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Date:   Mon, 20 Apr 2020 14:50:14 -0700
From:   Davidlohr Bueso <dave@stgolabs.net>
To:     Paolo Bonzini <pbonzini@redhat.com>
Cc:     Marc Zyngier <maz@kernel.org>, tglx@linutronix.de,
        kvm@vger.kernel.org, Davidlohr Bueso <dbueso@suse.de>,
        peterz@infradead.org, torvalds@linux-foundation.org,
        bigeasy@linutronix.de, linux-kernel@vger.kernel.org,
        rostedt@goodmis.org, linux-mips@vger.kernel.org,
        Paul Mackerras <paulus@ozlabs.org>, joel@joelfernandes.org,
        will@kernel.org, kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH v2] kvm: Replace vcpu->swait with rcuwait
Message-ID: <20200420215014.sarodevmhphnkkn7@linux-p48b>
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On Mon, 20 Apr 2020, Paolo Bonzini wrote:

>On 20/04/20 22:56, Davidlohr Bueso wrote:
>> On Mon, 20 Apr 2020, Marc Zyngier wrote:
>>
>>> This looks like a change in the semantics of the tracepoint. Before this
>>> change, 'waited' would have been true if the vcpu waited at all. Here,
>>> you'd
>>> have false if it has been interrupted by a signal, even if the vcpu
>>> has waited
>>> for a period of time.
>>
>> Hmm but sleeps are now uninterruptible as we're using TASK_IDLE.
>
>Hold on, does that mean that you can't anymore send a signal in order to
>kick a thread out of KVM_RUN?  Or am I just misunderstanding?

Considering that the return value of the interruptible wait is not
checked, I would not think this breaks KVM_RUN.

Thanks,
Davidlohr