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Subject[PATCH v6 2/4] x86/xen/time: set pvclock flags on xen_time_init()
Date
Specifically check for PVCLOCK_TSC_STABLE_BIT and if this bit is set,
then set it too on pvclock flags. This allows Xen clocksource to use it
and thus speeding up xen_clocksource_read() callers (i.e. sched_clock())

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
---
Changes since v5:
* Add Boris RoB

New in v5
---
arch/x86/xen/time.c | 9 +++++++++
1 file changed, 9 insertions(+)

diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 1ecb05db3632..fc0148d3a70d 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -372,6 +372,7 @@ static const struct pv_time_ops xen_time_ops __initconst = {

static void __init xen_time_init(void)
{
+ struct pvclock_vcpu_time_info *pvti;
int cpu = smp_processor_id();
struct timespec tp;

@@ -395,6 +396,14 @@ static void __init xen_time_init(void)

setup_force_cpu_cap(X86_FEATURE_TSC);

+ /*
+ * We check ahead on the primary time info if this
+ * bit is supported hence speeding up Xen clocksource.
+ */
+ pvti = &__this_cpu_read(xen_vcpu)->time;
+ if (pvti->flags & PVCLOCK_TSC_STABLE_BIT)
+ pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
+
xen_setup_runstate_info(cpu);
xen_setup_timer(cpu);
xen_setup_cpu_clockevents();
--
2.11.0
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