[PATCH v3 0/8] xen/events: bug fixes and some diagnostic aids

[PATCH v3 0/8] xen/events: bug fixes and some diagnostic aids

[Juergen Gross]

The first four patches are fixes for XSA-332. The avoid WARN splats
and a performance issue with interdomain events.

Patches 5 and 6 are some additions to event handling in order to add
some per pv-device statistics to sysfs and the ability to have a per
backend device spurious event delay control.

Patches 7 and 8 are minor fixes I had lying around.

Juergen Gross (8):
  xen/events: reset affinity of 2-level event when tearing it down
  xen/events: don't unmask an event channel when an eoi is pending
  xen/events: avoid handling the same event on two cpus at the same time
  xen/netback: fix spurious event detection for common event case
  xen/events: link interdomain events to associated xenbus device
  xen/events: add per-xenbus device event statistics and settings
  xen/evtchn: use smp barriers for user event ring
  xen/evtchn: use READ/WRITE_ONCE() for accessing ring indices

 .../ABI/testing/sysfs-devices-xenbus          |  41 ++++
 drivers/block/xen-blkback/xenbus.c            |   2 +-
 drivers/net/xen-netback/interface.c           |  24 ++-
 drivers/xen/events/events_2l.c                |  22 +-
 drivers/xen/events/events_base.c              | 199 +++++++++++++-----
 drivers/xen/events/events_fifo.c              |   7 -
 drivers/xen/events/events_internal.h          |  14 +-
 drivers/xen/evtchn.c                          |  29 ++-
 drivers/xen/pvcalls-back.c                    |   4 +-
 drivers/xen/xen-pciback/xenbus.c              |   2 +-
 drivers/xen/xen-scsiback.c                    |   2 +-
 drivers/xen/xenbus/xenbus_probe.c             |  66 ++++++
 include/xen/events.h                          |   7 +-
 include/xen/xenbus.h                          |   7 +
 14 files changed, 327 insertions(+), 99 deletions(-)
 create mode 100644 Documentation/ABI/testing/sysfs-devices-xenbus

-- 
2.26.2

[PATCH v3 4/8] xen/netback: fix spurious event detection for common event case

[Juergen Gross]

In case of a common event for rx and tx queue the event should be
regarded to be spurious if no rx and no tx requests are pending.

Unfortunately the condition for testing that is wrong causing to
decide a event being spurious if no rx OR no tx requests are
pending.

Fix that plus using local variables for rx/tx pending indicators in
order to split function calls and if condition.

Cc: stable@vger.kernel.org
Fixes: 23025393dbeb3b ("xen/netback: use lateeoi irq binding")
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Reviewed-by: Wei Liu <wl@xen.org>
---
V2:
- new patch, fixing FreeBSD performance issue
---
 drivers/net/xen-netback/interface.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index acb786d8b1d8..e02a4fbb74de 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -162,13 +162,15 @@ irqreturn_t xenvif_interrupt(int irq, void *dev_id)
 {
 	struct xenvif_queue *queue = dev_id;
 	int old;
+	bool has_rx, has_tx;
 
 	old = atomic_fetch_or(NETBK_COMMON_EOI, &queue->eoi_pending);
 	WARN(old, "Interrupt while EOI pending\n");
 
-	/* Use bitwise or as we need to call both functions. */
-	if ((!xenvif_handle_tx_interrupt(queue) |
-	     !xenvif_handle_rx_interrupt(queue))) {
+	has_tx = xenvif_handle_tx_interrupt(queue);
+	has_rx = xenvif_handle_rx_interrupt(queue);
+
+	if (!has_rx && !has_tx) {
 		atomic_andnot(NETBK_COMMON_EOI, &queue->eoi_pending);
 		xen_irq_lateeoi(irq, XEN_EOI_FLAG_SPURIOUS);
 	}
-- 
2.26.2

[PATCH v3 5/8] xen/events: link interdomain events to associated xenbus device

[Juergen Gross]

In order to support the possibility of per-device event channel
settings (e.g. lateeoi spurious event thresholds) add a xenbus device
pointer to struct irq_info() and modify the related event channel
binding interfaces to take the pointer to the xenbus device as a
parameter instead of the domain id of the other side.

While at it remove the stale prototype of bind_evtchn_to_irq_lateeoi().

