Re: [PATCH v14 07/23] x86/virt/tdx: Add skeleton to enable TDX on demand

[Huang, Kai]

> > +/*
> > + * Do the module global initialization once and return its result.
> > + * It can be done on any cpu.  It's always called with interrupts
> > + * disabled.
> > + */
> > +static int try_init_module_global(void)
> > +{
> > +	struct tdx_module_args args = {};
> > +	static DEFINE_RAW_SPINLOCK(sysinit_lock);
> > +	static bool sysinit_done;
> > +	static int sysinit_ret;
> > +
> > +	lockdep_assert_irqs_disabled();
> > +
> > +	raw_spin_lock(&sysinit_lock);
> > +
> > +	if (sysinit_done)
> > +		goto out;
> > +
> > +	/* RCX is module attributes and all bits are reserved */
> > +	args.rcx = 0;
> 
> Isn't args.rcx already initialized to 0, why explixitly set it?

The purpose was to indicate SYS.INIT takes RCX as input, but OK I agree it's
unnecessary.

I found the existing upstream TDX code uses this pattern (please see
tdx_parse_info(), hv_tdx_hypercall() and try_accept_one()):

	struct tdx_module_args args = {};

	args.xx = xx;
	args.yy = yy;
	...

So I followed in this series.  

But I think explicit zeroing the structure isn't needed, so I think I'll just
remove the explicit initialization in the @args declaration in all SEAMCALLs
which use this pattern in this series:

	struct tdx_module_args args;

	/* RCX is module attributes and all bits are reserved */
	args.rcx = 0;

Or just explicitly init RCX in the declaration:

	struct tdx_module_args args = {
		.rcx = 0;	/* Module attributes. All bits reserved. */
	};
	// other variable declarations

But it seems many people don't like tail comment.

Hi Kirill/Dave,

Do you have any preference?
>