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

Gupta, Pankaj
2022-07-19T14:34:20Z

>>> +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"

>
>>
>> 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