From: peter.maydell@linaro.org (Peter Maydell)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 05/10] KVM: arm/arm64: vgic: Relax vgic_can_sample_irq for edge IRQs
Date: Fri, 3 Jul 2015 10:57:59 +0100 [thread overview]
Message-ID: <CAFEAcA_TrNQvR-fooGXSg=04CNAULEpNr54iwXjqA=qvqYuLZw@mail.gmail.com> (raw)
In-Reply-To: <55965AFF.30509@arm.com>
On 3 July 2015 at 10:50, Marc Zyngier <marc.zyngier@arm.com> wrote:
> On 02/07/15 17:23, Christoffer Dall wrote:
>> If we had a different *shared* device than the timer which is
>> edge-triggered, don't we then also need to capture the physical
>> distributor's pending state along with the state of the device unless we
>> assume that upon restoring the state for the device count on the device
>> to have another rising/falling edge to trigger the interrupt again? (I
>> assume the line would always go high for a level-triggered interrupt in
>> this case).
>
> I'd definitely assume that restoring the state of the device would make
> it generate an interrupt. This has to be a property of the device,
> otherwise it is not really shareable between vcpus.
FWIW, QEMU's modelling approach to this is to say that devices
do *not* generate interrupts on restore. If the device had
previously generated an interrupt then this should be captured
by the state of the interrupt controller (or whatever else
it is connected to) and dealt with when the GIC state is restored.
If you say that restoring the device state is supposed to
generate an interrupt, you introduce an ordering requirement
that the state of the interrupt controller is restored
first and the device second (otherwise the incoming GIC
state will overwrite the interrupt that the device just
generated), which isn't ideal (especially since QEMU
makes no guarantees about restore order between devices).
thanks
-- PMM
WARNING: multiple messages have this Message-ID (diff)
From: Peter Maydell <peter.maydell@linaro.org>
To: Marc Zyngier <marc.zyngier@arm.com>
Cc: "linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
Andre Przywara <Andre.Przywara@arm.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>
Subject: Re: [PATCH 05/10] KVM: arm/arm64: vgic: Relax vgic_can_sample_irq for edge IRQs
Date: Fri, 3 Jul 2015 10:57:59 +0100 [thread overview]
Message-ID: <CAFEAcA_TrNQvR-fooGXSg=04CNAULEpNr54iwXjqA=qvqYuLZw@mail.gmail.com> (raw)
In-Reply-To: <55965AFF.30509@arm.com>
On 3 July 2015 at 10:50, Marc Zyngier <marc.zyngier@arm.com> wrote:
> On 02/07/15 17:23, Christoffer Dall wrote:
>> If we had a different *shared* device than the timer which is
>> edge-triggered, don't we then also need to capture the physical
>> distributor's pending state along with the state of the device unless we
>> assume that upon restoring the state for the device count on the device
>> to have another rising/falling edge to trigger the interrupt again? (I
>> assume the line would always go high for a level-triggered interrupt in
>> this case).
>
> I'd definitely assume that restoring the state of the device would make
> it generate an interrupt. This has to be a property of the device,
> otherwise it is not really shareable between vcpus.
FWIW, QEMU's modelling approach to this is to say that devices
do *not* generate interrupts on restore. If the device had
previously generated an interrupt then this should be captured
by the state of the interrupt controller (or whatever else
it is connected to) and dealt with when the GIC state is restored.
