[PATCH v2 2/3] iommu/vt-d: debugfs: Create/remove debugfs file per {device, pasid}

[Jingqi Liu]

Add a debugfs directory per pair of {device, pasid} if the mappings of
its page table are created and destroyed by the iommu_map/unmap()
interfaces. i.e. /sys/kernel/debug/iommu/intel/<device source id>/<pasid>.
Create a debugfs file in the directory for users to dump the page
table corresponding to {device, pasid}. e.g.
/sys/kernel/debug/iommu/intel/0000:00:02.0/0/domain_translation_struct.

When attaching device without pasid, create a debugfs file with
PASID#0, i.e. RID_PASID. When attaching a domain to a pasid of device,
create a debugfs file with the specified pasid.

When detaching without pasid, remove the directory and file for
PASID#0. When detaching with pasid, remove the debugfs directory and
file of the specified pasid. Remove the entire debugfs directory of
the specified device for releasing device.
e.g. /sys/kernel/debug/iommu/intel/0000:00:01.0

Signed-off-by: Jingqi Liu <Jingqi.liu@xxxxxxxxx>
---
 drivers/iommu/intel/debugfs.c | 117 ++++++++++++++++++++++++++++++++--
 drivers/iommu/intel/iommu.c   |  16 +++++
 drivers/iommu/intel/iommu.h   |   4 ++
 3 files changed, 132 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/intel/debugfs.c b/drivers/iommu/intel/debugfs.c
index e2a3c37943a0..9128febba3c6 100644
--- a/drivers/iommu/intel/debugfs.c
+++ b/drivers/iommu/intel/debugfs.c
@@ -32,6 +32,11 @@ struct iommu_regset {
 	const char *regs;
 };
 
+struct show_domain_info {
+	struct device *dev;
+	ioasid_t pasid;
+};
+
 #define DEBUG_BUFFER_SIZE	1024
 static char debug_buf[DEBUG_BUFFER_SIZE];
 
@@ -111,6 +116,8 @@ static const struct iommu_regset iommu_regs_64[] = {
 	IOMMU_REGSET_ENTRY(VCRSP),
 };
 
+static struct dentry *intel_iommu_debug;
+
 static int iommu_regset_show(struct seq_file *m, void *unused)
 {
 	struct dmar_drhd_unit *drhd;
@@ -673,16 +680,12 @@ static const struct file_operations dmar_perf_latency_fops = {
 
 void __init intel_iommu_debugfs_init(void)
 {
-	struct dentry *intel_iommu_debug = debugfs_create_dir("intel",
-						iommu_debugfs_dir);
+	intel_iommu_debug = debugfs_create_dir("intel", iommu_debugfs_dir);
 
 	debugfs_create_file("iommu_regset", 0444, intel_iommu_debug, NULL,
 			    &iommu_regset_fops);
 	debugfs_create_file("dmar_translation_struct", 0444, intel_iommu_debug,
 			    NULL, &dmar_translation_struct_fops);
-	debugfs_create_file("domain_translation_struct", 0444,
-			    intel_iommu_debug, NULL,
-			    &domain_translation_struct_fops);
 	debugfs_create_file("invalidation_queue", 0444, intel_iommu_debug,
 			    NULL, &invalidation_queue_fops);
 #ifdef CONFIG_IRQ_REMAP
@@ -692,3 +695,107 @@ void __init intel_iommu_debugfs_init(void)
 	debugfs_create_file("dmar_perf_latency", 0644, intel_iommu_debug,
 			    NULL, &dmar_perf_latency_fops);
 }
+
+/*
+ * Create a debugfs directory per pair of {device, pasid},
+ * then create the corresponding debugfs file in this directory
+ * for user to dump its page table. e.g.
+ * /sys/kernel/debug/iommu/intel/0000:00:01.0/0/domain_translation_struct
+ */
+void intel_iommu_debugfs_create_dev_pasid(struct device *dev, u32 pasid)
+{
+	struct dentry *pasid_dir = NULL, *dev_dir = NULL;
+	struct iommu_domain *domain = NULL;
+	struct show_domain_info *sinfo;
+	char pname[10];
+
+	if (pasid == IOMMU_NO_PASID) {
+		struct device_domain_info *info = dev_iommu_priv_get(dev);
+		if (!info)
+			return;
+		domain = &info->domain->domain;
+	} else
+		domain = iommu_get_domain_for_dev_pasid(dev, pasid, 0);
+
+	/*
+	 * The debugfs only dumps the page tables whose mappings are created
+	 * and destroyed by the iommu_map/unmap() interfaces. Check the
+	 * mapping type of the domain before creating debugfs directory.
+	 */
+	if (!domain || !(domain->type & __IOMMU_DOMAIN_PAGING))
+		return;
+
+	dev_dir = debugfs_lookup(dev_name(dev), intel_iommu_debug);
+	if (!dev_dir) {
+		dev_dir = debugfs_create_dir(dev_name(dev), intel_iommu_debug);
+		if (IS_ERR(dev_dir))
+			return;
+	}
+
+	sprintf(pname, "%x", pasid);
+	pasid_dir = debugfs_create_dir(pname, dev_dir);
+	if (IS_ERR(pasid_dir))
+		return;
+
+	sinfo = kzalloc(sizeof(*sinfo), GFP_KERNEL);
+	if (!sinfo)
+		return;
+
+	sinfo->dev = dev;
+	sinfo->pasid = pasid;
+
+	debugfs_create_file("domain_translation_struct", 0444,
+			    pasid_dir, sinfo,
+			    &domain_translation_struct_fops);
+}
+
+/*
+ * Remove the debugfs directory and file corresponding to each pair of
+ * {device, pasid}. There're two scenarios that will call this helper:
+ * 1) Detach the specified device with pasid.
+ * 2) IOMMU release a device.
+ */
+void intel_iommu_debugfs_remove_dev_pasid(struct device *dev, u32 pasid)
+{
+	struct dentry *pasid_dir = NULL, *dev_dir = NULL;
+	struct dentry *dentry = NULL;
+	char pname[10];
+
+	dev_dir = debugfs_lookup(dev_name(dev), intel_iommu_debug);
+	if (!dev_dir)
+		return;
+
+	/* Check if the entire debugfs directory needs to be removed. */
+	if (pasid == IOMMU_PASID_INVALID) {
+		struct list_head *plist;
+		struct dentry *sub_dentry;
+
+		list_for_each(plist, &(dev_dir->d_subdirs)) {
+			sub_dentry = list_entry(plist, struct dentry, d_child);
+			if(sub_dentry) {
+				dentry = debugfs_lookup("domain_translation_struct", sub_dentry);
+				if (!dentry)
+					continue;
+
+				if (dentry->d_inode->i_private)
+					kfree(dentry->d_inode->i_private);
+			}
+		}
+
+		debugfs_remove_recursive(dev_dir);
+	} else { /* Remove the directory with specified pasid. */
+		sprintf(pname, "%x", pasid);
+		pasid_dir = debugfs_lookup(pname, dev_dir);
+		if (!pasid_dir)
+			return;
+
+		dentry = debugfs_lookup("domain_translation_struct", pasid_dir);
+		if (!dentry)
+			return;
+
+		if (dentry->d_inode->i_private)
+			kfree(dentry->d_inode->i_private);
+
+		debugfs_remove_recursive(pasid_dir);
+	}
+}
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index dd8ff358867d..8d3c3ef1d0e2 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -2488,6 +2488,8 @@ static int dmar_domain_attach_device(struct dmar_domain *domain,
 
