This is a note to let you know that I've just added the patch titled
iommu/vt-d: Fix passthrough mode with translation-disabled devices
to the 4.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
iommu-vt-d-fix-passthrough-mode-with-translation-disabled-devices.patch
and it can be found in the queue-4.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 4ed6a540fab8ea4388c1703b73ecfed68a2009d1 Mon Sep 17 00:00:00 2001
From: David Woodhouse <David.Woodhouse@xxxxxxxxx>
Date: Mon, 11 May 2015 14:59:20 +0100
Subject: iommu/vt-d: Fix passthrough mode with translation-disabled devices
From: David Woodhouse <David.Woodhouse@xxxxxxxxx>
commit 4ed6a540fab8ea4388c1703b73ecfed68a2009d1 upstream.
When we use 'intel_iommu=igfx_off' to disable translation for the
graphics, and when we discover that the BIOS has misconfigured the DMAR
setup for I/OAT, we use a special DUMMY_DEVICE_DOMAIN_INFO value in
dev->archdata.iommu to indicate that translation is disabled.
With passthrough mode, we were attempting to dereference that as a
normal pointer to a struct device_domain_info when setting up an
identity mapping for the affected device.
This fixes the problem by making device_to_iommu() explicitly check for
the special value and indicate that no IOMMU was found to handle the
devices in question.
Signed-off-by: David Woodhouse <David.Woodhouse@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/iommu/intel-iommu.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -673,6 +673,11 @@ static void domain_update_iommu_cap(stru
domain->iommu_superpage = domain_update_iommu_superpage(NULL);
}
+static int iommu_dummy(struct device *dev)
+{
+ return dev->archdata.iommu == DUMMY_DEVICE_DOMAIN_INFO;
+}
+
static struct intel_iommu *device_to_iommu(struct device *dev, u8 *bus, u8 *devfn)
{
struct dmar_drhd_unit *drhd = NULL;
@@ -682,6 +687,9 @@ static struct intel_iommu *device_to_iom
u16 segment = 0;
int i;
+ if (iommu_dummy(dev))
+ return NULL;
+
if (dev_is_pci(dev)) {
pdev = to_pci_dev(dev);
segment = pci_domain_nr(pdev->bus);
@@ -2974,11 +2982,6 @@ static inline struct dmar_domain *get_va
return __get_valid_domain_for_dev(dev);
}
-static int iommu_dummy(struct device *dev)
-{
- return dev->archdata.iommu == DUMMY_DEVICE_DOMAIN_INFO;
-}
-
/* Check if the dev needs to go through non-identity map and unmap process.*/
static int iommu_no_mapping(struct device *dev)
{
Patches currently in stable-queue which might be from David.Woodhouse@xxxxxxxxx are
queue-4.0/iommu-vt-d-fix-passthrough-mode-with-translation-disabled-devices.patch
queue-4.0/iommu-vt-d-allow-rmrr-on-graphics-devices-too.patch
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