linux-kernel - [PATCH 2/6] x86/bugs: Remove MDS command line

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Message-Id: <20240924223140.1054918-3-daniel.sneddon@linux.intel.com>
Date: Tue, 24 Sep 2024 15:31:36 -0700
From: Daniel Sneddon <daniel.sneddon@...ux.intel.com>
To: Jonathan Corbet <corbet@....net>,
	Thomas Gleixner <tglx@...utronix.de>,
	Borislav Petkov <bp@...en8.de>,
	Peter Zijlstra <peterz@...radead.org>,
	Josh Poimboeuf <jpoimboe@...nel.org>,
	Ingo Molnar <mingo@...hat.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	x86@...nel.org
Cc: hpa@...or.com,
	linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	pawan.kumar.gupta@...ux.intel.com
Subject: [PATCH 2/6] x86/bugs: Remove MDS command line

Remove MDS command line option since it can be set using the common
clar_cpu_buffers parameter.

Signed-off-by: Daniel Sneddon <daniel.sneddon@...ux.intel.com>
---
 .../admin-guide/kernel-parameters.txt         | 32 -------------------
 arch/x86/kernel/cpu/bugs.c                    | 21 ------------
 2 files changed, 53 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 66b567c4dce5..2753a1e51da5 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3231,38 +3231,6 @@
 			Format: <first>,<last>
 			Specifies range of consoles to be captured by the MDA.
 
-	mds=		[X86,INTEL,EARLY]
-			Control mitigation for the Micro-architectural Data
-			Sampling (MDS) vulnerability.
-
-			Certain CPUs are vulnerable to an exploit against CPU
-			internal buffers which can forward information to a
-			disclosure gadget under certain conditions.
-
-			In vulnerable processors, the speculatively
-			forwarded data can be used in a cache side channel
-			attack, to access data to which the attacker does
-			not have direct access.
-
-			This parameter controls the MDS mitigation. The
-			options are:
-
-			full       - Enable MDS mitigation on vulnerable CPUs
-			full,nosmt - Enable MDS mitigation and disable
-				     SMT on vulnerable CPUs
-			off        - Unconditionally disable MDS mitigation
-
-			On TAA-affected machines, mds=off can be prevented by
-			an active TAA mitigation as both vulnerabilities are
-			mitigated with the same mechanism so in order to disable
-			this mitigation, you need to specify tsx_async_abort=off
-			too.
-
-			Not specifying this option is equivalent to
-			mds=full.
-
-			For details see: Documentation/admin-guide/hw-vuln/mds.rst
-
 	mem=nn[KMG]	[HEXAGON,EARLY] Set the memory size.
 			Must be specified, otherwise memory size will be 0.
 
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index b3c9e1eede12..ed5524bc3ee4 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -261,27 +261,6 @@ static void __init mds_select_mitigation(void)
 	}
 }
 
-static int __init mds_cmdline(char *str)
-{
-	if (!boot_cpu_has_bug(X86_BUG_MDS))
-		return 0;
-
-	if (!str)
-		return -EINVAL;
-
-	if (!strcmp(str, "off"))
-		mds_mitigation = MDS_MITIGATION_OFF;
-	else if (!strcmp(str, "full"))
-		mds_mitigation = MDS_MITIGATION_FULL;
-	else if (!strcmp(str, "full,nosmt")) {
-		mds_mitigation = MDS_MITIGATION_FULL;
-		mds_nosmt = true;
-	}
-
-	return 0;
-}
-early_param("mds", mds_cmdline);
-
 #undef pr_fmt
 #define pr_fmt(fmt)	"TAA: " fmt
 
-- 
2.25.1