[PATCH v14 26/44] arm64: RMI: Allow populating initial contents

[Suzuki K Poulose]

On 08/06/2026 14:53, Steven Price wrote:
> On 08/06/2026 10:41, Suzuki K Poulose wrote:
>> On 08/06/2026 10:36, Steven Price wrote:
>>> On 28/05/2026 06:30, Gavin Shan wrote:
>>>> Hi Steve,
>>>>
>>>> On 5/13/26 11:17 PM, Steven Price wrote:
>>>>> The VMM needs to populate the realm with some data before starting
>>>>> (e.g.
>>>>> a kernel and initrd). This is measured by the RMM and used as part of
>>>>> the attestation later on.
>>>>>
>>>>> Signed-off-by: Steven Price <steven.price at arm.com>
>>
>> ...
>>
>>>>> diff --git a/arch/arm64/kvm/rmi.c b/arch/arm64/kvm/rmi.c
>>>>> index a89873a5eb77..209087bcf399 100644
>>>>> --- a/arch/arm64/kvm/rmi.c
>>>>> +++ b/arch/arm64/kvm/rmi.c
>>>>> @@ -486,6 +486,75 @@ void kvm_realm_unmap_range(struct kvm *kvm,
>>>>> unsigned long start,
>>>>>             realm_unmap_private_range(kvm, start, end, may_block);
>>>>>     }
>>>>>     +static int realm_data_map_init(struct kvm *kvm, unsigned long ipa,
>>>>> +                   kvm_pfn_t dst_pfn, kvm_pfn_t src_pfn,
>>>>> +                   unsigned long flags)
>>>>> +{
>>>>> +    struct realm *realm = &kvm->arch.realm;
>>>>> +    phys_addr_t rd = virt_to_phys(realm->rd);
>>>>> +    phys_addr_t dst_phys, src_phys;
>>>>> +    int ret;
>>>>> +
>>>>> +    dst_phys = __pfn_to_phys(dst_pfn);
>>>>> +    src_phys = __pfn_to_phys(src_pfn);
>>>>> +
>>>>> +    if (rmi_delegate_page(dst_phys))
>>>>> +        return -ENXIO;
>>>>> +
>>>>> +    ret = rmi_rtt_data_map_init(rd, dst_phys, ipa, src_phys, flags);
>>>>> +    if (RMI_RETURN_STATUS(ret) == RMI_ERROR_RTT) {
>>>>> +        /* Create missing RTTs and retry */
>>>>> +        int level = RMI_RETURN_INDEX(ret);
>>>>> +
>>>>> +        KVM_BUG_ON(level == KVM_PGTABLE_LAST_LEVEL, kvm);
>>>>
>>>>           KVM_BUG_ON(level >= KVM_PGTABLE_LAST_LEVEL, kvm);
>>>
>>> Ack.
>>>
>>
>> Thinking more about this, I guess a buggy VMM can trigger this
>> by populating twice ? (level == KVM_PGTABLE_LAST_LEVEL). So, we should
>> return the error back, than warning here and suppressing the error ?
> 
> Populating twice causes rmi_delegate_page() to be run twice on the same
> page and the second one will then fail. So I don't think this is
> possible (please correct me if I've missed something!)

Good point, but I think this may not fail to allow the hugepages in the
future. The DELEGATE_RANGE would skip the granules in DELEGATED/DATA 
state. I am getting this clarified in the spec.


Suzuki

> 
> Thanks,
> Steve