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From: David Woodhouse <dwmw2@infradead.org>
To: Sean Christopherson <seanjc@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm <kvm@vger.kernel.org>, "Sironi, Filippo" <sironi@amazon.de>,
	"Raslan, KarimAllah" <karahmed@amazon.de>,
	Matt Gingell <gingell@google.com>,
	Steve Rutherford <srutherford@google.com>,
	liran@amazon.com
Subject: Re: [RFC PATCH] Fix split-irqchip vs interrupt injection window request.
Date: Thu, 26 Nov 2020 17:29:16 +0000	[thread overview]
Message-ID: <95c0c9a01ea9692b3b18ac677d7e7c6e7636bfe4.camel@infradead.org> (raw)
In-Reply-To: <99a9c1dfbb21744e5081d924291d3b09ab055813.camel@infradead.org>

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On Thu, 2020-11-26 at 11:10 +0000, David Woodhouse wrote:
> 
> > whether or not there's an IRQ in the
> > LAPIC should be irrelevant when deciding to exit to userspace.  Note, the
> > reinjection check covers vcpu->arch.interrupt.injected for the case where LAPIC
> > is in userspace.
> > 
> >         return kvm_arch_interrupt_allowed(vcpu) &&
> >                (!lapic_in_kernel(vcpu) || !kvm_cpu_has_extint(vcpu)) &&
> >                !kvm_event_needs_reinjection(vcpu) &&
> >                kvm_cpu_accept_dm_intr(vcpu);
> > }
> 
> Makes sense. I'm putting this version through some testing and will
> post it later...

Hm, that survived enough test iterations to persuade me to post it, but
then seems to have fallen over later. I'm reverting to the
kvm_cpu_has_injectable_intr() version to leave that one running too and
be sure it's gone in that.

Without either patch it's 100% repeatable, and will happen as soon as
the 'noapic' guest enabled lapic timer interrupts. I'm not sure I see
why your version would simply make it less frequent...


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  parent reply	other threads:[~2020-11-26 17:29 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-12 13:03 [RFC] Further hack request_interrupt_window handling to work around kvm_cpu_has_interrupt() nesting breakage David Woodhouse
2020-11-25 15:10 ` [RFC PATCH] Fix split-irqchip vs interrupt injection window request David Woodhouse
2020-11-25 21:19   ` Sean Christopherson
2020-11-26 11:10     ` David Woodhouse
2020-11-26 12:05       ` [PATCH] kvm/x86: Fix simultaneous ExtINT and lapic interrupt handling with APICv David Woodhouse
2020-11-26 18:00         ` Paolo Bonzini
2020-11-26 19:07           ` David Woodhouse
2020-11-26 17:29       ` David Woodhouse [this message]
2020-11-26 17:59         ` [RFC PATCH] Fix split-irqchip vs interrupt injection window request Paolo Bonzini
2020-11-26 21:48           ` David Woodhouse
2020-11-27  4:37             ` Paolo Bonzini

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