Re: [PATCH v11 05/20] x86/virt/tdx: Add SEAMCALL infrastructure

[David Hildenbrand]

On 20.06.23 14:20, kirill.shutemov@xxxxxxxxxxxxxxx wrote:
> On Tue, Jun 20, 2023 at 10:37:16AM +0000, Huang, Kai wrote:
> > > > +	/*
> > > > +	 * SEAMCALL caused #GP or #UD.  By reaching here %eax contains
> > > > +	 * the trap number.  Convert the trap number to the TDX error
> > > > +	 * code by setting TDX_SW_ERROR to the high 32-bits of %rax.
> > > > +	 *
> > > > +	 * Note cannot OR TDX_SW_ERROR directly to %rax as OR instruction
> > > > +	 * only accepts 32-bit immediate at most.
> > >
> > > Not sure if that comment is really helpful here. It's a common pattern
> > > for large immediates, no?
> >
> > I am not sure.  I guess I am not expert of x86 assembly but only casual writer.
> >
> > Hi Dave, Kirill,
> >
> > Are you OK to remove it?
>
> I would rather keep it. I wanted to ask why separate MOV is needed here,
> before I read the comment. Also size of $TDX_SW_ERROR is not visible here,
> so it contributes to possible confusion without the comment.

Fine with me, but I'd assume that the assembler will simply complain in 
case we'd try to use a large immediate.

--
Cheers,

David / dhildenb