Re: [PATCH 1/2] KVM: VMX: Add non-canonical check on writes to RTIT address MSRs

[Sean Christopherson <sean.j.christopherson@intel.com>]

On Tue, Dec 10, 2019 at 06:16:35PM -0800, Kang, Luwei wrote:
> > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index
> > 51e3b27f90ed..9aa2006dbe04 100644 --- a/arch/x86/kvm/vmx/vmx.c +++
> > b/arch/x86/kvm/vmx/vmx.c @@ -2152,6 +2152,8 @@ static int
> > vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info) (index >= 2 *
> > intel_pt_validate_cap(vmx->pt_desc.caps, PT_CAP_num_address_ranges)))
> > return 1; +		if (is_noncanonical_address(data, vcpu)) +
> > return 1;
> 
> Is this for live migrate a VM with 5 level page table to the VM with 4 level
> page table?

This is orthogonal to live migration or 5-level paging.  Unless I'm missing
something, KVM simply fails to validate the incoming address.