On Wed, May 26, 2021 at 12:46:25PM -0400, Eduardo Habkost wrote: > 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.
While it says "supported build platforms", that was implicitly assumed to also refer to "runtime platforms". We should just rename it to "supported-platforms.html" to make it more obvious. Thus, the minimum KVM kernel version we need follows the same rules. Look at whatever is the oldest kernel across the distros we target. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|