From: andre.przywara@arm.com (Andre Przywara)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 07/10] KVM: arm/arm64: vgic: Allow HW interrupts to be queued to a guest
Date: Thu, 11 Jun 2015 10:44:02 +0100 [thread overview]
Message-ID: <55795862.1050407@arm.com> (raw)
In-Reply-To: <557951C6.2090408@arm.com>
On 06/11/2015 10:15 AM, Marc Zyngier wrote:
> On 11/06/15 09:44, Andre Przywara wrote:
>> On 06/08/2015 06:04 PM, Marc Zyngier wrote:
...
>>> @@ -1344,6 +1364,35 @@ static bool vgic_process_maintenance(struct kvm_vcpu *vcpu)
>>> return level_pending;
>>> }
>>>
>>> +/* Return 1 if HW interrupt went from active to inactive, and 0 otherwise */
>>> +static int vgic_sync_hwirq(struct kvm_vcpu *vcpu, struct vgic_lr vlr)
>>> +{
>>> + struct irq_phys_map *map;
>>> + int ret;
>>> +
>>> + if (!(vlr.state & LR_HW))
>>> + return 0;
>>> +
>>> + map = vgic_irq_map_search(vcpu, vlr.irq);
>>
>> I wonder if it's safe to rely on that mapping here. Are we sure that
>> this hasn't changed while the VCPU was running? If I got this correctly,
>> currently only vcpu_reset will actually add a map entry, but I guess in
>> the future there will be more users.
>
> How can the guest interrupt change? This is HW, as far as the guest is
> concerned. An actual interrupt line. We don't reconfigure the HW live.
I was thinking about the rbtree mapping we introduced. There we map a
guest interrupt to a hardware interrupt. Are we sure that no one tears
down that mapping while we have an LR populated with this pair?
I am not talking about the timer here, but more about future users.
>> Also we rely on the irqdomain mapping to be still the same, but that is
>> probably a safe assumption.
>
> Like I said before, this *cannot* change.
OK, got it.
>
>> But I'd still find it more natural to use the hwirq number from the LR
>> at this point. Can't we use irq_find_mapping() here to learn Linux'
>> (current) irq number from that?
>
> I think you're confused.
>
> - The guest irq (vlr.irq) is entirely made up, and has no connection
> with reality. it is stable, and cannot change during the lifetime of the
> guest (think of it as a HW irq line).
>
> - The host hwirq (vlr.hwirq) is stable as well, for the same reason.
>
> - The Linux IRQ cannot change because we've been given it by the kernel,
> and that's what we use for *everything* as far as the kernel is
> concerned. Its mapping to hwirq is stable as well because this is how we
> talk to the HW.
Not disputing any of them, but:
> - irq_find_mapping gives you the *reverse* mapping (from hwirq to Linux
> irq), and for that to work, you need the domain on which you want to
> apply the translation. This is only useful when actually taking the
> interrupt (i.e. in an interrupt controller driver). I can't see how that
> could make sense here.
So if the guest has acked/EOIed it's IRQ, the GIC at the same time
acked/EOIed the hardware IRQ it found in the LR. Now we assume that this
is the very same as the HW IRQ we found doing our rbtree traversal.
I just wanted to be sure that this is always true and that this mapping
didn't change while the VCPU was running.
If you are sure of this, fine, I was just concerned that someone breaks
this assumption in the future by more dynamically mapping/unmapping
entries (say some irq forwarding user) and we will not notice.
Cheers,
Andre.
>
> The purpose of this mapping is to, given the guest irq (because that's
> what we inject), what the other values are:
> - hwirq: to provide GICH with the interrupt to deactivate
> - Linux irq: to control the active state through the irqchip state API.
>
>> Or am I too paranoid here?
>
> Hope it makes more sense to you now.
>
> Thanks,
>
> M.
