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Diffstat (limited to 'Documentation/kernel-parameters.txt')
| -rw-r--r-- | Documentation/kernel-parameters.txt | 68 |
1 files changed, 62 insertions, 6 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index d76cb9c8fbb0..a36a695318c6 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -1989,12 +1989,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted. for all guests. Default is 1 (enabled) if in 64-bit or 32-bit PAE mode. - kvm-intel.nosmt=[KVM,Intel] If the L1TF CPU bug is present (CVE-2018-3620) - and the system has SMT (aka Hyper-Threading) enabled then - don't allow guests to be created. - - Default is 0 (allow guests to be created). - kvm-intel.ept= [KVM,Intel] Disable extended page tables (virtualized MMU) support on capable Intel chips. Default is 1 (enabled) @@ -2032,6 +2026,68 @@ bytes respectively. Such letter suffixes can also be entirely omitted. feature (tagged TLBs) on capable Intel chips. Default is 1 (enabled) + l1tf= [X86] Control mitigation of the L1TF vulnerability on + affected CPUs + + The kernel PTE inversion protection is unconditionally + enabled and cannot be disabled. + + full + Provides all available mitigations for the + L1TF vulnerability. Disables SMT and + enables all mitigations in the + hypervisors, i.e. unconditional L1D flush. + + SMT control and L1D flush control via the + sysfs interface is still possible after + boot. Hypervisors will issue a warning + when the first VM is started in a + potentially insecure configuration, + i.e. SMT enabled or L1D flush disabled. + + full,force + Same as 'full', but disables SMT and L1D + flush runtime control. Implies the + 'nosmt=force' command line option. + (i.e. sysfs control of SMT is disabled.) + + flush + Leaves SMT enabled and enables the default + hypervisor mitigation, i.e. conditional + L1D flush. + + SMT control and L1D flush control via the + sysfs interface is still possible after + boot. Hypervisors will issue a warning + when the first VM is started in a + potentially insecure configuration, + i.e. SMT enabled or L1D flush disabled. + + flush,nosmt + + Disables SMT and enables the default + hypervisor mitigation. + + SMT control and L1D flush control via the + sysfs interface is still possible after + boot. Hypervisors will issue a warning + when the first VM is started in a + potentially insecure configuration, + i.e. SMT enabled or L1D flush disabled. + + flush,nowarn + Same as 'flush', but hypervisors will not + warn when a VM is started in a potentially + insecure configuration. + + off + Disables hypervisor mitigations and doesn't + emit any warnings. + + Default is 'flush'. + + For details see: Documentation/admin-guide/l1tf.rst + l2cr= [PPC] l3cr= [PPC] |