Re: [Patch v4 2/4] Add SMEP handling when setting CR4

Avi Kivity
2011-05-31T18:05:40Z

On 05/31/2011 08:52 PM, Marcelo Tosatti wrote:
> On Sun, May 29, 2011 at 07:41:57PM +0800, Yang, Wei Y wrote:
> > This patch adds SMEP handling when setting CR4.
> >
> > Signed-off-by: Yang, Wei<wei.y.yang@intel.com>
> > Signed-off-by: Shan, Haitao<haitao.shan@intel.com>
> > Signed-off-by: Li, Xin<xin.li@intel.com>
> >
> > ---
> > arch/x86/kvm/x86.c | 15 +++++++++++++--
> > 1 files changed, 13 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index 77c9d86..91bfc40 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -579,6 +579,14 @@ static bool guest_cpuid_has_xsave(struct kvm_vcpu *vcpu)
> > return best&& (best->ecx& bit(X86_FEATURE_XSAVE));
> > }
> >
> > +static bool guest_cpuid_has_smep(struct kvm_vcpu *vcpu)
> > +{
> > + struct kvm_cpuid_entry2 *best;
> > +
> > + best = kvm_find_cpuid_entry(vcpu, 7, 0);
> > + return best&& (best->ebx& bit(X86_FEATURE_SMEP));
> > +}
> > +
> > static void update_cpuid(struct kvm_vcpu *vcpu)
> > {
> > struct kvm_cpuid_entry2 *best;
> > @@ -598,14 +606,17 @@ static void update_cpuid(struct kvm_vcpu *vcpu)
> > int kvm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
> > {
> > unsigned long old_cr4 = kvm_read_cr4(vcpu);
> > - unsigned long pdptr_bits = X86_CR4_PGE | X86_CR4_PSE | X86_CR4_PAE;
> > -
> > + unsigned long pdptr_bits = X86_CR4_PGE | X86_CR4_PSE |
> > + X86_CR4_PAE | X86_CR4_SMEP;
> > if (cr4& CR4_RESERVED_BITS)
> > return 1;
> >
> > if (!guest_cpuid_has_xsave(vcpu)&& (cr4& X86_CR4_OSXSAVE))
> > return 1;
> >
> > + if (!guest_cpuid_has_smep(vcpu)&& (cr4& X86_CR4_SMEP))
> > + return 1;
> > +
> > if (is_long_mode(vcpu)) {
> > if (!(cr4& X86_CR4_PAE))
> > return 1;
>
> A new field in vcpu->arch.mmu.base_role for smep is required
> for shadow MMU (similar to nxe).

I plan to add that with my cr0.wp=0 fixup (it's only needed there, right?)

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.