 	iommu_enable_pci_caps(info);
 
+	intel_iommu_debugfs_create_dev_pasid(dev, IOMMU_NO_PASID);
+
 	return 0;
 }
 
@@ -3966,6 +3968,9 @@ static void dmar_remove_one_dev_info(struct device *dev)
 
 	domain_detach_iommu(domain, iommu);
 	info->domain = NULL;
+
+	/* Remove the entire debugfs directory specified by device. */
+	intel_iommu_debugfs_remove_dev_pasid(dev, IOMMU_PASID_INVALID);
 }
 
 /*
@@ -3997,6 +4002,12 @@ static void device_block_translation(struct device *dev)
 
 	domain_detach_iommu(info->domain, iommu);
 	info->domain = NULL;
+
+	/*
+	 * Remove the debugfs directory specified by device and
+	 * RID_PASID pasid.
+	 */
+	intel_iommu_debugfs_remove_dev_pasid(dev, IOMMU_NO_PASID);
 }
 
 static int md_domain_init(struct dmar_domain *domain, int guest_width)
@@ -4729,6 +4740,9 @@ static void intel_iommu_remove_dev_pasid(struct device *dev, ioasid_t pasid)
 out_tear_down:
 	intel_pasid_tear_down_entry(iommu, dev, pasid, false);
 	intel_drain_pasid_prq(dev, pasid);
+
+	/* Remove the debugfs directory specified by device and pasid. */
+	intel_iommu_debugfs_remove_dev_pasid(dev, pasid);
 }
 
 static int intel_iommu_set_dev_pasid(struct iommu_domain *domain,
@@ -4777,6 +4791,8 @@ static int intel_iommu_set_dev_pasid(struct iommu_domain *domain,
 	list_add(&dev_pasid->link_domain, &dmar_domain->dev_pasids);
 	spin_unlock_irqrestore(&dmar_domain->lock, flags);
 
+	intel_iommu_debugfs_create_dev_pasid(dev, pasid);
+
 	return 0;
 out_detach_iommu:
 	domain_detach_iommu(dmar_domain, iommu);
diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index c18fb699c87a..250178d8014b 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -883,8 +883,12 @@ static inline void intel_svm_remove_dev_pasid(struct device *dev, ioasid_t pasid
 
 #ifdef CONFIG_INTEL_IOMMU_DEBUGFS
 void intel_iommu_debugfs_init(void);
+void intel_iommu_debugfs_create_dev_pasid(struct device *dev, u32 pasid);
+void intel_iommu_debugfs_remove_dev_pasid(struct device *dev, u32 pasid);
 #else
 static inline void intel_iommu_debugfs_init(void) {}
+void intel_iommu_debugfs_create_dev_pasid(struct device *dev, u32 pasid) {}
+void intel_iommu_debugfs_remove_dev_pasid(struct device *dev, u32 pasid) {}
 #endif /* CONFIG_INTEL_IOMMU_DEBUGFS */
 
 extern const struct attribute_group *intel_iommu_groups[];
-- 
2.21.3