[PATCH 1/5] x86/cpufeatures: Introduce X86_FEATURE_NO_LMSLE

[Jim Mattson]

When AMD introduced "Long Mode Segment Limit Enable" (a.k.a. "VMware
mode"), the feature was not enumerated by a CPUID bit. Now that VMware
has abandoned binary translation, AMD has deprecated EFER.LMSLE.

The absence of the feature *is* now enumerated by a CPUID bit (a la
Intel's X86_FEATURE_ZERO_FCS_DCS and X86_FEATURE_FDP_EXCPTN_ONLY).

This defeature bit is already present in feature word 13, but it was
previously anonymous. Name it X86_FEATURE_NO_LMSLE, so that KVM can
reference it when deciding whether or not EFER.LMSLE should be a
reserved bit in a KVM guest.

Since this bit indicates the absence of a feature, don't enumerate it
in /proc/cpuinfo.

Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
---
 arch/x86/include/asm/cpufeatures.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index ef4775c6db01..0f5a3285d8d8 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -319,6 +319,7 @@
 #define X86_FEATURE_AMD_IBRS		(13*32+14) /* "" Indirect Branch Restricted Speculation */
 #define X86_FEATURE_AMD_STIBP		(13*32+15) /* "" Single Thread Indirect Branch Predictors */
 #define X86_FEATURE_AMD_STIBP_ALWAYS_ON	(13*32+17) /* "" Single Thread Indirect Branch Predictors always-on preferred */
+#define X86_FEATURE_NO_LMSLE		(13*32+20) /* "" EFER_LMSLE is unsupported */
 #define X86_FEATURE_AMD_PPIN		(13*32+23) /* Protected Processor Inventory Number */
 #define X86_FEATURE_AMD_SSBD		(13*32+24) /* "" Speculative Store Bypass Disable */
 #define X86_FEATURE_VIRT_SSBD		(13*32+25) /* Virtualized Speculative Store Bypass Disable */
-- 
2.37.3.968.ga6b4b080e4-goog