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SubjectRe: [PATCH v6 00/12] KVM: arm/arm64: Allow multiple GICv3 redistributor regions
Hi Eric,

On Mon, 30 Apr 2018 13:48:26 +0200
Eric Auger <eric.auger@redhat.com> wrote:

> At the moment the KVM VGICv3 only supports a single redistributor
> region (whose base address is set through the GICv3 kvm device
> KVM_DEV_ARM_VGIC_GRP_ADDR/KVM_VGIC_V3_ADDR_TYPE_REDIST). There,
> all the redistributors are laid out contiguously. The size of this
> single redistributor region is not set explicitly but instead
> induced at a late stage by the number of online vcpus.
>
> The GIC specification does not mandate all redistributors to be
> contiguous. Moreover DT and ACPI were specified so that multiple
> redistributors regions can be defined.
>
> The current interface brings a limitation on QEMU where ARM
> virt machine available GPA holes only allowed to assign a
> redistributor region fitting a max of 123 vcpus. Overcoming this
> limitation would force either to create a new machine or relocate
> the single rdist region or allow the allocation of multiple rdist
> regions.
>
> This series enables this last alternative. A new GICv3 KVM device
> KVM_DEV_ARM_VGIC_GRP_ADDR/KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION allows
> to register individual redistributor regions whose size is defined
> explicitly. Those rdist regions then are filled by vcpu rdist frames
> according to the need. The vgic init and related base address checks
> are impacted.

I've taken this series for a test run, and noticed that it breaks
kvmtool:

<quote>
maz@sy-borg:~$ ./kvmtool/lkvm run -c 1 -k Image --irqchip=gicv3
# lkvm run -k Image -m 256 -c 1 --name guest-4929
Info: Loaded kernel to 0x80080000 (20126208 bytes)
Info: Placing fdt at 0x8fe00000 - 0x8fffffff
Info: virtio-mmio.devices=0x200@0x10000:36

Info: virtio-mmio.devices=0x200@0x10200:37

Info: virtio-mmio.devices=0x200@0x10400:38

KVM_RUN failed: No such device or address
</quote>

Backing out the series results in a working setup.

I presume that the changes in the init has resulted in a stricter
initialization order that matches the QEMU flow, but that kvmtool
doesn't follow.

Could you please have a look at this? I'd like to have it in for 4.18,
just without regressions... ;-)

Thanks,

M.
--
Without deviation from the norm, progress is not possible.

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