Re: [PATCH] KVM: x86: Perform non-canonical checks in 32-bit KVM

Sean Christopherson
2020-01-16T15:51:00Z

On Wed, Jan 15, 2020 at 05:37:16PM -0800, Krish Sadhukhan wrote:
>
> On 01/15/2020 10:36 AM, Sean Christopherson wrote:
> > arch/x86/kvm/x86.h | 8 --------
> > 1 file changed, 8 deletions(-)
> >
> >diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
> >index cab5e71f0f0f..3ff590ec0238 100644
> >--- a/arch/x86/kvm/x86.h
> >+++ b/arch/x86/kvm/x86.h
> >@@ -166,21 +166,13 @@ static inline u64 get_canonical(u64 la, u8 vaddr_bits)
> > static inline bool is_noncanonical_address(u64 la, struct kvm_vcpu *vcpu)
> > {
> >-#ifdef CONFIG_X86_64
> > return get_canonical(la, vcpu_virt_addr_bits(vcpu)) != la;
> >-#else
> >- return false;
> >-#endif
> > }
> > static inline bool emul_is_noncanonical_address(u64 la,
> > struct x86_emulate_ctxt *ctxt)
> > {
> >-#ifdef CONFIG_X86_64
> > return get_canonical(la, ctxt_virt_addr_bits(ctxt)) != la;
> >-#else
> >- return false;
> >-#endif
> > }
> > static inline void vcpu_cache_mmio_info(struct kvm_vcpu *vcpu,
>
> nested_vmx_check_host_state() still won't call it on 32-bit because it has
> the CONFIG_X86_64 guard around the callee:
>
>  #ifdef CONFIG_X86_64
>         if (CC(is_noncanonical_address(vmcs12->host_fs_base, vcpu)) ||
>             CC(is_noncanonical_address(vmcs12->host_gs_base, vcpu)) ||
>  ...

Doh, I was looking at an older version of nested.c. Nice catch!

> Don't we need to remove these guards in the callers as well ?

Ya, that would be my preference.