Re: [PATCH v3 07/12] x86/tdx: Make TDX_HYPERCALL asm similar to TDX_MODULE_CALL

[Huang, Kai]

On Thu, 2023-07-27 at 20:10 +0300, kirill.shutemov@xxxxxxxxxxxxxxx wrote:
> On Wed, Jul 26, 2023 at 11:25:09PM +1200, Kai Huang wrote:
> > 
> > Remove the __tdx_hypercall_ret() as __tdx_hypercall() already does so.
> 
> Hm. So we now update struct on all VMCALLs. Is it a good idea? 
> 

Do you mean we "unconditionally save output registers to  the structure", right?

> We give
> more control to VMM where it is not needed. 
> 

I don't quite follow this.  Can you elaborate?

Do you worry about VMM being malicious and putting malicious values to the
registers?

> I would rather keep the struct
> read-only where possible.
> 

We can achieve this if there's a clean way to do, but I don't see that.