linux-kernel - [PATCH v6 3/3] x86/speculation: Propagate information about RSB filling mitigation to sysfs

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Message-ID: <nycvar.YFH.7.76.1809121107360.15880@cbobk.fhfr.pm>
Date:   Wed, 12 Sep 2018 11:08:04 +0200 (CEST)
From:   Jiri Kosina <jikos@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        "Woodhouse, David" <dwmw@...zon.co.uk>,
        Andi Kleen <ak@...ux.intel.com>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        "Schaufler, Casey" <casey.schaufler@...el.com>
cc:     linux-kernel@...r.kernel.org, x86@...nel.org
Subject: [PATCH v6 3/3] x86/speculation: Propagate information about RSB
 filling mitigation to sysfs

From: Jiri Kosina <jkosina@...e.cz>

If spectrev2 mitigation has been enabled, we're filling RSB on context switch
in order to protect from various classess of spectrev2 attacks.

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

Signed-off-by: Jiri Kosina <jkosina@...e.cz>
---
 arch/x86/kernel/cpu/bugs.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 6bc76bdf5a0a..ee46dcbae5fa 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -875,10 +875,11 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr
 
 	case X86_BUG_SPECTRE_V2:
 		mutex_lock(&spec_ctrl_mutex);
-		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());
 		mutex_unlock(&spec_ctrl_mutex);
 		return ret;

-- 
Jiri Kosina
SUSE Labs