On Thu, Jul 21, 2022 at 03:34:59PM +0800, Wei Wang wrote:
On 7/21/22 00:21, Sean Christopherson wrote:
On Wed, Jul 20, 2022, Gupta, Pankaj wrote:
> > +bool __weak kvm_arch_private_mem_supported(struct kvm *kvm)
Use kvm_arch_has_private_mem(), both because "has" makes it obvious this is checking a flag of sorts, and to align with other helpers of this nature (and with CONFIG_HAVE_KVM_PRIVATE_MEM).
$ git grep kvm_arch | grep supported | wc -l 0 $ git grep kvm_arch | grep has | wc -l 26
Make sense. kvm_arch_has_private_mem it actually better.
> > +#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(®ion, argp, sizeof(region))) > > + goto out; > > + > > + r = kvm_vm_ioctl_set_encrypted_region(kvm, ioctl, ®ion); > 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
Yes, no strong reason, just thought "kvm_vm_ioctl_set_private_region" would depict the actual functionality :)
this name matches the above kvm_arch_private_mem_supported perfectly.
BTW could not understand this, how "kvm_vm_ioctl_set_encrypted_region" matches "kvm_arch_private_mem_supported"?
Chao is saying that kvm_vm_ioctl_set_private_region() pairs nicely with kvm_arch_private_mem_supported(), not that the "encrypted" variant pairs nicely.
I also like using "private" instead of "encrypted", though we should probably find a different verb than "set", because calling "set_private" when making the region shared is confusing. I'm struggling to come up with a good alternative though.
kvm_vm_ioctl_set_memory_region() is already taken by KVM_SET_USER_MEMORY_REGION, and that also means that anything with "memory_region" in the name is bound to be confusing.
Hmm, and if we move away from "encrypted", it probably makes sense to pass in addr+size instead of a kvm_enc_region.
This makes sense.
Maybe this?
static int kvm_vm_ioctl_set_or_clear_mem_private(struct kvm *kvm, gpa_t gpa, gpa_t size, bool set_private)
Currently this should work.
and then:
#ifdef CONFIG_HAVE_KVM_PRIVATE_MEM case KVM_MEMORY_ENCRYPT_REG_REGION: case KVM_MEMORY_ENCRYPT_UNREG_REGION: { bool set = ioctl == KVM_MEMORY_ENCRYPT_REG_REGION; struct kvm_enc_region region;
if (!kvm_arch_private_mem_supported(kvm)) goto arch_vm_ioctl; r = -EFAULT; if (copy_from_user(®ion, argp, sizeof(region))) goto out; r = kvm_vm_ioctl_set_or_clear_mem_private(kvm, region.addr, region.size, set); break;} #endif
I don't love it, so if someone has a better idea...
Maybe you could tag it with cgs for all the confidential guest support related stuff: e.g. kvm_vm_ioctl_set_cgs_mem()
bool is_private = ioctl == KVM_MEMORY_ENCRYPT_REG_REGION; ... kvm_vm_ioctl_set_cgs_mem(, is_private)
If we plan to widely use such abbr. through KVM (e.g. it's well known), I'm fine.
I actually use mem_attr in patch: https://lkml.org/lkml/2022/7/20/610 But I also don't quite like it, it's so generic and sounds say nothing.
But I do want a name can cover future usages other than just private/shared (pKVM for example may have a third state).
Thanks, Chao