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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Juergen Gross <jgross@suse.com>,
        Jan Beulich <jbeulich@suse.com>, Wei Liu <wl@xen.org>
Subject: [PATCH 4.4 57/64] xen/events: use a common cpu hotplug hook for event channels
Date:   Tue, 17 Nov 2020 14:05:20 +0100
Message-Id: <20201117122108.995157963@linuxfoundation.org>
In-Reply-To: <20201117122106.144800239@linuxfoundation.org>
References: <20201117122106.144800239@linuxfoundation.org>
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From: Juergen Gross <jgross@suse.com>

commit 7beb290caa2adb0a399e735a1e175db9aae0523a upstream.

Today only fifo event channels have a cpu hotplug callback. In order
to prepare for more percpu (de)init work move that callback into
events_base.c and add percpu_init() and percpu_deinit() hooks to
struct evtchn_ops.

This is part of XSA-332.

Cc: stable@vger.kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Wei Liu <wl@xen.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/xen/events/events_base.c     |   47 +++++++++++++++++++++++++++
 drivers/xen/events/events_fifo.c     |   59 ++++++++++++++---------------------
 drivers/xen/events/events_internal.h |    3 +
 3 files changed, 74 insertions(+), 35 deletions(-)

--- a/drivers/xen/events/events_base.c
+++ b/drivers/xen/events/events_base.c
@@ -33,6 +33,7 @@
 #include <linux/irqnr.h>
 #include <linux/pci.h>
 #include <linux/spinlock.h>
+#include <linux/cpu.h>
 
 #ifdef CONFIG_X86
 #include <asm/desc.h>
@@ -1832,6 +1833,50 @@ void xen_callback_vector(void) {}
 static bool fifo_events = true;
 module_param(fifo_events, bool, 0);
 
+static int xen_evtchn_cpu_prepare(unsigned int cpu)
+{
+	int ret = 0;
+
+	if (evtchn_ops->percpu_init)
+		ret = evtchn_ops->percpu_init(cpu);
+
+	return ret;
+}
+
+static int xen_evtchn_cpu_dead(unsigned int cpu)
+{
+	int ret = 0;
+
+	if (evtchn_ops->percpu_deinit)
+		ret = evtchn_ops->percpu_deinit(cpu);
+
+	return ret;
+}
+
+static int evtchn_cpu_notification(struct notifier_block *self,
+				   unsigned long action, void *hcpu)
+{
+	int cpu = (long)hcpu;
+	int ret = 0;
+
+	switch (action) {
+	case CPU_UP_PREPARE:
+		ret = xen_evtchn_cpu_prepare(cpu);
+		break;
+	case CPU_DEAD:
+		ret = xen_evtchn_cpu_dead(cpu);
+		break;
+	default:
+		break;
+	}
+
+	return ret < 0 ? NOTIFY_BAD : NOTIFY_OK;
+}
+
+static struct notifier_block evtchn_cpu_notifier = {
+	.notifier_call  = evtchn_cpu_notification,
+};
+
 void __init xen_init_IRQ(void)
 {
 	int ret = -EINVAL;
@@ -1841,6 +1886,8 @@ void __init xen_init_IRQ(void)
 	if (ret < 0)
 		xen_evtchn_2l_init();
 
+	register_cpu_notifier(&evtchn_cpu_notifier);
+
 	evtchn_to_irq = kcalloc(EVTCHN_ROW(xen_evtchn_max_channels()),
 				sizeof(*evtchn_to_irq), GFP_KERNEL);
 	BUG_ON(!evtchn_to_irq);
--- a/drivers/xen/events/events_fifo.c
+++ b/drivers/xen/events/events_fifo.c
@@ -386,21 +386,6 @@ static void evtchn_fifo_resume(void)
 	event_array_pages = 0;
 }
 
