Re: [PATCH] KVM: x86: VMX: Make smaller physical guest address space support user-configurable

On 02/10/20 19:28, Naresh Kamboju wrote:

...

commit 608e2791d7353e7d777bf32038ca3e7d548155a4 (HEAD -> kvm-master) Author: Paolo Bonzini pbonzini@redhat.com Date: Tue Sep 29 08:31:32 2020 -0400

KVM: VMX: update PFEC_MASK/PFEC_MATCH together with PF intercept

The PFEC_MASK and PFEC_MATCH fields in the VMCS reverse the meaning of
the #PF intercept bit in the exception bitmap when they do not match.
This means that, if PFEC_MASK and/or PFEC_MATCH are set, the
hypervisor can get a vmexit for #PF exceptions even when the
corresponding bit is clear in the exception bitmap.

This is unexpected and is promptly reported as a WARN_ON_ONCE.
To fix it, reset PFEC_MASK and PFEC_MATCH when the #PF intercept
is disabled (as is common with enable_ept && !allow_smaller_maxphyaddr).

I have tested this patch on an x86_64 machine and the reported issue is gone.

Thanks, the issue with my disk is gone too so it'll get to Linus in time for rc8.

Paolo