On Fri, 11 Dec 2020 at 00:00, Marc Zyngier <maz@kernel.org> wrote:
>
> This is a rework of the NV series that I posted 10 months ago[1], as a
> lot of the KVM code has changed since, and the series apply anymore
> (not that anybody really cares as the the HW is, as usual, made of
> unobtainium...).
>
> From the previous version:
>
> - Integration with the new page-table code
> - New exception injection code
> - No more messing with the nVHE code
> - No AArch32!!!!
> - Rebased on v5.10-rc4 + kvmarm/next for 5.11
>
> From a functionality perspective, you can expect a L2 guest to work,
> but don't even think of L3, as we only partially emulate the
> ARMv8.{3,4}-NV extensions themselves. Same thing for vgic, debug, PMU,
> as well as anything that would require a Stage-1 PTW. What we want to
> achieve is that with NV disabled, there is no performance overhead and
> no regression.
>
> The series is roughly divided in 5 parts: exception handling, memory
> virtualization, interrupts and timers for ARMv8.3, followed by the
> ARMv8.4 support. There are of course some dependencies, but you'll
> hopefully get the gist of it.
>
> For the most courageous of you, I've put out a branch[2]. Of course,
> you'll need some userspace. Andre maintains a hacked version of
> kvmtool[3] that takes a --nested option, allowing the guest to be
> started at EL2. You can run the whole stack in the Foundation
> model. Don't be in a hurry ;-).
>
> And to be clear: although Jintack and Christoffer have written tons of
> the stuff originaly, I'm the one responsible for breaking it!
>
> [1] https://lore.kernel.org/r/20200211174938.27809-1-maz@kernel.org
> [2] git://git.kernel.org/pub/scm/linux/kernel/git/maz/arm-platforms.git
kvm-arm64/nv-5.11.-WIP
> [3] git://linux-arm.org/kvmtool.git nv/nv-wip-5.2-rc5

Hi Marc,

I have tried to enable the NV support in Qemu, and now I can successfully
boot a L2 guest
in Qemu KVM mode.

This patch series looks good from the Qemu side except for two minor
requirements:
(1) Qemu will check whether a feature was supported by the KVM cap when the
user tries
     to enable it in the command line, so a new capability was prefered for
the NV(KVM_CAP_ARM_NV?).
(2) According to the Documentation/virt/kvm/api.rst
<https://github.com/torvalds/linux/blob/master/Documentation/virt/kvm/api.rst#482-kvm_arm_vcpu_init>,
userspace can call KVM_ARM_VCPU_INIT
     multiple times for a given vcpu, but the kvm_vcpu_init_nested() do
have some issue when
     called multiple times(please refer to the detailed comments in patch
63)

Regards,
Haibo