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 <pbonz...@redhat.com>
> ---
> 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
