166,25 @@ static int evtchnl_alloc(struct xen_drm_front_info *front_info, int index,
 	evtchnl->index = index;
 	evtchnl->front_info = front_info;
 	evtchnl->state = EVTCHNL_STATE_DISCONNECTED;
-	evtchnl->gref = INVALID_GRANT_REF;
 
-	page = get_zeroed_page(GFP_NOIO | __GFP_HIGH);
-	if (!page) {
-		ret = -ENOMEM;
+	ret = xenbus_setup_ring(xb_dev, GFP_NOIO | __GFP_HIGH, &page,
+				1, &evtchnl->gref);
+	if (ret)
 		goto fail;
-	}
 
 	if (type == EVTCHNL_TYPE_REQ) {
 		struct xen_displif_sring *sring;
 
 		init_completion(&evtchnl->u.req.completion);
 		mutex_init(&evtchnl->u.req.req_io_lock);
-		sring = (struct xen_displif_sring *)page;
-		SHARED_RING_INIT(sring);
-		FRONT_RING_INIT(&evtchnl->u.req.ring, sring, XEN_PAGE_SIZE);
-
-		ret = xenbus_grant_ring(xb_dev, sring, 1, &gref);
-		if (ret < 0) {
-			evtchnl->u.req.ring.sring = NULL;
-			free_page(page);
-			goto fail;
-		}
+		sring = page;
+		XEN_FRONT_RING_INIT(&evtchnl->u.req.ring, sring, XEN_PAGE_SIZE);
 
 		handler = evtchnl_interrupt_ctrl;
 	} else {
-		ret = gnttab_grant_foreign_access(xb_dev->otherend_id,
-						  virt_to_gfn((void *)page), 0);
-		if (ret < 0) {
-			free_page(page);
-			goto fail;
-		}
-
-		evtchnl->u.evt.page = (struct xendispl_event_page *)page;
-		gref = ret;
+		evtchnl->u.evt.page = page;
 		handler = evtchnl_interrupt_evt;
 	}
-	evtchnl->gref = gref;
 
 	ret = xenbus_alloc_evtchn(xb_dev, &evtchnl->port);
 	if (ret < 0)
-- 
2.35.3

[PATCH v3 17/21] xen/pcifront: use xenbus_setup_ring() and xenbus_teardown_ring()

[Juergen Gross]

Simplify pcifront's shared page creation and removal via
xenbus_setup_ring() and xenbus_teardown_ring().

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/pci/xen-pcifront.c | 19 +++----------------
 1 file changed, 3 insertions(+), 16 deletions(-)

diff --git a/drivers/pci/xen-pcifront.c b/drivers/pci/xen-pcifront.c
index 3edc1565a27c..689271c4245c 100644
--- a/drivers/pci/xen-pcifront.c
+++ b/drivers/pci/xen-pcifront.c
@@ -709,9 +709,8 @@ static struct pcifront_device *alloc_pdev(struct xenbus_device *xdev)
 	if (pdev == NULL)
 		goto out;
 
-	pdev->sh_info =
-	    (struct xen_pci_sharedinfo *)__get_free_page(GFP_KERNEL);
-	if (pdev->sh_info == NULL) {
+	if (xenbus_setup_ring(xdev, GFP_KERNEL, (void **)&pdev->sh_info, 1,
+			      &pdev->gnt_ref)) {
 		kfree(pdev);
 		pdev = NULL;
 		goto out;
@@ -729,7 +728,6 @@ static struct pcifront_device *alloc_pdev(struct xenbus_device *xdev)
 	spin_lock_init(&pdev->sh_info_lock);
 
 	pdev->evtchn = INVALID_EVTCHN;
-	pdev->gnt_ref = INVALID_GRANT_REF;
 	pdev->irq = -1;
 
