Re: [Qemu-devel] [RFC 0/3] KVM/ARM: Fix >256 vcpus

[Zenghui Yu]

Hi Eric,

On 2019/8/28 0:05, Eric Auger wrote:
> Since 4.18, KVM/ARM exposes a KVM_MAX_VCPUS equal to 512. However it was
> reported [1] that a VM with more than 256 vcpus cannot be launched. 5.4
> is about to fix the situation with 2 patches:
> - one upgrade of the KVM_IRQ_LINE API [2] supporting a vcpu id encoded
>    on 12 bits,
> - the reduction of KVM IO devices consumed by each GICv3 redistributor [3]
>
> This series uses the new KVM_IRQ_LINE API and also checks the associated
> capability (KVM_CAP_ARM_IRQ_LINE_LAYOUT_2) in machvirt.
>
> Without the series, as soon as the -smp arguments exceeds 256, QEMU exits
> with "kvm_set_irq: Invalid argument".

For the series:

Tested-by: Zenghui Yu <address@hidden>

together with [2], [3].

> Best Regards
>
> Eric
>
> References:
> [1] Can we boot a 512U kvm guest?
>      https://patchwork.kernel.org/patch/11091501/
> [2] [PATCH] KVM: arm/arm64: vgic: Allow more than 256 vcpus for KVM_IRQ_LINE
>      https://patchwork.kernel.org/patch/11099609/
> [3] [PATCH] KVM: arm/arm64: vgic: Use a single IO device per redistributor
>      https://patchwork.kernel.org/patch/11112141/
>
> This series can be found at:
> https://github.com/eauger/qemu/tree/v4.1.0-256fix-rfc-v1
>
> Eric Auger (3):
>    linux headers: update for KVM_CAP_ARM_IRQ_LINE_LAYOUT_2
>    intc/arm_gic: Support PPI injection for more than 256 vpus
>    virt: Check KVM_CAP_ARM_IRQ_LINE_LAYOUT_2 for smp_cpus > 256

Thanks,
zenghui