From: Auger Eric <eric.auger@redhat.com>
To: Zenghui Yu <yuzenghui@huawei.com>, Marc Zyngier <maz@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org,
Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
Jason Cooper <jason@lakedaemon.net>,
Robert Richter <rrichter@marvell.com>,
Thomas Gleixner <tglx@linutronix.de>,
James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>
Subject: Re: [PATCH v5 20/23] KVM: arm64: GICv4.1: Plumb SGI implementation selection in the distributor
Date: Fri, 20 Mar 2020 08:59:48 +0100 [thread overview]
Message-ID: <e60578b5-910c-0355-d231-29322900679d@redhat.com> (raw)
In-Reply-To: <b98855a1-6300-d323-80f6-82d3b9854290@huawei.com>
Hi Zenghui,
On 3/20/20 4:08 AM, Zenghui Yu wrote:
> On 2020/3/20 4:38, Auger Eric wrote:
>> Hi Marc,
>> On 3/19/20 1:10 PM, Marc Zyngier wrote:
>>> Hi Zenghui,
>>>
>>> On 2020-03-18 06:34, Zenghui Yu wrote:
>>>> Hi Marc,
>>>>
>>>> On 2020/3/5 4:33, Marc Zyngier wrote:
>>>>> The GICv4.1 architecture gives the hypervisor the option to let
>>>>> the guest choose whether it wants the good old SGIs with an
>>>>> active state, or the new, HW-based ones that do not have one.
>>>>>
>>>>> For this, plumb the configuration of SGIs into the GICv3 MMIO
>>>>> handling, present the GICD_TYPER2.nASSGIcap to the guest,
>>>>> and handle the GICD_CTLR.nASSGIreq setting.
>>>>>
>>>>> In order to be able to deal with the restore of a guest, also
>>>>> apply the GICD_CTLR.nASSGIreq setting at first run so that we
>>>>> can move the restored SGIs to the HW if that's what the guest
>>>>> had selected in a previous life.
>>>>
>>>> I'm okay with the restore path. But it seems that we still fail to
>>>> save the pending state of vSGI - software pending_latch of HW-based
>>>> vSGIs will not be updated (and always be false) because we directly
>>>> inject them through ITS, so vgic_v3_uaccess_read_pending() can't
>>>> tell the correct pending state to user-space (the correct one should
>>>> be latched in HW).
>>>>
>>>> It would be good if we can sync the hardware state into pending_latch
>>>> at an appropriate time (just before save), but not sure if we can...
>>>
>>> The problem is to find the "appropriate time". It would require to
>>> define
>>> a point in the save sequence where we transition the state from HW to
>>> SW. I'm not keen on adding more state than we already have.
>>
>> may be we could use a dedicated device group/attr as we have for the ITS
>> save tables? the user space would choose.
>
> It means that userspace will be aware of some form of GICv4.1 details
> (e.g., get/set vSGI state at HW level) that KVM has implemented.
> Is it something that userspace required to know? I'm open to this ;-)
Not sure we would be obliged to expose fine details. This could be a
generic save/restore device group/attr whose implementation at KVM level
could differ depending on the version being implemented, no?
Thanks
Eric
>
>>
>> Thanks
>>
>> Eric
>>>
>>> But what we can do is to just ask the HW to give us the right state
>>> on userspace access, at all times. How about this:
>>>
>>> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c
>>> b/virt/kvm/arm/vgic/vgic-mmio-v3.c
>>> index 48fd9fc229a2..281fe7216c59 100644
>>> --- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
>>> +++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
>>> @@ -305,8 +305,18 @@ static unsigned long
>>> vgic_v3_uaccess_read_pending(struct kvm_vcpu *vcpu,
>>> */
>>> for (i = 0; i < len * 8; i++) {
>>> struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, intid
>>> + i);
>>> + bool state = irq->pending_latch;
>>>
>>> - if (irq->pending_latch)
>>> + if (irq->hw && vgic_irq_is_sgi(irq->intid)) {
>>> + int err;
>>> +
>>> + err = irq_get_irqchip_state(irq->host_irq,
>>> + IRQCHIP_STATE_PENDING,
>>> + &state);
>>> + WARN_ON(err);
>>> + }
>>> +
>>> + if (state)
>>> value |= (1U << i);
>>>
>>> vgic_put_irq(vcpu->kvm, irq);
>
> Anyway this looks good to me and will do the right thing on a userspace
> save.
>
>>>
>>> I can add this to "KVM: arm64: GICv4.1: Add direct injection capability
>>> to SGI registers".
