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x86/speculation/mds: Add 'mitigations=' support for MDS

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commit 5c14068f87 upstream.

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

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Josh Poimboeuf
2019-04-17 16:39:02 -05:00
committed by Greg Kroah-Hartman
parent 1709284f08
commit 025b9cf2a0
2 changed files with 5 additions and 2 deletions
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2
Documentation/kernel-parameters.txt
View File

@@ -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

5
arch/x86/kernel/cpu/bugs.c
View File

@@ -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);
}