On Mon, Oct 17, 2022, Fuad Tabba wrote:
> Hi,
>
> > > > +#ifdef CONFIG_HAVE_KVM_PRIVATE_MEM
> > > > +#define KVM_MEM_ATTR_SHARED 0x0001
> > > > +static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size,
> > > > + bool is_private)
> > > > +{
> > >
> > > I wonder if this ioctl should be implemented as an arch-specific
> > > ioctl. In this patch it performs some actions that pKVM might not need
> > > or might want to do differently.
> >
> > I think it's doable. We can provide the mem_attr_array kind thing in
> > common code and let arch code decide to use it or not. Currently
> > mem_attr_array is defined in the struct kvm, if those bytes are
> > unnecessary for pKVM it can even be moved to arch definition, but that
> > also loses the potential code sharing for confidential usages in other
> > non-architectures, e.g. if ARM also supports such usage. Or it can be
> > provided through a different CONFIG_ instead of
> > CONFIG_HAVE_KVM_PRIVATE_MEM.
>
> This sounds good. Thank you.
I like the idea of a separate Kconfig, e.g. CONFIG_KVM_GENERIC_PRIVATE_MEM or
something. I highly doubt there will be any non-x86 users for multiple years,
if ever, but it would allow testing the private memory stuff on ARM (and any other
non-x86 arch) without needing full pKVM support and with only minor KVM
modifications, e.g. the x86 support[*] to test UPM without TDX is shaping up to be
trivial.
[*] https://lore.kernel.org/all/Y0mu1FKugNQG5T8K@xxxxxxxxxx
