On 08/05/2012 05:42 PM, Gleb Natapov wrote:
> On Sun, Aug 05, 2012 at 05:35:21PM +0300, Avi Kivity wrote:
>> On 08/05/2012 03:58 PM, Gleb Natapov wrote:
>> > Usually all APICs are HW enabled so the check can be optimized out.
>> >
>> > Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx>
>> > ---
>> > arch/x86/kvm/lapic.c | 29 ++++++++++++++++++++++++++++-
>> > arch/x86/kvm/lapic.h | 1 +
>> > arch/x86/kvm/x86.c | 1 +
>> > 3 files changed, 30 insertions(+), 1 deletion(-)
>> >
>> > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
>> > index c3f14fe..1aa5528 100644
>> > --- a/arch/x86/kvm/lapic.c
>> > +++ b/arch/x86/kvm/lapic.c
>> > @@ -34,6 +34,7 @@
>> > #include <asm/current.h>
>> > #include <asm/apicdef.h>
>> > #include <linux/atomic.h>
>> > +#include <linux/jump_label.h>
>> > #include "kvm_cache_regs.h"
>> > #include "irq.h"
>> > #include "trace.h"
>> > @@ -117,9 +118,13 @@ static inline int __apic_test_and_clear_vector(int vec, void *bitmap)
>> > return __test_and_clear_bit(VEC_POS(vec), (bitmap) + REG_POS(vec));
>> > }
>> >
>> > +struct static_key_deferred apic_hw_disabled __read_mostly;
>>
>> On top of file please. Add all_ to the name to make it clear we're
>> talking about all apics.
>>
> This is count of disabled apics really. So I think all_apic_hw_disabled
> is misleading.
>
>> > +
>> > static inline int apic_hw_enabled(struct kvm_lapic *apic)
>> > {
>> > - return (apic)->vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE;
>> > + if (static_key_false(&apic_hw_disabled.key))
>> > + return apic->vcpu->arch.apic_base & MSR_IA32_APICBASE_ENABLE;
>>
>> Hm, for the test to be readable, it needs to be
>>
>> if (static_key_false(&all_apics_hw_enabled))
>>
> Exactly. all_ makes it so because apic_hw_disabled is a counter that
> counts disabled apics. So may be call it global_hw_disabled_apic_counter?
>
The problem is how static_key_false() is defined. It returns true if
the count > 0, opposite from what I'd expect. So anything with counter
semantics will be confusing. I guess we need to pick a neutral name
(apic_disabled_key or apic_disabled_slowpath or such) to force the
reader to look at the definitions.
--
error compiling committee.c: too many arguments to function
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