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Wei Liu <wei.liu@kernel.org>
Reviewed-by: Paul Durrant <paul@xen.org>
---
 drivers/block/xen-blkback/xenbus.c  |  2 +-
 drivers/net/xen-netback/interface.c | 16 +++++------
 drivers/xen/events/events_base.c    | 41 +++++++++++++++++------------
 drivers/xen/pvcalls-back.c          |  4 +--
 drivers/xen/xen-pciback/xenbus.c    |  2 +-
 drivers/xen/xen-scsiback.c          |  2 +-
 include/xen/events.h                |  7 ++---
 7 files changed, 41 insertions(+), 33 deletions(-)

diff --git a/drivers/block/xen-blkback/xenbus.c b/drivers/block/xen-blkback/xenbus.c
index 9860d4842f36..c2aaf690352c 100644
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -245,7 +245,7 @@ static int xen_blkif_map(struct xen_blkif_ring *ring, grant_ref_t *gref,
 	if (req_prod - rsp_prod > size)
 		goto fail;
 
-	err = bind_interdomain_evtchn_to_irqhandler_lateeoi(blkif->domid,
+	err = bind_interdomain_evtchn_to_irqhandler_lateeoi(blkif->be->dev,
 			evtchn, xen_blkif_be_int, 0, "blkif-backend", ring);
 	if (err < 0)
 		goto fail;
diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index e02a4fbb74de..50a94e58c150 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -630,13 +630,13 @@ int xenvif_connect_ctrl(struct xenvif *vif, grant_ref_t ring_ref,
 			unsigned int evtchn)
 {
 	struct net_device *dev = vif->dev;
+	struct xenbus_device *xendev = xenvif_to_xenbus_device(vif);
 	void *addr;
 	struct xen_netif_ctrl_sring *shared;
 	RING_IDX rsp_prod, req_prod;
 	int err;
 
-	err = xenbus_map_ring_valloc(xenvif_to_xenbus_device(vif),
-				     &ring_ref, 1, &addr);
+	err = xenbus_map_ring_valloc(xendev, &ring_ref, 1, &addr);
 	if (err)
 		goto err;
 
@@ -650,7 +650,7 @@ int xenvif_connect_ctrl(struct xenvif *vif, grant_ref_t ring_ref,
 	if (req_prod - rsp_prod > RING_SIZE(&vif->ctrl))
 		goto err_unmap;
 
-	err = bind_interdomain_evtchn_to_irq_lateeoi(vif->domid, evtchn);
+	err = bind_interdomain_evtchn_to_irq_lateeoi(xendev, evtchn);
 	if (err < 0)
 		goto err_unmap;
 
@@ -673,8 +673,7 @@ int xenvif_connect_ctrl(struct xenvif *vif, grant_ref_t ring_ref,
 	vif->ctrl_irq = 0;
 
 err_unmap:
-	xenbus_unmap_ring_vfree(xenvif_to_xenbus_device(vif),
-				vif->ctrl.sring);
+	xenbus_unmap_ring_vfree(xendev, vif->ctrl.sring);
 	vif->ctrl.sring = NULL;
 
 err:
@@ -719,6 +718,7 @@ int xenvif_connect_data(struct xenvif_queue *queue,
 			unsigned int tx_evtchn,
 			unsigned int rx_evtchn)
 {
+	struct xenbus_device *dev = xenvif_to_xenbus_device(queue->vif);
 	struct task_struct *task;
 	int err;
 
@@ -755,7 +755,7 @@ int xenvif_connect_data(struct xenvif_queue *queue,
 	if (tx_evtchn == rx_evtchn) {
 		/* feature-split-event-channels == 0 */
 		err = bind_interdomain_evtchn_to_irqhandler_lateeoi(
-			queue->vif->domid, tx_evtchn, xenvif_interrupt, 0,
+			dev, tx_evtchn, xenvif_interrupt, 0,
 			queue->name, queue);
 		if (err < 0)
 			goto err;
@@ -766,7 +766,7 @@ int xenvif_connect_data(struct xenvif_queue *queue,
 		snprintf(queue->tx_irq_name, sizeof(queue->tx_irq_name),
 			 "%s-tx", queue->name);
 		err = bind_interdomain_evtchn_to_irqhandler_lateeoi(
-			queue->vif->domid, tx_evtchn, xenvif_tx_interrupt, 0,
+			dev, tx_evtchn, xenvif_tx_interrupt, 0,
 			queue->tx_irq_name, queue);
 		if (err < 0)
 			goto err;
@@ -776,7 +776,7 @@ int xenvif_connect_data(struct xenvif_queue *queue,
 		snprintf(queue->rx_irq_name, sizeof(queue->rx_irq_name),
 			 "%s-rx", queue->name);
 		err = bind_interdomain_evtchn_to_irqhandler_lateeoi(
-			queue->vif->domid, rx_evtchn, xenvif_rx_interrupt, 0,
+			dev, rx_evtchn, xenvif_rx_interrupt, 0,
 			queue->rx_irq_name, queue);
 		if (err < 0)
 			goto err;
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 9d7ba7623510..b60df189ecbc 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -63,6 +63,7 @@
 #include <xen/interface/physdev.h>
 #include <xen/interface/sched.h>
 #include <xen/interface/vcpu.h>
+#include <xen/xenbus.h>
 #include <asm/hw_irq.h>
 
