[PATCH 0/5] xen: event handling cleanup

[PATCH 0/5] xen: event handling cleanup

[Juergen Gross]

Do some cleanups in Xen event handling code.

Juergen Gross (5):
  xen: remove no longer used functions
  xen/events: make struct irq_info private to events_base.c
  xen/events: only register debug interrupt for 2-level events
  xen/events: unmask a fifo event channel only if it was masked
  Documentation: add xen.fifo_events kernel parameter description

 .../admin-guide/kernel-parameters.txt         |  7 ++
 arch/x86/xen/smp.c                            | 19 ++--
 arch/x86/xen/xen-ops.h                        |  2 +
 drivers/xen/events/events_2l.c                |  7 +-
 drivers/xen/events/events_base.c              | 90 +++++++++++++------
 drivers/xen/events/events_fifo.c              |  9 +-
 drivers/xen/events/events_internal.h          | 70 ++-------------
 include/xen/events.h                          |  8 --
 8 files changed, 100 insertions(+), 112 deletions(-)

-- 
2.26.2

[PATCH 1/5] xen: remove no longer used functions

[Juergen Gross]

With the switch to the lateeoi model for interdomain event channels
some functions are no longer in use. Remove them.

Suggested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/xen/events/events_base.c | 21 ---------------------
 include/xen/events.h             |  8 --------
 2 files changed, 29 deletions(-)

diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index cc317739e786..436682db41c5 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -1145,14 +1145,6 @@ static int bind_interdomain_evtchn_to_irq_chip(unsigned int remote_domain,
 					       chip);
 }
 
-int bind_interdomain_evtchn_to_irq(unsigned int remote_domain,
-				   evtchn_port_t remote_port)
-{
-	return bind_interdomain_evtchn_to_irq_chip(remote_domain, remote_port,
-						   &xen_dynamic_chip);
-}
-EXPORT_SYMBOL_GPL(bind_interdomain_evtchn_to_irq);
-
 int bind_interdomain_evtchn_to_irq_lateeoi(unsigned int remote_domain,
 					   evtchn_port_t remote_port)
 {
@@ -1320,19 +1312,6 @@ static int bind_interdomain_evtchn_to_irqhandler_chip(
 	return irq;
 }
 
-int bind_interdomain_evtchn_to_irqhandler(unsigned int remote_domain,
-					  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,
-				remote_port, handler, irqflags, devname,
-				dev_id, &xen_dynamic_chip);
-}
-EXPORT_SYMBOL_GPL(bind_interdomain_evtchn_to_irqhandler);
-
 int bind_interdomain_evtchn_to_irqhandler_lateeoi(unsigned int remote_domain,
 						  evtchn_port_t remote_port,
 						  irq_handler_t handler,
diff --git a/include/xen/events.h b/include/xen/events.h
index 3b8155c2ea03..8ec418e30c7f 100644
--- a/include/xen/events.h
+++ b/include/xen/events.h
@@ -35,16 +35,8 @@ int bind_ipi_to_irqhandler(enum ipi_vector ipi,
 			   unsigned long irqflags,
 			   const char *devname,
 			   void *dev_id);
-int bind_interdomain_evtchn_to_irq(unsigned int remote_domain,
-				   evtchn_port_t remote_port);
 int bind_interdomain_evtchn_to_irq_lateeoi(unsigned int remote_domain,
 					   evtchn_port_t remote_port);
-int bind_interdomain_evtchn_to_irqhandler(unsigned int remote_domain,
-					  evtchn_port_t remote_port,
-					  irq_handler_t handler,
-					  unsigned long irqflags,
-					  const char *devname,
-					  void *dev_id);
 int bind_interdomain_evtchn_to_irqhandler_lateeoi(unsigned int remote_domain,
 						  evtchn_port_t remote_port,
 						  irq_handler_t handler,
-- 
2.26.2

[PATCH 2/5] xen/events: make struct irq_info private to events_base.c

[Juergen Gross]

The struct irq_info of Xen's event handling is used only for two
evtchn_ops functions outside of events_base.c. Those two functions
can easily be switched to avoid that usage.

