Merge branch 'core/speculation' of git://git.kernel.org/pub/scm/linux/kernel/git...

[sfrench/cifs-2.6.git] / Documentation / admin-guide / kernel-parameters.txt

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 2b8ee90bb64470d0d6d6ccadccf8b8fbbf86509d..cf82bac648cd909751b4c18350de66393135067f 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2544,6 +2544,38 @@
                        in the "bleeding edge" mini2440 support kernel at
                        http://repo.or.cz/w/linux-2.6/mini2440.git
 
+       mitigations=
+                       [X86,PPC,S390] Control optional mitigations for CPU
+                       vulnerabilities.  This is a set of curated,
+                       arch-independent options, each of which is an
+                       aggregation of existing arch-specific options.
+
+                       off
+                               Disable all optional CPU mitigations.  This
+                               improves system performance, but it may also
+                               expose users to several CPU vulnerabilities.
+                               Equivalent to: nopti [X86,PPC]
+                                              nospectre_v1 [PPC]
+                                              nobp=0 [S390]
+                                              nospectre_v2 [X86,PPC,S390]
+                                              spectre_v2_user=off [X86]
+                                              spec_store_bypass_disable=off [X86,PPC]
+                                              l1tf=off [X86]
+
+                       auto (default)
+                               Mitigate all CPU vulnerabilities, but leave SMT
+                               enabled, even if it's vulnerable.  This is for
+                               users who don't want to be surprised by SMT
+                               getting disabled across kernel upgrades, or who
+                               have other ways of avoiding SMT-based attacks.
+                               Equivalent to: (default behavior)
+
+                       auto,nosmt
+                               Mitigate all CPU vulnerabilities, disabling SMT
+                               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]
+
        mminit_loglevel=
                        [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
                        parameter allows control of the logging verbosity for