 #include "events_internal.h"
@@ -121,6 +122,7 @@ struct irq_info {
 			unsigned char flags;
 			uint16_t domid;
 		} pirq;
+		struct xenbus_device *interdomain;
 	} u;
 };
 
@@ -322,11 +324,16 @@ static int xen_irq_info_common_setup(struct irq_info *info,
 }
 
 static int xen_irq_info_evtchn_setup(unsigned irq,
-				     evtchn_port_t evtchn)
+				     evtchn_port_t evtchn,
+				     struct xenbus_device *dev)
 {
 	struct irq_info *info = info_for_irq(irq);
+	int ret;
 
-	return xen_irq_info_common_setup(info, irq, IRQT_EVTCHN, evtchn, 0);
+	ret = xen_irq_info_common_setup(info, irq, IRQT_EVTCHN, evtchn, 0);
+	info->u.interdomain = dev;
+
+	return ret;
 }
 
 static int xen_irq_info_ipi_setup(unsigned cpu,
@@ -1162,7 +1169,8 @@ int xen_pirq_from_irq(unsigned irq)
 }
 EXPORT_SYMBOL_GPL(xen_pirq_from_irq);
 
-static int bind_evtchn_to_irq_chip(evtchn_port_t evtchn, struct irq_chip *chip)
+static int bind_evtchn_to_irq_chip(evtchn_port_t evtchn, struct irq_chip *chip,
+				   struct xenbus_device *dev)
 {
 	int irq;
 	int ret;
@@ -1182,7 +1190,7 @@ static int bind_evtchn_to_irq_chip(evtchn_port_t evtchn, struct irq_chip *chip)
 		irq_set_chip_and_handler_name(irq, chip,
 					      handle_edge_irq, "event");
 
-		ret = xen_irq_info_evtchn_setup(irq, evtchn);
+		ret = xen_irq_info_evtchn_setup(irq, evtchn, dev);
 		if (ret < 0) {
 			__unbind_from_irq(irq);
 			irq = ret;
@@ -1209,7 +1217,7 @@ static int bind_evtchn_to_irq_chip(evtchn_port_t evtchn, struct irq_chip *chip)
 
 int bind_evtchn_to_irq(evtchn_port_t evtchn)
 {
-	return bind_evtchn_to_irq_chip(evtchn, &xen_dynamic_chip);
+	return bind_evtchn_to_irq_chip(evtchn, &xen_dynamic_chip, NULL);
 }
 EXPORT_SYMBOL_GPL(bind_evtchn_to_irq);
 
@@ -1258,27 +1266,27 @@ static int bind_ipi_to_irq(unsigned int ipi, unsigned int cpu)
 	return irq;
 }
 
-static int bind_interdomain_evtchn_to_irq_chip(unsigned int remote_domain,
+static int bind_interdomain_evtchn_to_irq_chip(struct xenbus_device *dev,
 					       evtchn_port_t remote_port,
 					       struct irq_chip *chip)
 {
 	struct evtchn_bind_interdomain bind_interdomain;
 	int err;
 
-	bind_interdomain.remote_dom  = remote_domain;
+	bind_interdomain.remote_dom  = dev->otherend_id;
 	bind_interdomain.remote_port = remote_port;
 
 	err = HYPERVISOR_event_channel_op(EVTCHNOP_bind_interdomain,
 					  &bind_interdomain);
 
 	return err ? : bind_evtchn_to_irq_chip(bind_interdomain.local_port,
-					       chip);
+					       chip, dev);
 }
 
-int bind_interdomain_evtchn_to_irq_lateeoi(unsigned int remote_domain,
+int bind_interdomain_evtchn_to_irq_lateeoi(struct xenbus_device *dev,
 					   evtchn_port_t remote_port)
 {
-	return bind_interdomain_evtchn_to_irq_chip(remote_domain, remote_port,
+	return bind_interdomain_evtchn_to_irq_chip(dev, remote_port,
 						   &xen_lateeoi_chip);
 }
 EXPORT_SYMBOL_GPL(bind_interdomain_evtchn_to_irq_lateeoi);
@@ -1391,7 +1399,7 @@ static int bind_evtchn_to_irqhandler_chip(evtchn_port_t evtchn,
 {
 	int irq, retval;
 
