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

[Sasha Levin]

On Wed, Oct 09, 2019 at 10:58:35PM +0200, Paolo Bonzini wrote:
> 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?

Sure, I've opted out KVM and removed all KVM patches from this series:

c1fac4516a61d kvm: vmx: Limit guest PMCs to those supported on the host
75b118586ec81 kvm: x86, powerpc: do not allow clearing largepages debugfs entry
06cd1710feaed KVM: VMX: Set VMENTER_L1D_FLUSH_NOT_REQUIRED if !X86_BUG_L1TF
c89fc5c082aa6 KVM: x86: Expose XSAVEERPTR to the guest
1eec6b4068e2e kvm: x86: Use AMD CPUID semantics for AMD vCPUs
5c56e6ba0afc8 kvm: x86: Improve emulation of CPUID leaves 0BH and 1FH
94a3c6f010bd2 kvm: x86: Fix a spurious -E2BIG in __do_cpuid_func
79a7ad6330bc5 KVM: arm/arm64: vgic: Use the appropriate TRACE_INCLUDE_PATH

--
Thanks,
Sasha