This allows to make struct irq_info and its related access functions
private to events_base.c.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/xen/events/events_2l.c       |  7 +--
 drivers/xen/events/events_base.c     | 63 ++++++++++++++++++++++---
 drivers/xen/events/events_fifo.c     |  6 +--
 drivers/xen/events/events_internal.h | 70 ++++------------------------
 4 files changed, 73 insertions(+), 73 deletions(-)

diff --git a/drivers/xen/events/events_2l.c b/drivers/xen/events/events_2l.c
index fe5ad0e89cd8..da87f3a1e351 100644
--- a/drivers/xen/events/events_2l.c
+++ b/drivers/xen/events/events_2l.c
@@ -47,10 +47,11 @@ static unsigned evtchn_2l_max_channels(void)
 	return EVTCHN_2L_NR_CHANNELS;
 }
 
-static void evtchn_2l_bind_to_cpu(struct irq_info *info, unsigned cpu)
+static void evtchn_2l_bind_to_cpu(evtchn_port_t evtchn, unsigned int cpu,
+				  unsigned int old_cpu)
 {
-	clear_bit(info->evtchn, BM(per_cpu(cpu_evtchn_mask, info->cpu)));
-	set_bit(info->evtchn, BM(per_cpu(cpu_evtchn_mask, cpu)));
+	clear_bit(evtchn, BM(per_cpu(cpu_evtchn_mask, old_cpu)));
+	set_bit(evtchn, BM(per_cpu(cpu_evtchn_mask, cpu)));
 }
 
 static void evtchn_2l_clear_pending(evtchn_port_t port)
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 436682db41c5..1c25580c7691 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -70,6 +70,57 @@
 #undef MODULE_PARAM_PREFIX
 #define MODULE_PARAM_PREFIX "xen."
 
+/* Interrupt types. */
+enum xen_irq_type {
+	IRQT_UNBOUND = 0,
+	IRQT_PIRQ,
+	IRQT_VIRQ,
+	IRQT_IPI,
+	IRQT_EVTCHN
+};
+
+/*
+ * Packed IRQ information:
+ * type - enum xen_irq_type
+ * event channel - irq->event channel mapping
+ * cpu - cpu this event channel is bound to
+ * index - type-specific information:
+ *    PIRQ - vector, with MSB being "needs EIO", or physical IRQ of the HVM
+ *           guest, or GSI (real passthrough IRQ) of the device.
+ *    VIRQ - virq number
+ *    IPI - IPI vector
+ *    EVTCHN -
+ */
+struct irq_info {
+	struct list_head list;
+	struct list_head eoi_list;
+	short refcnt;
+	short spurious_cnt;
+	enum xen_irq_type type; /* type */
+	unsigned irq;
+	evtchn_port_t evtchn;   /* event channel */
+	unsigned short cpu;     /* cpu bound */
+	unsigned short eoi_cpu; /* EOI must happen on this cpu-1 */
+	unsigned int irq_epoch; /* If eoi_cpu valid: irq_epoch of event */
+	u64 eoi_time;           /* Time in jiffies when to EOI. */
+
+	union {
+		unsigned short virq;
+		enum ipi_vector ipi;
+		struct {
+			unsigned short pirq;
+			unsigned short gsi;
+			unsigned char vector;
+			unsigned char flags;
+			uint16_t domid;
+		} pirq;
+	} u;
+};
+
+#define PIRQ_NEEDS_EOI	(1 << 0)
+#define PIRQ_SHAREABLE	(1 << 1)
+#define PIRQ_MSI_GROUP	(1 << 2)
+
 static uint __read_mostly event_loop_timeout = 2;
 module_param(event_loop_timeout, uint, 0644);
 
@@ -110,7 +161,7 @@ static DEFINE_PER_CPU(int [NR_VIRQS], virq_to_irq) = {[0 ... NR_VIRQS-1] = -1};
 /* IRQ <-> IPI mapping */
 static DEFINE_PER_CPU(int [XEN_NR_IPIS], ipi_to_irq) = {[0 ... XEN_NR_IPIS-1] = -1};
 
