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Subject[RFC][PATCH 12/12 sample] qemu-kvm: use new API for getting/switching dirty bitmaps
We use new API for light dirty log access if KVM supports it.

This conflicts with Marcelo's patches. So please take this as a sample patch.

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
---
kvm/include/linux/kvm.h | 11 ++++++
qemu-kvm.c | 81 ++++++++++++++++++++++++++++++++++++++++++-----
qemu-kvm.h | 1 +
3 files changed, 85 insertions(+), 8 deletions(-)

diff --git a/kvm/include/linux/kvm.h b/kvm/include/linux/kvm.h
index 6485981..efd9538 100644
--- a/kvm/include/linux/kvm.h
+++ b/kvm/include/linux/kvm.h
@@ -317,6 +317,14 @@ struct kvm_dirty_log {
};
};

+/* for KVM_GET_USER_DIRTY_LOG_ADDR */
+struct kvm_user_dirty_log {
+ __u32 slot;
+ __u32 flags;
+ __u64 dirty_bitmap;
+ __u64 dirty_bitmap_old;
+};
+
/* for KVM_SET_SIGNAL_MASK */
struct kvm_signal_mask {
__u32 len;
@@ -499,6 +507,7 @@ struct kvm_ioeventfd {
#define KVM_CAP_PPC_SEGSTATE 43

#define KVM_CAP_PCI_SEGMENT 47
+#define KVM_CAP_USER_DIRTY_LOG 55

#ifdef KVM_CAP_IRQ_ROUTING

@@ -595,6 +604,8 @@ struct kvm_clock_data {
struct kvm_userspace_memory_region)
#define KVM_SET_TSS_ADDR _IO(KVMIO, 0x47)
#define KVM_SET_IDENTITY_MAP_ADDR _IOW(KVMIO, 0x48, __u64)
+#define KVM_GET_USER_DIRTY_LOG_ADDR _IOW(KVMIO, 0x49, struct kvm_user_dirty_log)
+#define KVM_SWITCH_DIRTY_LOG _IO(KVMIO, 0x4a)
/* Device model IOC */
#define KVM_CREATE_IRQCHIP _IO(KVMIO, 0x60)
#define KVM_IRQ_LINE _IOW(KVMIO, 0x61, struct kvm_irq_level)
diff --git a/qemu-kvm.c b/qemu-kvm.c
index 91f0222..98777f0 100644
--- a/qemu-kvm.c
+++ b/qemu-kvm.c
@@ -143,6 +143,8 @@ struct slot_info {
unsigned long userspace_addr;
unsigned flags;
int logging_count;
+ unsigned long *dirty_bitmap;
+ unsigned long *dirty_bitmap_old;
};

struct slot_info slots[KVM_MAX_NUM_MEM_REGIONS];
@@ -232,6 +234,29 @@ int kvm_is_containing_region(kvm_context_t kvm, unsigned long phys_addr,
return 1;
}

