target-i386: support long addresses for 4MB pages (PSE-36)

4MB pages can use 40-bit addresses by putting the higher 8 bits in bits
20-13 of the PDE.  Bit 21 is reserved.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 9 insertions, 3 deletions

diff --git a/target-i386/helper.c b/target-i386/helper.c
index 94081e8..2b917ad 100644
--- a/target-i386/helper.c
+++ b/target-i386/helper.c
@@ -672,8 +672,13 @@ int x86_cpu_handle_mmu_fault(CPUState *cs, vaddr addr,
         if ((pde & PG_PSE_MASK) && (env->cr[4] & CR4_PSE_MASK)) {
             page_size = 4096 * 1024;
             pte_addr = pde_addr;
-            pte = pde;
-            goto do_check_protect;
+
+            /* Bits 20-13 provide bits 39-32 of the address, bit 21 is reserved.
+             * Leave bits 20-13 in place for setting accessed/dirty bits below.
+             */
+            pte = pde | ((pde & 0x1fe000) << (32 - 13));
+            rsvd_mask = 0x200000;
+            goto do_check_protect_pse36;
         }
 
         if (!(pde & PG_ACCESSED_MASK)) {
@@ -696,6 +701,7 @@ int x86_cpu_handle_mmu_fault(CPUState *cs, vaddr addr,
 
 do_check_protect:
     rsvd_mask |= (page_size - 1) & PG_ADDRESS_MASK & ~PG_PSE_PAT_MASK;
+do_check_protect_pse36:
     if (pte & rsvd_mask) {
         goto do_fault_rsvd;
     }
@@ -882,7 +888,7 @@ hwaddr x86_cpu_get_phys_page_debug(CPUState *cs, vaddr addr)
         if (!(pde & PG_PRESENT_MASK))
             return -1;
         if ((pde & PG_PSE_MASK) && (env->cr[4] & CR4_PSE_MASK)) {
-            pte = pde & ~0x003ff000; /* align to 4MB */
+            pte = pde | ((pde & 0x1fe000) << (32 - 13));
             page_size = 4096 * 1024;
         } else {
             /* page directory entry */