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

Paolo Bonzini
2019-10-09T20:58:43Z

On 09/10/19 19:05, Sasha Levin wrote:
> From: Jim Mattson <jmattson@google.com>
>
> [ 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@google.com>
> Reviewed-by: Marc Orr <marcorr@google.com>
> Reviewed-by: Peter Shier <pshier@google.com>
> Reviewed-by: Jacob Xu <jacobhxu@google.com>
> Cc: Sean Christopherson <sean.j.christopherson@intel.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> 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