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intel-iommu:make identity_map default for crash dump

PATCH In review Dave Young 2 participants 2 messages Oct 21, 2011 – Oct 22, 2011

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Dave Young

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#0 lore raw

PATCH 1/1 intel-iommu:make identity_map default for crash dump

kdump kernel sometimes will get DMAR faults which
is caused by random in-flight dma from 1st kernel

Here make the identity_mapping as default for this case

Signed-off-by Dave Young <[email protected]>
---
 drivers/iommu/intel-iommu.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)
drivers/iommu/intel-iommu.c +2 -1
index c621c98..8ac3895 100644
@@ -40,6 +40,7 @@
 #include <linux/tboot.h>
 #include <linux/dmi.h>
 #include <linux/pci-ats.h>
+#include <linux/crash_dump.h>
 #include <asm/cacheflush.h>
 #include <asm/iommu.h>
 

@@ -2481,7 +2482,7 @@ static int __init init_dmars(void)
 		}
 	}
 
-	if (iommu_pass_through)
+	if (iommu_pass_through || is_kdump_kernel())
 		iommu_identity_mapping |= IDENTMAP_ALL;
 
 #ifdef CONFIG_DMAR_BROKEN_GFX_WA
Signature · 7 lines
1.7.4.4


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#1 lore raw
Quoted 4 lines · Dave Young

kdump kernel sometimes will get DMAR faults which
is caused by random in-flight dma from 1st kernel

Here make the identity_mapping as default for this case

This seems reasonable to me. Although I am curious to know what the side effects of using IDENTMAP_ALL might be.