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Merge branches 'iommu/fixes', 'arm/renesas', 'arm/mediatek', 'arm/tegra', 'arm/omap...
[linux.git] / Documentation / admin-guide / kernel-parameters.txt
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                        causing system reset or hang due to sending
                        INIT from AP to BSP.
 
-       disable_counter_freezing [HW]
+       perf_v4_pmi=    [X86,INTEL]
+                       Format: <bool>
                        Disable Intel PMU counter freezing feature.
                        The feature only exists starting from
                        Arch Perfmon v4 (Skylake and newer).
                        By default, super page will be supported if Intel IOMMU
                        has the capability. With this option, super page will
                        not be supported.
-               ecs_off [Default Off]
-                       By default, extended context tables will be supported if
-                       the hardware advertises that it has support both for the
-                       extended tables themselves, and also PASID support. With
-                       this option set, extended tables will not be used even
-                       on hardware which claims to support them.
+               sm_off [Default Off]
+                       By default, scalable mode will be supported if the
+                       hardware advertises that it has support for the scalable
+                       mode translation. With this option set, scalable mode
+                       will not be used even on hardware which claims to support
+                       it.
                tboot_noforce [Default Off]
                        Do not force the Intel IOMMU enabled under tboot.
                        By default, tboot will force Intel IOMMU on, which
                        before loading.
                        See Documentation/blockdev/ramdisk.txt.
 
+       psi=            [KNL] Enable or disable pressure stall information
+                       tracking.
+                       Format: <bool>
+
        psmouse.proto=  [HW,MOUSE] Highest PS2 mouse protocol extension to
                        probe for; one of (bare|imps|exps|lifebook|any).
        psmouse.rate=   [HW,MOUSE] Set desired mouse report rate, in reports
 
        spectre_v2=     [X86] Control mitigation of Spectre variant 2
                        (indirect branch speculation) vulnerability.
+                       The default operation protects the kernel from
+                       user space attacks.
 
-                       on   - unconditionally enable
-                       off  - unconditionally disable
+                       on   - unconditionally enable, implies
+                              spectre_v2_user=on
+                       off  - unconditionally disable, implies
+                              spectre_v2_user=off
                        auto - kernel detects whether your CPU model is
                               vulnerable
 
                        CONFIG_RETPOLINE configuration option, and the
                        compiler with which the kernel was built.
 
+                       Selecting 'on' will also enable the mitigation
+                       against user space to user space task attacks.
+
+                       Selecting 'off' will disable both the kernel and
+                       the user space protections.
+
                        Specific mitigations can also be selected manually:
 
                        retpoline         - replace indirect branches
                        Not specifying this option is equivalent to
                        spectre_v2=auto.
 
+       spectre_v2_user=
+                       [X86] Control mitigation of Spectre variant 2
+                       (indirect branch speculation) vulnerability between
+                       user space tasks
+
+                       on      - Unconditionally enable mitigations. Is
+                                 enforced by spectre_v2=on
+
+                       off     - Unconditionally disable mitigations. Is
+                                 enforced by spectre_v2=off
+
+                       prctl   - Indirect branch speculation is enabled,
+                                 but mitigation can be enabled via prctl
+                                 per thread.  The mitigation control state
+                                 is inherited on fork.
+
+                       prctl,ibpb
+                               - Like "prctl" above, but only STIBP is
+                                 controlled per thread. IBPB is issued
+                                 always when switching between different user
+                                 space processes.
+
+                       seccomp
+                               - Same as "prctl" above, but all seccomp
+                                 threads will enable the mitigation unless
+                                 they explicitly opt out.
+
+                       seccomp,ibpb
+                               - Like "seccomp" above, but only STIBP is
+                                 controlled per thread. IBPB is issued
+                                 always when switching between different
+                                 user space processes.
+
+                       auto    - Kernel selects the mitigation depending on
+                                 the available CPU features and vulnerability.
+
+                       Default mitigation:
+                       If CONFIG_SECCOMP=y then "seccomp", otherwise "prctl"
+
+                       Not specifying this option is equivalent to
+                       spectre_v2_user=auto.
+
        spec_store_bypass_disable=
                        [HW] Control Speculative Store Bypass (SSB) Disable mitigation
                        (Speculative Store Bypass vulnerability)
                                        prevent spurious wakeup);
                                n = USB_QUIRK_DELAY_CTRL_MSG (Device needs a
                                        pause after every control message);
+                               o = USB_QUIRK_HUB_SLOW_RESET (Hub needs extra
+                                       delay after resetting its port);
                        Example: quirks=0781:5580:bk,0a5c:5834:gij
 
        usbhid.mousepoll=