On Thu, Aug 17, 2023, Kyle Meyer wrote: > > > 4096 is the current maximum value because of the Hyper-V TLFS. See > > > BUILD_BUG_ON in arch/x86/kvm/hyperv.c, commit 79661c3, and Vitaly's > > > comment on https://lore.kernel.org/all/87r136shcc.fsf@xxxxxxxxxx. > > > > Mostly out of curiosity, do you care about Hyper-V support? If not, at some > > point it'd probably be worth exploring a CONFIG_KVM_HYPERV option to allow > > disabling KVM's Hyper-V support at compile time so that we're not bound by the > > restrictions of the TLFS. > > Yes, I care about Hyper-V support. I would like this limitation to be addressed > in the future. > > > Rather than tightly couple this to MAXSMP, what if we add a Kconfig? I know of > > at least one scenario, SVM's AVIC/x2AVIC, where it would be desirable to configure > > KVM to a much smaller maximum. The biggest downside I can think of is that KVM > > selftests would need to be updated (they assume the max is >=512), and some of the > > tests might be completely invalid if KVM_MAX_VCPUS is too low (<256?). > > That sounds good to me. I would prefer to set the range from 1024 to 4096 in > this patch. Yeah, that's probably for the best.
