Re: [PATCH for_v23 1/9] x86/sgx: WARN once if an enclave is released with unfreed EPC pages

[Sean Christopherson <sean.j.christopherson@intel.com>]

On Mon, Oct 14, 2019 at 11:33:43PM +0300, Jarkko Sakkinen wrote:
> On Mon, Oct 14, 2019 at 11:31:56PM +0300, Jarkko Sakkinen wrote:
> > On Thu, Oct 10, 2019 at 02:42:53PM -0700, Sean Christopherson wrote:
> > > Add a WARN to detect EPC page leaks when releasing an enclave.  The
> > > release flow uses the common sgx_encl_destroy() helper, which is allowed
> > > to be called while the reclaimer holds references to the enclave's EPC
> > > pages and so can't WARN in the scenario where the SECS is leaked because
> > > it has active child pages.
> > > 
> > > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > > ---
> > >  arch/x86/kernel/cpu/sgx/encl.c | 1 +
> > >  1 file changed, 1 insertion(+)
> > > 
> > > diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
> > > index c13c3ba3430a..b4d7b2f9609f 100644
> > > --- a/arch/x86/kernel/cpu/sgx/encl.c
> > > +++ b/arch/x86/kernel/cpu/sgx/encl.c
> > > @@ -511,6 +511,7 @@ void sgx_encl_release(struct kref *ref)
> > >  		fput(encl->backing);
> > >  
> > >  	WARN_ONCE(!list_empty(&encl->mm_list), "mm_list non-empty");
> > > +	WARN_ON_ONCE(encl->secs_child_cnt || encl->secs.epc_page);
> > 
> > I'd prefer to have two WARN_ON_ONCE()'s. I think disjunction's should
> > not be used with WARN*() (conjunction's obviously should when they are
> > required).
> > 
> > I changed this to:
> > 
> > 	/* Detect EPC page leak's. */
> > 	WARN_ON_ONCE(encl->secs_child_cnt);
> > 	WARN_ON_ONCE(encl->secs.epc_page);
> > 
> > The patch has been merged.
> 
> Should the mm_list check also use the same macro? The associated message
> is somewhat useless, isn't it?

Yep.