x86/spec-ctrl: Rename SCF_ist_wrmsr to SCF_ist_sc_msr

We are about to introduce SCF_ist_ibpb, at which point SCF_ist_wrmsr becomes
ambiguous.

No functional change.

This is part of XSA-407.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
(cherry picked from commit 76d6a36f64)

xen/arch/x86/spec_ctrl.c

@@ -1086,7 +1086,7 @@ void __init init_speculation_mitigations(void)
     {
         if ( opt_msr_sc_pv )
         {
-            default_spec_ctrl_flags |= SCF_ist_wrmsr;
+            default_spec_ctrl_flags |= SCF_ist_sc_msr;
             setup_force_cpu_cap(X86_FEATURE_SC_MSR_PV);
         }
 
@@ -1097,7 +1097,7 @@ void __init init_speculation_mitigations(void)
              * Xen's value is not restored atomically.  An early NMI hitting
              * the VMExit path needs to restore Xen's value for safety.
              */
-            default_spec_ctrl_flags |= SCF_ist_wrmsr;
+            default_spec_ctrl_flags |= SCF_ist_sc_msr;
             setup_force_cpu_cap(X86_FEATURE_SC_MSR_HVM);
         }
     }
@@ -1110,7 +1110,7 @@ void __init init_speculation_mitigations(void)
          * on real hardware matches the availability of MSR_SPEC_CTRL in the
          * first place.
          *
-         * No need for SCF_ist_wrmsr because Xen's value is restored
+         * No need for SCF_ist_sc_msr because Xen's value is restored
          * atomically WRT NMIs in the VMExit path.
          *
          * TODO: Adjust cpu_has_svm_spec_ctrl to be usable earlier on boot.

xen/include/asm-x86/spec_ctrl.h

@@ -31,7 +31,7 @@
  * context switched per domain, and some inhibited in the S3 path.
  */
 #define SCF_use_shadow (1 << 0)
-#define SCF_ist_wrmsr  (1 << 1)
+#define SCF_ist_sc_msr (1 << 1)
 #define SCF_ist_rsb    (1 << 2)
 #define SCF_verw       (1 << 3)
 
@@ -46,7 +46,7 @@
  * These are the controls to inhibit on the S3 resume path until microcode has
  * been reloaded.
  */
-#define SCF_IST_MASK (SCF_ist_wrmsr)
+#define SCF_IST_MASK (SCF_ist_sc_msr)
 
 /*
  * Some speculative protections are per-domain.  These settings are merged

xen/include/asm-x86/spec_ctrl_asm.h

@@ -266,8 +266,8 @@
 
 .L\@_skip_rsb:
 
-    test $SCF_ist_wrmsr, %al
-    jz .L\@_skip_wrmsr
+    test $SCF_ist_sc_msr, %al
+    jz .L\@_skip_msr_spec_ctrl
 
     xor %edx, %edx
     testb $3, UREGS_cs(%rsp)
@@ -290,7 +290,7 @@ UNLIKELY_DISPATCH_LABEL(\@_serialise):
      * to speculate around the WRMSR.  As a result, we need a dispatch
      * serialising instruction in the else clause.
      */
-.L\@_skip_wrmsr:
+.L\@_skip_msr_spec_ctrl:
     lfence
     UNLIKELY_END(\@_serialise)
 .endm
@@ -301,7 +301,7 @@ UNLIKELY_DISPATCH_LABEL(\@_serialise):
  * Requires %rbx=stack_end
  * Clobbers %rax, %rcx, %rdx
  */
-    testb $SCF_ist_wrmsr, STACK_CPUINFO_FIELD(spec_ctrl_flags)(%rbx)
+    testb $SCF_ist_sc_msr, STACK_CPUINFO_FIELD(spec_ctrl_flags)(%rbx)
     jz .L\@_skip
 
     DO_SPEC_CTRL_EXIT_TO_XEN