From: Suravee Suthikulpanit <suravee.suthikulpa...@amd.com>
Changes in V3:
* Add proper commit message
* Change logic to avoid unnecessary indentaion
Changes in V2:
* Fix logic that check the processor model.
* Clear write enable bit after apply workaround
* Change function name
Commit Message:
Erratum 746: IOMMU Logging May Stall Transaction
Workaround: BIOS should disable L2B micellaneous clock gating by setting
L2_L2B_CK_GATE_CONTROL[CKGateL2BMiscDisable](D0F2xF4_x90[2]) = 1b
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpa...@amd.com>
diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 81837b0..934b017 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -975,6 +975,38 @@ static void __init free_iommu_all(void)
}
/*
+ * AMD family15h Model 10h-1fh erratum 746 (IOMMU Logging May Stall
Translations)
+ * Workaround:
+ * BIOS should disable L2B micellaneous clock gating by setting
+ * L2_L2B_CK_GATE_CONTROL[CKGateL2BMiscDisable](D0F2xF4_x90[2]) = 1b
+ */
+static void __init amd_iommu_erratum_746_workaround(struct amd_iommu *iommu)
+{
+ u32 value;
+
+ if ((boot_cpu_data.x86 != 0x15) ||
+ (boot_cpu_data.x86_model < 0x10) ||
+ (boot_cpu_data.x86_model > 0x1f))
+ return;
+
+ pci_write_config_dword(iommu->dev, 0xf0, 0x90);
+ pci_read_config_dword(iommu->dev, 0xf4, &value);
+
+ if (value & BIT(2))
+ return;
+
+ /* Select NB indirect register 0x90 and enable writing */
+ pci_write_config_dword(iommu->dev, 0xf0, 0x90 | (1 << 8));
+
+ pci_write_config_dword(iommu->dev, 0xf4, value | 0x4);
+ pr_info("AMD-Vi: Applying erratum 746 workaround for IOMMU at %s\n",
+ dev_name(&iommu->dev->dev));
+
+ /* Clear the enable writing bit */
+ pci_write_config_dword(iommu->dev, 0xf0, 0x90);
+}
+
+/*
* 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.
@@ -1171,6 +1203,8 @@ static int iommu_init_pci(struct amd_iommu *iommu)
for (i = 0; i < 0x83; i++)
iommu->stored_l2[i] = iommu_read_l2(iommu, i);
}
+
+ amd_iommu_erratum_746_workaround(iommu);
return pci_enable_device(iommu->dev);
}
--
1.7.10.4
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