Re: [PATCH v8 5/5] x86/tdx: Add Quote generation support

[Dave Hansen]

On 7/21/22 11:42, Isaku Yamahata wrote:
> Regarding to the size of quote, there is no hard limit because it's for future
> usage.  But here is a rough idea about it.
> 
> - 4KB(1 page) can accommodate TDREPORT that is defined right now.
> - 128KB is too small for foreseen use cases.
> - 1MB is too big. big enough for future.

Again, we're off in the weeds.

How does the VMM know how much to read/write?  I have a theory: the spec
says that R12 is:

	"Shared 4KB GPA as input – the memory contains a
	TDREPORT_STRUCT."

That's *A* 4KB GPA.  The maximum is one 4KB page.  That's the only thing
that makes sense because there's no length in the ABI anywhere.

What am I missing?