From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarkko Sakkinen Subject: Re: [PATCH v17 18/23] platform/x86: Intel SGX driver Date: Mon, 17 Dec 2018 20:01:02 +0200 Message-ID: <20181217180102.GA12560@linux.intel.com> References: <20181116010412.23967-1-jarkko.sakkinen@linux.intel.com> <20181116010412.23967-19-jarkko.sakkinen@linux.intel.com> <7d5cde02-4649-546b-0f03-2d6414bb80b5@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <7d5cde02-4649-546b-0f03-2d6414bb80b5@intel.com> Sender: linux-kernel-owner@vger.kernel.org To: Dave Hansen Cc: x86@kernel.org, platform-driver-x86@vger.kernel.org, linux-sgx@vger.kernel.org, sean.j.christopherson@intel.com, nhorman@redhat.com, npmccallum@redhat.com, serge.ayoun@intel.com, shay.katz-zamir@intel.com, haitao.huang@linux.intel.com, andriy.shevchenko@linux.intel.com, tglx@linutronix.de, kai.svahn@intel.com, mark.shanahan@intel.com, luto@amacapital.net, Suresh Siddha , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" , Darren Hart , Andy Shevchenko , "open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)" List-Id: platform-driver-x86.vger.kernel.org On Mon, Dec 17, 2018 at 09:45:40AM -0800, Dave Hansen wrote: > > +struct sgx_encl *sgx_encl_alloc(struct sgx_secs *secs) > > +{ > ... > > + kref_init(&encl->refcount); > > + INIT_LIST_HEAD(&encl->add_page_reqs); > > + INIT_RADIX_TREE(&encl->page_tree, GFP_KERNEL); > > + mutex_init(&encl->lock); > > + INIT_WORK(&encl->add_page_work, sgx_add_page_worker); > > + > > + encl->mm = current->mm; <---------------------------------> + encl->base = secs->base; > > + encl->size = secs->size; > > + encl->ssaframesize = secs->ssa_frame_size; > > + encl->backing = backing; > > + > > + return encl; > > +} > > How is this OK without taking a reference on the mm? > > I have a feeling a bunch of your bugs with the mmu notifiers and so > forth are because the refcounting is wrong here. > > Sean's SGX_ENCL_MM_RELEASED would, I think be unnecessary if you just > take a refcount here and release it when the enclave is destroyed. Right, atomic_inc(encl->mm->count) here and once when releasing. The we would not even need the whole mmu notifier in the first place. /Jarkko