x86/cpu, kvm: Add the NO_NESTED_DATA_BP feature

The "Processor ignores nested data breakpoints" feature was being
open-coded for KVM.  Add the feature to its newly introduced CPUID leaf
0x80000021 EAX proper.
Signed-off-by: Kim Phillips <kim.phillips@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20230124163319.2277355-4-kim.phillips@amd.com

arch/x86/include/asm/cpufeatures.h

@@ -427,6 +427,9 @@
 #define X86_FEATURE_V_TSC_AUX		(19*32+ 9) /* "" Virtual TSC_AUX */
 #define X86_FEATURE_SME_COHERENT	(19*32+10) /* "" AMD hardware-enforced cache coherency */
 
+/* AMD-defined Extended Feature 2 EAX, CPUID level 0x80000021 (EAX), word 20 */
+#define X86_FEATURE_NO_NESTED_DATA_BP	(20*32+ 0) /* "" No Nested Data Breakpoints */
+
 /*
  * BUG word(s)
  */

arch/x86/kvm/cpuid.c

@@ -742,7 +742,7 @@ void kvm_set_cpu_caps(void)
 		F(SME_COHERENT));
 
 	kvm_cpu_cap_mask(CPUID_8000_0021_EAX,
-		BIT(0) /* NO_NESTED_DATA_BP */ |
+		F(NO_NESTED_DATA_BP) |
 		BIT(2) /* LFENCE Always serializing */ | 0 /* SmmPgCfgLock */ |
 		BIT(6) /* NULL_SEL_CLR_BASE */ | 0 /* PrefetchCtlMsr */
 	);