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

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Message-Id: <1419239729-26529-3-git-send-email-zhen-hual@hp.com>
Date:	Mon, 22 Dec 2014 17:15:21 +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>
Subject: [PATCH 02/10] iommu/vt-d: Items required for kdump

Add structure type domain_values_entry used 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.

Signed-off-by: Bill Sumner <billsumnerlinux@...il.com>
Signed-off-by: Li, Zhen-Hua <zhen-hual@...com>
---
 drivers/iommu/intel-iommu.c | 70 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 70 insertions(+)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 2dc6250..5ce2850 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>
@@ -208,6 +209,12 @@ 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
@@ -228,6 +235,32 @@ 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;
@@ -313,6 +346,43 @@ 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 of IO Virtual Addresses (IOVA).
+ * 2. Do not re-enable IOMMU's translating.
+ * 3. In kdump kernel, use the old root entry table.
+ * 4. Leaves the current translations in-place so that legacy DMA will
+ *    continue to use its current buffers.
+ * 5. Allocates to the device drivers in the crashdump kernel
+ *    portions of the iova address ranges that are different
+ *    from the iova address ranges that were being used by the old kernel
+ *    at the time of the panic.
+ *
+ */
+
+struct domain_values_entry {
+	struct list_head link;		/* link entries into a list */
+	struct iova_domain iovad;	/* iova's that belong to this domain */
+	struct dma_pte	*pgd;		/* virtual address */
+	int    did;			/* domain id */
+	int    gaw;			/* max guest address width */
+	int    iommu_superpage;		/* Level of superpages supported:
+					   0 == 4KiB (no superpages), 1 == 2MiB,
+					   2 == 1GiB, 3 == 512GiB, 4 == 1TiB */
+};
+
+#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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