Re: [PATCH v7 0/9] i386: KVM: expand Hyper-V features early

[Eduardo Habkost <ehabkost@redhat.com>]

On Thu, Jun 03, 2021 at 01:48:26PM +0200, Vitaly Kuznetsov wrote:
> Changes since v6 [Eduardo]:
> - First 14 patches of v6 made it upstream!
> - New patches addressing feedback on the already merged patches added:
>   i386: make hyperv_expand_features() return bool
>   i386: hardcode supported eVMCS version to '1'
>   i386: clarify 'hv-passthrough' behavior
>   i386: avoid hardcoding '12' as 'hyperv_vendor_id' length
> - Some comments expanded.
> - HV_HYPERCALL_AVAILABLE setting moved to hyperv_fill_cpuids()
> 
> Note: Windows guest on QEMU are currently completely broken, see Claudio's
> https://lore.kernel.org/kvm/20210529091313.16708-1-cfontana@suse.de/
> 
> The last two functional patches are inspired by 'Fine-grained access check
> to Hyper-V hypercalls and MSRs' work for KVM:
> https://lore.kernel.org/kvm/20210521095204.2161214-1-vkuznets@redhat.com/
> 
> Original description:
> 
> Upper layer tools like libvirt want to figure out which Hyper-V features are
> supported by the underlying stack (QEMU/KVM) but currently they are unable to
> do so. We have a nice 'hv_passthrough' CPU flag supported by QEMU but it has
> no effect on e.g. QMP's 
> 
> query-cpu-model-expansion type=full model={"name":"host","props":{"hv-passthrough":true}}
> 
> command as we parse Hyper-V features after creating KVM vCPUs and not at
> feature expansion time. To support the use-case we first need to make 
> KVM_GET_SUPPORTED_HV_CPUID ioctl a system-wide ioctl as the existing
> vCPU version can't be used that early. This is what KVM part does. With
> that done, we can make early Hyper-V feature expansion (this series).

I'm finally queueing this.  Thanks, and sorry for the delay!

-- 
Eduardo