Re: [PATCHv4 16/30] x86/boot/compressed: Support TDX guest port I/O at decompression time

Dave Hansen
2022-02-24T22:22:46Z

On 2/24/22 07:56, Kirill A. Shutemov wrote:
> @@ -24,4 +88,11 @@ void early_tdx_detect(void)
>
> /* Cache TDX guest feature status */
> tdx_guest_detected = true;
> +
> + pio_ops.inb = tdx_inb;
> + pio_ops.inw = tdx_inw;
> + pio_ops.inl = tdx_inl;
> + pio_ops.outb = tdx_outb;
> + pio_ops.outw = tdx_outw;
> + pio_ops.outl = tdx_outl;
> }

I guess the kernel isn't going to get far if any of this goes wrong.
But, I do kinda wish that code ^^ was connected to the below code somehow:

> +static inline void init_io_ops(void)
> +{
> + pio_ops.inb = inb;
> + pio_ops.inw = inw;
> + pio_ops.inl = inl;
> + pio_ops.outb = outb;
> + pio_ops.outw = outw;
> + pio_ops.outl = outl;
> +}

Maybe just a comment would do it. Or, maybe init_io_ops() should just
be called init_default_io_ops(). I think this would do:

/*
* Use the normal I/O instructions by default.
* TDX guests override these to use hypercalls.
*/

if it went in init_io_ops() from the last patch.

>
> +static inline unsigned int tdx_io_in(int size, u16 port)
> +{
> + struct tdx_hypercall_args args = {
> + .r10 = TDX_HYPERCALL_STANDARD,
> + .r11 = EXIT_REASON_IO_INSTRUCTION,
> + .r12 = size,
> + .r13 = 0,

^ munged whitespace?

> + .r14 = port,
> + };
> +
> + if (__tdx_hypercall(&args, TDX_HCALL_HAS_OUTPUT))
> + return UINT_MAX;
> +
> + return args.r11;
> +}

With that fixed:

Acked-by: Dave Hansen <dave.hansen@linux.intel.com>