From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mika Westerberg Subject: Re: [PATCH 1/4] PCI / ACPI: Identify external PCI devices Date: Thu, 15 Nov 2018 21:32:01 +0200 Message-ID: <20181115193201.GF4179@lahna.fi.intel.com> References: <20181113114527.GA12821@e107981-ln.cambridge.arm.com> <20181115102239.GU2500@lahna.fi.intel.com> <20181115111356.GA599@e107981-ln.cambridge.arm.com> <20181115113737.GW2500@lahna.fi.intel.com> <20181115120736.pscly6zwd3k2tvd2@wunner.de> <20181115121627.GA2500@lahna.fi.intel.com> <20181115174608.GA17691@e107981-ln.cambridge.arm.com> <20181115191026.GE4179@lahna.fi.intel.com> <20181115192741.4ugt6usmsemokxle@wunner.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20181115192741.4ugt6usmsemokxle@wunner.de> Sender: linux-kernel-owner@vger.kernel.org To: Lukas Wunner Cc: Yehezkel Bernat , lorenzo.pieralisi@arm.com, iommu@lists.linux-foundation.org, joro@8bytes.org, David Woodhouse , baolu.lu@linux.intel.com, ashok.raj@intel.com, Bjorn Helgaas , rjw@rjwysocki.net, jacob.jun.pan@intel.com, Andreas Noever , michael.jamet@intel.com, Christian Kellner , Mario Limonciello , Anthony Wong , linux-acpi@vger.kernel.org, linux-pci@vger.kernel.org, LKML List-Id: linux-acpi@vger.kernel.org On Thu, Nov 15, 2018 at 08:27:41PM +0100, Lukas Wunner wrote: > On Thu, Nov 15, 2018 at 09:10:26PM +0200, Mika Westerberg wrote: > > I was thinking we could cover all these with is_external filling them > > based on the _DSD or some other means in the kernel. > > > > We would then deal all such devices as "untrusted" by default. > > Tinfoil hat on, even internal devices could be malicious. > What's the downside of enabling the feature for everything? Mostly performance, I think. That's the main reason we put all non external devices to passthrough IOMMU mode.