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authorDavid S. Miller <davem@davemloft.net>2019-11-16 18:47:31 -0800
committerDavid S. Miller <davem@davemloft.net>2019-11-16 21:51:42 -0800
commit19b7e21c55c81713c4011278143006af9f232504 (patch)
treee1312ccebbc23ee6b6928d1d02d644a15d695b67 /Documentation/admin-guide/kernel-parameters.txt
parent1e8795b1b20d2721620165434cdcf427ecd2ba85 (diff)
parent1d4c79ed324ad780cfc3ad38364ba1fd585dd2a8 (diff)
Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Lots of overlapping changes and parallel additions, stuff like that. Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt92
1 files changed, 92 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index a84a83f8881e..8dee8f68fe15 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2055,6 +2055,25 @@
KVM MMU at runtime.
Default is 0 (off)
+ kvm.nx_huge_pages=
+ [KVM] Controls the software workaround for the
+ X86_BUG_ITLB_MULTIHIT bug.
+ force : Always deploy workaround.
+ off : Never deploy workaround.
+ auto : Deploy workaround based on the presence of
+ X86_BUG_ITLB_MULTIHIT.
+
+ Default is 'auto'.
+
+ If the software workaround is enabled for the host,
+ guests do need not to enable it for nested guests.
+
+ kvm.nx_huge_pages_recovery_ratio=
+ [KVM] Controls how many 4KiB pages are periodically zapped
+ back to huge pages. 0 disables the recovery, otherwise if
+ the value is N KVM will zap 1/Nth of the 4KiB pages every
+ minute. The default is 60.
+
kvm-amd.nested= [KVM,AMD] Allow nested virtualization in KVM/SVM.
Default is 1 (enabled)
@@ -2636,6 +2655,13 @@
ssbd=force-off [ARM64]
l1tf=off [X86]
mds=off [X86]
+ tsx_async_abort=off [X86]
+ kvm.nx_huge_pages=off [X86]
+
+ Exceptions:
+ This does not have any effect on
+ kvm.nx_huge_pages when
+ kvm.nx_huge_pages=force.
auto (default)
Mitigate all CPU vulnerabilities, but leave SMT
@@ -2651,6 +2677,7 @@
be fully mitigated, even if it means losing SMT.
Equivalent to: l1tf=flush,nosmt [X86]
mds=full,nosmt [X86]
+ tsx_async_abort=full,nosmt [X86]
mminit_loglevel=
[KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this
@@ -4848,6 +4875,71 @@
interruptions from clocksource watchdog are not
acceptable).
+ tsx= [X86] Control Transactional Synchronization
+ Extensions (TSX) feature in Intel processors that
+ support TSX control.
+
+ This parameter controls the TSX feature. The options are:
+
+ on - Enable TSX on the system. Although there are
+ mitigations for all known security vulnerabilities,
+ TSX has been known to be an accelerator for
+ several previous speculation-related CVEs, and
+ so there may be unknown security risks associated
+ with leaving it enabled.
+
+ off - Disable TSX on the system. (Note that this
+ option takes effect only on newer CPUs which are
+ not vulnerable to MDS, i.e., have
+ MSR_IA32_ARCH_CAPABILITIES.MDS_NO=1 and which get
+ the new IA32_TSX_CTRL MSR through a microcode
+ update. This new MSR allows for the reliable
+ deactivation of the TSX functionality.)
+
+ auto - Disable TSX if X86_BUG_TAA is present,
+ otherwise enable TSX on the system.
+
+ Not specifying this option is equivalent to tsx=off.
+
+ See Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
+ for more details.
+
+ tsx_async_abort= [X86,INTEL] Control mitigation for the TSX Async
+ Abort (TAA) vulnerability.
+
+ Similar to Micro-architectural Data Sampling (MDS)
+ certain CPUs that support Transactional
+ Synchronization Extensions (TSX) are vulnerable to an
+ exploit against CPU internal buffers which can forward
+ information to a disclosure gadget under certain
+ conditions.
+
+ In vulnerable processors, the speculatively forwarded
+ data can be used in a cache side channel attack, to
+ access data to which the attacker does not have direct
+ access.
+
+ This parameter controls the TAA mitigation. The
+ options are:
+
+ full - Enable TAA mitigation on vulnerable CPUs
+ if TSX is enabled.
+
+ full,nosmt - Enable TAA mitigation and disable SMT on
+ vulnerable CPUs. If TSX is disabled, SMT
+ is not disabled because CPU is not
+ vulnerable to cross-thread TAA attacks.
+ off - Unconditionally disable TAA mitigation
+
+ Not specifying this option is equivalent to
+ tsx_async_abort=full. On CPUs which are MDS affected
+ and deploy MDS mitigation, TAA mitigation is not
+ required and doesn't provide any additional
+ mitigation.
+
+ For details see:
+ Documentation/admin-guide/hw-vuln/tsx_async_abort.rst
+
turbografx.map[2|3]= [HW,JOY]
TurboGraFX parallel port interface
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