RE: [PATCH v2 2/5] Drivers: hv: vmbus: Track decrypted status in vmbus_gpadl

[Michael Kelley]

From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
> 
> >>> @@ -886,6 +901,8 @@ int vmbus_teardown_gpadl(struct vmbus_channel *channel, struct vmbus_gpadl *gpad
> >>>  	if (ret)
> >>>  		pr_warn("Fail to set mem host visibility in GPADL teardown %d.\n", ret);
> >>
> >> Will this be called only if vmbus_establish_gpad() is successful? If not, you
> >> might want to skip set_memory_encrypted() call for decrypted = false case.
> >
> > It's only called if vmbus_establish_gpadl() is successful.  I agree
> > we don't want to call set_memory_encrypted() if the
> > set_memory_decrypted() wasn't executed or it failed.  But
> > vmbus_teardown_gpadl() is never called with decrypted = false.
> 
> Since you rely on  vmbus_teardown_gpadl() callers, personally I think it
> is better to add that check. It is up to you.
> 

In my judgment, a check isn't really necessary.  The structure of the GPADL
code has been stable for a long time, and I'm not aware of anything
pending that would motivate a change.  And if something did change
to call vmbus_teardown_gpadl() with the memory still encrypted,
the call to set_memory_encrypted() will cause an immediate error and
a WARN_ONCE from Rick's patch to __set_memory_enc_pgtable().
The problem won't go unnoticed.

Michael