linux-kernel - [Patch v4 04/18] x86/speculation: Add X86_FEATURE_USE_IBRS

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Message-Id: <ec6e021aea4d83f3be43fee88115b274c9411010.1540923609.git.tim.c.chen@linux.intel.com>
Date:   Tue, 30 Oct 2018 11:49:11 -0700
From:   Tim Chen <tim.c.chen@...ux.intel.com>
To:     Jiri Kosina <jikos@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Tim Chen <tim.c.chen@...ux.intel.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Andi Kleen <ak@...ux.intel.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Casey Schaufler <casey.schaufler@...el.com>,
        Asit Mallick <asit.k.mallick@...el.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        Jon Masters <jcm@...hat.com>,
        Waiman Long <longman9394@...il.com>,
        linux-kernel@...r.kernel.org, x86@...nel.org
Subject: [Patch v4 04/18] x86/speculation: Add X86_FEATURE_USE_IBRS_ENHANCED

Add X86_FEATURE_USE_IBRS_ENHANCED feature bit to indicate
enhanced IBRS is used for Spectre V2 mitigation.

Signed-off-by: Tim Chen <tim.c.chen@...ux.intel.com>
---
 arch/x86/include/asm/cpufeatures.h | 1 +
 arch/x86/kernel/cpu/bugs.c         | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 89a048c..612c2a3 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -221,6 +221,7 @@
 #define X86_FEATURE_ZEN			( 7*32+28) /* "" CPU is AMD family 0x17 (Zen) */
 #define X86_FEATURE_L1TF_PTEINV		( 7*32+29) /* "" L1TF workaround PTE inversion */
 #define X86_FEATURE_IBRS_ENHANCED	( 7*32+30) /* Enhanced IBRS */
+#define X86_FEATURE_USE_IBRS_ENHANCED	( 7*32+31) /* "" Enhanced IBRS enabled */
 
 /* Virtualization flags: Linux defined, word 8 */
 #define X86_FEATURE_TPR_SHADOW		( 8*32+ 0) /* Intel TPR Shadow */
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index af456f4..6095c9d 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -386,6 +386,7 @@ static void __init spectre_v2_select_mitigation(void)
 			/* Force it so VMEXIT will restore correctly */
 			x86_spec_ctrl_base |= SPEC_CTRL_IBRS;
 			wrmsrl(MSR_IA32_SPEC_CTRL, x86_spec_ctrl_base);
+			setup_force_cpu_cap(X86_FEATURE_USE_IBRS_ENHANCED);
 			goto specv2_set_mode;
 		}
 		if (IS_ENABLED(CONFIG_RETPOLINE))
-- 
2.9.4