From: Juergen Gross <jgross@suse.com>
To: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org,
x86@kernel.org
Cc: boris.ostrovsky@oracle.com, sstabellini@kernel.org,
hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com,
bp@alien8.de, hans@knorrie.org, Juergen Gross <jgross@suse.com>,
stable@vger.kernel.org
Subject: [PATCH] xen: Fix x86 sched_clock() interface for xen
Date: Thu, 10 Jan 2019 11:07:22 +0100 [thread overview]
Message-ID: <20190110100722.11216-1-jgross@suse.com> (raw)
Commit f94c8d11699759 ("sched/clock, x86/tsc: Rework the x86 'unstable'
sched_clock() interface") broke Xen guest time handling across
migration:
[ 187.249951] Freezing user space processes ... (elapsed 0.001 seconds) done.
[ 187.251137] OOM killer disabled.
[ 187.251137] Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done.
[ 187.252299] suspending xenstore...
[ 187.266987] xen:grant_table: Grant tables using version 1 layout
[18446743811.706476] OOM killer enabled.
[18446743811.706478] Restarting tasks ... done.
[18446743811.720505] Setting capacity to 16777216
Fix that by setting xen_sched_clock_offset at resume time to ensure a
monotonic clock value.
Fixes: f94c8d11699759 ("sched/clock, x86/tsc: Rework the x86 'unstable' sched_clock() interface")
Cc: <stable@vger.kernel.org> # 4.11
Reported-by: Hans van Kranenburg <hans@knorrie.org>
Signed-off-by: Juergen Gross <jgross@suse.com>
---
arch/x86/xen/suspend.c | 4 ++++
arch/x86/xen/time.c | 11 +++++++++++
arch/x86/xen/xen-ops.h | 2 ++
3 files changed, 17 insertions(+)
diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c
index 1d83152c761b..45fc9caf3880 100644
--- a/arch/x86/xen/suspend.c
+++ b/arch/x86/xen/suspend.c
@@ -67,6 +67,8 @@ void xen_arch_resume(void)
{
int cpu;
+ xen_clocksource_resume();
+
on_each_cpu(xen_vcpu_notify_restore, NULL, 1);
for_each_online_cpu(cpu)
@@ -81,4 +83,6 @@ void xen_arch_suspend(void)
xen_pmu_finish(cpu);
on_each_cpu(xen_vcpu_notify_suspend, NULL, 1);
+
+ xen_clocksource_suspend();
}
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 72bf446c3fee..117ce958ffe6 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -32,6 +32,7 @@
#define TIMER_SLOP 100000
static u64 xen_sched_clock_offset __read_mostly;
+static u64 xen_clock_value_saved;
/* Get the TSC speed from Xen */
static unsigned long xen_tsc_khz(void)
@@ -54,6 +55,16 @@ static u64 xen_clocksource_read(void)
return ret;
}
+void xen_clocksource_suspend(void)
+{
+ xen_clock_value_saved = xen_clocksource_read() - xen_sched_clock_offset;
+}
+
+void xen_clocksource_resume(void)
+{
+ xen_sched_clock_offset = xen_clocksource_read() - xen_clock_value_saved;
+}
+
static u64 xen_clocksource_get_cycles(struct clocksource *cs)
{
return xen_clocksource_read();
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 0e60bd918695..a17d3bdab6b8 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -63,6 +63,8 @@ void __init xen_build_dynamic_phys_to_machine(void);
void __init xen_vmalloc_p2m_tree(void);
void xen_init_irq_ops(void);
+void xen_clocksource_suspend(void);
+void xen_clocksource_resume(void);
void xen_setup_timer(int cpu);
void xen_setup_runstate_info(int cpu);
void xen_teardown_timer(int cpu);
--
2.16.4
next reply other threads:[~2019-01-10 10:07 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-10 10:07 Juergen Gross [this message]
2019-01-10 15:34 ` [PATCH] xen: Fix x86 sched_clock() interface for xen Boris Ostrovsky
2019-01-10 16:14 ` Juergen Gross
2019-01-10 17:17 ` Boris Ostrovsky
2019-01-10 23:10 ` Boris Ostrovsky
2019-01-11 7:15 ` Juergen Gross
2019-01-11 7:31 ` Juergen Gross
2019-01-10 16:19 ` Hans van Kranenburg
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