[v2,7/8] KVM: x86: Virtualize CR4.LASS
Commit Message
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.
Updating cr4_fixed1 to set CR4.LASS bit in the emulated IA32_VMX_CR4_FIXED1
MSR for guests and allow guests to enable LASS in nested VMX operation 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@intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
---
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(-)
@@ -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)
@@ -7603,6 +7603,9 @@ 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
}
@@ -529,6 +529,8 @@ 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; \
})