Re: [PATCH 1/2] KVM: VMX: Use kvm_read_cr4() to get cr4 value

[Xiaoyao Li]

On 4/11/2023 1:11 AM, Sean Christopherson wrote:
> On Mon, Apr 10, 2023, Xiaoyao Li wrote:
> > Directly use vcpu->arch.cr4 is not recommended since it gets stale value
> > if the cr4 is not available.
> >
> > Use kvm_read_cr4() instead to ensure correct value.
> >
> > Signed-off-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
> > ---
> >   arch/x86/kvm/vmx/vmx.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> > index d7bf14abdba1..befa2486836b 100644
> > --- a/arch/x86/kvm/vmx/vmx.c
> > +++ b/arch/x86/kvm/vmx/vmx.c
> > @@ -3431,7 +3431,7 @@ static bool vmx_is_valid_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
> >   
> >   void vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
> >   {
> > -	unsigned long old_cr4 = vcpu->arch.cr4;
> > +	unsigned long old_cr4 = kvm_read_cr4(vcpu);
>
> Ha!  I've been tempted to change this multiple times, but always thought I was
> just being a bit obsessive :-)
>
> Patches look good, but I'm going to hold them for 6.5 just in case this somehow
> causes a problem, e.g. if there's a bizzaro nested path that "works" because KVM
> _doesn't_ decache info from the current VMCS.

so you will put it in kvm-next after 6.4 merge windows?