 	INIT_WORK(&pdev->op_work, pcifront_do_aer);
@@ -754,11 +752,7 @@ static void free_pdev(struct pcifront_device *pdev)
 	if (pdev->evtchn != INVALID_EVTCHN)
 		xenbus_free_evtchn(pdev->xdev, pdev->evtchn);
 
-	if (pdev->gnt_ref != INVALID_GRANT_REF)
-		gnttab_end_foreign_access(pdev->gnt_ref,
-					  (unsigned long)pdev->sh_info);
-	else
-		free_page((unsigned long)pdev->sh_info);
+	xenbus_teardown_ring((void **)&pdev->sh_info, 1, &pdev->gnt_ref);
 
 	dev_set_drvdata(&pdev->xdev->dev, NULL);
 
@@ -769,13 +763,6 @@ static int pcifront_publish_info(struct pcifront_device *pdev)
 {
 	int err = 0;
 	struct xenbus_transaction trans;
-	grant_ref_t gref;
-
-	err = xenbus_grant_ring(pdev->xdev, pdev->sh_info, 1, &gref);
-	if (err < 0)
-		goto out;
-
-	pdev->gnt_ref = gref;
 
 	err = xenbus_alloc_evtchn(pdev->xdev, &pdev->evtchn);
 	if (err)
-- 
2.35.3

[PATCH v3 18/21] xen/scsifront: use xenbus_setup_ring() and xenbus_teardown_ring()

[Juergen Gross]

Simplify scsifront's ring creation and removal via xenbus_setup_ring()
and xenbus_teardown_ring().

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/scsi/xen-scsifront.c | 28 +++++++---------------------
 1 file changed, 7 insertions(+), 21 deletions(-)

diff --git a/drivers/scsi/xen-scsifront.c b/drivers/scsi/xen-scsifront.c
index 4c55e479fc36..51afc66e839d 100644
--- a/drivers/scsi/xen-scsifront.c
+++ b/drivers/scsi/xen-scsifront.c
@@ -798,27 +798,15 @@ static int scsifront_alloc_ring(struct vscsifrnt_info *info)
 {
 	struct xenbus_device *dev = info->dev;
 	struct vscsiif_sring *sring;
-	grant_ref_t gref;
-	int err = -ENOMEM;
+	int err;
 
 	/***** Frontend to Backend ring start *****/
-	sring = (struct vscsiif_sring *)__get_free_page(GFP_KERNEL);
-	if (!sring) {
-		xenbus_dev_fatal(dev, err,
-			"fail to allocate shared ring (Front to Back)");
+	err = xenbus_setup_ring(dev, GFP_KERNEL, (void **)&sring, 1,
+				&info->ring_ref);
+	if (err)
 		return err;
-	}
-	SHARED_RING_INIT(sring);
-	FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
 
-	err = xenbus_grant_ring(dev, sring, 1, &gref);
-	if (err < 0) {
-		free_page((unsigned long)sring);
-		xenbus_dev_fatal(dev, err,
-			"fail to grant shared ring (Front to Back)");
-		return err;
-	}
-	info->ring_ref = gref;
+	XEN_FRONT_RING_INIT(&info->ring, sring, PAGE_SIZE);
 
 	err = xenbus_alloc_evtchn(dev, &info->evtchn);
 	if (err) {
@@ -847,8 +835,7 @@ static int scsifront_alloc_ring(struct vscsifrnt_info *info)
 free_irq:
 	unbind_from_irqhandler(info->irq, info);
 free_gnttab:
-	gnttab_end_foreign_access(info->ring_ref,
-				  (unsigned long)info->ring.sring);
+	xenbus_teardown_ring((void **)&sring, 1, &info->ring_ref);
 
 	return err;
 }
@@ -856,8 +843,7 @@ static int scsifront_alloc_ring(struct vscsifrnt_info *info)
 static void scsifront_free_ring(struct vscsifrnt_info *info)
 {
 	unbind_from_irqhandler(info->irq, info);
-	gnttab_end_foreign_access(info->ring_ref,
-				  (unsigned long)info->ring.sring);
+	xenbus_teardown_ring((void **)&info->ring.sring, 1, &info->ring_ref);
 }
 
 static int scsifront_init_ring(struct vscsifrnt_info *info)
-- 
2.35.3

[PATCH v3 19/21] xen/usbfront: use xenbus_setup_ring() and xenbus_teardown_ring()

[Juergen Gross]

Simplify xen-hcd's ring creation and removal via xenbus_setup_ring()
and xenbus_teardown_ring().

