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Date: Tue, 4 Oct 2016 13:33:15 +0200
From: Igor Mammedov <imammedo@redhat.com>
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In-Reply-To: <20160930161013.9832-9-rkrcmar@redhat.com>
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	<20160930161013.9832-9-rkrcmar@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH v3 8/8] target-i386/kvm: cache the return
 value of kvm_enable_x2apic()
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To: Radim =?UTF-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>
Cc: qemu-devel@nongnu.org, Peter Xu <peterx@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Richard Henderson <rth@twiddle.net>, Eduardo Habkost <ehabkost@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>

On Fri, 30 Sep 2016 18:10:13 +0200
Radim Kr=C4=8Dm=C3=A1=C5=99 <rkrcmar@redhat.com> wrote:

> Assume that KVM would have returned the same on subsequent runs.
> Abstract the memoizaiton pattern into macros.
s/memoi/memori/i
Throughout whole patch

>=20
> Signed-off-by: Radim Kr=C4=8Dm=C3=A1=C5=99 <rkrcmar@redhat.com>
> ---
>  target-i386/kvm.c | 21 +++++++++++++++++++--
>  1 file changed, 19 insertions(+), 2 deletions(-)
>=20
> diff --git a/target-i386/kvm.c b/target-i386/kvm.c
> index 0fd664648665..113c5bf058ba 100644
> --- a/target-i386/kvm.c
> +++ b/target-i386/kvm.c
> @@ -129,10 +129,27 @@ static bool kvm_x2apic_api_set_flags(uint64_t flags)
>      return !kvm_vm_enable_cap(s, KVM_CAP_X2APIC_API, 0, flags);
>  }
> =20
> +#define MEMOIZE_RESULT(_result, _fn) \
> +    ({ \
> +        static bool _memoized; \
> +        if (_memoized) { \
> +            return _result; \
> +        } \
> +        _memoized =3D true; \
> +        _result =3D _fn; \
> +    })
> +
> +#define MEMOIZE(_fn) \
> +    ({ \
> +        static typeof(_fn) _result; \
> +        MEMOIZE_RESULT(_result, _fn); \
> +    })
> +
>  bool kvm_enable_x2apic(void)
>  {
> -    return kvm_x2apic_api_set_flags(KVM_X2APIC_API_USE_32BIT_IDS |
> -                                    KVM_X2APIC_API_DISABLE_BROADCAST_QUI=
RK);
> +    return MEMOIZE(
> +             kvm_x2apic_api_set_flags(KVM_X2APIC_API_USE_32BIT_IDS |
> +                                      KVM_X2APIC_API_DISABLE_BROADCAST_Q=
UIRK));
>  }
> =20
>  static int kvm_get_tsc(CPUState *cs)