-int **evtchn_to_irq;
+static int **evtchn_to_irq;
 #ifdef CONFIG_X86
 static unsigned long *pirq_eoi_map;
 #endif
@@ -190,7 +241,7 @@ int get_evtchn_to_irq(evtchn_port_t evtchn)
 }
 
 /* Get info for IRQ */
-struct irq_info *info_for_irq(unsigned irq)
+static struct irq_info *info_for_irq(unsigned irq)
 {
 	if (irq < nr_legacy_irqs())
 		return legacy_info_ptrs[irq];
@@ -228,7 +279,7 @@ static int xen_irq_info_common_setup(struct irq_info *info,
 
 	irq_clear_status_flags(irq, IRQ_NOREQUEST|IRQ_NOAUTOEN);
 
-	return xen_evtchn_port_setup(info);
+	return xen_evtchn_port_setup(evtchn);
 }
 
 static int xen_irq_info_evtchn_setup(unsigned irq,
@@ -351,7 +402,7 @@ static enum xen_irq_type type_from_irq(unsigned irq)
 	return info_for_irq(irq)->type;
 }
 
-unsigned cpu_from_irq(unsigned irq)
+static unsigned cpu_from_irq(unsigned irq)
 {
 	return info_for_irq(irq)->cpu;
 }
@@ -391,7 +442,7 @@ static void bind_evtchn_to_cpu(evtchn_port_t evtchn, unsigned int cpu)
 #ifdef CONFIG_SMP
 	cpumask_copy(irq_get_affinity_mask(irq), cpumask_of(cpu));
 #endif
-	xen_evtchn_port_bind_to_cpu(info, cpu);
+	xen_evtchn_port_bind_to_cpu(evtchn, cpu, info->cpu);
 
 	info->cpu = cpu;
 }
@@ -745,7 +796,7 @@ static unsigned int __startup_pirq(unsigned int irq)
 	info->evtchn = evtchn;
 	bind_evtchn_to_cpu(evtchn, 0);
 
-	rc = xen_evtchn_port_setup(info);
+	rc = xen_evtchn_port_setup(evtchn);
 	if (rc)
 		goto err;
 
diff --git a/drivers/xen/events/events_fifo.c b/drivers/xen/events/events_fifo.c
index 6085a808da95..243e7b6d7b96 100644
--- a/drivers/xen/events/events_fifo.c
+++ b/drivers/xen/events/events_fifo.c
@@ -138,9 +138,8 @@ static void init_array_page(event_word_t *array_page)
 		array_page[i] = 1 << EVTCHN_FIFO_MASKED;
 }
 
-static int evtchn_fifo_setup(struct irq_info *info)
+static int evtchn_fifo_setup(evtchn_port_t port)
 {
-	evtchn_port_t port = info->evtchn;
 	unsigned new_array_pages;
 	int ret;
 
@@ -186,7 +185,8 @@ static int evtchn_fifo_setup(struct irq_info *info)
 	return ret;
 }
 
-static void evtchn_fifo_bind_to_cpu(struct irq_info *info, unsigned cpu)
+static void evtchn_fifo_bind_to_cpu(evtchn_port_t evtchn, unsigned int cpu, 
+				    unsigned int old_cpu)
 {
 	/* no-op */
 }
diff --git a/drivers/xen/events/events_internal.h b/drivers/xen/events/events_internal.h
index 82937d90d7d7..0a97c0549db7 100644
--- a/drivers/xen/events/events_internal.h
+++ b/drivers/xen/events/events_internal.h
@@ -7,65 +7,15 @@
 #ifndef __EVENTS_INTERNAL_H__
 #define __EVENTS_INTERNAL_H__
 
