Virtualize CR4.LASS[bit 27] under KVM control instead of being guest-owned as CR4.LASS generally set once for each vCPU at boot time and won't be toggled at runtime. Besides, only if VM has LASS capability enumerated with CPUID.(EAX=07H.ECX=1):EAX.LASS[bit 6], KVM allows guest software to be able to set CR4.LASS. By design CR4.LASS can be manipulated by nested guest as well. Notes: Setting CR4.LASS to 1 enable LASS in IA-32e mode. It doesn't take effect in legacy mode even if CR4.LASS is set. Signed-off-by: Zeng Guang <guang.zeng@xxxxxxxxx> --- arch/x86/include/asm/kvm_host.h | 2 +- arch/x86/kvm/vmx/vmx.c | 3 +++ arch/x86/kvm/x86.h | 2 ++ 3 files changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 6aaae18f1854..8ff89a52ef66 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -125,7 +125,7 @@ | X86_CR4_PGE | X86_CR4_PCE | X86_CR4_OSFXSR | X86_CR4_PCIDE \ | X86_CR4_OSXSAVE | X86_CR4_SMEP | X86_CR4_FSGSBASE \ | X86_CR4_OSXMMEXCPT | X86_CR4_LA57 | X86_CR4_VMXE \ - | X86_CR4_SMAP | X86_CR4_PKE | X86_CR4_UMIP)) + | X86_CR4_SMAP | X86_CR4_PKE | X86_CR4_UMIP | X86_CR4_LASS)) #define CR8_RESERVED_BITS (~(unsigned long)X86_CR8_TPR) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 43ff3276918b..c923d7599d71 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -7569,6 +7569,9 @@ static void nested_vmx_cr_fixed1_bits_update(struct kvm_vcpu *vcpu) cr4_fixed1_update(X86_CR4_UMIP, ecx, feature_bit(UMIP)); cr4_fixed1_update(X86_CR4_LA57, ecx, feature_bit(LA57)); + entry = kvm_find_cpuid_entry_index(vcpu, 0x7, 1); + cr4_fixed1_update(X86_CR4_LASS, eax, feature_bit(LASS)); + #undef cr4_fixed1_update } diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h index 7c8a30d44c29..218f4c73789a 100644 --- a/arch/x86/kvm/x86.h +++ b/arch/x86/kvm/x86.h @@ -475,6 +475,8 @@ bool kvm_msr_allowed(struct kvm_vcpu *vcpu, u32 index, u32 type); __reserved_bits |= X86_CR4_VMXE; \ if (!__cpu_has(__c, X86_FEATURE_PCID)) \ __reserved_bits |= X86_CR4_PCIDE; \ + if (!__cpu_has(__c, X86_FEATURE_LASS)) \ + __reserved_bits |= X86_CR4_LASS; \ __reserved_bits; \ }) -- 2.27.0
