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

[Steven Price]

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!)

Thanks,
Steve