-	irq = bind_evtchn_to_irq_chip(evtchn, chip);
+	irq = bind_evtchn_to_irq_chip(evtchn, chip, NULL);
 	if (irq < 0)
 		return irq;
 	retval = request_irq(irq, handler, irqflags, devname, dev_id);
@@ -1426,14 +1434,13 @@ int bind_evtchn_to_irqhandler_lateeoi(evtchn_port_t evtchn,
 EXPORT_SYMBOL_GPL(bind_evtchn_to_irqhandler_lateeoi);
 
 static int bind_interdomain_evtchn_to_irqhandler_chip(
-		unsigned int remote_domain, evtchn_port_t remote_port,
+		struct xenbus_device *dev, evtchn_port_t remote_port,
 		irq_handler_t handler, unsigned long irqflags,
 		const char *devname, void *dev_id, struct irq_chip *chip)
 {
 	int irq, retval;
 
-	irq = bind_interdomain_evtchn_to_irq_chip(remote_domain, remote_port,
-						  chip);
+	irq = bind_interdomain_evtchn_to_irq_chip(dev, remote_port, chip);
 	if (irq < 0)
 		return irq;
 
@@ -1446,14 +1453,14 @@ static int bind_interdomain_evtchn_to_irqhandler_chip(
 	return irq;
 }
 
-int bind_interdomain_evtchn_to_irqhandler_lateeoi(unsigned int remote_domain,
+int bind_interdomain_evtchn_to_irqhandler_lateeoi(struct xenbus_device *dev,
 						  evtchn_port_t remote_port,
 						  irq_handler_t handler,
 						  unsigned long irqflags,
 						  const char *devname,
 						  void *dev_id)
 {
-	return bind_interdomain_evtchn_to_irqhandler_chip(remote_domain,
+	return bind_interdomain_evtchn_to_irqhandler_chip(dev,
 				remote_port, handler, irqflags, devname,
 				dev_id, &xen_lateeoi_chip);
 }
@@ -1727,7 +1734,7 @@ void rebind_evtchn_irq(evtchn_port_t evtchn, int irq)
 	   so there should be a proper type */
 	BUG_ON(info->type == IRQT_UNBOUND);
 
-	(void)xen_irq_info_evtchn_setup(irq, evtchn);
+	(void)xen_irq_info_evtchn_setup(irq, evtchn, NULL);
 
 	mutex_unlock(&irq_mapping_update_lock);
 
diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
index a7d293fa8d14..b47fd8435061 100644
--- a/drivers/xen/pvcalls-back.c
+++ b/drivers/xen/pvcalls-back.c
@@ -348,7 +348,7 @@ static struct sock_mapping *pvcalls_new_active_socket(
 	map->bytes = page;
 
 	ret = bind_interdomain_evtchn_to_irqhandler_lateeoi(
-			fedata->dev->otherend_id, evtchn,
+			fedata->dev, evtchn,
 			pvcalls_back_conn_event, 0, "pvcalls-backend", map);
 	if (ret < 0)
 		goto out;
@@ -948,7 +948,7 @@ static int backend_connect(struct xenbus_device *dev)
 		goto error;
 	}
 
-	err = bind_interdomain_evtchn_to_irq_lateeoi(dev->otherend_id, evtchn);
+	err = bind_interdomain_evtchn_to_irq_lateeoi(dev, evtchn);
 	if (err < 0)
 		goto error;
 	fedata->irq = err;
diff --git a/drivers/xen/xen-pciback/xenbus.c b/drivers/xen/xen-pciback/xenbus.c
index e7c692cfb2cf..5188f02e75fb 100644
--- a/drivers/xen/xen-pciback/xenbus.c
+++ b/drivers/xen/xen-pciback/xenbus.c
@@ -124,7 +124,7 @@ static int xen_pcibk_do_attach(struct xen_pcibk_device *pdev, int gnt_ref,
 	pdev->sh_info = vaddr;
 
