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SubjectRe: [PATCH 09/12] x86/xen: save and restore steal clock
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On Sat, May 30, 2020 at 07:44:06PM -0400, Boris Ostrovsky wrote:
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>
>
>
> On 5/19/20 7:28 PM, Anchal Agarwal wrote:
> > 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>
> > ---
> > 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();
>
>
> Doesn't make any difference but I think since this patch is where you
> are dealing with clock then pvclock_resume() should be added here and
> not in the earlier patch.
>
>
> -boris
I think the reason it may be in previous patch because it was a part
of syscore_resume and steal clock fix came in later.
It could me moved to this patch that deals with all clock stuff.

-Anchal
>
>

> >
> > + /* 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 c8897aad13cd..33d754564b09 100644
> > --- a/arch/x86/xen/time.c
> > +++ b/arch/x86/xen/time.c
> > @@ -545,6 +545,9 @@ 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
>
>
>

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