>
> Thanks,
> Zenghui
>
next prev parent reply other threads:[~2020-03-20 8:00 UTC|newest]
Thread overview: 114+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-04 20:33 [PATCH v5 00/23] irqchip/gic-v4: GICv4.1 architecture support Marc Zyngier
2020-03-04 20:33 ` [PATCH v5 01/23] irqchip/gic-v3: Use SGIs without active state if offered Marc Zyngier
2020-03-12 6:30 ` Zenghui Yu
2020-03-12 9:28 ` Marc Zyngier
2020-03-12 12:05 ` Marc Zyngier
2020-03-13 1:39 ` Zenghui Yu
2020-03-12 17:16 ` Auger Eric
2020-03-12 17:23 ` Marc Zyngier
2020-03-29 20:26 ` [tip: irq/core] " tip-bot2 for Marc Zyngier
2020-03-04 20:33 ` [PATCH v5 02/23] irqchip/gic-v4.1: Skip absent CPUs while iterating over redistributors Marc Zyngier
2020-03-16 17:10 ` Auger Eric
2020-03-29 20:26 ` [tip: irq/core] " tip-bot2 for Marc Zyngier
2020-03-04 20:33 ` [PATCH v5 03/23] irqchip/gic-v4.1: Ensure mutual exclusion between vPE affinity change and RD access Marc Zyngier
2020-03-12 6:56 ` Zenghui Yu
2020-03-29 20:26 ` [tip: irq/core] " tip-bot2 for Marc Zyngier
2020-03-04 20:33 ` [PATCH v5 04/23] irqchip/gic-v4.1: Wait for completion of redistributor's INVALL operation Marc Zyngier
2020-03-20 14:23 ` Auger Eric
2020-03-04 20:33 ` [PATCH v5 05/23] irqchip/gic-v4.1: Ensure mutual exclusion betwen invalidations on the same RD Marc Zyngier
2020-03-12 7:11 ` Zenghui Yu
2020-03-20 14:23 ` Auger Eric
2020-03-29 20:26 ` [tip: irq/core] " tip-bot2 for Marc Zyngier
2020-03-04 20:33 ` [PATCH v5 06/23] irqchip/gic-v4.1: Advertise support v4.1 to KVM Marc Zyngier
2020-03-16 17:10 ` Auger Eric
2020-03-29 20:26 ` [tip: irq/core] " tip-bot2 for Marc Zyngier
2020-03-04 20:33 ` [PATCH v5 07/23] irqchip/gic-v4.1: Map the ITS SGIR register page Marc Zyngier
2020-03-16 17:10 ` Auger Eric
2020-03-29 20:26 ` [tip: irq/core] " tip-bot2 for Marc Zyngier
2020-03-04 20:33 ` [PATCH v5 08/23] irqchip/gic-v4.1: Plumb skeletal VSGI irqchip Marc Zyngier
2020-03-16 17:10 ` Auger Eric
2020-03-19 10:03 ` Marc Zyngier
2020-03-29 20:26 ` [tip: irq/core] " tip-bot2 for Marc Zyngier
2020-03-04 20:33 ` [PATCH v5 09/23] irqchip/gic-v4.1: Add initial SGI configuration Marc Zyngier
2020-03-16 17:53 ` Auger Eric
2020-03-17 2:02 ` Zenghui Yu
2020-03-17 8:36 ` Auger Eric
2020-03-19 10:20 ` Marc Zyngier
2020-03-29 20:26 ` [tip: irq/core] " tip-bot2 for Marc Zyngier
2020-03-04 20:33 ` [PATCH v5 10/23] irqchip/gic-v4.1: Plumb mask/unmask SGI callbacks Marc Zyngier
2020-03-16 18:15 ` Auger Eric
2020-03-29 20:26 ` [tip: irq/core] " tip-bot2 for Marc Zyngier
2020-03-04 20:33 ` [PATCH v5 11/23] irqchip/gic-v4.1: Plumb get/set_irqchip_state " Marc Zyngier
2020-03-12 7:41 ` Zenghui Yu
2020-03-16 21:43 ` Auger Eric
2020-03-19 10:27 ` Marc Zyngier
2020-03-29 20:26 ` [tip: irq/core] " tip-bot2 for Marc Zyngier
2020-03-04 20:33 ` [PATCH v5 12/23] irqchip/gic-v4.1: Plumb set_vcpu_affinity " Marc Zyngier
2020-03-17 10:35 ` Auger Eric
2020-03-29 20:26 ` [tip: irq/core] " tip-bot2 for Marc Zyngier
2020-03-04 20:33 ` [PATCH v5 13/23] irqchip/gic-v4.1: Move doorbell management to the GICv4 abstraction layer Marc Zyngier
