x86/cpufeatures: Enumerate TSX suspend load address tracking instructions

Intel TSX suspend load tracking instructions aim to give a way to choose
which memory accesses do not need to be tracked in the TSX read set. Add
TSX suspend load tracking CPUID feature flag TSXLDTRK for enumeration.

A processor supports Intel TSX suspend load address tracking if
CPUID.0x07.0x0:EDX[16] is present. Two instructions XSUSLDTRK, XRESLDTRK
are available when this feature is present.

The CPU feature flag is shown as "tsxldtrk" in /proc/cpuinfo.
Signed-off-by: Kyung Min Park <kyung.min.park@intel.com>
Signed-off-by: Cathy Zhang <cathy.zhang@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/1598316478-23337-2-git-send-email-cathy.zhang@intel.com

arch/x86/include/asm/cpufeatures.h

@@ -368,6 +368,7 @@
 #define X86_FEATURE_MD_CLEAR		(18*32+10) /* VERW clears CPU buffers */
 #define X86_FEATURE_TSX_FORCE_ABORT	(18*32+13) /* "" TSX_FORCE_ABORT */
 #define X86_FEATURE_SERIALIZE		(18*32+14) /* SERIALIZE instruction */
+#define X86_FEATURE_TSXLDTRK		(18*32+16) /* TSX Suspend Load Address Tracking */
 #define X86_FEATURE_PCONFIG		(18*32+18) /* Intel PCONFIG */
 #define X86_FEATURE_ARCH_LBR		(18*32+19) /* Intel ARCH LBR */
 #define X86_FEATURE_SPEC_CTRL		(18*32+26) /* "" Speculation Control (IBRS + IBPB) */