[Xen-devel] [RFC PATCH v3 09/12] x86/xen: save and restore steal clock

[Anchal Agarwal <anchalag@xxxxxxxxxx>]

From: Munehisa Kamata <kamatam@xxxxxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Anchal Agarwal <anchalag@xxxxxxxxxx>
---
 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 784c4484100b..dae0f74f5390 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 befbdd8b17f0..8cf632dda605 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -537,6 +537,9 @@ 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
-- 
2.24.1.AMZN


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