iommu/vt-d: debugfs: Add support to show page table internals

Export page table internals of the domain attached to each device.
Example of such dump on a Skylake machine:

$ sudo cat /sys/kernel/debug/iommu/intel/domain_translation_struct
[ ... ]
Device 0000:00:14.0 with pasid 0 @0x15f3d9000
IOVA_PFN                PML5E                   PML4E
0x000000008ced0 |       0x0000000000000000      0x000000015f3da003
0x000000008ced1 |       0x0000000000000000      0x000000015f3da003
0x000000008ced2 |       0x0000000000000000      0x000000015f3da003
0x000000008ced3 |       0x0000000000000000      0x000000015f3da003
0x000000008ced4 |       0x0000000000000000      0x000000015f3da003
0x000000008ced5 |       0x0000000000000000      0x000000015f3da003
0x000000008ced6 |       0x0000000000000000      0x000000015f3da003
0x000000008ced7 |       0x0000000000000000      0x000000015f3da003
0x000000008ced8 |       0x0000000000000000      0x000000015f3da003
0x000000008ced9 |       0x0000000000000000      0x000000015f3da003

PDPE                    PDE                     PTE
0x000000015f3db003      0x000000015f3dc003      0x000000008ced0003
0x000000015f3db003      0x000000015f3dc003      0x000000008ced1003
0x000000015f3db003      0x000000015f3dc003      0x000000008ced2003
0x000000015f3db003      0x000000015f3dc003      0x000000008ced3003
0x000000015f3db003      0x000000015f3dc003      0x000000008ced4003
0x000000015f3db003      0x000000015f3dc003      0x000000008ced5003
0x000000015f3db003      0x000000015f3dc003      0x000000008ced6003
0x000000015f3db003      0x000000015f3dc003      0x000000008ced7003
0x000000015f3db003      0x000000015f3dc003      0x000000008ced8003
0x000000015f3db003      0x000000015f3dc003      0x000000008ced9003
[ ... ]
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/intel-iommu-debugfs.c

@@ -5,6 +5,7 @@
  * Authors: Gayatri Kammela <gayatri.kammela@intel.com>
  *	    Sohil Mehta <sohil.mehta@intel.com>
  *	    Jacob Pan <jacob.jun.pan@linux.intel.com>
+ *	    Lu Baolu <baolu.lu@linux.intel.com>
  */
 
 #include <linux/debugfs.h>
@@ -283,6 +284,77 @@ static int dmar_translation_struct_show(struct seq_file *m, void *unused)
 }
 DEFINE_SHOW_ATTRIBUTE(dmar_translation_struct);
 
+static inline unsigned long level_to_directory_size(int level)
+{
+	return BIT_ULL(VTD_PAGE_SHIFT + VTD_STRIDE_SHIFT * (level - 1));
+}
+
+static inline void
+dump_page_info(struct seq_file *m, unsigned long iova, u64 *path)
+{
+	seq_printf(m, "0x%013lx |\t0x%016llx\t0x%016llx\t0x%016llx\t0x%016llx\t0x%016llx\n",
+		   iova >> VTD_PAGE_SHIFT, path[5], path[4],
+		   path[3], path[2], path[1]);
+}
+
+static void pgtable_walk_level(struct seq_file *m, struct dma_pte *pde,
+			       int level, unsigned long start,
+			       u64 *path)
+{
+	int i;
+
+	if (level > 5 || level < 1)
+		return;
+
+	for (i = 0; i < BIT_ULL(VTD_STRIDE_SHIFT);
+			i++, pde++, start += level_to_directory_size(level)) {
+		if (!dma_pte_present(pde))
+			continue;
+
+		path[level] = pde->val;
+		if (dma_pte_superpage(pde) || level == 1)
+			dump_page_info(m, start, path);
+		else
+			pgtable_walk_level(m, phys_to_virt(dma_pte_addr(pde)),
+					   level - 1, start, path);
+		path[level] = 0;
+	}
+}
+
+static int show_device_domain_translation(struct device *dev, void *data)
+{
+	struct dmar_domain *domain = find_domain(dev);
+	struct seq_file *m = data;
+	u64 path[6] = { 0 };
+
+	if (!domain)
+		return 0;
+
+	seq_printf(m, "Device %s with pasid %d @0x%llx\n",
+		   dev_name(dev), domain->default_pasid,
+		   (u64)virt_to_phys(domain->pgd));
+	seq_puts(m, "IOVA_PFN\t\tPML5E\t\t\tPML4E\t\t\tPDPE\t\t\tPDE\t\t\tPTE\n");
+
+	pgtable_walk_level(m, domain->pgd, domain->agaw + 2, 0, path);
+	seq_putc(m, '\n');
+
+	return 0;
+}
+
+static int domain_translation_struct_show(struct seq_file *m, void *unused)
+{
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&device_domain_lock, flags);
+	ret = bus_for_each_dev(&pci_bus_type, NULL, m,
+			       show_device_domain_translation);
+	spin_unlock_irqrestore(&device_domain_lock, flags);
+
+	return ret;
+}
+DEFINE_SHOW_ATTRIBUTE(domain_translation_struct);
+
 #ifdef CONFIG_IRQ_REMAP
 static void ir_tbl_remap_entry_show(struct seq_file *m,
 				    struct intel_iommu *iommu)
@@ -396,6 +468,9 @@ void __init intel_iommu_debugfs_init(void)
 			    &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);
 #ifdef CONFIG_IRQ_REMAP
 	debugfs_create_file("ir_translation_struct", 0444, intel_iommu_debug,
 			    NULL, &ir_translation_struct_fops);

drivers/iommu/intel-iommu.c

@@ -396,7 +396,7 @@ EXPORT_SYMBOL_GPL(intel_iommu_gfx_mapped);
 
 #define DUMMY_DEVICE_DOMAIN_INFO ((struct device_domain_info *)(-1))
 #define DEFER_DEVICE_DOMAIN_INFO ((struct device_domain_info *)(-2))
-static DEFINE_SPINLOCK(device_domain_lock);
+DEFINE_SPINLOCK(device_domain_lock);
 static LIST_HEAD(device_domain_list);
 
 #define device_needs_bounce(d) (!intel_no_bounce && dev_is_pci(d) &&	\
@@ -2513,7 +2513,7 @@ static void domain_remove_dev_info(struct dmar_domain *domain)
 	spin_unlock_irqrestore(&device_domain_lock, flags);
 }
 
-static struct dmar_domain *find_domain(struct device *dev)
+struct dmar_domain *find_domain(struct device *dev)
 {
 	struct device_domain_info *info;
 

include/linux/intel-iommu.h

@@ -441,6 +441,7 @@ enum {
 #define VTD_FLAG_SVM_CAPABLE		(1 << 2)
 
 extern int intel_iommu_sm;
+extern spinlock_t device_domain_lock;
 
 #define sm_supported(iommu)	(intel_iommu_sm && ecap_smts((iommu)->ecap))
 #define pasid_supported(iommu)	(sm_supported(iommu) &&			\
@@ -663,6 +664,7 @@ int for_each_device_domain(int (*fn)(struct device_domain_info *info,
 				     void *data), void *data);
 void iommu_flush_write_buffer(struct intel_iommu *iommu);
 int intel_iommu_enable_pasid(struct intel_iommu *iommu, struct device *dev);
+struct dmar_domain *find_domain(struct device *dev);
 
 #ifdef CONFIG_INTEL_IOMMU_SVM
 extern void intel_svm_check(struct intel_iommu *iommu);