[PATCH] iommu/amd: Suppress IO_PAGE_FAULTs in kdump kernel

[Joerg Roedel]

From: Joerg Roedel <jroe...@suse.de>

When booting into a kdump kernel, suppress IO_PAGE_FAULTs by
default for all devices. But allow the faults again when a
domain is assigned to a device.

Signed-off-by: Joerg Roedel <jroe...@suse.de>
---
 drivers/iommu/amd_iommu.c       | 3 ++-
 drivers/iommu/amd_iommu_init.c  | 9 +++++++++
 drivers/iommu/amd_iommu_types.h | 1 +
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 80efa72..623ab53 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -2050,7 +2050,8 @@ static void set_dte_entry(u16 devid, struct 
protection_domain *domain, bool ats)
                flags    |= tmp;
        }
 
-       flags &= ~(0xffffUL);
+
+       flags &= ~(DTE_FLAG_SA | 0xffffULL);
        flags |= domain->id;
 
        amd_iommu_dev_table[devid].data[1]  = flags;
diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 5a11328..d9f5ddd 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -29,6 +29,7 @@
 #include <linux/export.h>
 #include <linux/iommu.h>
 #include <linux/kmemleak.h>
+#include <linux/crash_dump.h>
 #include <asm/pci-direct.h>
 #include <asm/iommu.h>
 #include <asm/gart.h>
@@ -1898,6 +1899,14 @@ static void init_device_table_dma(void)
        for (devid = 0; devid <= amd_iommu_last_bdf; ++devid) {
                set_dev_entry_bit(devid, DEV_ENTRY_VALID);
                set_dev_entry_bit(devid, DEV_ENTRY_TRANSLATION);
+               /*
+                * In kdump kernels in-flight DMA from the old kernel might
+                * cause IO_PAGE_FAULTs. There are no reports that a kdump
+                * actually failed because of that, so just disable fault
+                * reporting in the hardware to get rid of the messages
+                */
+               if (is_kdump_kernel())
+                       set_dev_entry_bit(devid, DEV_ENTRY_NO_PAGE_FAULT);
        }
 }
 
diff --git a/drivers/iommu/amd_iommu_types.h b/drivers/iommu/amd_iommu_types.h
index 4de8f41..4cad9b3 100644
--- a/drivers/iommu/amd_iommu_types.h
+++ b/drivers/iommu/amd_iommu_types.h
@@ -322,6 +322,7 @@
 #define IOMMU_PTE_IW (1ULL << 62)
 
 #define DTE_FLAG_IOTLB (1ULL << 32)
+#define DTE_FLAG_SA    (1ULL << 34)
 #define DTE_FLAG_GV    (1ULL << 55)
 #define DTE_FLAG_MASK  (0x3ffULL << 32)
 #define DTE_GLX_SHIFT  (56)
-- 
2.7.4