x86/amd-iommu: Workaround for erratum 63

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.

Cc: stable@kernel.org
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>

diff --git a/arch/x86/include/asm/amd_iommu.h b/arch/x86/include/asm/amd_iommu.h
index bdf96f1..9dbd403 100644 (file)
--- a/arch/x86/include/asm/amd_iommu.h
+++ b/arch/x86/include/asm/amd_iommu.h
@@ -30,6 +30,7 @@ extern irqreturn_t amd_iommu_int_handler(int irq, void *data);
 extern void amd_iommu_flush_all_domains(void);
 extern void amd_iommu_flush_all_devices(void);
 extern void amd_iommu_shutdown(void);
+extern void amd_iommu_apply_erratum_63(u16 devid);
 #else
 static inline int amd_iommu_init(void) { return -ENODEV; }
 static inline void amd_iommu_detect(void) { }

diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c
index 6c99f50..f95dfe5 100644 (file)
--- a/arch/x86/kernel/amd_iommu.c
+++ b/arch/x86/kernel/amd_iommu.c
@@ -1114,6 +1114,8 @@ static void __detach_device(struct protection_domain *domain, u16 devid)
        amd_iommu_dev_table[devid].data[1] = 0;
        amd_iommu_dev_table[devid].data[2] = 0;
 
+       amd_iommu_apply_erratum_63(devid);
+
        /* decrease reference counter */
        domain->dev_cnt -= 1;
 

diff --git a/arch/x86/kernel/amd_iommu_init.c b/arch/x86/kernel/amd_iommu_init.c
index c1b17e9..498c8c7 100644 (file)
--- a/arch/x86/kernel/amd_iommu_init.c
+++ b/arch/x86/kernel/amd_iommu_init.c
@@ -509,6 +509,26 @@ 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)
 {
@@ -537,6 +557,8 @@ 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);
 }