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| author | Ashok Raj <ashok.raj@intel.com> | 2022-08-14 01:38:21 +0300 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2022-08-18 16:57:53 +0300 |
| commit | 3ecf671f1d354f40228e407ab350abd41034410b (patch) | |
| tree | 3f2c80458e04291f28911c5e503f342cb72aeee2 /Documentation/admin-guide/tainted-kernels.rst | |
| parent | 568035b01cfb107af8d2e4bd2fb9aea22cf5b868 (diff) | |
| download | linux-3ecf671f1d354f40228e407ab350abd41034410b.tar.xz | |
x86/microcode: Document the whole late loading problem
Commit
d23d33ea0fcd ("x86/microcode: Taint and warn on late loading")
started tainting the kernel after microcode late loading.
There is some history behind why x86 microcode started doing the late
loading stop_machine() rendezvous. Document the whole situation.
No functional changes.
[ bp: Fix typos, heavily massage. ]
Signed-off-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220813223825.3164861-2-ashok.raj@intel.com
Diffstat (limited to 'Documentation/admin-guide/tainted-kernels.rst')
| -rw-r--r-- | Documentation/admin-guide/tainted-kernels.rst | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/admin-guide/tainted-kernels.rst b/Documentation/admin-guide/tainted-kernels.rst index 7d80e8c307d1..92a8a07f5c43 100644 --- a/Documentation/admin-guide/tainted-kernels.rst +++ b/Documentation/admin-guide/tainted-kernels.rst @@ -134,6 +134,12 @@ More detailed explanation for tainting scsi/snic on something else than x86_64, scsi/ips on non x86/x86_64/itanium, have broken firmware settings for the irqchip/irq-gic on arm64 ...). + - x86/x86_64: Microcode late loading is dangerous and will result in + tainting the kernel. It requires that all CPUs rendezvous to make sure + the update happens when the system is as quiescent as possible. However, + a higher priority MCE/SMI/NMI can move control flow away from that + rendezvous and interrupt the update, which can be detrimental to the + machine. 3) ``R`` if a module was force unloaded by ``rmmod -f``, ``' '`` if all modules were unloaded normally. |