diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2022-06-14 07:43:15 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-06-14 07:43:15 -0700 |
| commit | 8e8afafb0b5571b7cb10b529dc60cadb7241bed4 (patch) | |
| tree | ea734a6acea7f51e82921cc7120988d6d76f0b49 /Documentation/admin-guide/kernel-parameters.txt | |
| parent | b13baccc3850ca8b8cccbf8ed9912dbaa0fdf7f3 (diff) | |
| parent | 1dc6ff02c8bf77d71b9b5d11cbc9df77cfb28626 (diff) | |
Merge tag 'x86-bugs-2022-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 MMIO stale data fixes from Thomas Gleixner:
"Yet another hw vulnerability with a software mitigation: Processor
MMIO Stale Data.
They are a class of MMIO-related weaknesses which can expose stale
data by propagating it into core fill buffers. Data which can then be
leaked using the usual speculative execution methods.
Mitigations include this set along with microcode updates and are
similar to MDS and TAA vulnerabilities: VERW now clears those buffers
too"
* tag 'x86-bugs-2022-06-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/speculation/mmio: Print SMT warning
KVM: x86/speculation: Disable Fill buffer clear within guests
x86/speculation/mmio: Reuse SRBDS mitigation for SBDS
x86/speculation/srbds: Update SRBDS mitigation selection
x86/speculation/mmio: Add sysfs reporting for Processor MMIO Stale Data
x86/speculation/mmio: Enable CPU Fill buffer clearing on idle
x86/bugs: Group MDS, TAA & Processor MMIO Stale Data mitigations
x86/speculation/mmio: Add mitigation for Processor MMIO Stale Data
x86/speculation: Add a common function for MD_CLEAR mitigation update
x86/speculation/mmio: Enumerate Processor MMIO Stale Data bug
Documentation: Add documentation for Processor MMIO Stale Data
Diffstat (limited to 'Documentation/admin-guide/kernel-parameters.txt')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 8090130b544b..bba2f27d7358 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3176,6 +3176,7 @@ srbds=off [X86,INTEL] no_entry_flush [PPC] no_uaccess_flush [PPC] + mmio_stale_data=off [X86] Exceptions: This does not have any effect on @@ -3197,6 +3198,7 @@ Equivalent to: l1tf=flush,nosmt [X86] mds=full,nosmt [X86] tsx_async_abort=full,nosmt [X86] + mmio_stale_data=full,nosmt [X86] mminit_loglevel= [KNL] When CONFIG_DEBUG_MEMORY_INIT is set, this @@ -3206,6 +3208,40 @@ log everything. Information is printed at KERN_DEBUG so loglevel=8 may also need to be specified. + mmio_stale_data= + [X86,INTEL] Control mitigation for the Processor + MMIO Stale Data vulnerabilities. + + Processor MMIO Stale Data is a class of + vulnerabilities that may expose data after an MMIO + operation. Exposed data could originate or end in + the same CPU buffers as affected by MDS and TAA. + Therefore, similar to MDS and TAA, the mitigation + is to clear the affected CPU buffers. + + This parameter controls the mitigation. The + options are: + + full - Enable mitigation on vulnerable CPUs + + full,nosmt - Enable mitigation and disable SMT on + vulnerable CPUs. + + off - Unconditionally disable mitigation + + On MDS or TAA affected machines, + mmio_stale_data=off can be prevented by an active + MDS or TAA mitigation as these vulnerabilities are + mitigated with the same mechanism so in order to + disable this mitigation, you need to specify + mds=off and tsx_async_abort=off too. + + Not specifying this option is equivalent to + mmio_stale_data=full. + + For details see: + Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst + module.sig_enforce [KNL] When CONFIG_MODULE_SIG is set, this means that modules without (valid) signatures will fail to load. |