[PATCH v5 2/5] iommu/vt-d: Add debugfs support to show context internals

[Sohil Mehta <sohil.mehta@intel.com>]

From: Gayatri Kammela <gayatri.kammela@intel.com>

IOMMU internals states such as root and context can be exported to the
userspace.

Example of such dump in Kabylake:

root@OTC-KBLH-01:~# cat
/sys/kernel/debug/intel_iommu/dmar_translation_struct

IOMMU dmar0: Extended Root Table Addr:402b9e800
Extended Root table entries:
Bus 0 L: 402150001 H: 0
Lower Context table entries for Bus: 0
[entry] DID :B :D .F    Low             High
[80]    0000:00:0a.00   40214fa05       102
Higher Context table entries for Bus: 0
[80]    0000:00:0a.00   40260000c       0

IOMMU dmar1:    Root Table Addr:4558a3000
 Root tbl entries:
Bus 0 L: 4558aa001 H: 0
 Context table entries for Bus: 0
[entry] DID :B :D .F    Low             High
[160]   0000:00:14.00   4558a9001       102
[184]   0000:00:17.00   400eac001       302
[248]   0000:00:1f.00   4558af001       202
[251]   0000:00:1f.03   40070e001       502
[254]   0000:00:1f.06   4467c9001       602
 Root tbl entries:
Bus 1 L: 3fc8c2001 H: 0
 Context table entries for Bus: 1
[entry] DID :B :D .F    Low             High
[0]     0000:01:00.00   3fc8c3001       402

Cc: Sohil Mehta <sohil.mehta@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Gayatri Kammela <gayatri.kammela@intel.com>
---

v5: Change to a SPDX license tag
    Fix seq_printf formatting

v4: Remove the unused function parameter
    Fix checkpatch.pl warnings
    Remove error reporting for debugfs_create_file function
    Fix unnecessary reprogramming of the context entries
    Simplify and merge the show context and extended context patch into one
    Remove redundant IOMMU null check under for_each_active_iommu

v3: Add a macro for seq file operations 
    Change the intel_iommu_ctx file name to dmar_translation_struct

v2: No change

 drivers/iommu/Makefile            |   1 +
 drivers/iommu/intel-iommu-debug.c | 138 ++++++++++++++++++++++++++++++++++++++
 drivers/iommu/intel-iommu.c       |   4 ++
 3 files changed, 143 insertions(+)
 create mode 100644 drivers/iommu/intel-iommu-debug.c

diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
index 1fb6958..fdbaf46 100644
--- a/drivers/iommu/Makefile
+++ b/drivers/iommu/Makefile
@@ -15,6 +15,7 @@ obj-$(CONFIG_ARM_SMMU) += arm-smmu.o
 obj-$(CONFIG_ARM_SMMU_V3) += arm-smmu-v3.o
 obj-$(CONFIG_DMAR_TABLE) += dmar.o
 obj-$(CONFIG_INTEL_IOMMU) += intel-iommu.o
+obj-$(CONFIG_INTEL_IOMMU_DEBUG) += intel-iommu-debug.o
 obj-$(CONFIG_INTEL_IOMMU_SVM) += intel-svm.o
 obj-$(CONFIG_IPMMU_VMSA) += ipmmu-vmsa.o
 obj-$(CONFIG_IRQ_REMAP) += intel_irq_remapping.o irq_remapping.o
diff --git a/drivers/iommu/intel-iommu-debug.c b/drivers/iommu/intel-iommu-debug.c
new file mode 100644
index 0000000..94d710c
--- /dev/null
+++ b/drivers/iommu/intel-iommu-debug.c
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright © 2017 Intel Corporation.
+ *
+ * Authors: Gayatri Kammela <gayatri.kammela@intel.com>
+ *          Jacob Pan <jacob.jun.pan@linux.intel.com>
+ *
+ */
+
+#define pr_fmt(fmt)     "INTEL_IOMMU: " fmt
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/pm_runtime.h>
+#include <linux/debugfs.h>
+#include <linux/pci.h>
+#include <linux/iommu.h>
+#include <linux/intel-iommu.h>
+#include <linux/intel-svm.h>
+#include <linux/dmar.h>
+#include <linux/spinlock.h>
+
+#include "irq_remapping.h"
+
+#define TOTAL_BUS_NR (256) /* full bus range 256 */
+#define DEFINE_SHOW_ATTRIBUTE(__name)					\
+static int __name ## _open(struct inode *inode, struct file *file)	\
+{									\
+	return single_open(file, __name ## _show, inode->i_private);	\
+}									\
+static const struct file_operations __name ## _fops =			\
+{									\
+	.open		= __name ## _open,				\
+	.read		= seq_read,					\
+	.llseek		= seq_lseek,					\
+	.release	= single_release,				\
+	.owner		= THIS_MODULE,					\
+}
+
+static void ctx_tbl_entry_show(struct seq_file *m, struct intel_iommu *iommu,
+			       int bus, bool ext, bool new_ext)
+{
+	struct context_entry *context;
+	int ctx;
+	unsigned long flags;
+
+	seq_printf(m, "%s Context table entries for Bus: %d\n",
+		   ext ? "Lower" : "", bus);
+	seq_puts(m, "[entry]\tDID :B :D .F\tLow\t\tHigh\n");
+
+	spin_lock_irqsave(&iommu->lock, flags);
+
+	/* Publish either context entries or extended contenxt entries */
+	for (ctx = 0; ctx < (ext ? 128 : 256); ctx++) {
+		context = iommu_context_addr(iommu, bus, ctx, 0);
+		if (!context)
+			goto out;
+		if (context_present(context)) {
+			seq_printf(m, "[%d]\t%04x:%02x:%02x.%02x\t%llx\t%llx\n",
+				   ctx, iommu->segment, bus, PCI_SLOT(ctx),
+				   PCI_FUNC(ctx), context[0].lo, context[0].hi);
+
+			if (new_ext) {
+				seq_printf(m, "Higher Context table entries for Bus: %d\n",
+					   bus);
+				seq_printf(m, "[%d]\t%04x:%02x:%02x.%02x\t%llx\t%llx\n",
+					   ctx, iommu->segment, bus,
+					   PCI_SLOT(ctx), PCI_FUNC(ctx),
+					   context[1].lo, context[1].hi);
+			}
+		}
+	}
+out:
+	spin_unlock_irqrestore(&iommu->lock, flags);
+}
+
+static void root_tbl_entry_show(struct seq_file *m, struct intel_iommu *iommu,
+				u64 rtaddr_reg, bool ext, bool new_ext)
+{
+	int bus;
+
+	seq_printf(m, "\nIOMMU %s: %2s Root Table Addr:%llx\n", iommu->name,
+		   ext ? "Extended" : "", rtaddr_reg);
+	/* Publish extended root table entries or root table entries here */
+	for (bus = 0; bus < TOTAL_BUS_NR; bus++) {
+		if (!iommu->root_entry[bus].lo)
+			continue;
+
+		seq_printf(m, "%s Root table entries:\n",
+			   ext ? "Extended" : "");
+		seq_printf(m, "Bus %d L: %llx H: %llx\n",
+			   bus, iommu->root_entry[bus].lo,
+			   iommu->root_entry[bus].hi);
+
+		ctx_tbl_entry_show(m, iommu, bus, ext, new_ext);
+	}
+}
+
+static int dmar_translation_struct_show(struct seq_file *m, void *unused)
+{
+	struct dmar_drhd_unit *drhd;
+	struct intel_iommu *iommu;
+	u64 rtaddr_reg;
+	bool new_ext, ext;
+
+	rcu_read_lock();
+	for_each_active_iommu(iommu, drhd) {
+		/* Check if root table type is set */
+		rtaddr_reg = dmar_readq(iommu->reg + DMAR_RTADDR_REG);
+		ext        = !!(rtaddr_reg & DMA_RTADDR_RTT);
+		new_ext    = !!ecap_ecs(iommu->ecap);
+		if (new_ext != ext) {
+			seq_printf(m, "IOMMU %s: invalid ecs\n", iommu->name);
+			rcu_read_unlock();
+			return -EINVAL;
+		}
+		root_tbl_entry_show(m, iommu, rtaddr_reg, ext, new_ext);
+	}
+	rcu_read_unlock();
+
+	return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(dmar_translation_struct);
+
+void __init intel_iommu_debugfs_init(void)
+{
+	struct dentry *iommu_debug_root;
+
+	iommu_debug_root = debugfs_create_dir("intel_iommu", NULL);
+
+	if (!iommu_debug_root)
+		return;
+
+	debugfs_create_file("dmar_translation_struct", 0444, iommu_debug_root,
+			    NULL, &dmar_translation_struct_fops);
+}
diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index e05b8e0..351d4d9 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -4806,6 +4806,10 @@ int __init intel_iommu_init(void)
 			  intel_iommu_cpu_dead);
 	intel_iommu_enabled = 1;
 
+#ifdef CONFIG_INTEL_IOMMU_DEBUG
+	intel_iommu_debugfs_init();
+#endif
+
 	return 0;
 
 out_free_reserved_range:
-- 
2.7.4