[PATCH 3/4] x86/tsx: Remove opencoded MSR_ARCH_CAPS check

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

The current cpu_has_tsx_ctrl tristate is serving double pupose; to signal the
first pass through tsx_init(), and the availability of MSR_TSX_CTRL.

Drop the variable, replacing it with a once boolean, and altering
cpu_has_tsx_ctrl to come out of the feature information.

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
---
 xen/arch/x86/include/asm/cpufeature.h |  1 +
 xen/arch/x86/include/asm/processor.h  |  2 +-
 xen/arch/x86/tsx.c                    | 13 ++++++++-----
 3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/include/asm/cpufeature.h 
b/xen/arch/x86/include/asm/cpufeature.h
index 8446f98625f7..deca5bfc2629 100644
--- a/xen/arch/x86/include/asm/cpufeature.h
+++ b/xen/arch/x86/include/asm/cpufeature.h
@@ -185,6 +185,7 @@ static inline bool boot_cpu_has(unsigned int feat)
 
 /* MSR_ARCH_CAPS 10A */
 #define cpu_has_if_pschange_mc_no boot_cpu_has(X86_FEATURE_IF_PSCHANGE_MC_NO)
+#define cpu_has_tsx_ctrl        boot_cpu_has(X86_FEATURE_TSX_CTRL)
 
 /* Synthesized. */
 #define cpu_has_arch_perfmon    boot_cpu_has(X86_FEATURE_ARCH_PERFMON)
diff --git a/xen/arch/x86/include/asm/processor.h 
b/xen/arch/x86/include/asm/processor.h
index 0eaa2c3094d0..f983ff501d95 100644
--- a/xen/arch/x86/include/asm/processor.h
+++ b/xen/arch/x86/include/asm/processor.h
@@ -535,7 +535,7 @@ static inline uint8_t get_cpu_family(uint32_t raw, uint8_t 
*model,
     return fam;
 }
 
-extern int8_t opt_tsx, cpu_has_tsx_ctrl;
+extern int8_t opt_tsx;
 extern bool rtm_disabled;
 void tsx_init(void);
 
diff --git a/xen/arch/x86/tsx.c b/xen/arch/x86/tsx.c
index 41b6092cfe16..fc199815994d 100644
--- a/xen/arch/x86/tsx.c
+++ b/xen/arch/x86/tsx.c
@@ -19,7 +19,6 @@
  * controlling TSX behaviour, and where TSX isn't force-disabled by firmware.
  */
 int8_t __read_mostly opt_tsx = -1;
-int8_t __read_mostly cpu_has_tsx_ctrl = -1;
 bool __read_mostly rtm_disabled;
 
 static int __init cf_check parse_tsx(const char *s)
@@ -37,24 +36,28 @@ custom_param("tsx", parse_tsx);
 
 void tsx_init(void)
 {
+    static bool __read_mostly once;
+
     /*
      * This function is first called between microcode being loaded, and CPUID
      * being scanned generally.  Read into boot_cpu_data.x86_capability[] for
      * the cpu_has_* bits we care about using here.
      */
-    if ( unlikely(cpu_has_tsx_ctrl < 0) )
+    if ( unlikely(!once) )
     {
-        uint64_t caps = 0;
         bool has_rtm_always_abort;
 
+        once = true;
+
         if ( boot_cpu_data.cpuid_level >= 7 )
             boot_cpu_data.x86_capability[FEATURESET_7d0]
                 = cpuid_count_edx(7, 0);
 
         if ( cpu_has_arch_caps )
-            rdmsrl(MSR_ARCH_CAPABILITIES, caps);
+            rdmsr(MSR_ARCH_CAPABILITIES,
+                  boot_cpu_data.x86_capability[FEATURESET_10Al],
+                  boot_cpu_data.x86_capability[FEATURESET_10Ah]);
 
-        cpu_has_tsx_ctrl = !!(caps & ARCH_CAPS_TSX_CTRL);
         has_rtm_always_abort = cpu_has_rtm_always_abort;
 
         if ( cpu_has_tsx_ctrl && cpu_has_srbds_ctrl )
-- 
2.30.2