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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Borislav Petkov <bp@suse.de>,
	Anthony Steinhauser <asteinhauser@google.com>,
	Frank van der Linden <fllinden@amazon.com>
Subject: [PATCH 5.4 01/18] x86/speculation: Merge one test in spectre_v2_user_select_mitigation()
Date: Wed,  9 Mar 2022 16:59:50 +0100	[thread overview]
Message-ID: <20220309155856.596251147@linuxfoundation.org> (raw)
In-Reply-To: <20220309155856.552503355@linuxfoundation.org>

From: Borislav Petkov <bp@suse.de>

upstream commit a5ce9f2bb665d1d2b31f139a02dbaa2dfbb62fa6 upstream.

Merge the test whether the CPU supports STIBP into the test which
determines whether STIBP is required. Thus try to simplify what is
already an insane logic.

Remove a superfluous newline in a comment, while at it.

Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: Anthony Steinhauser <asteinhauser@google.com>
Link: https://lkml.kernel.org/r/20200615065806.GB14668@zn.tnic
[fllinden@amazon.com: fixed contextual conflict (comment) for 5.4]
Signed-off-by: Frank van der Linden <fllinden@amazon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/kernel/cpu/bugs.c |   13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -756,10 +756,12 @@ spectre_v2_user_select_mitigation(enum s
 	}
 
 	/*
-	 * If enhanced IBRS is enabled or SMT impossible, STIBP is not
+	 * If no STIBP, enhanced IBRS is enabled or SMT impossible, STIBP is not
 	 * required.
 	 */
-	if (!smt_possible || spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
+	if (!boot_cpu_has(X86_FEATURE_STIBP) ||
+	    !smt_possible ||
+	    spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
 		return;
 
 	/*
@@ -771,12 +773,6 @@ spectre_v2_user_select_mitigation(enum s
 	    boot_cpu_has(X86_FEATURE_AMD_STIBP_ALWAYS_ON))
 		mode = SPECTRE_V2_USER_STRICT_PREFERRED;
 
-	/*
-	 * If STIBP is not available, clear the STIBP mode.
-	 */
-	if (!boot_cpu_has(X86_FEATURE_STIBP))
-		mode = SPECTRE_V2_USER_NONE;
-
 	spectre_v2_user_stibp = mode;
 
 set_mode:
@@ -1267,7 +1263,6 @@ static int ib_prctl_set(struct task_stru
 		if (spectre_v2_user_ibpb == SPECTRE_V2_USER_NONE &&
 		    spectre_v2_user_stibp == SPECTRE_V2_USER_NONE)
 			return 0;
-
 		/*
 		 * With strict mode for both IBPB and STIBP, the instruction
 		 * code paths avoid checking this task flag and instead,



  reply	other threads:[~2022-03-09 16:10 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-09 15:59 [PATCH 5.4 00/18] 5.4.184-rc1 review Greg Kroah-Hartman
2022-03-09 15:59 ` Greg Kroah-Hartman [this message]
2022-03-09 15:59 ` [PATCH 5.4 02/18] x86,bugs: Unconditionally allow spectre_v2=retpoline,amd Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.4 03/18] x86/speculation: Rename RETPOLINE_AMD to RETPOLINE_LFENCE Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.4 04/18] x86/speculation: Add eIBRS + Retpoline options Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.4 05/18] Documentation/hw-vuln: Update spectre doc Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.4 06/18] x86/speculation: Include unprivileged eBPF status in Spectre v2 mitigation reporting Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.4 07/18] x86/speculation: Use generic retpoline by default on AMD Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.4 08/18] x86/speculation: Update link to AMD speculation whitepaper Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.4 09/18] x86/speculation: Warn about Spectre v2 LFENCE mitigation Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.4 10/18] x86/speculation: Warn about eIBRS + LFENCE + Unprivileged eBPF + SMT Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.4 11/18] arm/arm64: Provide a wrapper for SMCCC 1.1 calls Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.4 12/18] arm/arm64: smccc/psci: add arm_smccc_1_1_get_conduit() Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.4 13/18] ARM: report Spectre v2 status through sysfs Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.4 14/18] ARM: early traps initialisation Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.4 15/18] ARM: use LOADADDR() to get load address of sections Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.4 16/18] ARM: Spectre-BHB workaround Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.4 17/18] ARM: include unprivileged BPF status in Spectre V2 reporting Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.4 18/18] ARM: fix build error when BPF_SYSCALL is disabled Greg Kroah-Hartman
2022-03-09 17:38 ` [PATCH 5.4 00/18] 5.4.184-rc1 review Florian Fainelli
2022-03-09 17:50   ` Greg Kroah-Hartman
2022-03-09 19:27 ` Guenter Roeck
2022-03-09 20:25 ` Shuah Khan
2022-03-09 20:50 ` Daniel Díaz
2022-03-10  3:20 ` Samuel Zou
2022-03-10  4:01 ` Florian Fainelli

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