Re: [PATCH AUTOSEL 4.19 08/26] kvm: x86: Improve emulation of CPUID leaves 0BH and 1FH

[Paolo Bonzini]

On 09/10/19 19:05, Sasha Levin wrote:
> From: Jim Mattson <jmattson@xxxxxxxxxx>
> 
> [ Upstream commit 43561123ab3759eb6ff47693aec1a307af0aef83 ]
> 
> For these CPUID leaves, the EDX output is not dependent on the ECX
> input (i.e. the SIGNIFCANT_INDEX flag doesn't apply to
> EDX). Furthermore, the low byte of the ECX output is always identical
> to the low byte of the ECX input. KVM does not produce the correct ECX
> and EDX outputs for any undefined subleaves beyond the first.
> 
> Special-case these CPUID leaves in kvm_cpuid, so that the ECX and EDX
> outputs are properly generated for all undefined subleaves.
> 
> Fixes: 0771671749b59a ("KVM: Enhance guest cpuid management")
> Fixes: a87f2d3a6eadab ("KVM: x86: Add Intel CPUID.1F cpuid emulation support")
> Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
> Reviewed-by: Marc Orr <marcorr@xxxxxxxxxx>
> Reviewed-by: Peter Shier <pshier@xxxxxxxxxx>
> Reviewed-by: Jacob Xu <jacobhxu@xxxxxxxxxx>
> Cc: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
>  arch/x86/kvm/cpuid.c | 83 +++++++++++++++++++++++++-------------------
>  1 file changed, 47 insertions(+), 36 deletions(-)

This is absolutely not stable material.  Is it possible for KVM to opt
out of this AUTOSEL nonsense?

Paolo