bitkeeper revision 1.836.1.1 (4070ff6fJhQoaxeSlTRL6ojba0QXfw)

shadow logdirty mode added

3 files changed, 26 insertions, 3 deletions

diff --git a/xen/common/memory.c b/xen/common/memory.c
index b7896e3cfb..6b3b9d4e70 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -1149,7 +1149,12 @@ int do_update_va_mapping(unsigned long page_nr,
 	}
 
 	check_pagetable( p, p->mm.pagetable, "va" ); // debug
-    
+
+	/* if we're in logdirty mode, we need to note that we've updated the
+	   PTE in the PT-holding page. This is a bit of a pain as we don't
+	   know the physcial (machine) frame number of the page */
+	if ( p->mm.shadow_mode == SHM_logdirty )
+	  mark_dirty( &current->mm, va_to_l1mfn(page_nr<<PAGE_SHIFT) );    
     }
 
 
diff --git a/xen/include/asm-i386/page.h b/xen/include/asm-i386/page.h
index 1f8260e03c..54cbd85f11 100644
--- a/xen/include/asm-i386/page.h
+++ b/xen/include/asm-i386/page.h
@@ -93,6 +93,8 @@ typedef struct { unsigned long pt_lo; } pagetable_t;
 #define linear_pg_table ((l1_pgentry_t *)LINEAR_PT_VIRT_START)
 #define linear_l2_table ((l2_pgentry_t *)(LINEAR_PT_VIRT_START+(LINEAR_PT_VIRT_START>>(L2_PAGETABLE_SHIFT-L1_PAGETABLE_SHIFT))))
 
+#define va_to_l1mfn(_va) (l2_pgentry_val(linear_l2_table[_va>>L2_PAGETABLE_SHIFT]) >> PAGE_SHIFT)
+
 extern l2_pgentry_t idle_pg_table[ENTRIES_PER_L2_PAGETABLE];
 extern void paging_init(void);
 
diff --git a/xen/include/xen/shadow.h b/xen/include/xen/shadow.h
index f5c0d5327a..e5399d4ad0 100644
--- a/xen/include/xen/shadow.h
+++ b/xen/include/xen/shadow.h
@@ -82,8 +82,12 @@ static inline void mark_dirty( struct mm_struct *m, unsigned int mfn )
 	ASSERT(m->shadow_dirty_bitmap);
 	if( likely(pfn<m->shadow_dirty_bitmap_size) )
 	{
-		// use setbit to be smp guest safe
-		set_bit( pfn, m->shadow_dirty_bitmap );
+		/* use setbit to be smp guest safe. Since the same page is likely to 
+		   get marked dirty many times, examine the bit first before doing the
+		   expensive lock-prefixed opertion */
+
+		if (! test_bit( pfn, m->shadow_dirty_bitmap ) )
+			set_bit( pfn, m->shadow_dirty_bitmap );
 	}
 	else
 	{
@@ -328,6 +332,18 @@ static inline unsigned long get_shadow_status( struct mm_struct *m,
 {
 	unsigned long res;
 
+	/* If we get here, we know that this domain is running in shadow mode. 
+	   We also know that some sort of update has happened to the underlying
+	   page table page: either a PTE has been updated, or the page has
+	   changed type. If we're in log dirty mode, we should set the approrpiate
+	   bit in the dirty bitmap.
+	   NB: the VA update path doesn't use this so needs to be handled 
+	   independnetly. 
+	 */
+
+	if( m->shadow_mode == SHM_logdirty )
+		mark_dirty( m, gpfn );
+
 	spin_lock(&m->shadow_lock);
 	res = __shadow_status( m, gpfn );
 	if (!res) spin_unlock(&m->shadow_lock);