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Sat, 18 Jul 2020 05:51:06 +0000 (UTC) IronPort-SDR: +9v1tGWUJu2Aym3LoZHEKeN33XE6SMwzc6ksYQtTZQgJBQkdE0Baq7sMfySrPYQOnZEdOWX2t1 1j2Mzo7bCKZA== X-IronPort-AV: E=McAfee;i="6000,8403,9685"; a="129798716" X-IronPort-AV: E=Sophos;i="5.75,365,1589266800"; d="scan'208";a="129798716" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jul 2020 22:51:04 -0700 IronPort-SDR: Bc8yS/Mga/P/JELyDS9maVNQZIck4wfEmlGO3VkOyOrNQb8SVgJAdVZL/lTq/KBuOwtXK2wrMt piSYLWsQeJ9A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,365,1589266800"; d="scan'208";a="282993538" Received: from iweiny-desk2.sc.intel.com ([10.3.52.147]) by orsmga003.jf.intel.com with ESMTP; 17 Jul 2020 22:51:04 -0700 Date: Fri, 17 Jul 2020 22:51:03 -0700 From: Ira Weiny To: Peter Zijlstra Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Andy Lutomirski , x86@kernel.org, Dave Hansen , Dan Williams , Vishal Verma , Andrew Morton , Fenghua Yu , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH RFC V2 12/17] memremap: Add zone device access protection Message-ID: <20200718055103.GU3008823@iweiny-DESK2.sc.intel.com> References: <20200717072056.73134-1-ira.weiny@intel.com> <20200717072056.73134-13-ira.weiny@intel.com> <20200717091718.GA10769@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200717091718.GA10769@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.11.1 (2018-12-01) X-Rspamd-Queue-Id: D01E5168412 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Jul 17, 2020 at 11:17:18AM +0200, Peter Zijlstra wrote: > On Fri, Jul 17, 2020 at 12:20:51AM -0700, ira.weiny@intel.com wrote: > > +void dev_access_disable(void) > > +{ > > + unsigned long flags; > > + > > + if (!static_branch_unlikely(&dev_protection_static_key)) > > + return; > > + > > + local_irq_save(flags); > > + current->dev_page_access_ref--; > > + if (current->dev_page_access_ref == 0) > > if (!--current->dev_page_access_ref) It's not my style but I'm ok with it. > > > + pks_update_protection(dev_page_pkey, PKEY_DISABLE_ACCESS); > > + local_irq_restore(flags); > > +} > > +EXPORT_SYMBOL_GPL(dev_access_disable); > > + > > +void dev_access_enable(void) > > +{ > > + unsigned long flags; > > + > > + if (!static_branch_unlikely(&dev_protection_static_key)) > > + return; > > + > > + local_irq_save(flags); > > + /* 0 clears the PKEY_DISABLE_ACCESS bit, allowing access */ > > + if (current->dev_page_access_ref == 0) > > + pks_update_protection(dev_page_pkey, 0); > > + current->dev_page_access_ref++; > > if (!current->dev_page_access_ref++) Sure. > > > + local_irq_restore(flags); > > +} > > +EXPORT_SYMBOL_GPL(dev_access_enable); > > > Also, you probably want something like: > > static __always_inline devm_access_disable(void) Yes that is better. However, again Dan and I agree devm is not the right prefix here. I've updated. Thanks! Ira > { > if (static_branch_unlikely(&dev_protection_static_key)) > __devm_access_disable(); > } > > static __always_inline devm_access_enable(void) > { > if (static_branch_unlikely(&dev_protection_static_key)) > __devm_access_enable(); > }