[RFC,v2,0/6] KVM: moving dirty gitmaps to user space!

Commit Message

Takuya Yoshikawa April 20, 2010, 10:53 a.m. UTC

None

Patch

===

Appendix:

To test the patch 6, we are using the following patch for qemu-kvm.
---
 configure  |    2 +-
 qemu-kvm.c |   22 +++++++++++++++++-----
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/configure b/configure
index be8dac4..0b2d017 100755
--- a/configure
+++ b/configure
@@ -1498,7 +1498,7 @@  fi
 if test "$kvm" != "no" ; then
     cat > $TMPC <<EOF
 #include <linux/kvm.h>
-#if !defined(KVM_API_VERSION) || KVM_API_VERSION < 12 || KVM_API_VERSION > 12
+#if !defined(KVM_API_VERSION) || KVM_API_VERSION < 13 || KVM_API_VERSION > 13
 #error Invalid KVM version
 #endif
 #if !defined(KVM_CAP_USER_MEMORY)
diff --git a/qemu-kvm.c b/qemu-kvm.c
index cc5b352..087adea 100644
--- a/qemu-kvm.c
+++ b/qemu-kvm.c
@@ -44,7 +44,7 @@ 
 #define BUS_MCEERR_AO 5
 #endif
 
-#define EXPECTED_KVM_API_VERSION 12
+#define EXPECTED_KVM_API_VERSION 13
 
 #if EXPECTED_KVM_API_VERSION != KVM_API_VERSION
 #error libkvm: userspace and kernel version mismatch
@@ -684,6 +684,21 @@  static int kvm_get_map(kvm_context_t kvm, int ioctl_num, int slot, void *buf)
     return 0;
 }
 
+static int kvm_switch_map(kvm_context_t kvm, int slot, void **buf)
+{
+    int r;
+    struct kvm_dirty_log log = {
+        .slot = slot,
+    };
+
+    r = kvm_vm_ioctl(kvm_state, KVM_SWITCH_DIRTY_LOG, &log);
+    if (r < 0)
+        return r;
+
+    *buf = (void *)log.addr;
+    return 0;
+}
+
 int kvm_get_dirty_pages(kvm_context_t kvm, unsigned long phys_addr, void *buf)
 {
     int slot;
@@ -706,14 +721,11 @@  int kvm_get_dirty_pages_range(kvm_context_t kvm, unsigned long phys_addr,
     for (i = 0; i < KVM_MAX_NUM_MEM_REGIONS; ++i) {
         if ((slots[i].len && (uint64_t) slots[i].phys_addr >= phys_addr)
             && ((uint64_t) slots[i].phys_addr + slots[i].len <= end_addr)) {
-            buf = qemu_malloc(BITMAP_SIZE(slots[i].len));
-            r = kvm_get_map(kvm, KVM_GET_DIRTY_LOG, i, buf);
+            r = kvm_switch_map(kvm, i, &buf);
             if (r) {
-                qemu_free(buf);
                 return r;
             }
             r = cb(slots[i].phys_addr, slots[i].len, buf, opaque);
-            qemu_free(buf);
             if (r)
                 return r;
         }