[RFC PATCH 09/12] x86/xen: save and restore steal clock

Anchal Agarwal
2018-06-12T20:56:44Z

From: Munehisa Kamata <kamatam@amazon.com>

Save steal clock values of all present CPUs in the system core ops
suspend callbacks. Also, restore a boot CPU's steal clock in the system
core resume callback. For non-boot CPUs, restore after they're brought
up, because runstate info for non-boot CPUs are not active until then.

Signed-off-by: Munehisa Kamata <kamatam@amazon.com>
Signed-off-by: Anchal Agarwal <anchalag@amazon.com>
Reviewed-by: Munehisa Kamata <kamatam@amazon.com>
Reviewed-by: Eduardo Valentin <eduval@amazon.com>
---
arch/x86/xen/suspend.c | 13 ++++++++++++-
arch/x86/xen/time.c | 3 +++
2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c
index 784c448..dae0f74 100644
--- a/arch/x86/xen/suspend.c
+++ b/arch/x86/xen/suspend.c
@@ -91,12 +91,20 @@ void xen_arch_suspend(void)
static int xen_syscore_suspend(void)
{
struct xen_remove_from_physmap xrfp;
- int ret;
+ int cpu, ret;

/* Xen suspend does similar stuffs in its own logic */
if (xen_suspend_mode_is_xen_suspend())
return 0;

+ for_each_present_cpu(cpu) {
+ /*
+ * Nonboot CPUs are already offline, but the last copy of
+ * runstate info is still accessible.
+ */
+ xen_save_steal_clock(cpu);
+ }
+
xrfp.domid = DOMID_SELF;
xrfp.gpfn = __pa(HYPERVISOR_shared_info) >> PAGE_SHIFT;

@@ -118,6 +126,9 @@ static void xen_syscore_resume(void)

pvclock_resume();

+ /* Nonboot CPUs will be resumed when they're brought up */
+ xen_restore_steal_clock(smp_processor_id());
+
gnttab_resume();
}

diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index e0f1bcf..85f8534 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -523,6 +523,9 @@ static void xen_hvm_setup_cpu_clockevents(void)
{
int cpu = smp_processor_id();
xen_setup_runstate_info(cpu);
+ if (cpu)
+ xen_restore_steal_clock(cpu);
+
/*
* xen_setup_timer(cpu) - snprintf is bad in atomic context. Hence
* doing it xen_hvm_cpu_notify (which gets called by smp_init during
--
2.7.4