KVM: x86: Add a macro to init CPUID features that KVM emulates in software

Now that kvm_cpu_cap_init() is a macro with its own scope, add EMUL_F() to
OR-in features that KVM emulates in software, i.e. that don't depend on
the feature being available in hardware.  The contained scope
of kvm_cpu_cap_init() allows using a local variable to track the set of
emulated leaves, which in addition to avoiding confusing and/or
unnecessary variables, helps prevent misuse of EMUL_F().

Link: https://lore.kernel.org/r/20241128013424.4096668-31-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 67514cb4e000024b92a50e6a50d24182a7a19545..40e46098af485681e103e933f3ce9936c0b61fd4 100644 (file)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -632,6 +632,7 @@ do {                                                                        \
        const struct cpuid_reg cpuid = x86_feature_cpuid(leaf * 32);    \
        const u32 __maybe_unused kvm_cpu_cap_init_in_progress = leaf;   \
        u32 kvm_cpu_cap_passthrough = 0;                                \
+       u32 kvm_cpu_cap_emulated = 0;                                   \
                                                                        \
        if (leaf < NCAPINTS)                                            \
                kvm_cpu_caps[leaf] &= (mask);                           \
@@ -640,6 +641,7 @@ do {                                                                        \
                                                                        \
        kvm_cpu_caps[leaf] |= kvm_cpu_cap_passthrough;                  \
        kvm_cpu_caps[leaf] &= raw_cpuid_get(cpuid);                     \
+       kvm_cpu_caps[leaf] |= kvm_cpu_cap_emulated;                     \
 } while (0)
 
 /*
@@ -675,6 +677,16 @@ do {                                                                       \
        (IS_ENABLED(CONFIG_X86_64) ? F(name) : 0);              \
 })
 
+/*
+ * Emulated Feature - For features that KVM emulates in software irrespective
+ * of host CPU/kernel support.
+ */
+#define EMULATED_F(name)                                       \
+({                                                             \
+       kvm_cpu_cap_emulated |= F(name);                        \
+       F(name);                                                \
+})
+
 /*
  * Passthrough Feature - For features that KVM supports based purely on raw
  * hardware CPUID, i.e. that KVM virtualizes even if the host kernel doesn't
@@ -736,7 +748,7 @@ void kvm_set_cpu_caps(void)
                0 /* Reserved, DCA */ |
                F(XMM4_1) |
                F(XMM4_2) |
-               F(X2APIC) |
+               EMULATED_F(X2APIC) |
                F(MOVBE) |
                F(POPCNT) |
                0 /* Reserved*/ |
@@ -747,8 +759,6 @@ void kvm_set_cpu_caps(void)
                F(F16C) |
                F(RDRAND)
        );
-       /* KVM emulates x2apic in software irrespective of host support. */
-       kvm_cpu_cap_set(X86_FEATURE_X2APIC);
 
        kvm_cpu_cap_init(CPUID_1_EDX,
                F(FPU) |
@@ -782,6 +792,7 @@ void kvm_set_cpu_caps(void)
 
        kvm_cpu_cap_init(CPUID_7_0_EBX,
                F(FSGSBASE) |
+               EMULATED_F(TSC_ADJUST) |
                F(SGX) |
                F(BMI1) |
                F(HLE) |
@@ -844,7 +855,7 @@ void kvm_set_cpu_caps(void)
                F(AVX512_4FMAPS) |
                F(SPEC_CTRL) |
                F(SPEC_CTRL_SSBD) |
-               F(ARCH_CAPABILITIES) |
+               EMULATED_F(ARCH_CAPABILITIES) |
                F(INTEL_STIBP) |
                F(MD_CLEAR) |
                F(AVX512_VP2INTERSECT) |
@@ -858,10 +869,6 @@ void kvm_set_cpu_caps(void)
                F(FLUSH_L1D)
        );
 
-       /* TSC_ADJUST and ARCH_CAPABILITIES are emulated in software. */
-       kvm_cpu_cap_set(X86_FEATURE_TSC_ADJUST);
-       kvm_cpu_cap_set(X86_FEATURE_ARCH_CAPABILITIES);
-
        if (boot_cpu_has(X86_FEATURE_AMD_IBPB_RET) &&
            boot_cpu_has(X86_FEATURE_AMD_IBPB) &&
            boot_cpu_has(X86_FEATURE_AMD_IBRS))
@@ -1047,6 +1054,7 @@ void kvm_set_cpu_caps(void)
                0 /* SmmPgCfgLock */ |
                F(NULL_SEL_CLR_BASE) |
                F(AUTOIBRS) |
+               EMULATED_F(NO_SMM_CTL_MSR) |
                0 /* PrefetchCtlMsr */ |
                F(WRMSR_XX_BASE_NS)
        );
@@ -1073,7 +1081,6 @@ void kvm_set_cpu_caps(void)
                kvm_cpu_cap_set(X86_FEATURE_LFENCE_RDTSC);
        if (!static_cpu_has_bug(X86_BUG_NULL_SEG))
                kvm_cpu_cap_set(X86_FEATURE_NULL_SEL_CLR_BASE);
-       kvm_cpu_cap_set(X86_FEATURE_NO_SMM_CTL_MSR);
 
        kvm_cpu_cap_init(CPUID_C000_0001_EDX,
                F(XSTORE) |
@@ -1108,6 +1115,7 @@ EXPORT_SYMBOL_GPL(kvm_set_cpu_caps);
 #undef F
 #undef SF
 #undef X86_64_F
+#undef EMULATED_F
 #undef PASSTHROUGH_F
 #undef ALIASED_1_EDX_F