From: "Raj, Ashok" <ashok.raj@intel.com>
To: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: iommu@lists.linux-foundation.org, Joerg Roedel <joro@8bytes.org>,
David Woodhouse <dwmw2@infradead.org>,
Lu Baolu <baolu.lu@linux.intel.com>,
Bjorn Helgaas <bhelgaas@google.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Jacob jun Pan <jacob.jun.pan@intel.com>,
Andreas Noever <andreas.noever@gmail.com>,
Michael Jamet <michael.jamet@intel.com>,
Yehezkel Bernat <YehezkelShB@gmail.com>,
Lukas Wunner <lukas@wunner.de>,
Christian Kellner <ckellner@redhat.com>,
Mario.Limonciello@dell.com,
Anthony Wong <anthony.wong@canonical.com>,
linux-acpi@vger.kernel.org, linux-pci@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/4] iommu/vt-d: Do not enable ATS for external devices
Date: Mon, 12 Nov 2018 09:53:28 -0800 [thread overview]
Message-ID: <20181112175327.GC30341@araj-mobl1.jf.intel.com> (raw)
In-Reply-To: <20181112160628.86620-4-mika.westerberg@linux.intel.com>
On Mon, Nov 12, 2018 at 07:06:27PM +0300, Mika Westerberg wrote:
> Currently Linux automatically enables ATS (Address Translation Service)
> for any device that supports it (and IOMMU is turned on). ATS is used to
> accelerate DMA access as the device can cache translations locally so
> there is no need to do full translation on IOMMU side. However, as
> pointed out in [1] ATS can be used to bypass IOMMU based security
> completely by simply sending PCIe read/write transaction with AT
> (Address Translation) field set to "translated".
>
> To mitigate this modify the Intel IOMMU code so that it does not enable
> ATS for any device that is marked as being external. In case this turns
> out to cause performance issues we may selectively allow ATS based on
> user decision but currently use big hammer and disable it completely to
> be on the safe side.
>
> [1] https://www.repository.cam.ac.uk/handle/1810/274352
>
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Ashok Raj <ashok.raj@intel.com>
> ---
> drivers/iommu/intel-iommu.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
> index ada786b05a59..b79788da6971 100644
> --- a/drivers/iommu/intel-iommu.c
> +++ b/drivers/iommu/intel-iommu.c
> @@ -1473,7 +1473,8 @@ static void iommu_enable_dev_iotlb(struct device_domain_info *info)
> if (info->pri_supported && !pci_reset_pri(pdev) && !pci_enable_pri(pdev, 32))
> info->pri_enabled = 1;
> #endif
> - if (info->ats_supported && !pci_enable_ats(pdev, VTD_PAGE_SHIFT)) {
> + if (!pdev->is_external && info->ats_supported &&
> + !pci_enable_ats(pdev, VTD_PAGE_SHIFT)) {
> info->ats_enabled = 1;
> domain_update_iotlb(info->domain);
> info->ats_qdep = pci_ats_queue_depth(pdev);
> --
> 2.19.1
>
next prev parent reply other threads:[~2018-11-12 17:53 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-12 16:06 [PATCH 0/4] PCI / iommu / thunderbolt: IOMMU based DMA protection Mika Westerberg
2018-11-12 16:06 ` [PATCH 1/4] PCI / ACPI: Identify external PCI devices Mika Westerberg
2018-11-12 18:02 ` Lukas Wunner
2018-11-13 10:56 ` Lorenzo Pieralisi
2018-11-13 11:27 ` Mika Westerberg
2018-11-13 11:45 ` Lorenzo Pieralisi
2018-11-15 10:22 ` Mika Westerberg
2018-11-15 11:13 ` Lorenzo Pieralisi
2018-11-15 11:37 ` Mika Westerberg
2018-11-15 12:07 ` Lukas Wunner
2018-11-15 12:16 ` Mika Westerberg
2018-11-15 17:46 ` Lorenzo Pieralisi
2018-11-15 17:58 ` Yehezkel Bernat
2018-11-15 19:10 ` Mika Westerberg
2018-11-15 19:27 ` Lukas Wunner
2018-11-15 19:32 ` Mika Westerberg
2018-11-16 9:18 ` Christoph Hellwig
2018-11-16 9:32 ` Mika Westerberg
2018-11-22 10:48 ` Mika Westerberg
2018-11-22 10:59 ` Christoph Hellwig
2018-11-15 19:00 ` Mika Westerberg
2018-11-15 19:33 ` Mario.Limonciello
2018-11-16 10:57 ` Lorenzo Pieralisi
2018-11-20 21:43 ` Rafael J. Wysocki
2018-11-21 12:40 ` Lorenzo Pieralisi
2018-11-16 7:01 ` Mika Westerberg
2018-11-12 16:06 ` [PATCH 2/4] iommu/vt-d: Force IOMMU on for platform opt in hint Mika Westerberg
2018-11-12 17:49 ` Raj, Ashok
2018-11-12 18:09 ` Alex Williamson
2018-11-12 19:51 ` Raj, Ashok
2018-11-12 16:06 ` [PATCH 3/4] iommu/vt-d: Do not enable ATS for external devices Mika Westerberg
2018-11-12 17:53 ` Raj, Ashok [this message]
2018-11-12 16:06 ` [PATCH 4/4] thunderbolt: Export IOMMU based DMA protection support to userspace Mika Westerberg
2018-11-12 16:22 ` Mario.Limonciello
2018-11-13 10:36 ` Mika Westerberg
2018-11-12 16:59 ` Yehezkel Bernat
2018-11-13 10:55 ` Mika Westerberg
2018-11-13 11:13 ` Yehezkel Bernat
2018-11-13 11:40 ` Mika Westerberg
2018-11-13 14:42 ` Yehezkel Bernat
[not found] ` <20181113152038.GD2500@lahna.fi.intel.com>
2018-11-13 15:38 ` Yehezkel Bernat
2018-11-13 16:12 ` Mika Westerberg
2018-11-12 18:12 ` [PATCH 0/4] PCI / iommu / thunderbolt: IOMMU based DMA protection Lukas Wunner
2018-11-12 19:04 ` Yehezkel Bernat
2018-11-13 11:13 ` Mika Westerberg
2018-11-13 8:54 ` Joerg Roedel
2018-11-13 11:32 ` Mika Westerberg
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