If you say that restoring the device state is supposed to
generate an interrupt, you introduce an ordering requirement
that the state of the interrupt controller is restored
first and the device second (otherwise the incoming GIC
state will overwrite the interrupt that the device just
generated), which isn't ideal (especially since QEMU
makes no guarantees about restore order between devices).
thanks
-- PMM
next prev parent reply other threads:[~2015-07-03 9:57 UTC|newest]
Thread overview: 118+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-08 17:03 [PATCH 00/10] arm/arm64: KVM: Active interrupt state switching for shared devices Marc Zyngier
2015-06-08 17:03 ` Marc Zyngier
2015-06-08 17:03 ` [PATCH 01/10] arm/arm64: KVM: Fix ordering of timer/GIC on guest entry Marc Zyngier
2015-06-08 17:03 ` Marc Zyngier
2015-06-09 11:29 ` Alex Bennée
2015-06-09 11:29 ` Alex Bennée
2015-06-30 20:19 ` Christoffer Dall
2015-06-30 20:19 ` Christoffer Dall
2015-06-08 17:03 ` [PATCH 02/10] arm/arm64: KVM: Move vgic handling to a non-preemptible section Marc Zyngier
2015-06-08 17:03 ` Marc Zyngier
2015-06-09 11:38 ` Alex Bennée
2015-06-09 11:38 ` Alex Bennée
2015-06-30 20:19 ` Christoffer Dall
2015-06-30 20:19 ` Christoffer Dall
2015-06-08 17:03 ` [PATCH 03/10] KVM: arm/arm64: vgic: Convert struct vgic_lr to use bitfields Marc Zyngier
2015-06-08 17:03 ` Marc Zyngier
2015-06-09 13:12 ` Alex Bennée
2015-06-09 13:12 ` Alex Bennée
2015-06-10 17:23 ` Andre Przywara
2015-06-10 17:23 ` Andre Przywara
2015-06-10 18:04 ` Marc Zyngier
2015-06-10 18:04 ` Marc Zyngier
2015-06-08 17:03 ` [PATCH 04/10] KVM: arm/arm64: vgic: Allow HW irq to be encoded in LR Marc Zyngier
2015-06-08 17:03 ` Marc Zyngier
2015-06-09 13:21 ` Alex Bennée
2015-06-09 13:21 ` Alex Bennée
2015-06-09 14:03 ` Marc Zyngier
2015-06-09 14:03 ` Marc Zyngier
2015-06-17 11:53 ` Eric Auger
2015-06-17 11:53 ` Eric Auger
2015-06-17 12:39 ` Marc Zyngier
2015-06-17 12:39 ` Marc Zyngier
2015-06-17 13:21 ` Peter Maydell
2015-06-17 13:21 ` Peter Maydell
2015-06-17 13:34 ` Marc Zyngier
2015-06-17 13:34 ` Marc Zyngier
2015-06-08 17:04 ` [PATCH 05/10] KVM: arm/arm64: vgic: Relax vgic_can_sample_irq for edge IRQs Marc Zyngier
2015-06-08 17:04 ` Marc Zyngier
2015-06-30 20:19 ` Christoffer Dall
2015-06-30 20:19 ` Christoffer Dall
2015-07-01 9:17 ` Marc Zyngier
2015-07-01 9:17 ` Marc Zyngier
2015-07-01 11:58 ` Christoffer Dall
2015-07-01 11:58 ` Christoffer Dall
2015-07-01 18:18 ` Marc Zyngier
2015-07-01 18:18 ` Marc Zyngier
2015-07-02 16:23 ` Christoffer Dall
2015-07-02 16:23 ` Christoffer Dall
2015-07-03 9:50 ` Marc Zyngier
2015-07-03 9:50 ` Marc Zyngier
2015-07-03 9:57 ` Peter Maydell [this message]
2015-07-03 9:57 ` Peter Maydell
2015-06-08 17:04 ` [PATCH 06/10] KVM: arm/arm64: vgic: Allow dynamic mapping of physical/virtual interrupts Marc Zyngier
