kvm: kvm_log_sync() is only called with known memory sections

Flatview will make sure that we can only end up in this function with
memory sections that correspond to exactly one slot. So we don't
have to iterate multiple times. There won't be overlapping slots but
only matching slots.

Properly align the section and look up the corresponding slot. This
heavily simplifies this function.

We can now get rid of kvm_lookup_overlapping_slot().
Signed-off-by: NDavid Hildenbrand <david@redhat.com>
Message-Id: <20170911174933.20789-7-david@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

accel/kvm/kvm-all.c

@@ -218,34 +218,6 @@ static hwaddr kvm_align_section(MemoryRegionSection *section,
     return size;
 }
 
-/*
- * Find overlapping slot with lowest start address
- */
-static KVMSlot *kvm_lookup_overlapping_slot(KVMMemoryListener *kml,
-                                            hwaddr start_addr,
-                                            hwaddr end_addr)
-{
-    KVMState *s = kvm_state;
-    KVMSlot *found = NULL;
-    int i;
-
-    for (i = 0; i < s->nr_slots; i++) {
-        KVMSlot *mem = &kml->slots[i];
-
-        if (mem->memory_size == 0 ||
-            (found && found->start_addr < mem->start_addr)) {
-            continue;
-        }
-
-        if (end_addr > mem->start_addr &&
-            start_addr < mem->start_addr + mem->memory_size) {
-            found = mem;
-        }
-    }
-
-    return found;
-}
-
 int kvm_physical_memory_addr_from_host(KVMState *s, void *ram,
                                        hwaddr *phys_addr)
 {
@@ -489,18 +461,16 @@ static int kvm_physical_sync_dirty_bitmap(KVMMemoryListener *kml,
                                           MemoryRegionSection *section)
 {
     KVMState *s = kvm_state;
-    unsigned long size, allocated_size = 0;
     struct kvm_dirty_log d = {};
     KVMSlot *mem;
-    int ret = 0;
-    hwaddr start_addr = section->offset_within_address_space;
-    hwaddr end_addr = start_addr + int128_get64(section->size);
+    hwaddr start_addr, size;
 
-    d.dirty_bitmap = NULL;
-    while (start_addr < end_addr) {
-        mem = kvm_lookup_overlapping_slot(kml, start_addr, end_addr);
-        if (mem == NULL) {
-            break;
+    size = kvm_align_section(section, &start_addr);
+    if (size) {
+        mem = kvm_lookup_matching_slot(kml, start_addr, size);
+        if (!mem) {
+            fprintf(stderr, "%s: error finding slot\n", __func__);
+            abort();
         }
 
         /* XXX bad kernel interface alert
@@ -517,27 +487,20 @@ static int kvm_physical_sync_dirty_bitmap(KVMMemoryListener *kml,
          */
         size = ALIGN(((mem->memory_size) >> TARGET_PAGE_BITS),
                      /*HOST_LONG_BITS*/ 64) / 8;
-        if (!d.dirty_bitmap) {
-            d.dirty_bitmap = g_malloc(size);
-        } else if (size > allocated_size) {
-            d.dirty_bitmap = g_realloc(d.dirty_bitmap, size);
-        }
-        allocated_size = size;
-        memset(d.dirty_bitmap, 0, allocated_size);
+        d.dirty_bitmap = g_malloc0(size);
 
         d.slot = mem->slot | (kml->as_id << 16);
         if (kvm_vm_ioctl(s, KVM_GET_DIRTY_LOG, &d) == -1) {
             DPRINTF("ioctl failed %d\n", errno);
-            ret = -1;
-            break;
+            g_free(d.dirty_bitmap);
+            return -1;
         }
 
         kvm_get_dirty_pages_log_range(section, d.dirty_bitmap);
-        start_addr = mem->start_addr + mem->memory_size;
+        g_free(d.dirty_bitmap);
     }
-    g_free(d.dirty_bitmap);
 
-    return ret;
+    return 0;
 }
 
 static void kvm_coalesce_mmio_region(MemoryListener *listener,