On Wed, May 2, 2018 at 9:02 AM, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > On 02/05/2018 17:52, Jim Mattson wrote: >>>> vmcs_field_readonly is now unused. With that removed, >>>> >>>> Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> >>> Actually, no. The error must be kept if the host has disabled the >>> feature with a KVM_SET_MSR ioctl for MSR_IA32_VMX_MISC. >>> >> Coming back to this patch set... >> >> Is there a good reason to allow userspace to clear >> MSR_IA32_VMX_MISC_VMWRITE_SHADOW_RO_FIELDS? It's not yet possible to >> migrate a VMX-capable VM (though I think that ability is imminent), so >> there are no compatibility issues. Why not just force this on? > > I suppose that can be done, yes. The only reason is that silicon ties > that bit to the availability of shadow VMCS, but we can certainly do > things differently than actual processors. > > Technically it would be a small userspace API break, but we can live > with it. Does qemu explicitly set IA32_VMX_MISC today?
