[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] x86/xen: Disable APIC PM for Xen PV guests
On 04/03/14 02:40, Boris Ostrovsky wrote: > Xen PV guests support only few APIC registers and writes to > unsupported registers result in WARN_ONs. Most APIC accesses in these > guests have been eliminated; however, lapic_suspend/resume are still > called (on 32-bit kernels). > > We can disable APIC power management in xen_smp_prepare_boot_cpu() > (which is called after APIC has been initialized). Having looked at another APIC related problem recently, I wonder if Xen would be better served by having its own APIC driver instead of trying to piggy-back of some hardware one which doesn't do what we want. David > > Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> > --- > arch/x86/include/asm/apic.h | 2 ++ > arch/x86/kernel/apic/apic.c | 6 ++++++ > arch/x86/xen/smp.c | 4 ++++ > 3 files changed, 12 insertions(+) > > > An alternative could be to add another op to stuct apic. The advantage would > be > the fact that we never have a window of time when APIC PM is enabled. The > downside > is having yet another op (of which there are already plenty). > > We could also avoid loading lapic_syscore_ops but I couldn't think of a good > way > to figure out when not to do it. > > > > diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h > index 1d2091a..1f100f2 100644 > --- a/arch/x86/include/asm/apic.h > +++ b/arch/x86/include/asm/apic.h > @@ -687,6 +687,8 @@ extern int default_cpu_present_to_apicid(int mps_cpu); > extern int default_check_phys_apicid_present(int phys_apicid); > #endif > > +extern void apic_pm_deactivate(void); > + > #endif /* CONFIG_X86_LOCAL_APIC */ > extern void irq_enter(void); > extern void irq_exit(void); > diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c > index 7f26c9a..60607b3 100644 > --- a/arch/x86/kernel/apic/apic.c > +++ b/arch/x86/kernel/apic/apic.c > @@ -2424,6 +2424,11 @@ static void apic_pm_activate(void) > apic_pm_state.active = 1; > } > > +void apic_pm_deactivate(void) > +{ > + apic_pm_state.active = 0; > +} > + > static int __init init_lapic_sysfs(void) > { > /* XXX: remove suspend/resume procs if !apic_pm_state.active? */ > @@ -2439,6 +2444,7 @@ core_initcall(init_lapic_sysfs); > #else /* CONFIG_PM */ > > static void apic_pm_activate(void) { } > +void apic_pm_deactivate(void) { } > > #endif /* CONFIG_PM */ > > diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c > index a18eadd..33115d8 100644 > --- a/arch/x86/xen/smp.c > +++ b/arch/x86/xen/smp.c > @@ -298,6 +298,10 @@ static void __init xen_smp_prepare_boot_cpu(void) > > xen_filter_cpu_maps(); > xen_setup_vcpu_info_placement(); > + > +#ifdef CONFIG_X86_LOCAL_APIC > + apic_pm_deactivate(); > +#endif > } > /* > * The alternative logic (which patches the unlock/lock) runs before _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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