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/usb/host/xen-hcd.c | 61 ++++++++++----------------------------
 1 file changed, 15 insertions(+), 46 deletions(-)

diff --git a/drivers/usb/host/xen-hcd.c b/drivers/usb/host/xen-hcd.c
index 9cbc7c2dab02..de1b09158318 100644
--- a/drivers/usb/host/xen-hcd.c
+++ b/drivers/usb/host/xen-hcd.c
@@ -1098,19 +1098,10 @@ static void xenhcd_destroy_rings(struct xenhcd_info *info)
 		unbind_from_irqhandler(info->irq, info);
 	info->irq = 0;
 
-	if (info->urb_ring_ref != INVALID_GRANT_REF) {
-		gnttab_end_foreign_access(info->urb_ring_ref,
-					  (unsigned long)info->urb_ring.sring);
-		info->urb_ring_ref = INVALID_GRANT_REF;
-	}
-	info->urb_ring.sring = NULL;
-
-	if (info->conn_ring_ref != INVALID_GRANT_REF) {
-		gnttab_end_foreign_access(info->conn_ring_ref,
-					  (unsigned long)info->conn_ring.sring);
-		info->conn_ring_ref = INVALID_GRANT_REF;
-	}
-	info->conn_ring.sring = NULL;
+	xenbus_teardown_ring((void **)&info->urb_ring.sring, 1,
+			     &info->urb_ring_ref);
+	xenbus_teardown_ring((void **)&info->conn_ring.sring, 1,
+			     &info->conn_ring_ref);
 }
 
 static int xenhcd_setup_rings(struct xenbus_device *dev,
@@ -1118,46 +1109,24 @@ static int xenhcd_setup_rings(struct xenbus_device *dev,
 {
 	struct xenusb_urb_sring *urb_sring;
 	struct xenusb_conn_sring *conn_sring;
-	grant_ref_t gref;
 	int err;
 
-	info->urb_ring_ref = INVALID_GRANT_REF;
 	info->conn_ring_ref = INVALID_GRANT_REF;
-
-	urb_sring = (struct xenusb_urb_sring *)get_zeroed_page(
-							GFP_NOIO | __GFP_HIGH);
-	if (!urb_sring) {
-		xenbus_dev_fatal(dev, -ENOMEM, "allocating urb ring");
-		return -ENOMEM;
-	}
-	SHARED_RING_INIT(urb_sring);
-	FRONT_RING_INIT(&info->urb_ring, urb_sring, PAGE_SIZE);
-
-	err = xenbus_grant_ring(dev, urb_sring, 1, &gref);
-	if (err < 0) {
-		free_page((unsigned long)urb_sring);
-		info->urb_ring.sring = NULL;
-		goto fail;
-	}
-	info->urb_ring_ref = gref;
-
-	conn_sring = (struct xenusb_conn_sring *)get_zeroed_page(
-							GFP_NOIO | __GFP_HIGH);
-	if (!conn_sring) {
-		xenbus_dev_fatal(dev, -ENOMEM, "allocating conn ring");
-		err = -ENOMEM;
-		goto fail;
+	err = xenbus_setup_ring(dev, GFP_NOIO | __GFP_HIGH,
+				(void **)&urb_sring, 1, &info->urb_ring_ref);
+	if (err) {
+		xenbus_dev_fatal(dev, err, "allocating urb ring");
+		return err;
 	}
-	SHARED_RING_INIT(conn_sring);
-	FRONT_RING_INIT(&info->conn_ring, conn_sring, PAGE_SIZE);
+	XEN_FRONT_RING_INIT(&info->urb_ring, urb_sring, PAGE_SIZE);
 