2020-03-12 8:20 ` Zenghui Yu
2020-03-29 20:26 ` [tip: irq/core] " tip-bot2 for Marc Zyngier
2020-03-04 20:33 ` [PATCH v5 14/23] irqchip/gic-v4.1: Add VSGI allocation/teardown Marc Zyngier
2020-03-12 8:06 ` Zenghui Yu
2020-03-29 20:26 ` [tip: irq/core] " tip-bot2 for Marc Zyngier
2020-03-04 20:33 ` [PATCH v5 15/23] irqchip/gic-v4.1: Add VSGI property setup Marc Zyngier
2020-03-12 8:09 ` Zenghui Yu
2020-03-17 10:30 ` Auger Eric
2020-03-19 10:57 ` Marc Zyngier
2020-03-29 20:26 ` [tip: irq/core] " tip-bot2 for Marc Zyngier
2020-03-04 20:33 ` [PATCH v5 16/23] irqchip/gic-v4.1: Eagerly vmap vPEs Marc Zyngier
2020-03-12 8:12 ` Zenghui Yu
2020-03-17 2:49 ` Zenghui Yu
2020-03-19 10:55 ` Marc Zyngier
2020-03-20 2:31 ` Zenghui Yu
2020-03-29 20:26 ` [tip: irq/core] " tip-bot2 for Marc Zyngier
2020-03-04 20:33 ` [PATCH v5 17/23] KVM: arm64: GICv4.1: Let doorbells be auto-enabled Marc Zyngier
2020-03-12 8:15 ` Zenghui Yu
2020-03-17 11:04 ` Auger Eric
2020-03-04 20:33 ` [PATCH v5 18/23] KVM: arm64: GICv4.1: Add direct injection capability to SGI registers Marc Zyngier
2020-03-18 3:28 ` Zenghui Yu
2020-03-20 8:11 ` Auger Eric
2020-03-20 10:05 ` Marc Zyngier
2020-03-20 10:56 ` Auger Eric
2020-03-04 20:33 ` [PATCH v5 19/23] KVM: arm64: GICv4.1: Allow SGIs to switch between HW and SW interrupts Marc Zyngier
2020-03-19 16:16 ` Auger Eric
2020-03-19 19:52 ` Marc Zyngier
2020-03-19 20:13 ` Auger Eric
2020-03-20 9:17 ` Marc Zyngier
2020-03-20 4:22 ` Zenghui Yu
2020-03-04 20:33 ` [PATCH v5 20/23] KVM: arm64: GICv4.1: Plumb SGI implementation selection in the distributor Marc Zyngier
2020-03-18 6:34 ` Zenghui Yu
2020-03-19 12:10 ` Marc Zyngier
2020-03-19 20:38 ` Auger Eric
2020-03-20 3:08 ` Zenghui Yu
2020-03-20 7:59 ` Auger Eric [this message]
2020-03-20 9:46 ` Marc Zyngier
2020-03-20 11:09 ` Auger Eric
2020-03-20 11:20 ` Marc Zyngier
2020-03-20 3:53 ` Zenghui Yu
2020-03-20 9:01 ` Marc Zyngier
2020-03-23 8:11 ` Zenghui Yu
2020-03-23 8:25 ` Marc Zyngier
2020-03-23 12:40 ` Zenghui Yu
2020-03-04 20:33 ` [PATCH v5 21/23] KVM: arm64: GICv4.1: Reload VLPI configuration on distributor enable/disable Marc Zyngier
2020-03-18 3:17 ` Zenghui Yu
2020-03-19 12:18 ` Marc Zyngier
2020-03-04 20:33 ` [PATCH v5 22/23] KVM: arm64: GICv4.1: Allow non-trapping WFI when using HW SGIs Marc Zyngier
2020-03-20 4:23 ` Zenghui Yu
2020-03-20 8:12 ` Auger Eric
2020-03-04 20:33 ` [PATCH v5 23/23] KVM: arm64: GICv4.1: Expose HW-based SGIs in debugfs Marc Zyngier
2020-03-18 3:19 ` Zenghui Yu
2020-03-19 15:05 ` Auger Eric
2020-03-19 15:21 ` Marc Zyngier
2020-03-19 15:43 ` Auger Eric
2020-03-19 16:16 ` Marc Zyngier
2020-03-19 16:17 ` Auger Eric
2020-03-20 4:38 ` Zenghui Yu
2020-03-20 9:09 ` Marc Zyngier
2020-03-20 11:35 ` Zenghui Yu
2020-03-20 11:46 ` Marc Zyngier
2020-03-20 12:09 ` Zenghui Yu
2020-03-05 3:39 ` [PATCH v5 00/23] irqchip/gic-v4: GICv4.1 architecture support Zenghui Yu
2020-03-09 8:17 ` Zenghui Yu
2020-03-09 8:46 ` Marc Zyngier
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