Re: [PATCH v5 06/18] x86/sgx: Introduce EPC page states

[Huang, Kai]

On Mon, 2023-10-02 at 23:49 -0500, Haitao Huang wrote:
> On Wed, 27 Sep 2023 05:28:36 -0500, Huang, Kai <kai.huang@xxxxxxxxx> wrote:
> 
> > On Fri, 2023-09-22 at 20:06 -0700, Haitao Huang wrote:
> > > Use the lower 3 bits in the flags field of sgx_epc_page struct to
> > > track EPC states in its life cycle and define an enum for possible
> > > states. More state(s) will be added later.
> > 
> > This patch does more than what the changelog claims to do.  AFAICT it  
> > does
> > below:
> > 
> >  1) Use the lower 3 bits to track EPC page status
> >  2) Rename SGX_EPC_PAGE_RECLAIMER_TRACKED to SGX_EPC_PAGE_RERCLAIMABLE
> >  3) Introduce a new state SGX_EPC_PAGE_UNRECLAIMABLE
> >  4) Track SECS and VA pages as SGX_EPC_PAGE_UNRECLAIMABLE
> > 
> > The changelog only says 1) IIUC.
> > 
> I don't quite get why you would view 3) as a separate item from 1).

1) is about using some method to track EPC page status, 3) is adding a new
state.

Why cannot they be separated?

> In my view, 4) is not done as long as there is not separate list to track  
> it.

You are literally doing below:

@@ -113,6 +113,9 @@ static int sgx_encl_create(struct sgx_encl *encl, struct
sgx_secs *secs)
 	encl->attributes = secs->attributes;
 	encl->attributes_mask = SGX_ATTR_UNPRIV_MASK;
 
+	sgx_record_epc_page(encl->secs.epc_page,
+			    SGX_EPC_PAGE_UNRECLAIMABLE);
+

Which obviously is tracking SECS as unreclaimable page here.

The only thing you are not doing now is to put to the actual list, which you
introduced in a later patch.

But why not just doing them together?