[Qemu-devel] [PATCH 4/6] qemu-kvm: Introduce cpu_physical_memory_get_dirty_range().

[Yoshiaki Tamura]

Introduces cpu_physical_memory_get_dirty_range().
It checks the first row and puts dirty addr in the array.
If the first row is empty, it skips to the first non-dirty row 
or the end addr, and put the length in the first entry of the array.

Signed-off-by: Yoshiaki Tamura <address@hidden>
Signed-off-by: OHMURA Kei <address@hidden>
---
 exec.c |   73 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 73 insertions(+), 0 deletions(-)

diff --git a/exec.c b/exec.c
index b31c349..87056a6 100644
--- a/exec.c
+++ b/exec.c
@@ -1961,6 +1961,79 @@ static inline void tlb_reset_dirty_range(CPUTLBEntry 
*tlb_entry,
     }
 }
 
+/* It checks the first row and puts dirty addrs in the array.
+   If the first row is empty, it skips to the first non-dirty row
+   or the end addr, and put the length in the first entry of the array. */
+int cpu_physical_memory_get_dirty_range(ram_addr_t start, ram_addr_t end, 
+                                        ram_addr_t *dirty_rams, int length,
+                                        int dirty_flag)
+{
+    unsigned long phys_ram_dirty, page_number, *p;
+    ram_addr_t addr;
+    int s_idx = (start >> TARGET_PAGE_BITS) / HOST_LONG_BITS;
+    int e_idx = (end >> TARGET_PAGE_BITS) / HOST_LONG_BITS;
+    int i, j, offset;
+
+    switch (dirty_flag) {
+    case VGA_DIRTY_FLAG:
+        p = phys_ram_vga_dirty;
+        break;
+    case CODE_DIRTY_FLAG:
+        p = phys_ram_code_dirty;
+        break;
+    case MIGRATION_DIRTY_FLAG:
+        p = phys_ram_migration_dirty;
+        break;
+    default:
+        abort();
+    }
+
+    /* mask bits before the start addr */
+    offset = (start >> TARGET_PAGE_BITS) & (HOST_LONG_BITS - 1);
+    phys_ram_dirty = p[s_idx] & ~((1UL << offset) - 1);
+
+    if (s_idx == e_idx) {
+        /* mask bits after the end addr */
+        offset = (end >> TARGET_PAGE_BITS) & (HOST_LONG_BITS - 1);
+        phys_ram_dirty &= (1UL << offset) - 1;
+    }
+
+    if (phys_ram_dirty == 0) {
+        /* when the row is empty */
+        ram_addr_t skip;
+        if (s_idx == e_idx)
+            skip = end;
+        else {
+            /* skip empty rows */
+            while (s_idx < e_idx && p[++s_idx] == 0);
+            skip = (s_idx * HOST_LONG_BITS * TARGET_PAGE_SIZE);
+        }
+        dirty_rams[0] = skip - start;
+        i = 0;
+
+    } else if (phys_ram_dirty == ~0UL) {
+        /* when the row is fully dirtied */
+        addr = start;
+        for (i = 0; i < length; i++) {
+            dirty_rams[i] = addr;
+            addr += TARGET_PAGE_SIZE;
+        }
+    } else {
+        /* when the row is partially dirtied */
+        i = 0;
+        do {
+            j = ffsl(phys_ram_dirty) - 1;
+            phys_ram_dirty &= ~(1UL << j);
+            page_number = s_idx * HOST_LONG_BITS + j;
+            addr = page_number * TARGET_PAGE_SIZE;
+            dirty_rams[i] = addr;
+            i++;
+        } while (phys_ram_dirty != 0 && i < length);
+    }
+
+    return i;
+}
+
 /* Note: start and end must be within the same ram block.  */
 void cpu_physical_memory_reset_dirty(ram_addr_t start, ram_addr_t end,
                                      int dirty_flags)
-- 
1.7.0.31.g1df487