x86/amd-iommu: Workaround for erratum 63

commit c5cca146aa03e1f60fb179df65f0dbaf17bc64ed upstream.

There is an erratum for IOMMU hardware which documents
undefined behavior when forwarding SMI requests from
peripherals and the DTE of that peripheral has a sysmgt
value of 01b. This problem caused weird IO_PAGE_FAULTS in my
case.
This patch implements the suggested workaround for that
erratum into the AMD IOMMU driver.  The erratum is
documented with number 63.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index 3b06a9c..7d58f32 100644 (file)
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/arch/x86/kernel/amd_iommu_init.c
@@ -430,6 +430,27 @@ static void set_dev_entry_bit(u16 devid, u8 bit)
        amd_iommu_dev_table[devid].data[i] |= (1 << _bit);
 }
 
+static int get_dev_entry_bit(u16 devid, u8 bit)
+{
+       int i = (bit >> 5) & 0x07;
+       int _bit = bit & 0x1f;
+
+       return (amd_iommu_dev_table[devid].data[i] & (1 << _bit)) >> _bit;
+}
+
+
+void amd_iommu_apply_erratum_63(u16 devid)
+{
+       int sysmgt;
+
+       sysmgt = get_dev_entry_bit(devid, DEV_ENTRY_SYSMGT1) |
+               (get_dev_entry_bit(devid, DEV_ENTRY_SYSMGT2) << 1);
+
+       if (sysmgt == 0x01)
+               set_dev_entry_bit(devid, DEV_ENTRY_IW);
+}
+
+
 /* Writes the specific IOMMU for a device into the rlookup table */
 static void __init set_iommu_for_device(struct amd_iommu *iommu, u16 devid)
 {
@@ -458,6 +479,8 @@ static void __init set_dev_entry_from_acpi(struct amd_iommu *iommu,
        if (flags & ACPI_DEVFLAG_LINT1)
                set_dev_entry_bit(devid, DEV_ENTRY_LINT1_PASS);
 
+       amd_iommu_apply_erratum_63(devid);
+
        set_iommu_for_device(iommu, devid);
 }