[PATCH v7 03/18] x86/acrn: Introduce acrn_cpuid_base() and hypervisor feature bits

[shuo . a . liu]

From: Yin Fengwei <fengwei.yin@xxxxxxxxx>

ACRN Hypervisor reports hypervisor features via CPUID leaf 0x40000001
which is similar to KVM. A VM can check if it's the privileged VM using
the feature bits. The Service VM is the only privileged VM by design.

Signed-off-by: Yin Fengwei <fengwei.yin@xxxxxxxxx>
Signed-off-by: Shuo Liu <shuo.a.liu@xxxxxxxxx>
Reviewed-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Acked-by: Borislav Petkov <bp@xxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Fengwei Yin <fengwei.yin@xxxxxxxxx>
Cc: Zhi Wang <zhi.a.wang@xxxxxxxxx>
Cc: Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx>
Cc: Yu Wang <yu1.wang@xxxxxxxxx>
Cc: Reinette Chatre <reinette.chatre@xxxxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 arch/x86/include/asm/acrn.h | 16 ++++++++++++++++
 arch/x86/kernel/cpu/acrn.c  |  2 +-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/acrn.h b/arch/x86/include/asm/acrn.h
index ff259b69cde7..127f20672c5d 100644
--- a/arch/x86/include/asm/acrn.h
+++ b/arch/x86/include/asm/acrn.h
@@ -2,7 +2,23 @@
 #ifndef _ASM_X86_ACRN_H
 #define _ASM_X86_ACRN_H
 
+/*
+ * This CPUID returns feature bitmaps in EAX.
+ * Guest VM uses this to detect the appropriate feature bit.
+ */
+#define	ACRN_CPUID_FEATURES		0x40000001
+/* Bit 0 indicates whether guest VM is privileged */
+#define	ACRN_FEATURE_PRIVILEGED_VM	BIT(0)
+
 void acrn_setup_intr_handler(void (*handler)(void));
 void acrn_remove_intr_handler(void);
 
+static inline u32 acrn_cpuid_base(void)
+{
+	if (boot_cpu_has(X86_FEATURE_HYPERVISOR))
+		return hypervisor_cpuid_base("ACRNACRNACRN", 0);
+
+	return 0;
+}
+
 #endif /* _ASM_X86_ACRN_H */
diff --git a/arch/x86/kernel/cpu/acrn.c b/arch/x86/kernel/cpu/acrn.c
index e0c181781905..23f5f27b5a02 100644
--- a/arch/x86/kernel/cpu/acrn.c
+++ b/arch/x86/kernel/cpu/acrn.c
@@ -21,7 +21,7 @@
 
 static u32 __init acrn_detect(void)
 {
-	return hypervisor_cpuid_base("ACRNACRNACRN", 0);
+	return acrn_cpuid_base();
 }
 
 static void __init acrn_init_platform(void)
-- 
2.28.0