[PATCH v4 3/5] iommu/vt-d: Add debugfs support to show register contents

From: Sohil Mehta
Date: Tue Dec 19 2017 - 16:08:39 EST


From: Gayatri Kammela <gayatri.kammela@xxxxxxxxx>

Debugfs extension to dump all the register contents for each IOMMU
device to the user space via debugfs.

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

DMAR: dmar1: reg_base_addr fed90000
Name Offset Contents
VER 0x00 0x0000000000000010
CAP 0x08 0x01c0000c40660462
ECAP 0x10 0x0000019e2ff0505e
GCMD 0x18 0x0000000000000000
GSTS 0x1c 0x00000000c7000000
RTADDR 0x20 0x00000004558d6800
CCMD 0x28 0x0800000000000000
FSTS 0x34 0x0000000000000000
FECTL 0x38 0x0000000000000000
FEDATA 0x3c 0xfee0100c00004141

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

v4: Fix checkpatch.pl warnings
Remove error reporting for debugfs_create_file function
Remove redundant IOMMU null check under for_each_active_iommu

v3: Use a macro for seq file operations
Change the intel_iommu_regset file name to iommu_regset
Add information for MTRR registers

v2: Fix seq_printf formatting

drivers/iommu/intel-iommu-debug.c | 78 +++++++++++++++++++++++++++++++++++++++
include/linux/intel-iommu.h | 2 +
2 files changed, 80 insertions(+)

diff --git a/drivers/iommu/intel-iommu-debug.c b/drivers/iommu/intel-iommu-debug.c
index fa458904..c45c0f6 100644
--- a/drivers/iommu/intel-iommu-debug.c
+++ b/drivers/iommu/intel-iommu-debug.c
@@ -132,6 +132,81 @@ static int dmar_translation_struct_show(struct seq_file *m, void *unused)

DEFINE_SHOW_ATTRIBUTE(dmar_translation_struct);

+static int iommu_regset_show(struct seq_file *m, void *unused)
+{
+ struct dmar_drhd_unit *drhd;
+ struct intel_iommu *iommu;
+ unsigned long long base;
+ int i;
+ struct regset {
+ int offset;
+ char *regs;
+ };
+
+ static const struct regset regstr[] = {{DMAR_VER_REG, "VER"},
+ {DMAR_CAP_REG, "CAP"},
+ {DMAR_ECAP_REG, "ECAP"},
+ {DMAR_GCMD_REG, "GCMD"},
+ {DMAR_GSTS_REG, "GSTS"},
+ {DMAR_RTADDR_REG, "RTADDR"},
+ {DMAR_CCMD_REG, "CCMD"},
+ {DMAR_FSTS_REG, "FSTS"},
+ {DMAR_FECTL_REG, "FECTL"},
+ {DMAR_FEDATA_REG, "FEDATA"},
+ {DMAR_FEADDR_REG, "FEADDR"},
+ {DMAR_FEUADDR_REG, "FEUADDR"},
+ {DMAR_AFLOG_REG, "AFLOG"},
+ {DMAR_PMEN_REG, "PMEN"},
+ {DMAR_PLMBASE_REG, "PLMBASE"},
+ {DMAR_PLMLIMIT_REG, "PLMLIMIT"},
+ {DMAR_PHMBASE_REG, "PHMBASE"},
+ {DMAR_PHMLIMIT_REG, "PHMLIMIT"},
+ {DMAR_IQH_REG, "IQH"},
+ {DMAR_IQT_REG, "IQT"},
+ {DMAR_IQ_SHIFT, "IQ"},
+ {DMAR_IQA_REG, "IQA"},
+ {DMAR_ICS_REG, "ICS"},
+ {DMAR_IRTA_REG, "IRTA"},
+ {DMAR_PQH_REG, "PQH"},
+ {DMAR_PQT_REG, "PQT"},
+ {DMAR_PQA_REG, "PQA"},
+ {DMAR_PRS_REG, "PRS"},
+ {DMAR_PECTL_REG, "PECTL"},
+ {DMAR_PEDATA_REG, "PEDATA"},
+ {DMAR_PEADDR_REG, "PEADDR"},
+ {DMAR_PEUADDR_REG, "PEUADDR"},
+ {DMAR_MTRRCAP_REG, "MTRRCAP"},
+ {DMAR_MTRRDEF_REG, "MTRRDEF"} };
+
+ rcu_read_lock();
+ for_each_active_iommu(iommu, drhd) {
+ if (!drhd->reg_base_addr) {
+ seq_puts(m, "IOMMU: Invalid base address\n");
+ rcu_read_unlock();
+ return -EINVAL;
+ }
+
+ base = drhd->reg_base_addr;
+ seq_printf(m, "\nDMAR: %s: reg_base_addr %llx\n", iommu->name,
+ base);
+ seq_puts(m, "Name\t\t\tOffset\t\tContents\n");
+ /*
+ * Publish the contents of the 64-bit hardware registers
+ * by adding the offset to the pointer(virtual addr)
+ */
+ for (i = 0 ; i < ARRAY_SIZE(regstr); i++) {
+ seq_printf(m, "%-8s\t\t0x%02x\t\t0x%016lx\n",
+ regstr[i].regs, regstr[i].offset,
+ readq(iommu->reg + regstr[i].offset));
+ }
+ }
+ rcu_read_unlock();
+
+ return 0;
+}
+
+DEFINE_SHOW_ATTRIBUTE(iommu_regset);
+
void __init intel_iommu_debugfs_init(void)
{
struct dentry *iommu_debug_root;
@@ -143,4 +218,7 @@ void __init intel_iommu_debugfs_init(void)

debugfs_create_file("dmar_translation_struct", 0444, iommu_debug_root,
NULL, &dmar_translation_struct_fops);
+
+ debugfs_create_file("iommu_regset", 0444, iommu_debug_root, NULL,
+ &iommu_regset_fops);
}
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index b8591dc..9d46250 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -71,6 +71,8 @@
#define DMAR_PEDATA_REG 0xe4 /* Page request event interrupt data register */
#define DMAR_PEADDR_REG 0xe8 /* Page request event interrupt addr register */
#define DMAR_PEUADDR_REG 0xec /* Page request event Upper address register */
+#define DMAR_MTRRCAP_REG 0x100 /* Memory type range register capability register */
+#define DMAR_MTRRDEF_REG 0x108 /* Memory type range register default type register */

#define OFFSET_STRIDE (9)

--
2.7.4