[PATCH v3 for-4.5 3/9] xen: arm: handle concatenated root tables in dump_pt_walk

[Ian Campbell <ian.campbell@citrix.com>]

ARM allows for the concatenation of pages at the root of a p2m (but not a
regular page table) in order to support a larger IPA space than the number of
levels in the P2M would normally support. We use this to support 40-bit guest
addresses.

Previously we were unable to dump IPAs which were outside the first page of the
root. To fix this we adjust dump_pt_walk to take the machine address of the
page table root instead of expecting the caller to have mapped it. This allows
the walker code to select the correct page to map.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Reviewed-by: Julien Grall <julien.grall@linaro.org>

---
v3:
 - s/mapper/mapped/
 - Use %u to print unsigned thing
v2:
 - nr_root_tables is unsigned int
 - spell concatenate properly
---
 xen/arch/arm/mm.c          |   47 ++++++++++++++++++++++++++++++--------------
 xen/arch/arm/p2m.c         |   13 +++---------
 xen/include/asm-arm/page.h |   16 +++++++++++++--
 3 files changed, 49 insertions(+), 27 deletions(-)

diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
index 207264e..0294fa8 100644
--- a/xen/arch/arm/mm.c
+++ b/xen/arch/arm/mm.c
@@ -167,33 +167,53 @@ static inline void check_memory_layout_alignment_constraints(void) {
 #endif
 }
 
-void dump_pt_walk(lpae_t *root, paddr_t addr,
-                  unsigned int root_level)
+void dump_pt_walk(paddr_t ttbr, paddr_t addr,
+                  unsigned int root_level,
+                  unsigned int nr_root_tables)
 {
     static const char *level_strs[4] = { "0TH", "1ST", "2ND", "3RD" };
+    const unsigned long root_pfn = paddr_to_pfn(ttbr);
     const unsigned int offsets[4] = {
         zeroeth_table_offset(addr),
         first_table_offset(addr),
         second_table_offset(addr),
         third_table_offset(addr)
     };
-    lpae_t pte, *mappings[4] = { 0, };
-    unsigned int level;
+    lpae_t pte, *mapping;
+    unsigned int level, root_table;
 
-    BUG_ON(!root);
 #ifdef CONFIG_ARM_32
     BUG_ON(root_level < 1);
 #endif
     BUG_ON(root_level > 3);
 
-    mappings[root_level] = root;
+    if ( nr_root_tables > 1 )
+    {
+        /*
+         * Concatenated root-level tables. The table number will be
+         * the offset at the previous level. It is not possible to
+         * concatenate a level-0 root.
+         */
+        BUG_ON(root_level == 0);
+        root_table = offsets[root_level - 1];
+        printk("Using concatenated root table %u\n", root_table);
+        if ( root_table >= nr_root_tables )
+        {
+            printk("Invalid root table offset\n");
+            return;
+        }
+    }
+    else
+        root_table = 0;
+
+    mapping = map_domain_page(root_pfn + root_table);
 
     for ( level = root_level; ; level++ )
     {
         if ( offsets[level] > LPAE_ENTRIES )
             break;
 
-        pte = mappings[level][offsets[level]];
+        pte = mapping[offsets[level]];
 
         printk("%s[0x%x] = 0x%"PRIpaddr"\n",
                level_strs[level], offsets[level], pte.bits);
@@ -201,15 +221,12 @@ void dump_pt_walk(lpae_t *root, paddr_t addr,
         if ( level == 3 || !pte.walk.valid || !pte.walk.table )
             break;
 
-        mappings[level+1] = map_domain_page(pte.walk.base);
+        /* For next iteration */
+        unmap_domain_page(mapping);
+        mapping = map_domain_page(pte.walk.base);
     }
 
-    /* mappings[root_level] is provided by the caller so don't unmap that */
-    do
-    {
-        unmap_domain_page(mappings[level]);
-    }
-    while ( level-- > root_level );
+    unmap_domain_page(mapping);
 }
 
 void dump_hyp_walk(vaddr_t addr)
@@ -225,7 +242,7 @@ void dump_hyp_walk(vaddr_t addr)
         BUG_ON( (lpae_t *)(unsigned long)(ttbr - phys_offset) != pgtable );
     else
         BUG_ON( virt_to_maddr(pgtable) != ttbr );
-    dump_pt_walk(pgtable, addr, HYP_PT_ROOT_LEVEL);
+    dump_pt_walk(ttbr, addr, HYP_PT_ROOT_LEVEL, 1);
 }
 
 /* Map a 4k page in a fixmap entry */
diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 660d4c5..fa64aa5 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -16,6 +16,7 @@
 /* First level P2M is 2 consecutive pages */
 #define P2M_ROOT_ORDER 1
 #define P2M_ROOT_ENTRIES (LPAE_ENTRIES<<P2M_ROOT_ORDER)
+#define P2M_ROOT_PAGES    (1<<P2M_ROOT_ORDER)
 
 static bool_t p2m_valid(lpae_t pte)
 {
@@ -56,22 +57,14 @@ void memory_type_changed(struct domain *d)
 void dump_p2m_lookup(struct domain *d, paddr_t addr)
 {
     struct p2m_domain *p2m = &d->arch.p2m;
-    lpae_t *first;
 
     printk("dom%d IPA 0x%"PRIpaddr"\n", d->domain_id, addr);
 
-    if ( first_linear_offset(addr) > LPAE_ENTRIES )
-    {
-        printk("Cannot dump addresses in second of first level pages...\n");
-        return;
-    }
-
     printk("P2M @ %p mfn:0x%lx\n",
            p2m->root, page_to_mfn(p2m->root));
 
-    first = __map_domain_page(p2m->root);
-    dump_pt_walk(first, addr, P2M_ROOT_LEVEL);
-    unmap_domain_page(first);
+    dump_pt_walk(page_to_maddr(p2m->root), addr,
+                 P2M_ROOT_LEVEL, P2M_ROOT_PAGES);
 }
 
 static void p2m_load_VTTBR(struct domain *d)
diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
index 4c21863..773822f 100644
--- a/xen/include/asm-arm/page.h
+++ b/xen/include/asm-arm/page.h
@@ -351,8 +351,20 @@ static inline void flush_xen_data_tlb_range_va(unsigned long va,
 /* Flush the dcache for an entire page. */
 void flush_page_to_ram(unsigned long mfn);
 
-/* Print a walk of an arbitrary page table */
-void dump_pt_walk(lpae_t *table, paddr_t addr, unsigned int root_level);
+/*
+ * Print a walk of a page table or p2m
+ *
+ * ttbr is the base address register (TTBR0_EL2 or VTTBR_EL2)
+ * addr is the PA or IPA to translate
+ * root_level is the starting level of the page table
+ *   (e.g. TCR_EL2.SL0 or VTCR_EL2.SL0 )
+ * nr_root_tables is the number of concatenated tables at the root.
+ *   this can only be != 1 for P2M walks starting at the first or
+ *   subsequent level.
+ */
+void dump_pt_walk(paddr_t ttbr, paddr_t addr,
+                  unsigned int root_level,
+                  unsigned int nr_root_tables);
 
 /* Print a walk of the hypervisor's page tables for a virtual addr. */
 extern void dump_hyp_walk(vaddr_t addr);
-- 
1.7.10.4