Re: [PATCH v5 07/12] x86/cpu/keylocker: Load an internal wrapping key at boot-time

Chang S. Bae
2022-08-24T22:21:09Z

On 8/23/2022 8:49 AM, Evan Green wrote:
> On Wed, Jan 12, 2022 at 1:21 PM Chang S. Bae <chang.seok.bae@intel.com> wrote:
>>
<snip>
>> +
>> +static void __init load_keylocker(void)
>
> I am late to this party by 6 months, but:
> load_keylocker() cannot be __init, as it gets called during SMP core onlining.

Yeah, it looks like the case with this patch only.

But the next patch [1] limits the call during boot time only:

if (c == &boot_cpu_data) {
...
load_keylocker();
...
} else {
...
if (!kl_setup.initialized) {
load_keylocker();
} else if (valid_kl) {
rc = copy_keylocker();
...
}
}

kl_setup.initialized is set by native_smp_cpus_done() ->
destroy_keylocker_data() when CPUs are booted. Then load_keylocker() is
not called because the root key (aka IWKey) is no longer available in
memory.

Now this 'valid_kl' flag should be always on unless the root key backup
is corrupted. Then copy_keylocker() loads the root key from the backup
in the platform state.

So I think the onlining CPU won't call it.

Maybe this bit can be much clarified in a separate (new) patch, instead
of being part of another like [1].

Thanks,
Chang

[1]: