[xen stable-4.16] x86/spec-ctrl: Use a taint for CET without MSR_SPEC_CTRL

[patchbot@xxxxxxx]

commit bf67861f787cf2b32503005575d326fc2d0a2ff7
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Mon Jun 5 11:09:11 2023 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Tue Aug 8 16:02:54 2023 +0100

    x86/spec-ctrl: Use a taint for CET without MSR_SPEC_CTRL
    
    Reword the comment for 'S' to include an incompatible set of features on the
    same core.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
    (cherry picked from commit 3f63f4510422c29fda7ba238b880cbb53eca34fe)
---
 xen/arch/x86/spec_ctrl.c | 3 +++
 xen/common/kernel.c      | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/spec_ctrl.c b/xen/arch/x86/spec_ctrl.c
index 701843311c..302a53fa12 100644
--- a/xen/arch/x86/spec_ctrl.c
+++ b/xen/arch/x86/spec_ctrl.c
@@ -1139,7 +1139,10 @@ void __init init_speculation_mitigations(void)
     if ( read_cr4() & X86_CR4_CET )
     {
         if ( !has_spec_ctrl )
+        {
             printk(XENLOG_WARNING "?!? CET active, but no MSR_SPEC_CTRL?\n");
+            add_taint(TAINT_CPU_OUT_OF_SPEC);
+        }
         else if ( opt_ibrs == -1 )
             opt_ibrs = ibrs = true;
 
diff --git a/xen/common/kernel.c b/xen/common/kernel.c
index 7ed96521f9..9f22399063 100644
--- a/xen/common/kernel.c
+++ b/xen/common/kernel.c
@@ -339,7 +339,7 @@ unsigned int tainted;
  *  'H' - HVM forced emulation prefix is permitted.
  *  'M' - Machine had a machine check experience.
  *  'U' - Platform is unsecure (usually due to an errata on the platform).
- *  'S' - Out of spec CPU (One core has a feature incompatible with others).
+ *  'S' - Out of spec CPU (Incompatible features on one or more cores).
  *
  *      The string is overwritten by the next call to print_taint().
  */
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.16