iommu/amd: Suppress IO_PAGE_FAULTs in kdump kernel

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 <jroedel@suse.de>

drivers/iommu/amd_iommu.c

@@ -2078,7 +2078,8 @@ 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;

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>
@@ -1900,6 +1901,14 @@ 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);
 	}
 }
 

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)