From: Xin Li <xin3.li@xxxxxxxxx>
Add is_fred_enabled() to detect if FRED is enabled on a vCPU.
Signed-off-by: Xin Li <xin3.li@xxxxxxxxx>
[ Sean: removed the "kvm_" prefix from the function name ]
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Xin Li (Intel) <xin@xxxxxxxxx>
Tested-by: Shan Kang <shan.kang@xxxxxxxxx>
---
arch/x86/kvm/kvm_cache_regs.h | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h
index b1eb46e26b2e..386c79f5dcb8 100644
--- a/arch/x86/kvm/kvm_cache_regs.h
+++ b/arch/x86/kvm/kvm_cache_regs.h
@@ -187,6 +187,21 @@ 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_EXREG_CR3))
--
2.46.2
