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| Started by | Paolo Bonzini <pbonzini@redhat.com> |
|---|---|
| First post | 2016-03-07 15:20 +0100 |
| Last post | 2016-03-07 15:20 +0100 |
| Articles | 1 — 1 participant |
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[PATCH 9/9] KVM: MMU: micro-optimize gpte_access Paolo Bonzini <pbonzini@redhat.com> - 2016-03-07 15:20 +0100
| From | Paolo Bonzini <pbonzini@redhat.com> |
|---|---|
| Date | 2016-03-07 15:20 +0100 |
| Subject | [PATCH 9/9] KVM: MMU: micro-optimize gpte_access |
| Message-ID | <ra4aS-3TP-9@gated-at.bofh.it> |
Avoid AND-NOT, most x86 processor lack an instruction for it. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- arch/x86/kvm/paging_tmpl.h | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index a1f5459edcec..6013f3685ef4 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -189,8 +189,11 @@ static inline unsigned FNAME(gpte_access)(struct kvm_vcpu *vcpu, u64 gpte) ((gpte & VMX_EPT_EXECUTABLE_MASK) ? ACC_EXEC_MASK : 0) | ACC_USER_MASK; #else - access = (gpte & (PT_WRITABLE_MASK | PT_USER_MASK)) | ACC_EXEC_MASK; - access &= ~(gpte >> PT64_NX_SHIFT); + BUILD_BUG_ON(ACC_EXEC_MASK != PT_PRESENT_MASK); + BUILD_BUG_ON(ACC_EXEC_MASK != 1); + access = gpte & (PT_WRITABLE_MASK | PT_USER_MASK | PT_PRESENT_MASK); + /* Combine NX with P (which is set here) to get ACC_EXEC_MASK. */ + access ^= (gpte >> PT64_NX_SHIFT); #endif return access; -- 1.8.3.1
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