Re: [PATCH v12 07/22] x86/virt/tdx: Add skeleton to enable TDX on demand

[Huang, Kai]

On Tue, 2023-06-27 at 12:50 +0300, kirill.shutemov@xxxxxxxxxxxxxxx wrote:
> On Tue, Jun 27, 2023 at 02:12:37AM +1200, Kai Huang wrote:
> > +	/*
> > +	 * The TDX module global initialization only needs to be done
> > +	 * once on any cpu.
> > +	 */
> > +	raw_spin_lock_irqsave(&tdx_global_init_lock, flags);
> 
> I don't understand how the comment justifies using raw spin lock.
> 

This comment is for using lock in general.  The reason to use raw_ version is
because this function gets called in IRQ context, and for PREEMPT_RT kernel the
normal spinlock is converted to sleeping lock.

Dave suggested to comment on the function rather than comment on the
raw_spin_lock directly, e.g.,  no other kernel code does that:

https://lore.kernel.org/linux-mm/d2b3bc5e-1371-0c50-8ecb-64fc70917d42@xxxxxxxxx/

So I commented the function in this version:

+/*
+ * Do the module global initialization if not done yet.
+ * It's always called with interrupts and preemption disabled.
+ */