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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: 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 59a14fb583
commit 12a0dad799
2 changed files with 5 additions and 2 deletions
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2
Documentation/admin-guide/kernel-parameters.txt
View File

@ -2519,6 +2519,7 @@
spectre_v2_user=off [X86]
spec_store_bypass_disable=off [X86,PPC]
l1tf=off [X86]
mds=off [X86]
auto (default)
Mitigate all CPU vulnerabilities, but leave SMT
@ -2533,6 +2534,7 @@
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

@ -231,7 +231,7 @@ 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;
}
@ -242,7 +242,8 @@ 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);
}