linux-kernel - Re: [PATCH v3 0/4] KVM: arm64: Add VLPI migration support on GICv4.1

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Message-ID: <ba9511e7-a23f-f644-e310-f0bf1bce835a@huawei.com>
Date:   Thu, 11 Mar 2021 15:03:21 +0800
From:   Shenming Lu <lushenming@...wei.com>
To:     Marc Zyngier <maz@...nel.org>, Eric Auger <eric.auger@...hat.com>,
        "Will Deacon" <will@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <kvmarm@...ts.cs.columbia.edu>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
CC:     Alex Williamson <alex.williamson@...hat.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        <wanghaibin.wang@...wei.com>, <yuzenghui@...wei.com>
Subject: Re: [PATCH v3 0/4] KVM: arm64: Add VLPI migration support on GICv4.1

Hi,

Sorry to bother again, I am really hoping a response for this series. :-)

Thanks,
Shenming

On 2021/2/26 16:58, Shenming Lu wrote:
> Hi Marc,
> 
> Gentle ping. Does this series need any further modification? Wish you can pick it up. :-)
> 
> Thanks,
> Shenming
> 
> On 2021/1/27 20:13, Shenming Lu wrote:
>> Hi Marc, sorry for the late commit.
>>
>> In GICv4.1, migration has been supported except for (directly-injected)
>> VLPI. And GICv4.1 Spec explicitly gives a way to get the VLPI's pending
>> state (which was crucially missing in GICv4.0). So we make VLPI migration
>> capable on GICv4.1 in this patch set.
>>
>> In order to support VLPI migration, we need to save and restore all
>> required configuration information and pending states of VLPIs. But
>> in fact, the configuration information of VLPIs has already been saved
>> (or will be reallocated on the dst host...) in vgic(kvm) migration.
>> So we only have to migrate the pending states of VLPIs specially.
>>
>> Below is the related workflow in migration.
>>
>> On the save path:
>> 	In migration completion:
>> 		pause all vCPUs
>> 				|
>> 		call each VM state change handler:
>> 			pause other devices (just keep from sending interrupts, and
>> 			such as VFIO migration protocol has already realized it [1])
>> 					|
>> 			flush ITS tables into guest RAM
>> 					|
>> 			flush RDIST pending tables (also flush VLPI state here)
>> 				|
>> 		...
>> On the resume path:
>> 	load each device's state:
>> 		restore ITS tables (include pending tables) from guest RAM
>> 				|
>> 		for other (PCI) devices (paused), if configured to have VLPIs,
>> 		establish the forwarding paths of their VLPIs (and transfer
>> 		the pending states from kvm's vgic to VPT here)
>>
>> We have tested this series in VFIO migration, and found some related
>> issues in QEMU [2].
>>
>> Links:
>> [1] vfio: UAPI for migration interface for device state:
>>     https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a8a24f3f6e38103b77cf399c38eb54e1219d00d6
>> [2] vfio: Some fixes and optimizations for VFIO migration:
>>     https://patchwork.ozlabs.org/cover/1413263/
>>
>> History:
>>
>> v2 -> v3
>>  - Add the vgic initialized check to ensure that the allocation and enabling
>>    of the doorbells have already been done before unmapping the vPEs.
>>  - Check all get_vlpi_state related conditions in save_pending_tables in one place.
>>  - Nit fixes.
>>
>> v1 -> v2:
>>  - Get the VLPI state from the KVM side.
>>  - Nit fixes.
>>
>> Thanks,
>> Shenming
>>
>>
>> Shenming Lu (3):
>>   KVM: arm64: GICv4.1: Add function to get VLPI state
>>   KVM: arm64: GICv4.1: Try to save hw pending state in
>>     save_pending_tables
>>   KVM: arm64: GICv4.1: Give a chance to save VLPI's pending state
>>
>> Zenghui Yu (1):
>>   KVM: arm64: GICv4.1: Restore VLPI's pending state to physical side
>>
>>  .../virt/kvm/devices/arm-vgic-its.rst         |  2 +-
>>  arch/arm64/kvm/vgic/vgic-its.c                |  6 +-
>>  arch/arm64/kvm/vgic/vgic-v3.c                 | 61 +++++++++++++++++--
>>  arch/arm64/kvm/vgic/vgic-v4.c                 | 33 ++++++++++
>>  arch/arm64/kvm/vgic/vgic.h                    |  1 +
>>  5 files changed, 93 insertions(+), 10 deletions(-)
>>