| From 5bf948d37f165a70fb0b682598b7f16df4ec885e Mon Sep 17 00:00:00 2001 |
| From: Josh Poimboeuf <jpoimboe@redhat.com> |
| Date: Wed, 17 Apr 2019 16:39:02 -0500 |
| Subject: [PATCH 27/30] x86/speculation/mds: Add 'mitigations=' support for MDS |
| |
| commit 5c14068f87d04adc73ba3f41c2a303d3c3d1fa12 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> |
| --- |
| Documentation/admin-guide/kernel-parameters.txt | 2 ++ |
| arch/x86/kernel/cpu/bugs.c | 5 +++-- |
| 2 files changed, 5 insertions(+), 2 deletions(-) |
| |
| diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt |
| index 4f3efaaa46bd..a29301d6e6c6 100644 |
| --- a/Documentation/admin-guide/kernel-parameters.txt |
| +++ b/Documentation/admin-guide/kernel-parameters.txt |
| @@ -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 |
| diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c |
| index 904d55cf80a2..9b096f26d1c8 100644 |
| --- a/arch/x86/kernel/cpu/bugs.c |
| +++ b/arch/x86/kernel/cpu/bugs.c |
| @@ -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); |
| } |
| |
| -- |
| 2.21.0 |
| |