-	err = xenbus_grant_ring(dev, conn_sring, 1, &gref);
-	if (err < 0) {
-		free_page((unsigned long)conn_sring);
-		info->conn_ring.sring = NULL;
+	err = xenbus_setup_ring(dev, GFP_NOIO | __GFP_HIGH,
+				(void **)&conn_sring, 1, &info->conn_ring_ref);
+	if (err) {
+		xenbus_dev_fatal(dev, err, "allocating conn ring");
 		goto fail;
 	}
-	info->conn_ring_ref = gref;
+	XEN_FRONT_RING_INIT(&info->conn_ring, conn_sring, PAGE_SIZE);
 
 	err = xenbus_alloc_evtchn(dev, &info->evtchn);
 	if (err) {
-- 
2.35.3

[PATCH v3 20/21] xen/sndfront: use xenbus_setup_ring() and xenbus_teardown_ring()

[Juergen Gross]

Simplify sndfront's ring creation and removal via xenbus_setup_ring()
and xenbus_teardown_ring().

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 sound/xen/xen_snd_front_evtchnl.c | 44 +++++++------------------------
 1 file changed, 10 insertions(+), 34 deletions(-)

diff --git a/sound/xen/xen_snd_front_evtchnl.c b/sound/xen/xen_snd_front_evtchnl.c
index 3e21369c8216..26d1b3987887 100644
--- a/sound/xen/xen_snd_front_evtchnl.c
+++ b/sound/xen/xen_snd_front_evtchnl.c
@@ -143,12 +143,12 @@ void xen_snd_front_evtchnl_flush(struct xen_snd_front_evtchnl *channel)
 static void evtchnl_free(struct xen_snd_front_info *front_info,
 			 struct xen_snd_front_evtchnl *channel)
 {
-	unsigned long page = 0;
+	void *page = NULL;
 
 	if (channel->type == EVTCHNL_TYPE_REQ)
-		page = (unsigned long)channel->u.req.ring.sring;
+		page = channel->u.req.ring.sring;
 	else if (channel->type == EVTCHNL_TYPE_EVT)
-		page = (unsigned long)channel->u.evt.page;
+		page = channel->u.evt.page;
 
 	if (!page)
 		return;
@@ -167,10 +167,7 @@ static void evtchnl_free(struct xen_snd_front_info *front_info,
 		xenbus_free_evtchn(front_info->xb_dev, channel->port);
 
 	/* End access and free the page. */
-	if (channel->gref != INVALID_GRANT_REF)
-		gnttab_end_foreign_access(channel->gref, page);
-	else
-		free_page(page);
+	xenbus_teardown_ring(&page, 1, &channel->gref);
 
 	memset(channel, 0, sizeof(*channel));
 }
@@ -196,8 +193,7 @@ static int evtchnl_alloc(struct xen_snd_front_info *front_info, int index,
 			 enum xen_snd_front_evtchnl_type type)
 {
 	struct xenbus_device *xb_dev = front_info->xb_dev;
-	unsigned long page;
-	grant_ref_t gref;
+	void *page;
 	irq_handler_t handler;
 	char *handler_name = NULL;
 	int ret;
@@ -207,12 +203,9 @@ static int evtchnl_alloc(struct xen_snd_front_info *front_info, int index,
 	channel->index = index;
 	channel->front_info = front_info;
 	channel->state = EVTCHNL_STATE_DISCONNECTED;
-	channel->gref = INVALID_GRANT_REF;
-	page = get_zeroed_page(GFP_KERNEL);
-	if (!page) {
-		ret = -ENOMEM;
+	ret = xenbus_setup_ring(xb_dev, GFP_KERNEL, &page, 1, &channel->gref);
+	if (ret)
 		goto fail;
-	}
 
