[PATCH] x86/cpufeatures: Add CPUID_LNX_5 to track recently added Linux-defined word

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Add CPUID_LNX_5 to track cpufeatures' word 21, and add the appropriate
compile-time assert in KVM to prevent direct lookups on the features in
CPUID_LNX_5.  KVM uses X86_FEATURE_* flags to manage guest CPUID, and so
must translate features that are scattered by Linux from the Linux-defined
bit to the hardware-defined bit, i.e. should never try to directly access
scattered features in guest CPUID.

Opportunistically add NR_CPUID_WORDS to enum cpuid_leafs, along with a
compile-time assert in KVM's CPUID infrastructure to ensure that future
additions update cpuid_leafs along with NCAPINTS.

No functional change intended.

Fixes: 7f274e609f3d ("x86/cpufeatures: Add new word for scattered features")
Cc: Sandipan Das <sandipan.das@xxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
 arch/x86/include/asm/cpufeature.h | 2 ++
 arch/x86/kvm/reverse_cpuid.h      | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index 42157ddcc09d..686e92d2663e 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -33,6 +33,8 @@ enum cpuid_leafs
 #define X86_CAP_FMT_NUM "%d:%d"
diff --git a/arch/x86/kvm/reverse_cpuid.h b/arch/x86/kvm/reverse_cpuid.h
index aadefcaa9561..58ac8d69c94b 100644
--- a/arch/x86/kvm/reverse_cpuid.h
+++ b/arch/x86/kvm/reverse_cpuid.h
@@ -102,10 +102,12 @@ static const struct cpuid_reg reverse_cpuid[] = {
 static __always_inline void reverse_cpuid_check(unsigned int x86_leaf)
 	BUILD_BUG_ON(x86_leaf == CPUID_LNX_1);
 	BUILD_BUG_ON(x86_leaf == CPUID_LNX_2);
 	BUILD_BUG_ON(x86_leaf == CPUID_LNX_3);
 	BUILD_BUG_ON(x86_leaf == CPUID_LNX_4);
+	BUILD_BUG_ON(x86_leaf == CPUID_LNX_5);
 	BUILD_BUG_ON(x86_leaf >= ARRAY_SIZE(reverse_cpuid));
 	BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0);

base-commit: c85af715cac0a951eea97393378e84bb49384734

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