-/* Interrupt types. */
-enum xen_irq_type {
-	IRQT_UNBOUND = 0,
-	IRQT_PIRQ,
-	IRQT_VIRQ,
-	IRQT_IPI,
-	IRQT_EVTCHN
-};
-
-/*
- * Packed IRQ information:
- * type - enum xen_irq_type
- * event channel - irq->event channel mapping
- * cpu - cpu this event channel is bound to
- * index - type-specific information:
- *    PIRQ - vector, with MSB being "needs EIO", or physical IRQ of the HVM
- *           guest, or GSI (real passthrough IRQ) of the device.
- *    VIRQ - virq number
- *    IPI - IPI vector
- *    EVTCHN -
- */
-struct irq_info {
-	struct list_head list;
-	struct list_head eoi_list;
-	short refcnt;
-	short spurious_cnt;
-	enum xen_irq_type type;	/* type */
-	unsigned irq;
-	evtchn_port_t evtchn;	/* event channel */
-	unsigned short cpu;	/* cpu bound */
-	unsigned short eoi_cpu;	/* EOI must happen on this cpu */
-	unsigned int irq_epoch;	/* If eoi_cpu valid: irq_epoch of event */
-	u64 eoi_time;		/* Time in jiffies when to EOI. */
-
-	union {
-		unsigned short virq;
-		enum ipi_vector ipi;
-		struct {
-			unsigned short pirq;
-			unsigned short gsi;
-			unsigned char vector;
-			unsigned char flags;
-			uint16_t domid;
-		} pirq;
-	} u;
-};
-
-#define PIRQ_NEEDS_EOI	(1 << 0)
-#define PIRQ_SHAREABLE	(1 << 1)
-#define PIRQ_MSI_GROUP	(1 << 2)
-
 struct evtchn_loop_ctrl;
 
 struct evtchn_ops {
 	unsigned (*max_channels)(void);
 	unsigned (*nr_channels)(void);
 
-	int (*setup)(struct irq_info *info);
-	void (*bind_to_cpu)(struct irq_info *info, unsigned cpu);
+	int (*setup)(evtchn_port_t port);
+	void (*bind_to_cpu)(evtchn_port_t evtchn, unsigned int cpu,
+			    unsigned int old_cpu);
 
 	void (*clear_pending)(evtchn_port_t port);
 	void (*set_pending)(evtchn_port_t port);
@@ -83,12 +33,9 @@ struct evtchn_ops {
 
 extern const struct evtchn_ops *evtchn_ops;
 
-extern int **evtchn_to_irq;
 int get_evtchn_to_irq(evtchn_port_t evtchn);
 void handle_irq_for_port(evtchn_port_t port, struct evtchn_loop_ctrl *ctrl);
 
-struct irq_info *info_for_irq(unsigned irq);
-unsigned cpu_from_irq(unsigned irq);
 unsigned int cpu_from_evtchn(evtchn_port_t evtchn);
 
 static inline unsigned xen_evtchn_max_channels(void)
@@ -100,17 +47,18 @@ static inline unsigned xen_evtchn_max_channels(void)
  * Do any ABI specific setup for a bound event channel before it can
  * be unmasked and used.
  */
-static inline int xen_evtchn_port_setup(struct irq_info *info)
+static inline int xen_evtchn_port_setup(evtchn_port_t evtchn)
 {
 	if (evtchn_ops->setup)
-		return evtchn_ops->setup(info);
+		return evtchn_ops->setup(evtchn);
 	return 0;
 }
 
-static inline void xen_evtchn_port_bind_to_cpu(struct irq_info *info,
-					       unsigned cpu)
+static inline void xen_evtchn_port_bind_to_cpu(evtchn_port_t evtchn,
+					       unsigned int cpu,
+					       unsigned int old_cpu)
 {
-	evtchn_ops->bind_to_cpu(info, cpu);
+	evtchn_ops->bind_to_cpu(evtchn, cpu, old_cpu);
 }
 
 static inline void clear_evtchn(evtchn_port_t port)
-- 
2.26.2

[PATCH 3/5] xen/events: only register debug interrupt for 2-level events

[Juergen Gross]

xen_debug_interrupt() is specific to 2-level event handling. So don't
register it with fifo event handling being active.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 arch/x86/xen/smp.c               | 19 +++++++++++--------
 arch/x86/xen/xen-ops.h           |  2 ++
 drivers/xen/events/events_base.c |  6 ++++--
 3 files changed, 17 insertions(+), 10 deletions(-)

diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index 2097fa0ebdb5..b544e511b3c2 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -88,14 +88,17 @@ int xen_smp_intr_init(unsigned int cpu)
 	per_cpu(xen_callfunc_irq, cpu).irq = rc;
 	per_cpu(xen_callfunc_irq, cpu).name = callfunc_name;
 
