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authorJay Cornwall <jay@jcornwall.me>2016-02-10 15:48:01 -0600
committerSasha Levin <sasha.levin@oracle.com>2016-03-09 13:15:09 -0500
commit15115bf3b764c4f2b36ea202f45181fd18d4a574 (patch)
tree39b6c2062eccbd89e2632acf3ddc0ce57aab2a5d
parent91d212c02743084892b687fb5cf166fffc01d0f9 (diff)
iommu/amd: Apply workaround for ATS write permission check
[ Upstream commit 358875fd52ab8f00f66328cbf1a1d2486f265829 ] The AMD Family 15h Models 30h-3Fh (Kaveri) BIOS and Kernel Developer's Guide omitted part of the BIOS IOMMU L2 register setup specification. Without this setup the IOMMU L2 does not fully respect write permissions when handling an ATS translation request. The IOMMU L2 will set PTE dirty bit when handling an ATS translation with write permission request, even when PTE RW bit is clear. This may occur by direct translation (which would cause a PPR) or by prefetch request from the ATC. This is observed in practice when the IOMMU L2 modifies a PTE which maps a pagecache page. The ext4 filesystem driver BUGs when asked to writeback these (non-modified) pages. Enable ATS write permission check in the Kaveri IOMMU L2 if BIOS has not. Signed-off-by: Jay Cornwall <jay@jcornwall.me> Cc: <stable@vger.kernel.org> # v3.19+ Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
-rw-r--r--drivers/iommu/amd_iommu_init.c29
1 files changed, 29 insertions, 0 deletions
diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 44c1c5701454..1750db0ef61c 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -1070,6 +1070,34 @@ static void amd_iommu_erratum_746_workaround(struct amd_iommu *iommu)
}
/*
+ * Family15h Model 30h-3fh (IOMMU Mishandles ATS Write Permission)
+ * Workaround:
+ * BIOS should enable ATS write permission check by setting
+ * L2_DEBUG_3[AtsIgnoreIWDis](D0F2xF4_x47[0]) = 1b
+ */
+static void amd_iommu_ats_write_check_workaround(struct amd_iommu *iommu)
+{
+ u32 value;
+
+ if ((boot_cpu_data.x86 != 0x15) ||
+ (boot_cpu_data.x86_model < 0x30) ||
+ (boot_cpu_data.x86_model > 0x3f))
+ return;
+
+ /* Test L2_DEBUG_3[AtsIgnoreIWDis] == 1 */
+ value = iommu_read_l2(iommu, 0x47);
+
+ if (value & BIT(0))
+ return;
+
+ /* Set L2_DEBUG_3[AtsIgnoreIWDis] = 1 */
+ iommu_write_l2(iommu, 0x47, value | BIT(0));
+
+ pr_info("AMD-Vi: Applying ATS write check workaround for IOMMU at %s\n",
+ dev_name(&iommu->dev->dev));
+}
+
+/*
* This function clues the initialization function for one IOMMU
* together and also allocates the command buffer and programs the
* hardware. It does NOT enable the IOMMU. This is done afterwards.
@@ -1343,6 +1371,7 @@ static int iommu_init_pci(struct amd_iommu *iommu)
}
amd_iommu_erratum_746_workaround(iommu);
+ amd_iommu_ats_write_check_workaround(iommu);
iommu->iommu_dev = iommu_device_create(&iommu->dev->dev, iommu,
amd_iommu_groups, "ivhd%d",