Re: [PATCH v7 11/14] KVM: Register/unregister the guest private memory regions

Chao Peng
2022-07-20T15:12:15Z

On Tue, Jul 19, 2022 at 04:23:52PM +0200, Gupta, Pankaj wrote:
>
> > > > +bool __weak kvm_arch_private_mem_supported(struct kvm *kvm)
> > > > +{
> > > > + return false;
> > > > +}
> > >
> > > Does this function has to be overriden by SEV and TDX to support the private
> > > regions?
> >
> > Yes it should be overridden by architectures which want to support it.
>
> o.k
> >
> > >
> > > > +
> > > > static int check_memory_region_flags(const struct kvm_user_mem_region *mem)
> > > > {
> > > > u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES;
> > > > @@ -4689,6 +4729,22 @@ static long kvm_vm_ioctl(struct file *filp,
> > > > r = kvm_vm_ioctl_set_memory_region(kvm, &mem);
> > > > break;
> > > > }
> > > > +#ifdef CONFIG_HAVE_KVM_PRIVATE_MEM
> > > > + case KVM_MEMORY_ENCRYPT_REG_REGION:
> > > > + case KVM_MEMORY_ENCRYPT_UNREG_REGION: {
> > > > + struct kvm_enc_region region;
> > > > +
> > > > + if (!kvm_arch_private_mem_supported(kvm))
> > > > + goto arch_vm_ioctl;
> > > > +
> > > > + r = -EFAULT;
> > > > + if (copy_from_user(&region, argp, sizeof(region)))
> > > > + goto out;
> > > > +
> > > > + r = kvm_vm_ioctl_set_encrypted_region(kvm, ioctl, &region);
> > >
> > > this is to store private region metadata not only the encrypted region?
> >
> > Correct.
>
> Sorry for not being clear, was suggesting name change of this function from:
> "kvm_vm_ioctl_set_encrypted_region" to "kvm_vm_ioctl_set_private_region"

Though I don't have strong reason to change it, I'm fine with this and
this name matches the above kvm_arch_private_mem_supported perfectly.

Thanks,
Chao
>
> >
> > >
> > > Also, seems same ioctl can be used to put other regions (e.g firmware, later
> > > maybe DAX backend etc) into private memory?
> >
> > Possibly. Depends on what exactly the semantics is. If just want to set
> > those regions as private current code already support that.
>
> Agree. Sure!
>
>
> Thanks,
> Pankaj