On 5/18/2024 1:38 AM, Sean Christopherson wrote:
Add a macro to mask-in feature flags that are supported only on 64-bit
kernels/KVM. In addition to reducing overall #ifdeffery, using a macro
will allow hardening the kvm_cpu_cap initialization sequences to assert
that the features being advertised are indeed included in the word being
initialized. And arguably using *F() macros through is more readable.
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Very nice patch!
Reviewed-by: Xiaoyao Li <xiaoyao.li@xxxxxxxxx>
---
arch/x86/kvm/cpuid.c | 22 ++++++++++------------
1 file changed, 10 insertions(+), 12 deletions(-)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 5a4d6138c4f1..5e3b97d06374 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -70,6 +70,12 @@ u32 xstate_required_size(u64 xstate_bv, bool compacted)
(boot_cpu_has(X86_FEATURE_##name) ? F(name) : 0); \
})
+/* Features that KVM supports only on 64-bit kernels. */
+#define X86_64_F(name) \
+({ \
+ (IS_ENABLED(CONFIG_X86_64) ? F(name) : 0); \
+})
+
/*
* Raw Feature - For features that KVM supports based purely on raw host CPUID,
* i.e. that KVM virtualizes even if the host kernel doesn't use the feature.
@@ -639,15 +645,6 @@ static __always_inline void kvm_cpu_cap_init(enum cpuid_leafs leaf, u32 mask)
void kvm_set_cpu_caps(void)
{
-#ifdef CONFIG_X86_64
- unsigned int f_gbpages = F(GBPAGES);
- unsigned int f_lm = F(LM);
- unsigned int f_xfd = F(XFD);
-#else
- unsigned int f_gbpages = 0;
- unsigned int f_lm = 0;
- unsigned int f_xfd = 0;
-#endif
memset(kvm_cpu_caps, 0, sizeof(kvm_cpu_caps));
BUILD_BUG_ON(sizeof(kvm_cpu_caps) - (NKVMCAPINTS * sizeof(*kvm_cpu_caps)) >
@@ -744,7 +741,8 @@ void kvm_set_cpu_caps(void)
);
kvm_cpu_cap_init(CPUID_D_1_EAX,
- F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1) | F(XSAVES) | f_xfd
+ F(XSAVEOPT) | F(XSAVEC) | F(XGETBV1) | F(XSAVES) |
+ X86_64_F(XFD)
);
kvm_cpu_cap_init_kvm_defined(CPUID_12_EAX,
@@ -766,8 +764,8 @@ void kvm_set_cpu_caps(void)
F(MTRR) | F(PGE) | F(MCA) | F(CMOV) |
F(PAT) | F(PSE36) | 0 /* Reserved */ |
F(NX) | 0 /* Reserved */ | F(MMXEXT) | F(MMX) |
- F(FXSR) | F(FXSR_OPT) | f_gbpages | F(RDTSCP) |
- 0 /* Reserved */ | f_lm | F(3DNOWEXT) | F(3DNOW)
+ F(FXSR) | F(FXSR_OPT) | X86_64_F(GBPAGES) | F(RDTSCP) |
+ 0 /* Reserved */ | X86_64_F(LM) | F(3DNOWEXT) | F(3DNOW)
);
if (!tdp_enabled && IS_ENABLED(CONFIG_X86_64))
