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

Sasha Levin
2019-10-09T22:41:32Z

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@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?

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