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Commit 025b9cf2 authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by Greg Kroah-Hartman
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x86/speculation/mds: Add 'mitigations=' support for MDS 



commit 5c14068f87d04adc73ba3f41c2a303d3c3d1fa12 upstream.

Add MDS to the new 'mitigations=' cmdline option.

Signed-off-by: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 1709284f

Documentation/kernel-parameters.txt

+2 −0
Original line number Diff line number Diff line
@@ -2488,6 +2488,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. 
					       spectre_v2_user=off [X86]

					       spec_store_bypass_disable=off [X86]

					       l1tf=off [X86]

					       mds=off [X86]



			auto (default)

				Mitigate all CPU vulnerabilities, but leave SMT
@@ -2502,6 +2503,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted. 
				if needed.  This is for users who always want to

				be fully mitigated, even if it means losing SMT.

				Equivalent to: l1tf=flush,nosmt [X86]

					       mds=full,nosmt [X86]



	mminit_loglevel=

			[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this

arch/x86/kernel/cpu/bugs.c

+3 −2
Original line number Diff line number Diff line
@@ -230,7 +230,7 @@ static const char * const mds_strings[] = { 


static void __init mds_select_mitigation(void)

{

	if (!boot_cpu_has_bug(X86_BUG_MDS)) {

	if (!boot_cpu_has_bug(X86_BUG_MDS) || cpu_mitigations_off()) {

		mds_mitigation = MDS_MITIGATION_OFF;

		return;

	}
@@ -241,7 +241,8 @@ static void __init mds_select_mitigation(void) 


		static_branch_enable(&mds_user_clear);



		if (mds_nosmt && !boot_cpu_has(X86_BUG_MSBDS_ONLY))

		if (!boot_cpu_has(X86_BUG_MSBDS_ONLY) &&

		    (mds_nosmt || cpu_mitigations_auto_nosmt()))

			cpu_smt_disable(false);

	}