On Wed, Dec 26, 2018 at 04:52:38PM +0800, Liran Alon wrote:

Thanks Liran for pointing out the issues!
I'll fix them in next version.
> 
> 
> > On 26 Dec 2018, at 10:15, Yang Weijiang <weijiang.y...@intel.com> wrote:
> > 
> > This bit controls whether guest CET states will be loaded on guest entry.
> > 
> > Signed-off-by: Zhang Yi Z <yi.z.zh...@linux.intel.com>
> > Signed-off-by: Yang Weijiang <weijiang.y...@intel.com>
> > ---
> > arch/x86/kvm/vmx.c | 19 +++++++++++++++++++
> > 1 file changed, 19 insertions(+)
> > 
> > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> > index 7bbb8b26e901..25fa6bd2fb95 100644
> > --- a/arch/x86/kvm/vmx.c
> > +++ b/arch/x86/kvm/vmx.c
> > @@ -1045,6 +1045,8 @@ struct vcpu_vmx {
> > 
> >     bool req_immediate_exit;
> > 
> > +   bool vcpu_cet_on;
> > +
> >     /* Support for PML */
> > #define PML_ENTITY_NUM              512
> >     struct page *pml_pg;
> > @@ -5409,6 +5411,23 @@ static int vmx_set_cr4(struct kvm_vcpu *vcpu, 
> > unsigned long cr4)
> >                     return 1;
> >     }
> > 
> > +   /*
> > +    * When CET.CR4 is being set, it means we're enabling CET for
> 
> You probably meant to write here CR4.CET.
> 
> > +    * the guest, then enable loading CET state bit in entry control.
> > +    * Otherwise, clear loading CET bit to disable guest CET.
> > +    */
> > +   if (cr4 & X86_CR4_CET) {
> > +           if (!to_vmx(vcpu)->vcpu_cet_on) {
> > +                   vmcs_set_bits(VM_ENTRY_CONTROLS,
> > +                                 VM_ENTRY_LOAD_GUEST_CET_STATE);
> > +                   to_vmx(vcpu)->vcpu_cet_on = 1;
> > +           }
> > +   } else if (to_vmx(vcpu)->vcpu_cet_on) {
> > +           vmcs_clear_bits(VM_ENTRY_CONTROLS,
> > +                           VM_ENTRY_LOAD_GUEST_CET_STATE);
> > +           to_vmx(vcpu)->vcpu_cet_on = 0;
> > +   }
> > +
> >     if (to_vmx(vcpu)->nested.vmxon && !nested_cr4_valid(vcpu, cr4))
> >             return 1;
> > 
> > -- 
> > 2.17.1
> > 
> 
> I haven’t seen a patch in the series that modifies kvm_set_cr4() to verify 
> CR4.CET is not set when CET is not reported as supported by CPUID.
> I think that is missing from the series.
> 
> -Liran
> 
> 

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