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Date:   Tue, 8 Sep 2020 20:09:39 +0200
From:   Ingo Molnar <mingo@kernel.org>
To:     Paolo Bonzini <pbonzini@redhat.com>
Cc:     torvalds@linux-foundation.org, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org, Will Deacon <will@kernel.org>
Subject: Re: [GIT PULL] First batch of KVM changes for Linux 5.9
Message-ID: <20200908180939.GA2378263@gmail.com>
References: <20200805182606.12621-1-pbonzini@redhat.com>
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hi,

* Paolo Bonzini <pbonzini@redhat.com> wrote:

> Paolo Bonzini (11):
>       Merge branch 'kvm-async-pf-int' into HEAD

kvmtool broke in this merge window, hanging during bootup right after CPU bringup:

 [    1.289404]  #63
 [    0.012468] kvm-clock: cpu 63, msr 6ff69fc1, secondary cpu clock
 [    0.012468] [Firmware Bug]: CPU63: APIC id mismatch. Firmware: 3f APIC: 14
 [    1.302320] kvm-guest: KVM setup async PF for cpu 63
 [    1.302320] kvm-guest: stealtime: cpu 63, msr 1379d7600

Eventually trigger an RCU stall warning:

 [   22.302392] rcu: INFO: rcu_sched detected stalls on CPUs/tasks:
 [   22.302392] rcu: 	1-...!: (68 GPs behind) idle=00c/0/0x0 softirq=0/0 fqs=0  (false positive?)

I've bisected this down to the above merge commit. The individual commit:

   b1d405751cd5: ("KVM: x86: Switch KVM guest to using interrupts for page ready APF delivery")

appears to be working fine standalone.

I'm using x86-64 defconfig+kvmconfig on SVM. Can send more info on request.

The kvmtool.git commit I've tested is 90b2d3adadf2.

Thanks,

	Ingo