Re: [PATCH Part2 RFC v4 25/40] KVM: SVM: Reclaim the guest pages when SEV-SNP VM terminates

[Brijesh Singh]

On 7/20/21 11:40 AM, Sean Christopherson wrote:
> On Mon, Jul 19, 2021, Brijesh Singh wrote:
> > On 7/19/21 2:03 PM, Sean Christopherson wrote:
> > > On Mon, Jul 19, 2021, Brijesh Singh wrote:
> > > Ah, not firmwrare, gotcha.  But we can still use a helper, e.g. an inner
> > > double-underscore helper, __rmp_make_private().
> >
> > In that case we are basically passing the all the fields defined in the
> > 'struct rmpupdate' as individual arguments.
>
> Yes, but (a) not _all_ fields, (b) it would allow hiding "struct rmpupdate", and
> (c) this is much friendlier to readers:
>
> 	__rmp_make_private(pfn, gpa, PG_LEVEL_4K, svm->asid, true);
>
> than:
>
> 	rmpupdate(&rmpupdate);

Ok.

> For the former, I can see in a single line of code that KVM is creating a 4k
> private, immutable guest page.  With the latter, I need to go hunt down all code
> that modifies rmpupdate to understand what the code is doing.
>
> > How about something like this:
> >
> > * core kernel exports the rmpupdate()
> > * the include/linux/sev.h header file defines the helper functions
> >
> >    int rmp_make_private(u64 pfn, u64 gpa, int psize, int asid)
>
> I think we'll want s/psize/level, i.e. make it more obvious clear that the input
> is PG_LEVEL_*.

ok, I will stick to x86 PG_LEVEL_*

thanks