From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH v7 0/5] Add Intel IOMMU debugfs support Date: Thu, 29 Mar 2018 10:48:24 +0200 Message-ID: <20180329084824.fvy7cg2wban4by4n@8bytes.org> References: <1517619001-148586-1-git-send-email-sohil.mehta@intel.com> <20180213140303.42mbzfxpypljy37l@8bytes.org> <20180213214002.GA27066@otc-nc-03> <20180213145332.35c73eda@jacob-builder> <20180215095337.fccoozdclfnbepi4@8bytes.org> <20180215083811.3ec86e49@jacob-builder> <20180315131854.s6xmltsvsysublcw@8bytes.org> <20180319093714.3afe698b@jacob-builder> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20180319093714.3afe698b@jacob-builder> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Jacob Pan Cc: Ravi V Shankar , "Raj, Ashok" , Fenghua Yu , iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Andy Shevchenko , David Woodhouse , Gayatri Kammela List-Id: iommu@lists.linux-foundation.org [ Adding Gary from AMD to Cc ] On Mon, Mar 19, 2018 at 09:37:14AM -0700, Jacob Pan wrote: > On Thu, 15 Mar 2018 14:18:54 +0100 > Joerg Roedel wrote: > > > On Thu, Feb 15, 2018 at 08:38:11AM -0800, Jacob Pan wrote: > > > Just wondering if your concern is on the implementation or the > > > debugfs idea in general. Perhaps have some common IOMMU debugfs? > > > > My concern mainly is that we add interfaces which reveal > > potentially security relevant information > I don;t think security is any worse than existing kernel page table in > debugfs. i.e. /sys/kernel/debug/page_tables > This is a debug feature. Okay, so here is the way to go: Please introduce a basic debugfs facility to the core iommu code. It should basically only create a 'iommu/' directory in debugfs where drivers can create their own sub-directories. This must be enabled by a new kconfig option (CONFIG_IOMMU_DEBUGFS) and the kernel should print a big fat warning at boot when it is enabled. This hopefully prevents anyone from enabling it for production kernels. Then in the next cycle I will review again more closely what information about VT-d and AMD-Vi is revealed there and will probably apply what I can live with. Thanks, Joerg