 	err = bind_interdomain_evtchn_to_irqhandler_lateeoi(
-		pdev->xdev->otherend_id, remote_evtchn, xen_pcibk_handle_event,
+		pdev->xdev, remote_evtchn, xen_pcibk_handle_event,
 		0, DRV_NAME, pdev);
 	if (err < 0) {
 		xenbus_dev_fatal(pdev->xdev, err,
diff --git a/drivers/xen/xen-scsiback.c b/drivers/xen/xen-scsiback.c
index 862162dca33c..8b59897b2df9 100644
--- a/drivers/xen/xen-scsiback.c
+++ b/drivers/xen/xen-scsiback.c
@@ -799,7 +799,7 @@ static int scsiback_init_sring(struct vscsibk_info *info, grant_ref_t ring_ref,
 	sring = (struct vscsiif_sring *)area;
 	BACK_RING_INIT(&info->ring, sring, PAGE_SIZE);
 
-	err = bind_interdomain_evtchn_to_irq_lateeoi(info->domid, evtchn);
+	err = bind_interdomain_evtchn_to_irq_lateeoi(info->dev, evtchn);
 	if (err < 0)
 		goto unmap_page;
 
diff --git a/include/xen/events.h b/include/xen/events.h
index 8ec418e30c7f..c204262d9fc2 100644
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -12,10 +12,11 @@
 #include <asm/xen/hypercall.h>
 #include <asm/xen/events.h>
 
+struct xenbus_device;
+
 unsigned xen_evtchn_nr_channels(void);
 
 int bind_evtchn_to_irq(evtchn_port_t evtchn);
-int bind_evtchn_to_irq_lateeoi(evtchn_port_t evtchn);
 int bind_evtchn_to_irqhandler(evtchn_port_t evtchn,
 			      irq_handler_t handler,
 			      unsigned long irqflags, const char *devname,
@@ -35,9 +36,9 @@ int bind_ipi_to_irqhandler(enum ipi_vector ipi,
 			   unsigned long irqflags,
 			   const char *devname,
 			   void *dev_id);
-int bind_interdomain_evtchn_to_irq_lateeoi(unsigned int remote_domain,
+int bind_interdomain_evtchn_to_irq_lateeoi(struct xenbus_device *dev,
 					   evtchn_port_t remote_port);
-int bind_interdomain_evtchn_to_irqhandler_lateeoi(unsigned int remote_domain,
+int bind_interdomain_evtchn_to_irqhandler_lateeoi(struct xenbus_device *dev,
 						  evtchn_port_t remote_port,
 						  irq_handler_t handler,
 						  unsigned long irqflags,
-- 
2.26.2

Re: [PATCH v3 5/8] xen/events: link interdomain events to associated xenbus device

[Roger Pau Monné]

On Fri, Feb 19, 2021 at 04:40:27PM +0100, Juergen Gross wrote:
> In order to support the possibility of per-device event channel
> settings (e.g. lateeoi spurious event thresholds) add a xenbus device
> pointer to struct irq_info() and modify the related event channel
> binding interfaces to take the pointer to the xenbus device as a
> parameter instead of the domain id of the other side.
> 
> While at it remove the stale prototype of bind_evtchn_to_irq_lateeoi().
> 
> Signed-off-by: Juergen Gross <jgross@suse.com>
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Reviewed-by: Wei Liu <wei.liu@kernel.org>
> Reviewed-by: Paul Durrant <paul@xen.org>
> ---
>  drivers/block/xen-blkback/xenbus.c  |  2 +-

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

Thanks, Roger.

Re: [PATCH v3 0/8] xen/events: bug fixes and some diagnostic aids

[Boris Ostrovsky]

On 2/19/21 10:40 AM, Juergen Gross wrote:
> The first four patches are fixes for XSA-332. The avoid WARN splats
> and a performance issue with interdomain events.
>
> Patches 5 and 6 are some additions to event handling in order to add
> some per pv-device statistics to sysfs and the ability to have a per
> backend device spurious event delay control.
>
> Patches 7 and 8 are minor fixes I had lying around.
>
> Juergen Gross (8):
>   xen/events: reset affinity of 2-level event when tearing it down
>   xen/events: don't unmask an event channel when an eoi is pending
>   xen/events: avoid handling the same event on two cpus at the same time
>   xen/netback: fix spurious event detection for common event case
>   xen/events: link interdomain events to associated xenbus device
>   xen/events: add per-xenbus device event statistics and settings
>   xen/evtchn: use smp barriers for user event ring
>   xen/evtchn: use READ/WRITE_ONCE() for accessing ring indices
>

I am going to pick up the last 3 patches since Ross appears to be having some issues with #2 (and 4 and 5 went in via netdev tree)


-boris