linux-kernel - Re: [PATCH v3 00/26] KVM: x86: Halt and APICv overhaul

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Date:   Thu, 09 Dec 2021 08:31:56 +0200
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        kvm@...r.kernel.org, iommu@...ts.linux-foundation.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 00/26] KVM: x86: Halt and APICv overhaul

On Thu, 2021-12-09 at 01:37 +0000, Sean Christopherson wrote:
> On Thu, Dec 09, 2021, Maxim Levitsky wrote:
> > On Thu, 2021-12-09 at 01:00 +0200, Maxim Levitsky wrote:
> > > Probably just luck (can't reproduce this anymore) but
> > > while running some kvm unit tests with this patch series (and few my patches
> > > for AVIC co-existance which shouldn't affect this) I got this
> > > 
> > > (warning about is_running already set)
> 
> ...
>  
> > Also got this while trying a VM with passed through device:
> 
> A tangentially related question: have you seen any mysterious crashes on your AMD
> system?  I've been bisecting (well, attempting to bisect) bizarre crashes that
> AFAICT showed up between v5.15 and v5.16-rc2.  Things like runqueues being NULL
> deep in the scheduler when a CPU is coming out of idle.  I _think_ the issues have
> been fixed as of v5.16-rc4, but I don't have a good reproducer so bisecting in
> either direction has been a complete mess.  I've reproduced on multiple AMD hosts,
> but never on an Intel system.  I have a sinking feeling that the issue is
> relatively unique to our systems :-/

I did had my 3970X lockup hard once on 5.16-rc2. It locked up completely without even
sending anything over a a pcie serial port card I. 

I don't remember what I was doing during the crash but probably had some VMs running.

Since then it didn't happen again, and I am running 5.16-rc3 for some time
with Paolo's kvm/queue merged and my own patches.

> 
> And a request: any testing and bug fixes you can throw at the AVIC changes would be
> greatly appreciated.  I've been partially blocked on testing the AVIC stuff for the
> better part of the week.  If the crashes I'm seeing have been resolved, then I should
> be able to help hunt down the issues, but if not...
> 

This is what I started doing last evening, and I'll go through all of the usual testing
I do soon.

Best regards,
	Maxim Levitsky