linux-kernel - [PATCH v7 5/6] x86/paravirt: add active_sched_clock to pv_time

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Message-Id: <20171102172644.28555-6-pasha.tatashin@oracle.com>
Date:   Thu,  2 Nov 2017 13:26:43 -0400
From:   Pavel Tatashin <pasha.tatashin@...cle.com>
To:     steven.sistare@...cle.com, daniel.m.jordan@...cle.com,
        linux@...linux.org.uk, schwidefsky@...ibm.com,
        heiko.carstens@...ibm.com, john.stultz@...aro.org,
        sboyd@...eaurora.org, x86@...nel.org, linux-kernel@...r.kernel.org,
        mingo@...hat.com, tglx@...utronix.de, hpa@...or.com,
        douly.fnst@...fujitsu.com
Subject: [PATCH v7 5/6] x86/paravirt: add active_sched_clock to pv_time_ops

Early boot clock might differ from the clock that is used later on,
therefore add a new field to pv_time_ops, that shows currently active
clock. If platform supports early boot clock, this field will be changed
to use that clock early in boot, and later will be replaced with the
permanent clock.

Signed-off-by: Pavel Tatashin <pasha.tatashin@...cle.com>
---
 arch/x86/include/asm/paravirt.h       | 2 +-
 arch/x86/include/asm/paravirt_types.h | 1 +
 arch/x86/kernel/paravirt.c            | 1 +
 arch/x86/xen/time.c                   | 7 ++++---
 4 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 12deec722cf0..f624c9636003 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -171,7 +171,7 @@ static inline int rdmsrl_safe(unsigned msr, unsigned long long *p)
 
 static inline unsigned long long paravirt_sched_clock(void)
 {
-	return PVOP_CALL0(unsigned long long, pv_time_ops.sched_clock);
+	return PVOP_CALL0(unsigned long long, pv_time_ops.active_sched_clock);
 }
 
 struct static_key;
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index 280d94c36dad..afbda404c1f7 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -97,6 +97,7 @@ struct pv_lazy_ops {
 struct pv_time_ops {
 	unsigned long long (*sched_clock)(void);
 	unsigned long long (*steal_clock)(int cpu);
+	unsigned long long (*active_sched_clock)(void);
 } __no_randomize_layout;
 
 struct pv_cpu_ops {
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 19a3e8f961c7..895c7c0e9c2e 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -310,6 +310,7 @@ struct pv_init_ops pv_init_ops = {
 struct pv_time_ops pv_time_ops = {
 	.sched_clock = native_sched_clock,
 	.steal_clock = native_steal_clock,
+	.active_sched_clock = native_sched_clock,
 };
 
 __visible struct pv_irq_ops pv_irq_ops = {
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 1ecb05db3632..6a77038e23f5 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -407,8 +407,8 @@ static void __init xen_time_init(void)
 
 void __ref xen_init_time_ops(void)
 {
-	pv_time_ops = xen_time_ops;
-
+	pv_time_ops.sched_clock = xen_time_ops.sched_clock;
+	pv_time_ops.steal_clock = xen_time_ops.steal_clock;
 	x86_init.timers.timer_init = xen_time_init;
 	x86_init.timers.setup_percpu_clockev = x86_init_noop;
 	x86_cpuinit.setup_percpu_clockev = x86_init_noop;
@@ -449,7 +449,8 @@ void __init xen_hvm_init_time_ops(void)
 		return;
 	}
 
-	pv_time_ops = xen_time_ops;
+	pv_time_ops.sched_clock = xen_time_ops.sched_clock;
+	pv_time_ops.steal_clock = xen_time_ops.steal_clock;
 	x86_init.timers.setup_percpu_clockev = xen_time_init;
 	x86_cpuinit.setup_percpu_clockev = xen_hvm_setup_cpu_clockevents;
 
-- 
2.15.0