bitkeeper revision 1.891.1.13 (40a24fd6V2eF76NjMSt5mccf1Jh1qQ)

Lazy page-table switching.

3 files changed, 29 insertions, 23 deletions

diff --git a/xen/arch/i386/process.c b/xen/arch/i386/process.c
index 29c4fde8cb..408daa1f14 100644
--- a/xen/arch/i386/process.c
+++ b/xen/arch/i386/process.c
@@ -270,7 +270,7 @@ void switch_to(struct task_struct *prev_p, struct task_struct *next_p)
         tss->ss1  = next->guestos_ss;
 
         /* Maybe switch the debug registers. */
-        if ( next->debugreg[7] )
+        if ( unlikely(next->debugreg[7]) )
         {
             loaddebug(next, 0);
             loaddebug(next, 1);
@@ -280,10 +280,17 @@ void switch_to(struct task_struct *prev_p, struct task_struct *next_p)
             loaddebug(next, 6);
             loaddebug(next, 7);
         }
+
+        /* Switch page tables. */
+        write_ptbase(&next_p->mm);
+        tlb_clocktick();
     }
 
-    if ( ( prev_p->io_bitmap != NULL ) || ( next_p->io_bitmap != NULL ) ) {
-        if ( next_p->io_bitmap != NULL ) {
+    if ( unlikely(prev_p->io_bitmap != NULL) || 
+         unlikely(next_p->io_bitmap != NULL) )
+    {
+        if ( next_p->io_bitmap != NULL )
+        {
             /* Copy in the appropriate parts of the IO bitmap.  We use the
              * selector to copy only the interesting parts of the bitmap. */
 
@@ -314,7 +321,9 @@ void switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 
             tss->bitmap = IO_BITMAP_OFFSET;
 
-	} else {
+	}
+        else
+        {
             /* In this case, we're switching FROM a task with IO port access,
              * to a task that doesn't use the IO bitmap.  We set any TSS bits
              * that might have been cleared, ready for future use. */
@@ -332,11 +341,6 @@ void switch_to(struct task_struct *prev_p, struct task_struct *next_p)
             tss->bitmap = INVALID_IO_BITMAP_OFFSET;
 	}
     }
-    
-    
-    /* Switch page tables. */
-    write_ptbase(&next_p->mm);
-    tlb_clocktick();
 
     set_current(next_p);
 
diff --git a/xen/common/domain.c b/xen/common/domain.c
index 1b8759e912..f19c05eaf2 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -214,10 +214,6 @@ void __kill_domain(struct task_struct *p)
     *pp = p->next_hash;
     write_unlock_irqrestore(&tasklist_lock, flags);
 
-    if ( atomic_read(&p->refcnt) >2 )
-	DPRINTK("Domain refcnt>1 so kil deferred. Missing put_task? p=%p cur=%p cnt=%d\n",p,current,atomic_read(&p->refcnt));
-
-
     if ( p == current )
     {
         __enter_scheduler();
@@ -412,7 +408,16 @@ void free_all_dom_mem(struct task_struct *p)
 
     INIT_LIST_HEAD(&zombies);
 
-    if ( p->mm.shadow_mode ) shadow_mode_disable(p);
+    /*
+     * If we're executing the idle task then we may still be running over the 
+     * dead domain's page tables. We'd better fix that before freeing them!
+     */
+    if ( is_idle_task(current) )
+        write_ptbase(&current->mm);
+
+    /* Exit shadow mode before deconstructing final guest page table. */
+    if ( p->mm.shadow_mode )
+        shadow_mode_disable(p);
 
     /* STEP 1. Drop the in-use reference to the page-table base. */
     put_page_and_type(&frame_table[pagetable_val(p->mm.pagetable) >>
@@ -1066,7 +1071,7 @@ int construct_dom0(struct task_struct *p,
 
     set_bit(PF_CONSTRUCTED, &p->flags);
 
-#if 0 // XXXXX DO NOT CHECK IN ENABLED !!! (but useful for testing so leave) 
+#if 0 /* XXXXX DO NOT CHECK IN ENABLED !!! (but useful for testing so leave) */
     shadow_mode_enable(&p->mm, SHM_test); 
 #endif
 
diff --git a/xen/common/memory.c b/xen/common/memory.c
index 5acfae8482..3f8ee288ee 100644
--- a/xen/common/memory.c
+++ b/xen/common/memory.c
@@ -194,7 +194,6 @@ static struct {
  */
 void __init init_frametable(unsigned long nr_pages)
 {
-    int i;
     unsigned long mfn;
 
     memset(percpu_info, 0, sizeof(percpu_info));
@@ -209,15 +208,13 @@ void __init init_frametable(unsigned long nr_pages)
     INIT_LIST_HEAD(&free_list);    
     free_pfns = 0;
 
-    /* so that we can map them latter, set the ownership of pages
-       belonging to the machine_to_phys_mapping to CPU0 idle task */
-    
-    mfn = virt_to_phys((void *)RDWR_MPT_VIRT_START)>>PAGE_SHIFT;
-//    for(i=0;i<nr_pages;i+=1024,mfn++)
-    for(i=0;i<1024*1024;i+=1024,mfn++)
+    /* Pin the ownership of the MP table so that DOM0 can map it later. */
+    for ( mfn = virt_to_phys((void *)RDWR_MPT_VIRT_START)>>PAGE_SHIFT;
+          mfn < virt_to_phys((void *)RDWR_MPT_VIRT_END)>>PAGE_SHIFT;
+          mfn++ )
     {
 	frame_table[mfn].count_and_flags = 1 | PGC_allocated;
-	frame_table[mfn].type_and_flags = 1 | PGT_gdt_page; // anything non RW
+	frame_table[mfn].type_and_flags = 1 | PGT_gdt_page; /* non-RW type */
 	frame_table[mfn].u.domain = &idle0_task;
     }
 }