Re: [PATCH v7 13/20] x86/virt/tdx: Allocate and set up PAMTs for TDMRs

[Huang, Kai]

On Mon, 2022-11-28 at 14:56 -0800, Hansen, Dave wrote:
> On 11/28/22 14:48, Huang, Kai wrote:
> > > Maybe even a little ASCII diagram about the different tmb configurations
> > > that this can find:
> > > 
> > > > TDMR1 | TDMR2 |
> > >    |---tmb---|
> > >           |tmb|
> > >           |------tmb-------|          <- case 3)
> > >    |------tmb-------|                 <- case 4
> > Thanks for the diagram!
> > 
> > But IIUC it seems the above case 3) and 4) are actually not possible, since when
> > one TDMR is created, it's end is always rounded up to the end of TMB it tries to
> > cover (the rounded-up end may cover the entire or only partial of other TMBs,
> > though).
> 
> OK, but at the same time, we shouldn't *STRICTLY* specialize every
> single little chunk of this code to be aware of every other tiny little
> implementation detail.
> 
> Let's say tomorrow's code has lots of TDMRs left, but fills up one
> TDMR's reserved areas and has to "split" it.  Want to bet on whether the
> person that adds that patch will be able to find this code and fix it up?

Yeah good point.

> 
> Or, say that the TDMR creation algorithm changes and they're not done in
> order of ascending physical address.
> 
> This code actually gets easier and more obvious if you ignore the other
> details.

Agreed.  Thanks.