Merge tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64...

[linux-2.6-microblaze.git] / Documentation / admin-guide / kernel-parameters.txt

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 3c78af0..5e9147f 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3182,6 +3182,7 @@
                                               no_entry_flush [PPC]
                                               no_uaccess_flush [PPC]
                                               mmio_stale_data=off [X86]
+                                              retbleed=off [X86]
 
                                Exceptions:
                                               This does not have any effect on
@@ -3204,6 +3205,7 @@
                                               mds=full,nosmt [X86]
                                               tsx_async_abort=full,nosmt [X86]
                                               mmio_stale_data=full,nosmt [X86]
+                                              retbleed=auto,nosmt [X86]
 
        mminit_loglevel=
                        [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
@@ -5203,6 +5205,30 @@
 
        retain_initrd   [RAM] Keep initrd memory after extraction
 
+       retbleed=       [X86] Control mitigation of RETBleed (Arbitrary
+                       Speculative Code Execution with Return Instructions)
+                       vulnerability.
+
+                       off          - no mitigation
+                       auto         - automatically select a migitation
+                       auto,nosmt   - automatically select a mitigation,
+                                      disabling SMT if necessary for
+                                      the full mitigation (only on Zen1
+                                      and older without STIBP).
+                       ibpb         - mitigate short speculation windows on
+                                      basic block boundaries too. Safe, highest
+                                      perf impact.
+                       unret        - force enable untrained return thunks,
+                                      only effective on AMD f15h-f17h
+                                      based systems.
+                       unret,nosmt  - like unret, will disable SMT when STIBP
+                                      is not available.
+
+                       Selecting 'auto' will choose a mitigation method at run
+                       time according to the CPU.
+
+                       Not specifying this option is equivalent to retbleed=auto.
+
        rfkill.default_state=
                0       "airplane mode".  All wifi, bluetooth, wimax, gps, fm,
                        etc. communication is blocked by default.
@@ -5574,6 +5600,7 @@
                        eibrs             - enhanced IBRS
                        eibrs,retpoline   - enhanced IBRS + Retpolines
                        eibrs,lfence      - enhanced IBRS + LFENCE
+                       ibrs              - use IBRS to protect kernel
 
                        Not specifying this option is equivalent to
                        spectre_v2=auto.
@@ -5777,6 +5804,24 @@
                        expediting.  Set to zero to disable automatic
                        expediting.
 
+       srcutree.srcu_max_nodelay [KNL]
+                       Specifies the number of no-delay instances
+                       per jiffy for which the SRCU grace period
+                       worker thread will be rescheduled with zero
+                       delay. Beyond this limit, worker thread will
+                       be rescheduled with a sleep delay of one jiffy.
+
+       srcutree.srcu_max_nodelay_phase [KNL]
+                       Specifies the per-grace-period phase, number of
+                       non-sleeping polls of readers. Beyond this limit,
+                       grace period worker thread will be rescheduled
+                       with a sleep delay of one jiffy, between each
+                       rescan of the readers, for a grace period phase.
+
+       srcutree.srcu_retry_check_delay [KNL]
+                       Specifies number of microseconds of non-sleeping
+                       delay between each non-sleeping poll of readers.
+
        srcutree.small_contention_lim [KNL]
                        Specifies the number of update-side contention
                        events per jiffy will be tolerated before