Re: [PATCH 0/6] x86/kvm: add boot parameters for max vcpu configs

[Paolo Bonzini]

On 01/07/21 17:40, Juergen Gross wrote:
> In order to be able to have a single kernel for supporting even huge
> numbers of vcpus per guest some arrays should be sized dynamically.
>
> The easiest way to do that is to add boot parameters for the maximum
> number of vcpus and the highest supported vcpu-id overwriting the
> normal default.
>
> This patch series is doing that for x86. The same scheme can be easily
> adapted to other architectures, but I don't want to do that in the
> first iteration.
>
> In the long term I'd suggest to have a per-guest setting of the two
> parameters allowing to spare some memory for smaller guests. OTOH this
> would require new ioctl()s and respective qemu modifications, so I let
> those away for now.
>
> I've tested the series not to break normal guest operation and the new
> parameters to be effective on x86. For Arm64 I did a compile test only.
>
> Juergen Gross (6):
>    x86/kvm: fix vcpu-id indexed array sizes
>    x86/kvm: remove non-x86 stuff from arch/x86/kvm/ioapic.h
>    x86/kvm: add boot parameter for maximum vcpu-id
>    x86/kvm: introduce per cpu vcpu masks
>    kvm: allocate vcpu pointer array separately
>    x86/kvm: add boot parameter for setting max number of vcpus per guest
>
>   .../admin-guide/kernel-parameters.txt         | 18 +++++++
>   arch/arm64/kvm/arm.c                          | 28 +++++++++--
>   arch/x86/include/asm/kvm_host.h               | 22 ++++++---
>   arch/x86/kvm/hyperv.c                         | 25 +++++++---
>   arch/x86/kvm/ioapic.c                         | 14 +++++-
>   arch/x86/kvm/ioapic.h                         |  8 +--
>   arch/x86/kvm/irq_comm.c                       |  9 +++-
>   arch/x86/kvm/x86.c                            | 49 ++++++++++++++++++-
>   include/linux/kvm_host.h                      | 17 ++++++-
>   9 files changed, 160 insertions(+), 30 deletions(-)

Queued patches 1-2, thanks (1 for stable too).

Paolo