Messages in this thread |  | | From | Thomas Gleixner <> | Subject | Re: [PATCH 0/1] x86/split_lock: check split lock feature on initialization | Date | Mon, 06 Apr 2020 23:21:13 +0200 |
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Benjamin Lamowski <benjamin.lamowski@kernkonzept.com> writes: > During regression testing of our hypervisor[1] with the current git tip, > we got writes to the TEST_CTRL MSR on hardware that does not support > split lock detection. While the original split_lock implementation does > not exhibit this behavior, the reworked initialization from > dbaba47085b0c unconditionally calls split_lock_verify_msr() from > split_lock_init(). > > After the elaborate checks in cpu_set_core_cap_bits() this seems like an > oversight. The following simple patch fixes our regression by checking > for X86_FEATURE_SPLIT_LOCK_DETECT before accessing the TEST_CTRL MSR.
No. It's not an oversight, it's a simplification and it's perfectly legit. rdsmrl_safe() on a unimplemented MSR results in a #GP which is caught and fixed up. Nothing to see here.
Thanks,
tglx
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