Re: [Xen-devel] [PATCH v2 1/2] x86/msr: Carry on after a non-"safe" MSR access fails without !panic_on_oops

[Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>]

On Mon, Sep 21, 2015 at 9:49 AM, Arjan van de Ven <arjan@xxxxxxxxxxxxxxx> wrote:
>>
>> How many msr reads are <i>so</i> critical that the function call
>> overhead would matter?
>
> if anything qualifies it'd be switch_to() and friends.

Is there anything else than the FS/GS_BASE thing (possibly hidden
behind inlines etc that I didn't get from a quick grep)? And why is
that sometimes using the "safe" version (in do_arch_prctl()), and
sometimes not (switch_to())?

I'm not convinced that mess is a good argument for the status quo ;)

> note that I'm not entirely happy about the notion of "safe" MSRs.
> They're safe as in "won't fault".

I wouldn't object to renaming them.

                Linus

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