2015-06-08 17:04 ` Marc Zyngier
2015-06-11 8:43 ` Andre Przywara
2015-06-11 8:43 ` Andre Przywara
2015-06-11 8:56 ` Marc Zyngier
2015-06-11 8:56 ` Marc Zyngier
2015-06-15 15:44 ` Eric Auger
2015-06-15 15:44 ` Eric Auger
2015-06-16 8:28 ` Marc Zyngier
2015-06-16 8:28 ` Marc Zyngier
2015-06-16 9:10 ` Eric Auger
2015-06-16 9:10 ` Eric Auger
2015-06-30 20:19 ` Christoffer Dall
2015-06-30 20:19 ` Christoffer Dall
2015-07-01 10:20 ` Marc Zyngier
2015-07-01 10:20 ` Marc Zyngier
2015-07-01 11:45 ` Christoffer Dall
2015-07-01 11:45 ` Christoffer Dall
2015-06-08 17:04 ` [PATCH 07/10] KVM: arm/arm64: vgic: Allow HW interrupts to be queued to a guest Marc Zyngier
2015-06-08 17:04 ` Marc Zyngier
2015-06-11 8:44 ` Andre Przywara
2015-06-11 8:44 ` Andre Przywara
2015-06-11 9:15 ` Marc Zyngier
2015-06-11 9:15 ` Marc Zyngier
2015-06-11 9:44 ` Andre Przywara
2015-06-11 9:44 ` Andre Przywara
2015-06-11 10:02 ` Marc Zyngier
2015-06-11 10:02 ` Marc Zyngier
2015-06-15 16:11 ` Eric Auger
2015-06-15 16:11 ` Eric Auger
2015-06-17 11:51 ` Eric Auger
2015-06-17 11:51 ` Eric Auger
2015-06-17 12:23 ` Marc Zyngier
2015-06-17 12:23 ` Marc Zyngier
2015-06-08 17:04 ` [PATCH 08/10] KVM: arm/arm64: vgic: Add vgic_{get, set}_phys_irq_active Marc Zyngier
2015-06-08 17:04 ` [PATCH 08/10] KVM: arm/arm64: vgic: Add vgic_{get,set}_phys_irq_active Marc Zyngier
2015-06-17 15:11 ` [PATCH 08/10] KVM: arm/arm64: vgic: Add vgic_{get, set}_phys_irq_active Eric Auger
2015-06-17 15:11 ` [PATCH 08/10] KVM: arm/arm64: vgic: Add vgic_{get,set}_phys_irq_active Eric Auger
2015-06-08 17:04 ` [PATCH 09/10] KVM: arm/arm64: timer: Allow the timer to control the active state Marc Zyngier
2015-06-08 17:04 ` Marc Zyngier
2015-06-08 17:04 ` [PATCH 10/10] KVM: arm/arm64: vgic: Allow non-shared device HW interrupts Marc Zyngier
2015-06-08 17:04 ` Marc Zyngier
2015-06-17 15:11 ` Eric Auger
2015-06-17 15:11 ` Eric Auger
2015-06-17 15:37 ` Marc Zyngier
2015-06-17 15:37 ` Marc Zyngier
2015-06-17 15:50 ` Eric Auger
2015-06-17 15:50 ` Eric Auger
2015-06-18 8:37 ` Marc Zyngier
2015-06-18 8:37 ` Marc Zyngier
2015-06-18 17:51 ` Eric Auger
2015-06-18 17:51 ` Eric Auger
2015-06-30 20:19 ` Christoffer Dall
2015-06-30 20:19 ` Christoffer Dall
2015-07-01 8:26 ` Marc Zyngier
2015-07-01 8:26 ` Marc Zyngier
2015-07-01 8:57 ` Christoffer Dall
2015-07-01 8:57 ` Christoffer Dall
2015-06-10 8:33 ` [PATCH 00/10] arm/arm64: KVM: Active interrupt state switching for shared devices Eric Auger
2015-06-10 8:33 ` Eric Auger
2015-06-10 9:03 ` Marc Zyngier
2015-06-10 9:03 ` Marc Zyngier
2015-06-10 11:13 ` Eric Auger
2015-06-10 11:13 ` Eric Auger
2015-06-18 6:51 ` Eric Auger
2015-06-18 6:51 ` Eric Auger
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