4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jiri Kosina [email protected]

commit bb4b3b7762735cdaba5a40fd94c9303d9ffa147a upstream

If spectrev2 mitigation has been enabled, RSB is filled on context switch
in order to protect from various classes of spectrev2 attacks.

If this mitigation is enabled, say so in sysfs for spectrev2.

Signed-off-by: Jiri Kosina <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc:  "WoodhouseDavid" <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Tim Chen <[email protected]>
Cc:  "SchauflerCasey" <[email protected]>
Link: 
https://lkml.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>


---
 arch/x86/kernel/cpu/bugs.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -874,10 +874,11 @@ static ssize_t cpu_show_common(struct de
                return sprintf(buf, "Mitigation: __user pointer 
sanitization\n");
 
        case X86_BUG_SPECTRE_V2:
-               ret = sprintf(buf, "%s%s%s%s%s\n", 
spectre_v2_strings[spectre_v2_enabled],
+               ret = sprintf(buf, "%s%s%s%s%s%s\n", 
spectre_v2_strings[spectre_v2_enabled],
                               boot_cpu_has(X86_FEATURE_USE_IBPB) ? ", IBPB" : 
"",
                               boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", 
IBRS_FW" : "",
                               (x86_spec_ctrl_base & SPEC_CTRL_STIBP) ? ", 
STIBP" : "",
+                              boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? ", RSB 
filling" : "",
                               spectre_v2_module_string());
                return ret;
 


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