linux-kernel - [PATCH v2 01/35] x86/bugs: Add X86_BUG_SPECTRE_V2

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Message-ID: <20241105215455.359471-2-david.kaplan@amd.com>
Date: Tue, 5 Nov 2024 15:54:21 -0600
From: David Kaplan <david.kaplan@....com>
To: Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...en8.de>,
	Peter Zijlstra <peterz@...radead.org>, Josh Poimboeuf <jpoimboe@...nel.org>,
	Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>, Ingo Molnar
	<mingo@...hat.com>, Dave Hansen <dave.hansen@...ux.intel.com>,
	<x86@...nel.org>, "H . Peter Anvin" <hpa@...or.com>
CC: <linux-kernel@...r.kernel.org>
Subject: [PATCH v2 01/35] x86/bugs: Add X86_BUG_SPECTRE_V2_USER

All CPU vulnerabilities with command line options map to a single
X86_BUG bit except for Spectre V2 where both the spectre_v2 and
spectre_v2_user command line options are related to the same bug.  The
spectre_v2 command line options mostly relate to user->kernel and
guest->host mitigations, while the spectre_v2_user command line options
relate to user->user or guest->guest protections.

Define a new X86_BUG bit for spectre_v2_user so each
*_select_mitigation() function in bugs.c is related to a unique X86_BUG
bit.

Signed-off-by: David Kaplan <david.kaplan@....com>
---
 arch/x86/include/asm/cpufeatures.h | 1 +
 arch/x86/kernel/cpu/common.c       | 4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 924f530129d7..0c4c974a616b 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -528,4 +528,5 @@
 #define X86_BUG_RFDS			X86_BUG(1*32 + 2) /* "rfds" CPU is vulnerable to Register File Data Sampling */
 #define X86_BUG_BHI			X86_BUG(1*32 + 3) /* "bhi" CPU is affected by Branch History Injection */
 #define X86_BUG_IBPB_NO_RET	   	X86_BUG(1*32 + 4) /* "ibpb_no_ret" IBPB omits return target predictions */
+#define X86_BUG_SPECTRE_V2_USER		X86_BUG(1*32 + 5) /* "spectre_v2_user" CPU is affected by Spectre variant 2 attack between user processes */
 #endif /* _ASM_X86_CPUFEATURES_H */
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 8f41ab219cf1..a2bc1c1b31a9 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1332,8 +1332,10 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
 
 	setup_force_cpu_bug(X86_BUG_SPECTRE_V1);
 
-	if (!cpu_matches(cpu_vuln_whitelist, NO_SPECTRE_V2))
+	if (!cpu_matches(cpu_vuln_whitelist, NO_SPECTRE_V2)) {
 		setup_force_cpu_bug(X86_BUG_SPECTRE_V2);
+		setup_force_cpu_bug(X86_BUG_SPECTRE_V2_USER);
+	}
 
 	if (!cpu_matches(cpu_vuln_whitelist, NO_SSB) &&
 	    !(x86_arch_cap_msr & ARCH_CAP_SSB_NO) &&
-- 
2.34.1