 	handler_name = kasprintf(GFP_KERNEL, "%s-%s", XENSND_DRIVER_NAME,
 				 type == EVTCHNL_TYPE_REQ ?
@@ -226,33 +219,18 @@ static int evtchnl_alloc(struct xen_snd_front_info *front_info, int index,
 	mutex_init(&channel->ring_io_lock);
 
 	if (type == EVTCHNL_TYPE_REQ) {
-		struct xen_sndif_sring *sring = (struct xen_sndif_sring *)page;
+		struct xen_sndif_sring *sring = page;
 
 		init_completion(&channel->u.req.completion);
 		mutex_init(&channel->u.req.req_io_lock);
-		SHARED_RING_INIT(sring);
-		FRONT_RING_INIT(&channel->u.req.ring, sring, XEN_PAGE_SIZE);
-
-		ret = xenbus_grant_ring(xb_dev, sring, 1, &gref);
-		if (ret < 0) {
-			channel->u.req.ring.sring = NULL;
-			goto fail;
-		}
+		XEN_FRONT_RING_INIT(&channel->u.req.ring, sring, XEN_PAGE_SIZE);
 
 		handler = evtchnl_interrupt_req;
 	} else {
-		ret = gnttab_grant_foreign_access(xb_dev->otherend_id,
-						  virt_to_gfn((void *)page), 0);
-		if (ret < 0)
-			goto fail;
-
-		channel->u.evt.page = (struct xensnd_event_page *)page;
-		gref = ret;
+		channel->u.evt.page = page;
 		handler = evtchnl_interrupt_evt;
 	}
 
-	channel->gref = gref;
-
 	ret = xenbus_alloc_evtchn(xb_dev, &channel->port);
 	if (ret < 0)
 		goto fail;
@@ -279,8 +257,6 @@ static int evtchnl_alloc(struct xen_snd_front_info *front_info, int index,
 	return 0;
 
 fail:
-	if (page)
-		free_page(page);
 	kfree(handler_name);
 	dev_err(&xb_dev->dev, "Failed to allocate ring: %d\n", ret);
 	return ret;
-- 
2.35.3

[PATCH v3 21/21] xen/xenbus: eliminate xenbus_grant_ring()

[Juergen Gross]

There is no external user of xenbus_grant_ring() left, so merge it into
the only caller xenbus_setup_ring().

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
---
V2:
- make error message more precise (Andrew Cooper)
---
 drivers/xen/xenbus/xenbus_client.c | 65 +++++++++---------------------
 include/xen/xenbus.h               |  2 -
 2 files changed, 19 insertions(+), 48 deletions(-)

diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index 1a2e0d94ccd1..d6fdd2d209d3 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -363,50 +363,6 @@ static void xenbus_switch_fatal(struct xenbus_device *dev, int depth, int err,
 		__xenbus_switch_state(dev, XenbusStateClosing, 1);
 }
 
