Re: [Qemu-devel] [PATCH rebased for-2.4] target-i386: add ABM to Haswell* and Broadwell* CPU models

[Eduardo Habkost]

On Tue, Jul 07, 2015 at 12:42:01PM +0200, Paolo Bonzini wrote:
> ABM is only implemented as a single instruction set by AMD; all AMD
> processors support both instructions or neither. Intel considers POPCNT
> as part of SSE4.2, and LZCNT as part of BMI1, but Intel also uses AMD's
> ABM flag to indicate support for both POPCNT and LZCNT.  It has to be
> added to Haswell and Broadwell because Haswell, by adding LZCNT, has
> completed the ABM.
> 
> Tested with "qemu-kvm -cpu Haswell-noTSX,enforce" (and also with older
> machine types) on an Haswell-EP machine.
> 
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
>  hw/i386/pc_piix.c | 4 ++++
>  hw/i386/pc_q35.c  | 4 ++++
>  target-i386/cpu.c | 8 ++++----
>  3 files changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> index 56cdcb9..d9e9987 100644
> --- a/hw/i386/pc_piix.c
> +++ b/hw/i386/pc_piix.c
> @@ -312,6 +312,10 @@ static void pc_compat_2_3(MachineState *machine)
>      if (kvm_enabled()) {
>          pcms->smm = ON_OFF_AUTO_OFF;
>      }
> +    x86_cpu_compat_set_features("Haswell", FEAT_8000_0001_ECX, 0, 
> CPUID_EXT3_ABM);
> +    x86_cpu_compat_set_features("Haswell-noTSX", FEAT_8000_0001_ECX, 0, 
> CPUID_EXT3_ABM);
> +    x86_cpu_compat_set_features("Broadwell", FEAT_8000_0001_ECX, 0, 
> CPUID_EXT3_ABM);
> +    x86_cpu_compat_set_features("Broadwell-noTSX", FEAT_8000_0001_ECX, 0, 
> CPUID_EXT3_ABM);

x86_cpu_compat_set_features() is not necessary anymore, please use
PC_COMPAT_2_3 to disable ABM.

-- 
Eduardo