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);