[PATCH 1/1] AMD Family15h Model10-1Fh erratum 746 Workaround

[PATCH 1/1] AMD Family15h Model10-1Fh erratum 746 Workaround

[suravee.suthikulpanit]

From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>

This patch implements workaround for the AMD Family15h Model10-1Fh erratum 746.

(http://support.amd.com/us/Processor_TechDocs/48931_15h_Mod_10h-1Fh_Rev_Guide.pdf)

Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>

diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 81837b0..26c0448 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -975,6 +975,30 @@ 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_apply_erratum_746(struct amd_iommu *iommu)
+{
+	u32 value;
+
+	if ((boot_cpu_data.x86 != 0x15) || !(boot_cpu_data.x86_model & 0x10))
+		return;
+	
+	/* Select Northbridge indirect register 0x90 and enable writing */
+	pci_write_config_dword(iommu->dev, 0xf0, 0x90 | (1 << 8));
+	pci_read_config_dword(iommu->dev, 0xf4, &value); 
+
+	if (!(value & 0x4)) {
+		pci_write_config_dword(iommu->dev, 0xf4, value | 0x4);
+		pr_info("AMD-Vi: Applying erratum 746 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.
@@ -1171,6 +1195,8 @@ 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_apply_erratum_746(iommu);
 
 	return pci_enable_device(iommu->dev);
 }
-- 
1.7.10.4

Re: [PATCH 1/1] AMD Family15h Model10-1Fh erratum 746 Workaround

[Joerg Roedel]

On Tue, Jan 22, 2013 at 05:19:10PM -0600, Suthikulpanit, Suravee wrote:
> From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
> @@ -1171,6 +1195,8 @@ 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_apply_erratum_746(iommu);

This will also be applied to RD890 IOMMUs, right? This workaround should
be limited to Trinity IOMMUs.

Udo, can you please test if you can trigger the erratum again with this
patch?


	Joerg

Re: [PATCH 1/1] AMD Family15h Model10-1Fh erratum 746 Workaround

[Suravee Suthikulpanit]

On 1/23/2013 1:06 AM, Joerg Roedel wrote:

> On Tue, Jan 22, 2013 at 05:19:10PM -0600, Suthikulpanit, Suravee wrote:
>> From: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
>> @@ -1171,6 +1195,8 @@ 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_apply_erratum_746(iommu);
> This will also be applied to RD890 IOMMUs, right? This workaround should
> be limited to Trinity IOMMUs.

Inside the function, it checks the family and model number.  Only Trinitiy is affected.

Suravee