Add kvm_is_fred_enabled() to get if FRED is enabled on a vCPU.
Signed-off-by: Xin Li xin3.li@intel.com Tested-by: Shan Kang shan.kang@intel.com ---
Change since v1: * Explain why it is ok to only check CR4.FRED (Chao Gao). --- arch/x86/kvm/kvm_cache_regs.h | 17 +++++++++++++++++ 1 file changed, 17 insertions(+)
diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h index 75eae9c4998a..1d431c703fdf 100644 --- a/arch/x86/kvm/kvm_cache_regs.h +++ b/arch/x86/kvm/kvm_cache_regs.h @@ -187,6 +187,23 @@ static __always_inline bool kvm_is_cr4_bit_set(struct kvm_vcpu *vcpu, return !!kvm_read_cr4_bits(vcpu, cr4_bit); }
+/* + * It's enough to check just CR4.FRED (X86_CR4_FRED) to tell if + * a vCPU is running with FRED enabled, because: + * 1) CR4.FRED can be set to 1 only _after_ IA32_EFER.LMA = 1. + * 2) To leave IA-32e mode, CR4.FRED must be cleared first. + * + * More details at FRED Spec 6.0 Section 4.2 Enabling in CR4. + */ +static __always_inline bool kvm_is_fred_enabled(struct kvm_vcpu *vcpu) +{ +#ifdef CONFIG_X86_64 + return kvm_is_cr4_bit_set(vcpu, X86_CR4_FRED); +#else + return false; +#endif +} + static inline ulong kvm_read_cr3(struct kvm_vcpu *vcpu) { if (!kvm_register_is_available(vcpu, VCPU_EXREG_CR3))