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Date: Tue, 2 Jun 2020 18:43:00 +0000 From: Rajat Jain <rajatja@...gle.com> To: Mika Westerberg <mika.westerberg@...el.com> Cc: David Woodhouse <dwmw2@...radead.org>, Lu Baolu <baolu.lu@...ux.intel.com>, Joerg Roedel <joro@...tes.org>, iommu@...ts.linux-foundation.org, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, Ashok Raj <ashok.raj@...el.com>, "Krishnakumar, Lalithambika" <lalithambika.krishnakumar@...el.com>, Rajat Jain <rajatxjain@...il.com>, Prashant Malani <pmalani@...gle.com>, Benson Leung <bleung@...gle.com>, Alex Levin <levinale@...gle.com>, Zubin Mithra <zsm@...gle.com>, Mattias Nissler <mnissler@...gle.com>, Todd Broch <tbroch@...gle.com> Subject: Re: [PATCH] iommu/vt-d: Don't apply gfx quirks to untrusted devices Hi MIka, Thanks for taking a look. On Tue, Jun 2, 2020 at 2:50 AM Mika Westerberg <mika.westerberg@...el.com> wrote: > > On Mon, Jun 01, 2020 at 10:45:17PM -0700, Rajat Jain wrote: > > Currently, an external malicious PCI device can masquerade the VID:PID > > of faulty gfx devices, and thus apply iommu quirks to effectively > > disable the IOMMU restrictions for itself. > > > > Thus we need to ensure that the device we are applying quirks to, is > > indeed an internal trusted device. > > > > Signed-off-by: Rajat Jain <rajatja@...gle.com> > > --- > > drivers/iommu/intel-iommu.c | 28 ++++++++++++++++++++++++++++ > > 1 file changed, 28 insertions(+) > > > > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > > index ef0a5246700e5..f2a480168a02f 100644 > > --- a/drivers/iommu/intel-iommu.c > > +++ b/drivers/iommu/intel-iommu.c > > @@ -6214,6 +6214,11 @@ const struct iommu_ops intel_iommu_ops = { > > > > static void quirk_iommu_igfx(struct pci_dev *dev) > > { > > + if (dev->untrusted) { > > + pci_warn(dev, "skipping iommu quirk for untrusted gfx dev\n"); > > I think you should be consistent with other messages. For example iommu > should be spelled IOMMU as done below. > > Also this is visible to users so maybe put bit more information there: > > pci_warn(dev, "Will not apply IOMMU quirk for untrusted graphics device\n"); > > Ditto for all the other places. Also is "untrusted" good word here? If > an ordinary user sees this will it trigger some sort of panic reaction. > Perhaps we should call it "potentially untrusted" or something like > that? Fixed it, posted new patch at https://lkml.org/lkml/2020/6/2/822 Thanks, Rajat > > > + return; > > + } > > + > > pci_info(dev, "Disabling IOMMU for graphics on this chipset\n"); > > dmar_map_gfx = 0;
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