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

[Peter Zijlstra]

On Tue, Jun 27, 2023 at 02:12:37AM +1200, Kai Huang wrote:

> +static int try_init_module_global(void)
> +{
> +	unsigned long flags;
> +	int ret;
> +
> +	/*
> +	 * The TDX module global initialization only needs to be done
> +	 * once on any cpu.
> +	 */
> +	raw_spin_lock_irqsave(&tdx_global_init_lock, flags);
> +
> +	if (tdx_global_initialized) {
> +		ret = 0;
> +		goto out;
> +	}
> +
> +	/* All '0's are just unused parameters. */
> +	ret = seamcall(TDH_SYS_INIT, 0, 0, 0, 0, NULL, NULL);
> +	if (!ret)
> +		tdx_global_initialized = true;
> +out:
> +	raw_spin_unlock_irqrestore(&tdx_global_init_lock, flags);
> +
> +	return ret;
> +}

How long does that TDX_SYS_INIT take and why is a raw_spinlock with IRQs
disabled the right way to serialize this?