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

[Marcelo Tosatti <mtosatti@redhat.com>]

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).