linux-kernel - [PATCH v2 23/49] KVM: x86: Handle kernel- and KVM-defined CPUID words in a single helper

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Message-ID: <20240517173926.965351-24-seanjc@google.com>
Date: Fri, 17 May 2024 10:39:00 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>, Sean Christopherson <seanjc@...gle.com>, 
	Vitaly Kuznetsov <vkuznets@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Hou Wenlong <houwenlong.hwl@...group.com>, Kechen Lu <kechenl@...dia.com>, 
	Oliver Upton <oliver.upton@...ux.dev>, Maxim Levitsky <mlevitsk@...hat.com>, 
	Binbin Wu <binbin.wu@...ux.intel.com>, Yang Weijiang <weijiang.yang@...el.com>, 
	Robert Hoo <robert.hoo.linux@...il.com>
Subject: [PATCH v2 23/49] KVM: x86: Handle kernel- and KVM-defined CPUID words
 in a single helper

Merge kvm_cpu_cap_init() and kvm_cpu_cap_init_kvm_defined() into a single
helper.  The only advantage of separating the two was to make it somewhat
obvious that KVM directly initializes the KVM-defined words, whereas using
a common helper will allow for hardening both kernel- and KVM-defined
CPUID words without needing copy+paste.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/cpuid.c | 44 +++++++++++++++-----------------------------
 1 file changed, 15 insertions(+), 29 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index f2bd2f5c4ea3..8efffd48cdf1 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -622,37 +622,23 @@ static __always_inline u32 raw_cpuid_get(struct cpuid_reg cpuid)
 	return *__cpuid_entry_get_reg(&entry, cpuid.reg);
 }
 
-/* Mask kvm_cpu_caps for @leaf with the raw CPUID capabilities of this CPU. */
-static __always_inline void __kvm_cpu_cap_mask(unsigned int leaf)
+static __always_inline void kvm_cpu_cap_init(u32 leaf, u32 mask)
 {
 	const struct cpuid_reg cpuid = x86_feature_cpuid(leaf * 32);
 
-	reverse_cpuid_check(leaf);
+	/*
+	 * For kernel-defined leafs, mask the boot CPU's pre-populated value.
+	 * For KVM-defined leafs, explicitly set the leaf, as KVM is the one
+	 * and only authority.
+	 */
+	if (leaf < NCAPINTS)
+		kvm_cpu_caps[leaf] &= mask;
+	else
+		kvm_cpu_caps[leaf] = mask;
 
 	kvm_cpu_caps[leaf] &= raw_cpuid_get(cpuid);
 }
 
-static __always_inline
-void kvm_cpu_cap_init_kvm_defined(enum kvm_only_cpuid_leafs leaf, u32 mask)
-{
-	/* Use kvm_cpu_cap_init for leafs that aren't KVM-only. */
-	BUILD_BUG_ON(leaf < NCAPINTS);
-
-	kvm_cpu_caps[leaf] = mask;
-
-	__kvm_cpu_cap_mask(leaf);
-}
-
-static __always_inline void kvm_cpu_cap_init(enum cpuid_leafs leaf, u32 mask)
-{
-	/* Use kvm_cpu_cap_init_kvm_defined for KVM-only leafs. */
-	BUILD_BUG_ON(leaf >= NCAPINTS);
-
-	kvm_cpu_caps[leaf] &= mask;
-
-	__kvm_cpu_cap_mask(leaf);
-}
-
 void kvm_set_cpu_caps(void)
 {
 	memset(kvm_cpu_caps, 0, sizeof(kvm_cpu_caps));
@@ -740,12 +726,12 @@ void kvm_set_cpu_caps(void)
 		F(AMX_FP16) | F(AVX_IFMA) | F(LAM)
 	);
 
-	kvm_cpu_cap_init_kvm_defined(CPUID_7_1_EDX,
+	kvm_cpu_cap_init(CPUID_7_1_EDX,
 		F(AVX_VNNI_INT8) | F(AVX_NE_CONVERT) | F(PREFETCHITI) |
 		F(AMX_COMPLEX)
 	);
 
-	kvm_cpu_cap_init_kvm_defined(CPUID_7_2_EDX,
+	kvm_cpu_cap_init(CPUID_7_2_EDX,
 		F(INTEL_PSFD) | F(IPRED_CTRL) | F(RRSBA_CTRL) | F(DDPD_U) |
 		F(BHI_CTRL) | F(MCDT_NO)
 	);
@@ -755,7 +741,7 @@ void kvm_set_cpu_caps(void)
 		X86_64_F(XFD)
 	);
 
-	kvm_cpu_cap_init_kvm_defined(CPUID_12_EAX,
+	kvm_cpu_cap_init(CPUID_12_EAX,
 		SF(SGX1) | SF(SGX2) | SF(SGX_EDECCSSA)
 	);
 
@@ -781,7 +767,7 @@ void kvm_set_cpu_caps(void)
 	if (!tdp_enabled && IS_ENABLED(CONFIG_X86_64))
 		kvm_cpu_cap_set(X86_FEATURE_GBPAGES);
 
-	kvm_cpu_cap_init_kvm_defined(CPUID_8000_0007_EDX,
+	kvm_cpu_cap_init(CPUID_8000_0007_EDX,
 		SF(CONSTANT_TSC)
 	);
 
@@ -835,7 +821,7 @@ void kvm_set_cpu_caps(void)
 	kvm_cpu_cap_check_and_set(X86_FEATURE_IBPB_BRTYPE);
 	kvm_cpu_cap_check_and_set(X86_FEATURE_SRSO_NO);
 
-	kvm_cpu_cap_init_kvm_defined(CPUID_8000_0022_EAX,
+	kvm_cpu_cap_init(CPUID_8000_0022_EAX,
 		F(PERFMON_V2)
 	);
 
-- 
2.45.0.215.g3402c0e53f-goog