linux-kernel - Re: [PATCH 12/13] KVM: x86: Replace late check_nested

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Date:   Wed, 29 Apr 2020 09:45:48 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Jim Mattson <jmattson@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Joerg Roedel <joro@...tes.org>, kvm list <kvm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Oliver Upton <oupton@...gle.com>,
        Peter Shier <pshier@...gle.com>
Subject: Re: [PATCH 12/13] KVM: x86: Replace late check_nested_events() hack
 with more precise fix

On Wed, Apr 29, 2020 at 10:36:17AM +0200, Paolo Bonzini wrote:
> On 29/04/20 00:20, Sean Christopherson wrote:
> >> So, that's what this mess was all about! Well, this certainly looks better.
> > Right?  I can't count the number of times I've looked at this code and
> > wondered what the hell it was doing.
> > 
> > Side topic, I just realized you're reviewing my original series.  Paolo
> > commandeered it to extend it to SVM. https://patchwork.kernel.org/cover/11508679/
> 
> If you can just send a patch to squash into 9/13 I can take care of it.

Ugh, correctly prioritizing SMI is a mess.  It has migration implications,
a proper fix requires non-trivial changes to inject_pending_event(), there
are pre-existing (minor) bugs related to MTF handling, and technically INIT
should have lower priority than non-trap exceptions (because the exception
happens before the event window is opened).

Can you just drop 9/13, "Prioritize SMI over nested IRQ/NMI" from kvm/queue?
It's probably best to deal with this in a new series rather than trying to
squeeze it in.