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

[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 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

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