Messages in this thread | | | Date | Tue, 6 Sep 2022 23:00:36 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] x86/cpu: Avoid writing MSR_IA32_TSX_CTRL when writing it is not supported |
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On Tue, Sep 06, 2022 at 10:56:47PM +0200, Hans de Goede wrote: > Hi, > > On 9/6/22 22:43, Peter Zijlstra wrote: > > On Tue, Sep 06, 2022 at 10:17:43PM +0200, Hans de Goede wrote: > >> On an Intel Atom N2600 (and presumable other Cedar Trail models) > >> MSR_IA32_TSX_CTRL can be read, causing saved_msr.valid to be set for it > >> by msr_build_context(). > >> > >> This causes restore_processor_state() to try and restore it, but writing > >> this MSR is not allowed on the Intel Atom N2600 leading to: > > > > FWIW, virt tends to do this same thing a lot. They'll allow reading > > random MSRs and only fail on write. > > Right. So I guess I should send a v2 with an updated commit > message mentioning this ?
Nah, just saying this is a somewhat common pattern with MSRs.
The best ones are the one where writing the value read is invalid :/ or those who also silently eat a 0 write just for giggles. Luckily that doesn't happen often.
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