[Qemu-devel] [PATCH 01/24] Add support for multi-level phys map.

[Tristan Gingold <gingold@adacore.com>]

As Alpha physical addresses are 44 bits, l1_phys_map can't be anymore 2 levels.
Use a more generic multi-level approach and explain why we don't need to
extend l1_map.

Signed-off-by: Tristan Gingold <gingold@adacore.com>
---
 exec.c |   50 ++++++++++++++++++++++++++++++++++++++------------
 1 files changed, 38 insertions(+), 12 deletions(-)

diff --git a/exec.c b/exec.c
index abe37c3..fd3e441 100644
--- a/exec.c
+++ b/exec.c
@@ -150,14 +150,17 @@ typedef struct PhysPageDesc {
 } PhysPageDesc;
 
 #define L2_BITS 10
-#if defined(CONFIG_USER_ONLY) && defined(TARGET_VIRT_ADDR_SPACE_BITS)
-/* XXX: this is a temporary hack for alpha target.
- *      In the future, this is to be replaced by a multi-level table
- *      to actually be able to handle the complete 64 bits address space.
- */
-#define L1_BITS (TARGET_VIRT_ADDR_SPACE_BITS - L2_BITS - TARGET_PAGE_BITS)
+
+#if TARGET_PHYS_ADDR_SPACE_BITS > (32 + 32 - L2_BITS - TARGET_PAGE_BITS)
+# define MULTILEVEL_PHYS_MAP
+# define L1_BITS_ ((TARGET_PHYS_ADDR_SPACE_BITS - TARGET_PAGE_BITS) % L2_BITS)
+# if L1_BITS_ < 4 /* avoid ridiculous small l1 */
+#  define L1_BITS (L1_BITS_ + L2_BITS)
+# else
+#  define L1_BITS L1_BITS_
+# endif
 #else
-#define L1_BITS (32 - L2_BITS - TARGET_PAGE_BITS)
+# define L1_BITS (32 - L2_BITS - TARGET_PAGE_BITS)
 #endif
 
 #define L1_SIZE (1 << L1_BITS)
@@ -168,7 +171,9 @@ unsigned long qemu_host_page_bits;
 unsigned long qemu_host_page_size;
 unsigned long qemu_host_page_mask;
 
-/* XXX: for system emulation, it could just be an array */
+/* XXX: for system emulation, it could just be an array.  As this is currently
+   a two level map this limits the size of RAM memory that can contains
+   target code.  In practice this is large enough (>= 4GB) */
 static PageDesc *l1_map[L1_SIZE];
 static PhysPageDesc **l1_phys_map;
 
@@ -342,12 +347,31 @@ static PhysPageDesc *phys_page_find_alloc(target_phys_addr_t index, int alloc)
     void **lp, **p;
     PhysPageDesc *pd;
 
+#ifdef MULTILEVEL_PHYS_MAP
+    int i;
+#define L1_SHIFT (TARGET_PHYS_ADDR_SPACE_BITS - TARGET_PAGE_BITS - L1_BITS)
+
+    /* Level 1.  */
+    p = (void **)l1_phys_map;
+    lp = p + ((index >> L1_SHIFT) & (L1_SIZE - 1));
+
+    /* Level 2..n-1 */
+    for (i = (L1_SHIFT / L2_BITS) - 1; i > 0; i--) {
+	p = *lp;
+	if (!p) {
+	    /* allocate if not found */
+	    if (!alloc)
+		return NULL;
+	    p = qemu_vmalloc(sizeof(void *) * L2_SIZE);
+	    memset(p, 0, sizeof(void *) * L2_SIZE);
+	    *lp = p;
+	}
+	lp = p + ((index >> (i * L2_BITS)) & (L2_SIZE - 1));
+    }
+#else
     p = (void **)l1_phys_map;
-#if TARGET_PHYS_ADDR_SPACE_BITS > 32
 
-#if TARGET_PHYS_ADDR_SPACE_BITS > (32 + L1_BITS)
-#error unsupported TARGET_PHYS_ADDR_SPACE_BITS
-#endif
+#if TARGET_PHYS_ADDR_SPACE_BITS > 32
     lp = p + ((index >> (L1_BITS + L2_BITS)) & (L1_SIZE - 1));
     p = *lp;
     if (!p) {
@@ -360,6 +384,8 @@ static PhysPageDesc *phys_page_find_alloc(target_phys_addr_t index, int alloc)
     }
 #endif
     lp = p + ((index >> L2_BITS) & (L1_SIZE - 1));
+#endif
+
     pd = *lp;
     if (!pd) {
         int i;
-- 
1.6.2