+static int kvm_user_dirty_log_works(void)
+{
+ return kvm_state->user_dirty_log;
+}
+
+static int kvm_set_user_dirty_log(int slot)
+{
+ int r;
+ struct kvm_user_dirty_log dlog;
+
+ dlog.slot = slot;
+ r = kvm_vm_ioctl(kvm_state, KVM_GET_USER_DIRTY_LOG_ADDR, &dlog);
+ if (r < 0) {
+ DPRINTF("KVM_GET_USER_DIRTY_LOG_ADDR failed: %s\n", strerror(-r));
+ return r;
+ }
+ slots[slot].dirty_bitmap = (unsigned long *)
+ ((unsigned long)dlog.dirty_bitmap);
+ slots[slot].dirty_bitmap_old = (unsigned long *)
+ ((unsigned long)dlog.dirty_bitmap_old);
+ return r;
+}
+
/*
* dirty pages logging control
*/
@@ -265,8 +290,16 @@ static int kvm_dirty_pages_log_change(kvm_context_t kvm,
DPRINTF("slot %d start %llx len %llx flags %x\n",
mem.slot, mem.guest_phys_addr, mem.memory_size, mem.flags);
r = kvm_vm_ioctl(kvm_state, KVM_SET_USER_MEMORY_REGION, &mem);
- if (r < 0)
+ if (r < 0) {
fprintf(stderr, "%s: %m\n", __FUNCTION__);
+ return r;
+ }
+ }
+ if (flags & KVM_MEM_LOG_DIRTY_PAGES) {
+ r = kvm_set_user_dirty_log(slot);
+ } else {
+ slots[slot].dirty_bitmap = NULL;
+ slots[slot].dirty_bitmap_old = NULL;
}
return r;
}
@@ -589,7 +622,6 @@ int kvm_register_phys_mem(kvm_context_t kvm,
unsigned long phys_start, void *userspace_addr,
unsigned long len, int log)
{
-
struct kvm_userspace_memory_region memory = {
.memory_size = len,
.guest_phys_addr = phys_start,
@@ -608,6 +640,9 @@ int kvm_register_phys_mem(kvm_context_t kvm,
fprintf(stderr, "create_userspace_phys_mem: %s\n", strerror(-r));
return -1;
}
+ if (log) {
+ r = kvm_set_user_dirty_log(memory.slot);
+ }
register_slot(memory.slot, memory.guest_phys_addr, memory.memory_size,
memory.userspace_addr, memory.flags);
return 0;
@@ -652,6 +687,8 @@ void kvm_destroy_phys_mem(kvm_context_t kvm, unsigned long phys_start,
fprintf(stderr, "destroy_userspace_phys_mem: %s", strerror(-r));
return;
}
+ slots[memory.slot].dirty_bitmap = NULL;
+ slots[memory.slot].dirty_bitmap_old = NULL;

free_slot(memory.slot);
}
@@ -692,6 +729,21 @@ int kvm_get_dirty_pages(kvm_context_t kvm, unsigned long phys_addr, void *buf)
return kvm_get_map(kvm, KVM_GET_DIRTY_LOG, slot, buf);
}

+static int kvm_switch_map(int slot)
+{
+ int r;
+
+ r = kvm_vm_ioctl(kvm_state, KVM_SWITCH_DIRTY_LOG, slot);
+ if (r == 0) {
+ unsigned long *dirty_bitmap;
+
+ dirty_bitmap = slots[slot].dirty_bitmap;
+ slots[slot].dirty_bitmap = slots[slot].dirty_bitmap_old;
+ slots[slot].dirty_bitmap_old = dirty_bitmap;
+ }
+ return r;
+}
+
int kvm_get_dirty_pages_range(kvm_context_t kvm, unsigned long phys_addr,
unsigned long len, void *opaque,
int (*cb)(unsigned long start,
@@ -706,14 +758,25 @@ 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);
- if (r) {
+ if (kvm_user_dirty_log_works()) {
+ r = kvm_switch_map(i);
+ if (r == 1) { /* slot was clean */
+ continue;
+ } else if (r < 0) {
+ return r;
+ }
+ r = cb(slots[i].phys_addr, slots[i].len,
+ slots[i].dirty_bitmap_old, opaque);
+ } else {
+ buf = qemu_malloc(BITMAP_SIZE(slots[i].len));
+ r = kvm_get_map(kvm, KVM_GET_DIRTY_LOG, i, buf);
+ if (r) {
+ qemu_free(buf);
+ return r;
+ }
+ r = cb(slots[i].phys_addr, slots[i].len, buf, opaque);
qemu_free(buf);
- return r;
}
- r = cb(slots[i].phys_addr, slots[i].len, buf, opaque);
- qemu_free(buf);
if (r)
return r;
}
@@ -2097,6 +2160,8 @@ static int kvm_create_context(void)
#ifdef TARGET_I386
destroy_region_works = kvm_destroy_memory_region_works(kvm_context);
#endif
+ kvm_state->user_dirty_log
+ = kvm_check_extension(kvm_state, KVM_CAP_USER_DIRTY_LOG);

r = kvm_arch_init_irq_routing();
if (r < 0) {
diff --git a/qemu-kvm.h b/qemu-kvm.h
index ba3808a..aea89df 100644
--- a/qemu-kvm.h
+++ b/qemu-kvm.h
@@ -973,6 +973,7 @@ struct KVMState {
#endif
int irqchip_in_kernel;
int pit_in_kernel;
+ int user_dirty_log;

struct kvm_context kvm_context;
};
--
1.7.0.4


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