-static const struct evtchn_ops evtchn_ops_fifo = {
-	.max_channels      = evtchn_fifo_max_channels,
-	.nr_channels       = evtchn_fifo_nr_channels,
-	.setup             = evtchn_fifo_setup,
-	.bind_to_cpu       = evtchn_fifo_bind_to_cpu,
-	.clear_pending     = evtchn_fifo_clear_pending,
-	.set_pending       = evtchn_fifo_set_pending,
-	.is_pending        = evtchn_fifo_is_pending,
-	.test_and_set_mask = evtchn_fifo_test_and_set_mask,
-	.mask              = evtchn_fifo_mask,
-	.unmask            = evtchn_fifo_unmask,
-	.handle_events     = evtchn_fifo_handle_events,
-	.resume            = evtchn_fifo_resume,
-};
-
 static int evtchn_fifo_alloc_control_block(unsigned cpu)
 {
 	void *control_block = NULL;
@@ -423,29 +408,34 @@ static int evtchn_fifo_alloc_control_blo
 	return ret;
 }
 
-static int evtchn_fifo_cpu_notification(struct notifier_block *self,
-						  unsigned long action,
-						  void *hcpu)
+static int evtchn_fifo_percpu_init(unsigned int cpu)
 {
-	int cpu = (long)hcpu;
-	int ret = 0;
+	if (!per_cpu(cpu_control_block, cpu))
+		return evtchn_fifo_alloc_control_block(cpu);
+	return 0;
+}
 
-	switch (action) {
-	case CPU_UP_PREPARE:
-		if (!per_cpu(cpu_control_block, cpu))
-			ret = evtchn_fifo_alloc_control_block(cpu);
-		break;
-	case CPU_DEAD:
-		__evtchn_fifo_handle_events(cpu, true);
-		break;
-	default:
-		break;
-	}
-	return ret < 0 ? NOTIFY_BAD : NOTIFY_OK;
+static int evtchn_fifo_percpu_deinit(unsigned int cpu)
+{
+	__evtchn_fifo_handle_events(cpu, true);
+	return 0;
 }
 
-static struct notifier_block evtchn_fifo_cpu_notifier = {
-	.notifier_call	= evtchn_fifo_cpu_notification,
+static const struct evtchn_ops evtchn_ops_fifo = {
+	.max_channels      = evtchn_fifo_max_channels,
+	.nr_channels       = evtchn_fifo_nr_channels,
+	.setup             = evtchn_fifo_setup,
+	.bind_to_cpu       = evtchn_fifo_bind_to_cpu,
+	.clear_pending     = evtchn_fifo_clear_pending,
+	.set_pending       = evtchn_fifo_set_pending,
+	.is_pending        = evtchn_fifo_is_pending,
+	.test_and_set_mask = evtchn_fifo_test_and_set_mask,
+	.mask              = evtchn_fifo_mask,
+	.unmask            = evtchn_fifo_unmask,
+	.handle_events     = evtchn_fifo_handle_events,
+	.resume            = evtchn_fifo_resume,
+	.percpu_init       = evtchn_fifo_percpu_init,
+	.percpu_deinit     = evtchn_fifo_percpu_deinit,
 };
 
 int __init xen_evtchn_fifo_init(void)
@@ -461,7 +451,6 @@ int __init xen_evtchn_fifo_init(void)
 
 	evtchn_ops = &evtchn_ops_fifo;
 
-	register_cpu_notifier(&evtchn_fifo_cpu_notifier);
 out:
 	put_cpu();
 	return ret;
--- a/drivers/xen/events/events_internal.h
+++ b/drivers/xen/events/events_internal.h
@@ -71,6 +71,9 @@ struct evtchn_ops {
 
 	void (*handle_events)(unsigned cpu);
 	void (*resume)(void);
+
+	int (*percpu_init)(unsigned int cpu);
+	int (*percpu_deinit)(unsigned int cpu);
 };
 
 extern const struct evtchn_ops *evtchn_ops;