[PATCH 4.9 71/78] xen/events: use a common cpu hotplug hook for event channels

Greg Kroah-Hartman
2020-11-17T13:13:21Z

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 | 25 ++++++++++++++++++++++
drivers/xen/events/events_fifo.c | 39 +++++++++++++++++------------------
drivers/xen/events/events_internal.h | 3 ++
3 files changed, 47 insertions(+), 20 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/cpuhotplug.h>

#ifdef CONFIG_X86
#include <asm/desc.h>
@@ -1833,6 +1834,26 @@ 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;
+}
+
void __init xen_init_IRQ(void)
{
int ret = -EINVAL;
@@ -1842,6 +1863,10 @@ void __init xen_init_IRQ(void)
if (ret < 0)
xen_evtchn_2l_init();

+ cpuhp_setup_state_nocalls(CPUHP_XEN_EVTCHN_PREPARE,
+ "CPUHP_XEN_EVTCHN_PREPARE",
+ xen_evtchn_cpu_prepare, xen_evtchn_cpu_dead);
+
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;
@@ -423,19 +408,36 @@ static int evtchn_fifo_alloc_control_blo
return ret;
}

-static int xen_evtchn_cpu_prepare(unsigned int cpu)
+static int evtchn_fifo_percpu_init(unsigned int cpu)
{
if (!per_cpu(cpu_control_block, cpu))
return evtchn_fifo_alloc_control_block(cpu);
return 0;
}

-static int xen_evtchn_cpu_dead(unsigned int cpu)
+static int evtchn_fifo_percpu_deinit(unsigned int cpu)
{
__evtchn_fifo_handle_events(cpu, true);
return 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,
+ .percpu_init = evtchn_fifo_percpu_init,
+ .percpu_deinit = evtchn_fifo_percpu_deinit,
+};
+
int __init xen_evtchn_fifo_init(void)
{
int cpu = get_cpu();
@@ -449,9 +451,6 @@ int __init xen_evtchn_fifo_init(void)

evtchn_ops = &evtchn_ops_fifo;

- cpuhp_setup_state_nocalls(CPUHP_XEN_EVTCHN_PREPARE,
- "CPUHP_XEN_EVTCHN_PREPARE",
- xen_evtchn_cpu_prepare, xen_evtchn_cpu_dead);
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;