On Mon, Jul 02, 2018 at 10:54:56AM +0200, Greg Kurz wrote: > It is currently not possible to run a pseries-2.12 or older machine > with HV KVM. QEMU prints the following and exits right away. > > qemu-system-ppc64: KVM doesn't support for base page shift 34 > > The "hpt-max-page-size" capability was recently added to spapr to hide > host configuration details from HPT mode guests. Its default value for > newer machine types is 64k. > > For backwards compatibility, pseries-2.12 and older machine types need > a different value. This is handled as usual in a class init function. > The default value is 16G, ie, all page sizes supported by POWER7 and > newer CPUs, but HV KVM requires guest pages to be hpa contiguous as > well as gpa contiguous. The default value is the page size used to > back the guest RAM in this case. > > Unfortunately kvmppc_hpt_needs_host_contiguous_pages()->kvm_enabled() is > called way before KVM init and returns false, even if the user requested > KVM. We thus end up selecting 16G, which isn't supported by HV KVM. The > default value must be set during machine init, because we can safely > assume that KVM is initialized at this point. > > We fix this by moving the logic to default_caps_with_cpu(). Since the > user cannot pass cap-hpt-max-page-size=0, we set the default to 0 in > the pseries-2.12 class init function and use that as a flag to do the > real work. > > Signed-off-by: Greg Kurz <gr...@kaod.org>
Reviewed-by: Eduardo Habkost <ehabk...@redhat.com> -- Eduardo
