x86/speculation: Propagate information about RSB filling mitigation to sysfs

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]

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 53eb14a65610687ddbf7a30d431ee78bc18ebf83..fe32103fcdc7ea4ca97847b37c84f1c67be7ec31 100644 (file)
--- 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 device *dev, struct device_attribute *attr
                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;