-	debug_name = kasprintf(GFP_KERNEL, "debug%d", cpu);
-	rc = bind_virq_to_irqhandler(VIRQ_DEBUG, cpu, xen_debug_interrupt,
-				     IRQF_PERCPU | IRQF_NOBALANCING,
-				     debug_name, NULL);
-	if (rc < 0)
-		goto fail;
-	per_cpu(xen_debug_irq, cpu).irq = rc;
-	per_cpu(xen_debug_irq, cpu).name = debug_name;
+	if (!fifo_events) {
+		debug_name = kasprintf(GFP_KERNEL, "debug%d", cpu);
+		rc = bind_virq_to_irqhandler(VIRQ_DEBUG, cpu,
+					     xen_debug_interrupt,
+					     IRQF_PERCPU | IRQF_NOBALANCING,
+					     debug_name, NULL);
+		if (rc < 0)
+			goto fail;
+		per_cpu(xen_debug_irq, cpu).irq = rc;
+		per_cpu(xen_debug_irq, cpu).name = debug_name;
+	}
 
 	callfunc_name = kasprintf(GFP_KERNEL, "callfuncsingle%d", cpu);
 	rc = bind_ipi_to_irqhandler(XEN_CALL_FUNCTION_SINGLE_VECTOR,
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 45d556f71858..e444c78b6e2b 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -29,6 +29,8 @@ extern struct start_info *xen_start_info;
 extern struct shared_info xen_dummy_shared_info;
 extern struct shared_info *HYPERVISOR_shared_info;
 
+extern bool fifo_events;
+
 void xen_setup_mfn_list_list(void);
 void xen_build_mfn_list_list(void);
 void xen_setup_machphys_mapping(void);
diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c
index 1c25580c7691..bb18cce4db06 100644
--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -2050,7 +2050,7 @@ void xen_setup_callback_vector(void) {}
 static inline void xen_alloc_callback_vector(void) {}
 #endif
 
-static bool fifo_events = true;
+bool fifo_events = true;
 module_param(fifo_events, bool, 0);
 
 static int xen_evtchn_cpu_prepare(unsigned int cpu)
@@ -2082,8 +2082,10 @@ void __init xen_init_IRQ(void)
 
 	if (fifo_events)
 		ret = xen_evtchn_fifo_init();
-	if (ret < 0)
+	if (ret < 0) {
 		xen_evtchn_2l_init();
+		fifo_events = false;
+	}
 
 	xen_cpu_init_eoi(smp_processor_id());
 
-- 
2.26.2

Re: [PATCH 3/5] xen/events: only register debug interrupt for 2-level events

[Jan Beulich]

On 22.10.2020 09:42, Juergen Gross wrote:
> --- a/drivers/xen/events/events_base.c
> +++ b/drivers/xen/events/events_base.c
> @@ -2050,7 +2050,7 @@ void xen_setup_callback_vector(void) {}
>  static inline void xen_alloc_callback_vector(void) {}
>  #endif
>  
> -static bool fifo_events = true;
> +bool fifo_events = true;

When making this non-static, perhaps better to also prefix it with
xen_?

Jan

Re: [PATCH 3/5] xen/events: only register debug interrupt for 2-level events

[Jürgen Groß]

On 22.10.20 09:54, Jan Beulich wrote:
> On 22.10.2020 09:42, Juergen Gross wrote:
>> --- a/drivers/xen/events/events_base.c
>> +++ b/drivers/xen/events/events_base.c
>> @@ -2050,7 +2050,7 @@ void xen_setup_callback_vector(void) {}
>>   static inline void xen_alloc_callback_vector(void) {}
>>   #endif
>>   
>> -static bool fifo_events = true;
>> +bool fifo_events = true;
> 
> When making this non-static, perhaps better to also prefix it with
> xen_?

Fine with me.


