From: "Xin Li (Intel)" <[email protected]> Add is_fred_enabled() to detect if FRED is enabled on a vCPU.
Signed-off-by: Xin Li (Intel) <[email protected]> [ Sean: removed the "kvm_" prefix from the function name ] Signed-off-by: Sean Christopherson <[email protected]> Signed-off-by: Sohil Mehta <[email protected]> Tested-by: Shan Kang <[email protected]> Tested-by: Xuelian Guo <[email protected]> Reviewed-by: Chao Gao <[email protected]> --- v10: - Add back the change log (Binbin Wu and Sean). --- arch/x86/kvm/regs.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/arch/x86/kvm/regs.h b/arch/x86/kvm/regs.h index 447f0ec3e63e..4e641a6c20f9 100644 --- a/arch/x86/kvm/regs.h +++ b/arch/x86/kvm/regs.h @@ -364,6 +364,21 @@ 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. + */ +static inline bool 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_REG_CR3)) -- 2.43.0
