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

From: Sohil Mehta
Date: Thu Dec 21 2017 - 19:33:26 EST

From: Gayatri Kammela <gayatri.kammela@xxxxxxxxx>

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@xxxxxxxxx>
Cc: Fenghua Yu <fenghua.yu@xxxxxxxxx>
Cc: Ashok Raj <ashok.raj@xxxxxxxxx>
Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
Signed-off-by: Gayatri Kammela <gayatri.kammela@xxxxxxxxx>
---

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@xxxxxxxxx>
+ * Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
+ *
+ */
+
+#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