From: Marc Zyngier <maz@kernel.org>
To: Shenming Lu <lushenming@huawei.com>
Cc: James Morse <james.morse@arm.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Eric Auger <eric.auger@redhat.com>,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org,
Christoffer Dall <christoffer.dall@arm.com>,
Alex Williamson <alex.williamson@redhat.com>,
Kirti Wankhede <kwankhede@nvidia.com>,
Cornelia Huck <cohuck@redhat.com>, Neo Jia <cjia@nvidia.com>,
wanghaibin.wang@huawei.com, yuzenghui@huawei.com
Subject: Re: [RFC PATCH v1 3/4] KVM: arm64: GICv4.1: Restore VLPI's pending state to physical side
Date: Tue, 01 Dec 2020 11:50:00 +0000 [thread overview]
Message-ID: <274dafb2e21f49326a64bb575e668793@kernel.org> (raw)
In-Reply-To: <9b80d460-e149-20c8-e9b3-e695310b4ed1@huawei.com>
On 2020-12-01 11:40, Shenming Lu wrote:
> On 2020/12/1 18:55, Marc Zyngier wrote:
>> On 2020-11-30 07:23, Shenming Lu wrote:
>>
>> Hi Shenming,
>>
>>> We are pondering over this problem these days, but still don't get a
>>> good solution...
>>> Could you give us some advice on this?
>>>
>>> Or could we move the restoring of the pending states (include the
>>> sync
>>> from guest RAM and the transfer to HW) to the GIC VM state change
>>> handler,
>>> which is completely corresponding to save_pending_tables (more
>>> symmetric?)
>>> and don't expose GICv4...
>>
>> What is "the GIC VM state change handler"? Is that a QEMU thing?
>
> Yeah, it is a a QEMU thing...
>
>> We don't really have that concept in KVM, so I'd appreciate if you
>> could
>> be a bit more explicit on this.
>
> My thought is to add a new interface (to QEMU) for the restoring of
> the pending states, which is completely corresponding to
> KVM_DEV_ARM_VGIC_SAVE_PENDING_TABLES...
> And it is called from the GIC VM state change handler in QEMU, which
> is happening after the restoring (call kvm_vgic_v4_set_forwarding())
> but before the starting (running) of the VFIO device.
Right, that makes sense. I still wonder how much the GIC save/restore
stuff differs from other architectures that implement similar features,
such as x86 with VT-D.
It is obviously too late to change the userspace interface, but I wonder
whether we missed something at the time.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2020-12-01 11:50 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-23 6:54 [RFC PATCH v1 0/4] KVM: arm64: Add VLPI migration support on GICv4.1 Shenming Lu
2020-11-23 6:54 ` [RFC PATCH v1 1/4] irqchip/gic-v4.1: Plumb get_irqchip_state VLPI callback Shenming Lu
2020-11-23 9:01 ` Marc Zyngier
2020-11-24 7:38 ` Shenming Lu
2020-11-24 8:08 ` Marc Zyngier
2020-11-28 7:19 ` luojiaxing
2020-11-28 10:18 ` Marc Zyngier
2020-12-01 9:38 ` luojiaxing
2020-12-01 10:58 ` Marc Zyngier
2020-11-23 6:54 ` [RFC PATCH v1 2/4] KVM: arm64: GICv4.1: Try to save hw pending state in save_pending_tables Shenming Lu
2020-11-23 9:18 ` Marc Zyngier
2020-11-24 7:40 ` Shenming Lu
2020-11-24 8:26 ` Marc Zyngier
2020-11-24 13:10 ` Shenming Lu
2020-11-23 6:54 ` [RFC PATCH v1 3/4] KVM: arm64: GICv4.1: Restore VLPI's pending state to physical side Shenming Lu
2020-11-23 9:27 ` Marc Zyngier
2020-11-24 8:10 ` Shenming Lu
2020-11-24 8:44 ` Marc Zyngier
2020-11-24 13:12 ` Shenming Lu
2020-11-30 7:23 ` Shenming Lu
2020-12-01 10:55 ` Marc Zyngier
2020-12-01 11:40 ` Shenming Lu
2020-12-01 11:50 ` Marc Zyngier [this message]
2020-12-01 12:15 ` Shenming Lu
2020-12-08 8:25 ` Shenming Lu
2020-12-16 10:35 ` Auger Eric
2020-12-17 4:19 ` Shenming Lu
2020-11-23 6:54 ` [RFC PATCH v1 4/4] KVM: arm64: GICv4.1: Give a chance to save VLPI's pending state Shenming Lu
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