linux-kernel - [PATCH 1/6] Crashdump-Accepting-Active-IOMMU-Flags-and-Prototypes

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Date:	Tue,  3 Dec 2013 12:41:29 -0700
From:	Bill Sumner <bill.sumner@...com>
To:	dwmw2@...radead.org, indou.takao@...fujitsu.com, bhe@...hat.com
Cc:	iommu@...ts.linux-foundation.org, kexec@...ts.infradead.org,
	alex.williamson@...hat.com, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, ddutile@...hat.com,
	ishii.hironobu@...fujitsu.com, bhelgaas@...gle.com,
	bill.sumner@...com, doug.hatch@...com
Subject: [PATCH 1/6] Crashdump-Accepting-Active-IOMMU-Flags-and-Prototypes


Signed-off-by: Bill Sumner <bill.sumner@...com>
---
 drivers/iommu/intel-iommu.c | 75 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 15e9b57..a0e8a76 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -48,6 +48,7 @@
 
 #include "irq_remapping.h"
 #include "pci.h"
+#include <linux/crash_dump.h>
 
 #define ROOT_SIZE		VTD_PAGE_SIZE
 #define CONTEXT_SIZE		VTD_PAGE_SIZE
@@ -164,6 +165,80 @@ static inline unsigned long virt_to_dma_pfn(void *p)
 	return page_to_dma_pfn(virt_to_page(p));
 }
 
+#ifdef CONFIG_CRASH_DUMP
+/* ===================================================================
+ * Crashdump Accepting Active IOMMU
+ * Enhances the crashdump kernel to deal with an active iommu
+ * and legacy DMA from the (old) panic'd 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.
+ *
+ * This code:
+ * 1. accepts the iommu hardware in an active state from the old kernel,
+ * 2. leaves the current translations in-place so that legacy DMA will
+ *    continue to use its current buffers,
+ * 3. 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.
+ * -------------------------------------------------------------------
+ */
+
+/* Flags for Crashdump Accepting Active IOMMU */
+
+static int crashdump_accepting_active_iommu;	/* activate this feature */
+static int intel_iommu_translation_tables_are_mapped;	/* table copy done */
+
+static struct {				/* run-time pr_debug() flags */
+	unsigned in_crashdump:1;	/* if crashdump_accepting_active_iommu */
+	unsigned domain_get:1;		/* pr_debug in domain_get* functions */
+	unsigned copy_page_table:1;	/* enter/leave copy_page_table() */
+	unsigned copy_page_addr:1;	/* enter/leave copy_page_addr() */
+	unsigned addr_ranges:1;		/* accumulated addr ranges */
+	unsigned reserved_ranges:1;	/* accumulated addr ranges reserved */
+	unsigned page_addr:1;		/* adr(each page table) */
+	unsigned enter_oldcopy:1;	/* enter oldcopy() parameters */
+	unsigned leave_oldcopy:1;	/* leave oldcopy() parameters */
+} pr_dbg  = {				/* Enable flags below here */
+	.in_crashdump = 1,
+	.domain_get = 1,
+	.copy_page_table = 1,
+	.copy_page_addr = 0,
+	.addr_ranges = 0,
+	.reserved_ranges = 0,
+	.page_addr = 0,
+	.enter_oldcopy = 0,
+	.leave_oldcopy = 0,
+};
+
+/* Prototypes of interface functions for Crashdump Accepting Active IOMMU */
+
+static int
+copy_intel_iommu_translation_tables(struct dmar_drhd_unit *drhd,
+	struct root_entry **root_old_p, struct root_entry **root_new_p);
+
+static int
+domain_get_did_from_old_kernel(struct intel_iommu *iommu, struct pci_dev *pdev);
+
+static int
+domain_get_gaw_from_old_kernel(struct intel_iommu *iommu, struct pci_dev *pdev);
+
+static u64
+domain_get_pgd_from_old_kernel(struct intel_iommu *iommu, struct pci_dev *pdev);
+
+static void
+domain_get_ranges_from_old_kernel(struct dmar_domain *domain,
+		  struct intel_iommu *iommu, struct pci_dev *pdev);
+static int
+intel_iommu_get_dids_from_old_kernel(struct intel_iommu *iommu);
+
+/* Debug-print functions for  Crashdump Accepting Active IOMMU */
+
+static void
+print_intel_iommu_registers(struct dmar_drhd_unit *drhd);
+#endif	/* CONFIG_CRASH_DUMP */
+
+
 /* global iommu list, set NULL for ignored DMAR units */
 static struct intel_iommu **g_iommus;
 
-- 
Bill Sumner <bill.sumner@...com>

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