linux-kernel - Re: AMD IOMMU causing filesystem corruption

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Date:   Fri, 7 Apr 2017 12:27:39 +0200
From:   Joerg Roedel <joro@...tes.org>
To:     Samuel Sieb <samuel@...b.net>
Cc:     Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: AMD IOMMU causing filesystem corruption

On Tue, Apr 04, 2017 at 09:29:37AM -0700, Samuel Sieb wrote:
> That's what I did.  While running with iommu=off, I compiled and
> installed a 4.11rc kernel with the patch.  I rebooted to use that
> kernel and then compiled and installed a 4.10 kernel with that patch
> and another unrelated patch.  That is what I described above.  The
> filesystem destruction happened while running the 4.11rc kernel with
> that patch.  Is there any way to verify that the patch was actually
> having any effect?  Can I check if ATS is enabled or not?  I will
> have to rebuild the system before I can test again.

Also, please try the attached debug-diff on your kernel. It completly
disables the use of ATS in the amd-iommu driver.

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 98940d1392cb..f019aa67c54c 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -467,7 +467,7 @@ static int iommu_init_device(struct device *dev)
 		struct amd_iommu *iommu;
 
 		iommu = amd_iommu_rlookup_table[dev_data->devid];
-		dev_data->iommu_v2 = iommu->is_iommu_v2;
+		dev_data->iommu_v2 = false;
 	}
 
 	dev->archdata.iommu = dev_data;
diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 6130278c5d71..41d0e645960c 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -171,7 +171,7 @@ int amd_iommus_present;
 
 /* IOMMUs have a non-present cache? */
 bool amd_iommu_np_cache __read_mostly;
-bool amd_iommu_iotlb_sup __read_mostly = true;
+bool amd_iommu_iotlb_sup __read_mostly = false;
 
 u32 amd_iommu_max_pasid __read_mostly = ~0;