Merge remote-tracking branch 'asoc/topic/intel' into asoc-next

[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 faccc582c0f9ded37b951e6d9809ac455b3d3c55..46b26bfee27ba81267703a1ceac7c0e082f1e5ec 100644 (file)
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2623,6 +2623,11 @@
        nosmt           [KNL,S390] Disable symmetric multithreading (SMT).
                        Equivalent to smt=1.
 
+       nospectre_v2    [X86] Disable all mitigations for the Spectre variant 2
+                       (indirect branch prediction) vulnerability. System may
+                       allow data leaks with this option, which is equivalent
+                       to spectre_v2=off.
+
        noxsave         [BUGS=X86] Disables x86 extended register state save
                        and restore using xsave. The kernel will fallback to
                        enabling legacy floating-point and sse state.
@@ -2709,8 +2714,6 @@
                        steal time is computed, but won't influence scheduler
                        behaviour
 
-       nopti           [X86-64] Disable kernel page table isolation
-
        nolapic         [X86-32,APIC] Do not enable or use the local APIC.
 
        nolapic_timer   [X86-32,APIC] Do not use the local APIC timer.
@@ -3291,11 +3294,20 @@
        pt.             [PARIDE]
                        See Documentation/blockdev/paride.txt.
 
-       pti=            [X86_64]
-                       Control user/kernel address space isolation:
-                       on - enable
-                       off - disable
-                       auto - default setting
+       pti=            [X86_64] Control Page Table Isolation of user and
+                       kernel address spaces.  Disabling this feature
+                       removes hardening, but improves performance of
+                       system calls and interrupts.
+
+                       on   - unconditionally enable
+                       off  - unconditionally disable
+                       auto - kernel detects whether your CPU model is
+                              vulnerable to issues that PTI mitigates
+
+                       Not specifying this option is equivalent to pti=auto.
+
+       nopti           [X86_64]
+                       Equivalent to pti=off
 
        pty.legacy_count=
                        [KNL] Number of legacy pty's. Overwrites compiled-in
@@ -3946,6 +3958,29 @@
        sonypi.*=       [HW] Sony Programmable I/O Control Device driver
                        See Documentation/laptops/sonypi.txt
 
+       spectre_v2=     [X86] Control mitigation of Spectre variant 2
+                       (indirect branch speculation) vulnerability.
+
+                       on   - unconditionally enable
+                       off  - unconditionally disable
+                       auto - kernel detects whether your CPU model is
+                              vulnerable
+
+                       Selecting 'on' will, and 'auto' may, choose a
+                       mitigation method at run time according to the
+                       CPU, the available microcode, the setting of the
+                       CONFIG_RETPOLINE configuration option, and the
+                       compiler with which the kernel was built.
+
+                       Specific mitigations can also be selected manually:
+
+                       retpoline         - replace indirect branches
+                       retpoline,generic - google's original retpoline
+                       retpoline,amd     - AMD-specific minimal thunk
+
+                       Not specifying this option is equivalent to
+                       spectre_v2=auto.
+
        spia_io_base=   [HW,MTD]
        spia_fio_base=
        spia_pedr=