]> git.baikalelectronics.ru Git - kernel.git/commit
x86/perf: Default set FREEZE_ON_SMI for all
authorPeter Zijlstra <peterz@infradead.org>
Thu, 27 Jan 2022 11:32:51 +0000 (12:32 +0100)
committerPeter Zijlstra <peterz@infradead.org>
Wed, 2 Feb 2022 12:11:39 +0000 (13:11 +0100)
commit9346561b9f0330083f0e3326981967e579abbaf9
treead6495f3deb0de9b1e807a9fd08275fde256d696
parent59e766ff6f8c2d0f016dfe97ff01198e0de898dc
x86/perf: Default set FREEZE_ON_SMI for all

Kyle reported that rr[0] has started to malfunction on Comet Lake and
later CPUs due to EFI starting to make use of CPL3 [1] and the PMU
event filtering not distinguishing between regular CPL3 and SMM CPL3.

Since this is a privilege violation, default disable SMM visibility
where possible.

Administrators wanting to observe SMM cycles can easily change this
using the sysfs attribute while regular users don't have access to
this file.

[0] https://rr-project.org/

[1] See the Intel white paper "Trustworthy SMM on the Intel vPro Platform"
at https://bugzilla.kernel.org/attachment.cgi?id=300300, particularly the
end of page 5.

Reported-by: Kyle Huey <me@kylehuey.com>
Suggested-by: Andrew Cooper <Andrew.Cooper3@citrix.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@kernel.org
Link: https://lkml.kernel.org/r/YfKChjX61OW4CkYm@hirez.programming.kicks-ass.net
arch/x86/events/intel/core.c