Juergen

[PATCH 4/5] xen/events: unmask a fifo event channel only if it was masked

[Juergen Gross]

Unmasking an event channel with fifo events channels being used can
require a hypercall to be made, so try to avoid that by checking
whether the event channel was really masked.

Suggested-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
 drivers/xen/events/events_fifo.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/xen/events/events_fifo.c b/drivers/xen/events/events_fifo.c
index 243e7b6d7b96..f60c5a9ec833 100644
--- a/drivers/xen/events/events_fifo.c
+++ b/drivers/xen/events/events_fifo.c
@@ -236,6 +236,9 @@ static bool clear_masked_cond(volatile event_word_t *word)
 
 	w = *word;
 
+	if (!(w & (1 << EVTCHN_FIFO_MASKED)))
+		return true;
+
 	do {
 		if (w & (1 << EVTCHN_FIFO_PENDING))
 			return false;
-- 
2.26.2

Re: [PATCH 4/5] xen/events: unmask a fifo event channel only if it was masked

[Jan Beulich]

On 22.10.2020 09:42, Juergen Gross wrote:
> --- a/drivers/xen/events/events_fifo.c
> +++ b/drivers/xen/events/events_fifo.c
> @@ -236,6 +236,9 @@ static bool clear_masked_cond(volatile event_word_t *word)
>  
>  	w = *word;
>  
> +	if (!(w & (1 << EVTCHN_FIFO_MASKED)))
> +		return true;

Maybe better move this ...

>  	do {
>  		if (w & (1 << EVTCHN_FIFO_PENDING))
>  			return false;
> 

... into the loop, above this check?

Jan

Re: [PATCH 4/5] xen/events: unmask a fifo event channel only if it was masked

[Jürgen Groß]

On 22.10.20 09:55, Jan Beulich wrote:
> On 22.10.2020 09:42, Juergen Gross wrote:
>> --- a/drivers/xen/events/events_fifo.c
>> +++ b/drivers/xen/events/events_fifo.c
>> @@ -236,6 +236,9 @@ static bool clear_masked_cond(volatile event_word_t *word)
>>   
>>   	w = *word;
>>   
>> +	if (!(w & (1 << EVTCHN_FIFO_MASKED)))
>> +		return true;
> 
> Maybe better move this ...
> 
>>   	do {
>>   		if (w & (1 << EVTCHN_FIFO_PENDING))
>>   			return false;
>>
> 
> ... into the loop, above this check?

Yes, that should be better.


Juergen

[PATCH 5/5] Documentation: add xen.fifo_events kernel parameter description

[Juergen Gross]

The kernel boot parameter xen.fifo_events isn't listed in
Documentation/admin-guide/kernel-parameters.txt. Add it.

Signed-off-by: Juergen Gross <jgross@suse.com>
---
 Documentation/admin-guide/kernel-parameters.txt | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 02d4adbf98d2..526d65d8573a 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5978,6 +5978,13 @@
 			After which time (jiffies) the event handling loop
 			should start to delay EOI handling. Default is 2.
 
+	xen.fifo_events=	[XEN]
+			Boolean parameter to disable using fifo event handling
+			even if available. Normally fifo event handling is
+			preferred over the 2-level event handling, as it is
+			fairer and the number of possible event channels is
+			much higher. Default is on (use fifo events).
+
 	nopv=		[X86,XEN,KVM,HYPER_V,VMWARE]
 			Disables the PV optimizations forcing the guest to run
 			as generic guest with no PV drivers. Currently support
-- 
2.26.2

Re: [PATCH 0/5] xen: event handling cleanup

[Jan Beulich]

On 22.10.2020 09:42, Juergen Gross wrote:
> Do some cleanups in Xen event handling code.
> 
> Juergen Gross (5):
>   xen: remove no longer used functions
>   xen/events: make struct irq_info private to events_base.c
>   xen/events: only register debug interrupt for 2-level events
>   xen/events: unmask a fifo event channel only if it was masked
>   Documentation: add xen.fifo_events kernel parameter description

With the two remarks to individual patches suitably taken care of
one way or another
Reviewed-by: Jan Beulich <jbeulich@suse.com>

Jan