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

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 <jkosina@suse.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc:  "WoodhouseDavid" <dwmw@amazon.co.uk>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc:  "SchauflerCasey" <casey.schaufler@intel.com>
Link: https://lkml.kernel.org/r/nycvar.YFH.7.76.1809251438580.15880@cbobk.fhfr.pm
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index fc1c1cbc3627f7859356cfcd023d1bc209214110..03ebc0adcd8202e50a405b1005f8091582ca3d7f 100644 (file)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -869,10 +869,11 @@ 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;