>
WARNING: multiple messages have this Message-ID (diff)
From: Andre Przywara <andre.przywara@arm.com>
To: Marc Zyngier <marc.zyngier@arm.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Cc: "kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [PATCH 07/10] KVM: arm/arm64: vgic: Allow HW interrupts to be queued to a guest
Date: Thu, 11 Jun 2015 10:44:02 +0100 [thread overview]
Message-ID: <55795862.1050407@arm.com> (raw)
In-Reply-To: <557951C6.2090408@arm.com>
On 06/11/2015 10:15 AM, Marc Zyngier wrote:
> On 11/06/15 09:44, Andre Przywara wrote:
>> On 06/08/2015 06:04 PM, Marc Zyngier wrote:
...
>>> @@ -1344,6 +1364,35 @@ static bool vgic_process_maintenance(struct kvm_vcpu *vcpu)
>>> return level_pending;
>>> }
>>>
>>> +/* Return 1 if HW interrupt went from active to inactive, and 0 otherwise */
>>> +static int vgic_sync_hwirq(struct kvm_vcpu *vcpu, struct vgic_lr vlr)
>>> +{
>>> + struct irq_phys_map *map;
>>> + int ret;
>>> +
>>> + if (!(vlr.state & LR_HW))
>>> + return 0;
>>> +
>>> + map = vgic_irq_map_search(vcpu, vlr.irq);
>>
>> I wonder if it's safe to rely on that mapping here. Are we sure that
>> this hasn't changed while the VCPU was running? If I got this correctly,
>> currently only vcpu_reset will actually add a map entry, but I guess in
>> the future there will be more users.
>
> How can the guest interrupt change? This is HW, as far as the guest is
> concerned. An actual interrupt line. We don't reconfigure the HW live.
I was thinking about the rbtree mapping we introduced. There we map a
guest interrupt to a hardware interrupt. Are we sure that no one tears
down that mapping while we have an LR populated with this pair?
I am not talking about the timer here, but more about future users.
>> Also we rely on the irqdomain mapping to be still the same, but that is
>> probably a safe assumption.
>
> Like I said before, this *cannot* change.
OK, got it.
>
>> But I'd still find it more natural to use the hwirq number from the LR
>> at this point. Can't we use irq_find_mapping() here to learn Linux'
>> (current) irq number from that?
>
> I think you're confused.
>
> - The guest irq (vlr.irq) is entirely made up, and has no connection
> with reality. it is stable, and cannot change during the lifetime of the
> guest (think of it as a HW irq line).
>
> - The host hwirq (vlr.hwirq) is stable as well, for the same reason.
>
> - The Linux IRQ cannot change because we've been given it by the kernel,
> and that's what we use for *everything* as far as the kernel is
> concerned. Its mapping to hwirq is stable as well because this is how we
> talk to the HW.
Not disputing any of them, but:
> - irq_find_mapping gives you the *reverse* mapping (from hwirq to Linux
> irq), and for that to work, you need the domain on which you want to
> apply the translation. This is only useful when actually taking the
> interrupt (i.e. in an interrupt controller driver). I can't see how that
> could make sense here.
So if the guest has acked/EOIed it's IRQ, the GIC at the same time
acked/EOIed the hardware IRQ it found in the LR. Now we assume that this
is the very same as the HW IRQ we found doing our rbtree traversal.
I just wanted to be sure that this is always true and that this mapping
didn't change while the VCPU was running.
If you are sure of this, fine, I was just concerned that someone breaks
this assumption in the future by more dynamically mapping/unmapping
entries (say some irq forwarding user) and we will not notice.
Cheers,
Andre.
>
> The purpose of this mapping is to, given the guest irq (because that's
> what we inject), what the other values are:
> - hwirq: to provide GICH with the interrupt to deactivate
> - Linux irq: to control the active state through the irqchip state API.
>
>> Or am I too paranoid here?
>
> Hope it makes more sense to you now.
>
> Thanks,
>
> M.
>
next prev parent reply other threads:[~2015-06-11 9:44 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
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 [this message]
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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