linux-kernel - [PATCH v9 02/10] iommu/vt-d: Items required for kdump

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Date:	Thu, 19 Mar 2015 13:36:20 +0800
From:	"Li, Zhen-Hua" <zhen-hual@...com>
To:	<dwmw2@...radead.org>, <indou.takao@...fujitsu.com>,
	<bhe@...hat.com>, <joro@...tes.org>, <vgoyal@...hat.com>,
	<dyoung@...hat.com>
Cc:	<iommu@...ts.linux-foundation.org>, <linux-kernel@...r.kernel.org>,
	<linux-pci@...r.kernel.org>, <kexec@...ts.infradead.org>,
	<alex.williamson@...hat.com>, <ddutile@...hat.com>,
	<ishii.hironobu@...fujitsu.com>, <bhelgaas@...gle.com>,
	<doug.hatch@...com>, <jerry.hoemann@...com>, <tom.vaden@...com>,
	<li.zhang6@...com>, <lisa.mitchell@...com>,
	<billsumnerlinux@...il.com>, <zhen-hual@...com>, <rwright@...com>
Subject: [PATCH v9 02/10] iommu/vt-d: Items required for kdump

Add context entry functions needed for kdump.

Bill Sumner:
    Original version;

Li, Zhenhua:
    Changed the name of new functions, make them consistent with current
    context get/set functions.
    Remove the structure dve which is not used in new version.

Signed-off-by: Bill Sumner <billsumnerlinux@...il.com>
Signed-off-by: Li, Zhen-Hua <zhen-hual@...com>
---
 drivers/iommu/intel-iommu.c | 56 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 76674a1..577d5de 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -40,6 +40,7 @@
 #include <linux/pci-ats.h>
 #include <linux/memblock.h>
 #include <linux/dma-contiguous.h>
+#include <linux/crash_dump.h>
 #include <asm/irq_remapping.h>
 #include <asm/cacheflush.h>
 #include <asm/iommu.h>
@@ -211,6 +212,12 @@ get_context_addr_from_root(struct root_entry *root)
 		NULL);
 }
 
+static inline unsigned long
+get_context_phys_from_root(struct root_entry *root)
+{
+	return  root_present(root) ? (root->val & VTD_PAGE_MASK) : 0;
+}
+
 /*
  * low 64 bits:
  * 0: present
@@ -231,6 +238,32 @@ static inline bool context_present(struct context_entry *context)
 {
 	return (context->lo & 1);
 }
+
+static inline int context_fault_enable(struct context_entry *c)
+{
+	return((c->lo >> 1) & 0x1);
+}
+
+static inline int context_translation_type(struct context_entry *c)
+{
+	return((c->lo >> 2) & 0x3);
+}
+
+static inline u64 context_address_root(struct context_entry *c)
+{
+	return((c->lo >> VTD_PAGE_SHIFT));
+}
+
+static inline int context_address_width(struct context_entry *c)
+{
+	return((c->hi >> 0) & 0x7);
+}
+
+static inline int context_domain_id(struct context_entry *c)
+{
+	return((c->hi >> 8) & 0xffff);
+}
+
 static inline void context_set_present(struct context_entry *context)
 {
 	context->lo |= 1;
@@ -316,6 +349,29 @@ static inline int first_pte_in_page(struct dma_pte *pte)
 	return !((unsigned long)pte & ~VTD_PAGE_MASK);
 }
 
+
+#ifdef CONFIG_CRASH_DUMP
+
+/*
+ * Fix Crashdump failure caused by leftover DMA through a hardware IOMMU
+ *
+ * Fixes the crashdump kernel to deal with an active iommu and legacy
+ * DMA from the (old) panicked kernel in a manner similar to how legacy
+ * DMA is handled when no hardware iommu was in use by the old kernel --
+ * allow the legacy DMA to continue into its current buffers.
+ *
+ * In the crashdump kernel, this code:
+ * 1. skips disabling the IOMMU's translating.
+ * 2. Do not re-enable IOMMU's translating.
+ * 3. In kdump kernel, use the old root entry table.
+ * 4. Allocate pages for new context entry, copy data from old context entries
+ *    in the old kernel to the new ones.
+ *
+ */
+
+
+#endif /* CONFIG_CRASH_DUMP */
+
 /*
  * This domain is a statically identity mapping domain.
  *	1. This domain creats a static 1:1 mapping to all usable memory.
-- 
2.0.0-rc0

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