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SubjectRe: [RFC 7/7] KVM: VMX: Enable PKS for nested VM
On Wed, Aug 12, 2020 at 8:00 AM Sean Christopherson
<sean.j.christopherson@intel.com> wrote:
>
> On Mon, Aug 10, 2020 at 05:05:36PM -0700, Jim Mattson wrote:
> > On Fri, Aug 7, 2020 at 1:47 AM Chenyi Qiang <chenyi.qiang@intel.com> wrote:
> > >
> > > PKS MSR passes through guest directly. Configure the MSR to match the
> > > L0/L1 settings so that nested VM runs PKS properly.
> > >
> > > Signed-off-by: Chenyi Qiang <chenyi.qiang@intel.com>
> > > ---
> > > arch/x86/kvm/vmx/nested.c | 32 ++++++++++++++++++++++++++++++++
> > > arch/x86/kvm/vmx/vmcs12.c | 2 ++
> > > arch/x86/kvm/vmx/vmcs12.h | 6 +++++-
> > > arch/x86/kvm/vmx/vmx.c | 10 ++++++++++
> > > arch/x86/kvm/vmx/vmx.h | 1 +
> > > 5 files changed, 50 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
> > > index df2c2e733549..1f9823d21ecd 100644
> > > --- a/arch/x86/kvm/vmx/nested.c
> > > +++ b/arch/x86/kvm/vmx/nested.c
> > > @@ -647,6 +647,12 @@ static inline bool nested_vmx_prepare_msr_bitmap(struct kvm_vcpu *vcpu,
> > > MSR_IA32_PRED_CMD,
> > > MSR_TYPE_W);
> > >
> > > + if (!msr_write_intercepted_l01(vcpu, MSR_IA32_PKRS))
> > > + nested_vmx_disable_intercept_for_msr(
> > > + msr_bitmap_l1, msr_bitmap_l0,
> > > + MSR_IA32_PKRS,
> > > + MSR_TYPE_R | MSR_TYPE_W);
> >
> > What if L1 intercepts only *reads* of MSR_IA32_PKRS?
>
> nested_vmx_disable_intercept_for_msr() handles merging L1's desires, the
> (MSR_TYPE_R | MSR_TYPE_W) param is effectively L0's desire for L2.

I should know better than to assume that a function in kvm actually
does anything like what its name implies, but I never seem to learn.
:-(

Thanks!

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