Re: [PATCH v11 18/20] x86: Handle TDX erratum to reset TDX private memory during kexec() and reboot

[Dave Hansen]

On 6/19/23 07:46, kirill.shutemov@xxxxxxxxxxxxxxx wrote:
>>>
>>> Using atomic_set() requires changing tdmr->pamt_4k_base to atomic_t, which is a
>>> little bit silly or overkill IMHO.  Looking at the code, it seems
>>> arch_atomic_set() simply uses __WRITE_ONCE():
>> How about _adding_ a variable that protects tdmr->pamt_4k_base?
>> Wouldn't that be more straightforward than mucking around with existing
>> types?
> What's wrong with simple global spinlock that protects all tdmr->pamt_*?
> It is much easier to follow than a custom serialization scheme.

Quick, what prevents a:

	spin_lock() => #MC => spin_lock()

deadlock?

Plain old test/sets don't deadlock ever.