Re: [PATCH char-misc 1/1] Drivers: hv: vmbus: Make synic_initialized flag per-cpu

From: Vitaly Kuznetsov
Date: Tue Aug 28 2018 - 16:59:55 EST

"Michael Kelley (EOSG)" <Michael.H.Kelley@xxxxxxxxxxxxx> writes:

> From: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx> Sent: Wednesday, August 1, 2018 2:26 AM
>> > I was trying to decide if there are any arguments in favor of one
>> > approach vs. the other: a per-cpu flag in memory or checking
>> > the synic_control "enable" bit. Seems like a wash to me, in which
>> > case I have a slight preference for the per-cpu flag in memory vs.
>> > creating another function to return sctrl.enable. But I'm completely
>> > open to reasons why checking sctrl.enable is better.
>> Just a few thoughts: reading MSR is definitely slower but we avoid
>> 'shadowing' the state, the reading is always correct. In case there's a
>> chance the SynIC will get disabled from host side we can only find this
>> out by doing MSR read. This is a purely theoretical possibility, I
>> believe, we can go ahead with this patch.
> Vitaly -- just to confirm: you are OK with the patch as is? (I'll
> check, but I may need to rebase on the latest code.)

Yes, feel free to use my R-b tag.