-/**
- * xenbus_grant_ring
- * @dev: xenbus device
- * @vaddr: starting virtual address of the ring
- * @nr_pages: number of pages to be granted
- * @grefs: grant reference array to be filled in
- *
- * Grant access to the given @vaddr to the peer of the given device.
- * Then fill in @grefs with grant references.  Return 0 on success, or
- * -errno on error.  On error, the device will switch to
- * XenbusStateClosing, and the error will be saved in the store.
- */
-int xenbus_grant_ring(struct xenbus_device *dev, void *vaddr,
-		      unsigned int nr_pages, grant_ref_t *grefs)
-{
-	int err;
-	unsigned int i;
-	grant_ref_t gref_head;
-
-	err = gnttab_alloc_grant_references(nr_pages, &gref_head);
-	if (err) {
-		xenbus_dev_fatal(dev, err, "granting access to ring page");
-		return err;
-	}
-
-	for (i = 0; i < nr_pages; i++) {
-		unsigned long gfn;
-
-		if (is_vmalloc_addr(vaddr))
-			gfn = pfn_to_gfn(vmalloc_to_pfn(vaddr));
-		else
-			gfn = virt_to_gfn(vaddr);
-
-		grefs[i] = gnttab_claim_grant_reference(&gref_head);
-		gnttab_grant_foreign_access_ref(grefs[i], dev->otherend_id,
-						gfn, 0);
-
-		vaddr = vaddr + XEN_PAGE_SIZE;
-	}
-
-	return 0;
-}
-EXPORT_SYMBOL_GPL(xenbus_grant_ring);
-
 /*
  * xenbus_setup_ring
  * @dev: xenbus device
@@ -424,6 +380,7 @@ int xenbus_setup_ring(struct xenbus_device *dev, gfp_t gfp, void **vaddr,
 		      unsigned int nr_pages, grant_ref_t *grefs)
 {
 	unsigned long ring_size = nr_pages * XEN_PAGE_SIZE;
+	grant_ref_t gref_head;
 	unsigned int i;
 	int ret;
 
@@ -433,9 +390,25 @@ int xenbus_setup_ring(struct xenbus_device *dev, gfp_t gfp, void **vaddr,
 		goto err;
 	}
 
-	ret = xenbus_grant_ring(dev, *vaddr, nr_pages, grefs);
-	if (ret)
+	ret = gnttab_alloc_grant_references(nr_pages, &gref_head);
+	if (ret) {
+		xenbus_dev_fatal(dev, ret, "granting access to %u ring pages",
+				 nr_pages);
 		goto err;
+	}
+
+	for (i = 0; i < nr_pages; i++) {
+		unsigned long gfn;
+
+		if (is_vmalloc_addr(*vaddr))
+			gfn = pfn_to_gfn(vmalloc_to_pfn(vaddr[i]));
+		else
+			gfn = virt_to_gfn(vaddr[i]);
+
+		grefs[i] = gnttab_claim_grant_reference(&gref_head);
+		gnttab_grant_foreign_access_ref(grefs[i], dev->otherend_id,
+						gfn, 0);
+	}
 
 	return 0;
 
diff --git a/include/xen/xenbus.h b/include/xen/xenbus.h
index b533b4adc835..eaa932b99d8a 100644
--- a/include/xen/xenbus.h
+++ b/include/xen/xenbus.h
@@ -224,8 +224,6 @@ int xenbus_watch_pathfmt(struct xenbus_device *dev, struct xenbus_watch *watch,
 			 const char *pathfmt, ...);
 
 int xenbus_switch_state(struct xenbus_device *dev, enum xenbus_state new_state);
-int xenbus_grant_ring(struct xenbus_device *dev, void *vaddr,
-		      unsigned int nr_pages, grant_ref_t *grefs);
 int xenbus_setup_ring(struct xenbus_device *dev, gfp_t gfp, void **vaddr,
 		      unsigned int nr_pages, grant_ref_t *grefs);
 void xenbus_teardown_ring(void **vaddr, unsigned int nr_pages,
-- 
2.35.3

Re: [PATCH v3 00/21] xen: simplify frontend side ring setup

[Boris Ostrovsky]

On 5/5/22 4:16 AM, Juergen Gross wrote:
> Many Xen PV frontends share similar code for setting up a ring page
> (allocating and granting access for the backend) and for tearing it
> down.
>
> Create new service functions doing all needed steps in one go.
>
> This requires all frontends to use a common value for an invalid
> grant reference in order to make the functions idempotent.
>
> Changes in V3:
> - new patches 1 and 2, comments addressed
>
> Changes in V2:
> - new patch 9 and related changes in patches 10-18


For the patches that I was explicitly copied on:


Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

Re: [PATCH v3 00/21] xen: simplify frontend side ring setup

[Oleksandr]

On 05.05.22 11:16, Juergen Gross wrote:

Hello Juergen.



