From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: [Patch v4 2/4] Add SMEP handling when setting CR4
Date: Tue, 31 May 2011 21:05:35 +0300
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References: <5D8008F58939784290FAB48F5497519844E9278011@shsmsx502.ccr.corp.intel.com> <20110531175232.GA2721@amt.cnet>
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Cc: "Yang, Wei Y" <wei.y.yang@intel.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>
To: Marcelo Tosatti <mtosatti@redhat.com>
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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.