[RFC PATCH 27/27] KVM: TDX: Replace hardcoded CPUID filtering with the allowed mask

[Binbin Wu <binbin.wu@linux.intel.com>]

Replace TDX's ad-hoc CPUID filtering of TSX (HLE/RTM) and WAITPKG with
the generic kvm_cpuid_get_allowed_mask() helper, which returns the
allowed bitmask from the TDX CPUID overlay for any leaf/subleaf/register.

This makes the TDX CPUID filtering automatically cover all features
governed by the overlay infrastructure, eliminating the need to add new
per-feature helpers as more features are restricted for TDX.

Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
---
 arch/x86/kvm/vmx/tdx.c | 42 +++++++++++++-----------------------------
 1 file changed, 13 insertions(+), 29 deletions(-)

diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index a996e7f761ed..2b980335b667 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -120,42 +120,26 @@ static u32 tdx_set_guest_phys_addr_bits(const u32 eax, int addr_bits)
 	return (eax & ~GENMASK(23, 16)) | (addr_bits & 0xff) << 16;
 }
 
-#define TDX_FEATURE_TSX (__feature_bit(X86_FEATURE_HLE) | __feature_bit(X86_FEATURE_RTM))
-
-static bool has_tsx(const struct kvm_cpuid_entry2 *entry)
-{
-	return entry->function == 7 && entry->index == 0 &&
-	       (entry->ebx & TDX_FEATURE_TSX);
-}
-
-static void clear_tsx(struct kvm_cpuid_entry2 *entry)
-{
-	entry->ebx &= ~TDX_FEATURE_TSX;
-}
-
-static bool has_waitpkg(const struct kvm_cpuid_entry2 *entry)
-{
-	return entry->function == 7 && entry->index == 0 &&
-	       (entry->ecx & __feature_bit(X86_FEATURE_WAITPKG));
-}
-
-static void clear_waitpkg(struct kvm_cpuid_entry2 *entry)
-{
-	entry->ecx &= ~__feature_bit(X86_FEATURE_WAITPKG);
-}
-
 static void tdx_clear_unsupported_cpuid(struct kvm_cpuid_entry2 *entry)
 {
-	if (has_tsx(entry))
-		clear_tsx(entry);
+	u32 *reg = &entry->eax;
 
-	if (has_waitpkg(entry))
-		clear_waitpkg(entry);
+	for (int i = CPUID_EAX; i <= CPUID_EDX; i++)
+		reg[i] &= kvm_cpuid_get_allowed_mask(entry->function, entry->index,
+						     i, CPUID_OL_TDX);
 }
 
 static bool tdx_unsupported_cpuid(const struct kvm_cpuid_entry2 *entry)
 {
-	return has_tsx(entry) || has_waitpkg(entry);
+	const u32 *reg = &entry->eax;
+
+	for (int i = CPUID_EAX; i <= CPUID_EDX; i++) {
+		if (reg[i] & ~kvm_cpuid_get_allowed_mask(entry->function, entry->index,
+							 i, CPUID_OL_TDX))
+			return true;
+	}
+
+	return false;
 }
 
 #define KVM_TDX_CPUID_NO_SUBLEAF	((__u32)-1)
-- 
2.46.0