> Many Xen PV frontends share similar code for setting up a ring page
> (allocating and granting access for the backend) and for tearing it
> down.
>
> Create new service functions doing all needed steps in one go.
>
> This requires all frontends to use a common value for an invalid
> grant reference in order to make the functions idempotent.
>
> Changes in V3:
> - new patches 1 and 2, comments addressed
>
> Changes in V2:
> - new patch 9 and related changes in patches 10-18
>
> Juergen Gross (21):
>    xen: update grant_table.h
>    xen/grant-table: never put a reserved grant on the free list
>    xen/blkfront: switch blkfront to use INVALID_GRANT_REF
>    xen/netfront: switch netfront to use INVALID_GRANT_REF
>    xen/scsifront: remove unused GRANT_INVALID_REF definition
>    xen/usb: switch xen-hcd to use INVALID_GRANT_REF
>    xen/drm: switch xen_drm_front to use INVALID_GRANT_REF
>    xen/sound: switch xen_snd_front to use INVALID_GRANT_REF
>    xen/dmabuf: switch gntdev-dmabuf to use INVALID_GRANT_REF
>    xen/shbuf: switch xen-front-pgdir-shbuf to use INVALID_GRANT_REF
>    xen: update ring.h
>    xen/xenbus: add xenbus_setup_ring() service function
>    xen/blkfront: use xenbus_setup_ring() and xenbus_teardown_ring()
>    xen/netfront: use xenbus_setup_ring() and xenbus_teardown_ring()
>    xen/tpmfront: use xenbus_setup_ring() and xenbus_teardown_ring()
>    xen/drmfront: use xenbus_setup_ring() and xenbus_teardown_ring()
>    xen/pcifront: use xenbus_setup_ring() and xenbus_teardown_ring()
>    xen/scsifront: use xenbus_setup_ring() and xenbus_teardown_ring()
>    xen/usbfront: use xenbus_setup_ring() and xenbus_teardown_ring()
>    xen/sndfront: use xenbus_setup_ring() and xenbus_teardown_ring()
>    xen/xenbus: eliminate xenbus_grant_ring()


For the patches that touch PV display (#07, #16), PV sound (#08, #20) 
and shared buffer framework used by both frontends (#10):

Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>


Also I didn't see any issues with these frontends while testing on Arm64 
based board.
So, you can also add:

[Arm64 only]
Tested-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>


Thanks!


>
>   drivers/block/xen-blkfront.c                |  57 +++----
>   drivers/char/tpm/xen-tpmfront.c             |  18 +--
>   drivers/gpu/drm/xen/xen_drm_front.h         |   9 --
>   drivers/gpu/drm/xen/xen_drm_front_evtchnl.c |  43 ++----
>   drivers/net/xen-netfront.c                  |  85 ++++-------
>   drivers/pci/xen-pcifront.c                  |  19 +--
>   drivers/scsi/xen-scsifront.c                |  31 +---
>   drivers/usb/host/xen-hcd.c                  |  65 ++------
>   drivers/xen/gntdev-dmabuf.c                 |  13 +-
>   drivers/xen/grant-table.c                   |  12 +-
>   drivers/xen/xen-front-pgdir-shbuf.c         |  18 +--
>   drivers/xen/xenbus/xenbus_client.c          |  82 +++++++---
>   include/xen/grant_table.h                   |   2 -
>   include/xen/interface/grant_table.h         | 161 ++++++++++++--------
>   include/xen/interface/io/ring.h             |  19 ++-
>   include/xen/xenbus.h                        |   4 +-
>   sound/xen/xen_snd_front_evtchnl.c           |  44 ++----
>   sound/xen/xen_snd_front_evtchnl.h           |   9 --
>   18 files changed, 287 insertions(+), 404 deletions(-)
>
-- 
Regards,

Oleksandr Tyshchenko