On Mon, May 24, 2021 at 02:08:26PM +0200, Vitaly Kuznetsov wrote:
[...]
> >> @@ -980,7 +989,7 @@ static struct kvm_cpuid2
> >> *get_supported_hv_cpuid(CPUState *cs)
> >> * information early, just check for the capability and set the bit
> >> * manually.
> >> */
> >> - if (kvm_check_extension(cs->kvm_state,
> >> + if (!do_sys_ioctl && kvm_check_extension(cs->kvm_state,
> >> KVM_CAP_HYPERV_ENLIGHTENED_VMCS) > 0) {
> >
> > Oh, this conditional replaces the comment I suggested in patch
> > 10/19. It makes it obvious that the hack can be deleted if we
> > remove support for the VCPU ioctl.
> >
> > So, when exactly will we be able to delete the VCPU ioctl code
> > and support only the system ioctl?
>
> When QEMU drops support for kernels < 5.11? Note, current RHEL8 already
> supports system version so we're talking about upstream kernels/Ubuntu
> LTS/...
>
> I remember there was a list of supported kernels for QEMU somewhere but
> don't seem to be able to find it quickly, could you maybe point me in
> the right direction?
The KVM-specific kernel requirement is documented here:
https://qemu-project.gitlab.io/qemu/system/target-i386.html?highlight=kvm#os-requirements
I took a while to find it. Maybe we should have a more visible
"runtime requirements" section in the docs, or it should be
moved to the supported build platforms section.
We have a clear policy on supported build platforms
[https://qemu-project.gitlab.io/qemu/system/build-platforms.html],
but not a clear policy for KVM kernel dependencies.
There's a table with Python and GCC versions at
[https://wiki.qemu.org/Supported_Build_Platforms].
Maybe it could include kernel version information as well.
--
Eduardo
