[Qemu-devel] [PATCH] Introduce kvm logging interface.

[Glauber Costa <glommer@redhat.com>]

Introduce functions to stop and start logging of memory regions.
We select region based on its start address.

Signed-off-by: Glauber Costa <glommer@redhat.com>
---
 kvm-all.c |  140 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 kvm.h     |    5 ++
 2 files changed, 145 insertions(+), 0 deletions(-)

diff --git a/kvm-all.c b/kvm-all.c
index 6d50609..c2c253f 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -31,8 +31,15 @@
     do { } while (0)
 #endif
 
+#define warning(fmt, ...) \
+    do { fprintf(stderr, "%s:%d" fmt, __func__, __LINE__, ## __VA_ARGS__); } while (0)
+
 typedef struct kvm_userspace_memory_region KVMSlot;
 
+#define kvm_uaddr(addr) ((addr) + (ram_addr_t)phys_ram_base)
+
+typedef struct kvm_dirty_log KVMDirty;
+
 int kvm_allowed = 0;
 
 struct KVMState
@@ -71,6 +78,24 @@ static KVMSlot *kvm_lookup_slot(KVMState *s, target_phys_addr_t start_addr)
     return NULL;
 }
 
+/* find the slot correspondence using userspace_addr as a key */
+static KVMSlot *kvm_lookup_slot_uaddr(KVMState *s, ram_addr_t addr)
+{
+    int i;
+    
+    uint64_t uaddr = (uint64_t)kvm_uaddr(addr);
+
+    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
+        KVMSlot *mem = &s->slots[i];
+
+        if (uaddr >= mem->userspace_addr &&
+            uaddr < (mem->userspace_addr + mem->memory_size))
+            return mem;
+    }
+
+    return NULL;
+}
+
 int kvm_init_vcpu(CPUState *env)
 {
     KVMState *s = kvm_state;
@@ -109,6 +134,121 @@ err:
     return ret;
 }
 
+/* 
+ *  * dirty pages logging control 
+ *   */
+static int kvm_dirty_pages_log_change(KVMSlot *mem,
+                                      unsigned flags,
+                                      unsigned mask)
+{
+    int r = -1;
+    KVMState *s = kvm_state;
+
+    flags = (mem->flags & ~mask) | flags;
+    if (flags == mem->flags)
+            return 0;
+
+    mem->flags = flags;
+
+    r = kvm_vm_ioctl(s, KVM_SET_USER_MEMORY_REGION, mem);
+    if (r == -1)
+        fprintf(stderr, "%s: %m\n", __FUNCTION__);
+
+    return r;
+}
+
+int kvm_log_start(target_phys_addr_t phys_addr, target_phys_addr_t len)
+{
+        KVMState *s = kvm_state;
+        KVMSlot *mem = kvm_lookup_slot(s, phys_addr);
+
+        if (mem == NULL)  {
+                fprintf(stderr, "BUG: %s: invalid parameters\n", __func__);
+                return -EINVAL;
+        }
+
+        /* Already logging, no need to issue ioctl */
+        if (mem->flags & KVM_MEM_LOG_DIRTY_PAGES)
+            return 0;
+
+        dprintf("slot %d: enable logging (phys %llx, uaddr %llx)\n",
+                 mem->slot, mem->guest_phys_addr, mem->userspace_addr);
+
+        return kvm_dirty_pages_log_change(mem,
+                                          KVM_MEM_LOG_DIRTY_PAGES,
+                                          KVM_MEM_LOG_DIRTY_PAGES);
+}
+
+int kvm_log_stop(target_phys_addr_t phys_addr, target_phys_addr_t len)
+{
+
+        KVMState *s = kvm_state;
+        KVMSlot *mem = kvm_lookup_slot(s, phys_addr);
+
+        if (mem == NULL) {
+                fprintf(stderr, "BUG: %s: invalid parameters\n", __func__);
+                return -EINVAL;
+        }
+
+        /* Not logging, no need to issue ioctl */
+        if (!(mem->flags & KVM_MEM_LOG_DIRTY_PAGES))
+            return 0;
+
+        dprintf("slot %d: disabling logging\n", mem->slot);
+        return kvm_dirty_pages_log_change(mem,
+                                          0,
+                                          KVM_MEM_LOG_DIRTY_PAGES);
+}
+
+static inline int lookup_bitmap_phys(unsigned long *dirty, unsigned nr)
+{
+    unsigned word = nr / (sizeof(*dirty) * 8);
+    unsigned bit = nr % (sizeof(*dirty) * 8);
+    int ret;
+
+    ret = (dirty[word] >> bit) & 1;
+    return ret;
+}
+
+void kvm_physical_sync_dirty_bitmap(ram_addr_t start_addr, ram_addr_t end_addr)
+{
+    KVMState *s = kvm_state;
+    KVMSlot *mem = kvm_lookup_slot_uaddr(s, start_addr);
+    KVMDirty d;
+    unsigned long alloc_size = mem->memory_size >> TARGET_PAGE_BITS / sizeof(d.dirty_bitmap);
+    ram_addr_t addr;
+
+    dprintf("sync addr: %lx %llx %llx\n", start_addr, mem->guest_phys_addr, kvm_uaddr(start_addr));
+    if (mem == NULL) {
+            fprintf(stderr, "BUG: %s: invalid parameters\n", __func__);
+            return;
+    }
+
+    d.dirty_bitmap = qemu_mallocz(alloc_size);
+
+    if (d.dirty_bitmap == NULL) {
+        warning("Could not allocate dirty bitmap\n");
+        return;
+    }
+
+    d.slot = mem->slot;
+    dprintf("slot %d, phys_addr %llx, uaddr: %llx\n",
+            d.slot, mem->guest_phys_addr, mem->userspace_addr);
+
+    if (kvm_vm_ioctl(s, KVM_GET_DIRTY_LOG, &d) == -1) {
+        warning("ioctl failed %d\n", errno);
+        goto out;
+    }
+    
+    for (addr = start_addr; addr < end_addr; addr += TARGET_PAGE_SIZE){
+        unsigned nr;
+        nr = (uint32_t)((uint64_t)kvm_uaddr(addr) - mem->userspace_addr) >> TARGET_PAGE_BITS;
+        phys_ram_dirty[addr >> TARGET_PAGE_BITS] |= lookup_bitmap_phys((unsigned long *)d.dirty_bitmap, nr);
+    }
+out:
+    qemu_free(d.dirty_bitmap);
+}
+
 int kvm_init(int smp_cpus)
 {
     KVMState *s;
diff --git a/kvm.h b/kvm.h
index 37102b4..39e9048 100644
--- a/kvm.h
+++ b/kvm.h
@@ -38,6 +38,11 @@ void kvm_set_phys_mem(target_phys_addr_t start_addr,
                       ram_addr_t size,
                       ram_addr_t phys_offset);
 
+int kvm_physical_memory_get_dirty(ram_addr_t addr);
+void kvm_physical_sync_dirty_bitmap(ram_addr_t start_addr, ram_addr_t end_addr);
+
+int kvm_log_start(target_phys_addr_t phys_addr, target_phys_addr_t len);
+int kvm_log_stop(target_phys_addr_t phys_addr, target_phys_addr_t len);
 /* internal API */
 
 struct KVMState;
-- 
1.5.6.5