KVM: cleanup {kvm_vm_ioctl, kvm}_get_dirty_log()

Using bitmap_empty() to see whether memslot->dirty_bitmap is empty

Changlog:
cleanup x86 specific kvm_vm_ioctl_get_dirty_log() and fix a local parameter's type address Takuya Yoshikawa's suggestion

arch/x86/kvm/x86.c +4 -13

@@ -2644,22 +2644,17 @@ static int kvm_vm_ioctl_reinject(struct kvm *kvm,
 int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
 				      struct kvm_dirty_log *log)
 {
-	int r, n, i;
+	int r, n, is_dirty = 0;
 	struct kvm_memory_slot *memslot;
-	unsigned long is_dirty = 0;
 	unsigned long *dirty_bitmap = NULL;
 
 	mutex_lock(&kvm->slots_lock);
 
-	r = -EINVAL;
-	if (log->slot >= KVM_MEMORY_SLOTS)
+	r = kvm_get_dirty_log(kvm, log, &is_dirty);
+	if (r)
 		goto out;
 
 	memslot = &kvm->memslots->memslots[log->slot];
-	r = -ENOENT;
-	if (!memslot->dirty_bitmap)
-		goto out;
-
 	n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
 
 	r = -ENOMEM;

@@ -2668,9 +2663,6 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
 		goto out;
 	memset(dirty_bitmap, 0, n);
 
-	for (i = 0; !is_dirty && i < n/sizeof(long); i++)
-		is_dirty = memslot->dirty_bitmap[i];
-
 	/* If nothing is dirty, don't bother messing with page tables. */
 	if (is_dirty) {
 		struct kvm_memslots *slots, *old_slots;

@@ -2694,8 +2686,7 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
 	}
 
 	r = 0;
-	if (copy_to_user(log->dirty_bitmap, dirty_bitmap, n))
-		r = -EFAULT;
+
 out_free:
 	vfree(dirty_bitmap);
 out:

virt/kvm/kvm_main.c +2 -5

index bcd08b8..b08a7de 100644
@@ -767,9 +767,7 @@ int kvm_get_dirty_log(struct kvm *kvm,
 			struct kvm_dirty_log *log, int *is_dirty)
 {
 	struct kvm_memory_slot *memslot;
-	int r, i;
-	int n;
-	unsigned long any = 0;
+	int r, n, any = 0;
 
 	r = -EINVAL;
 	if (log->slot >= KVM_MEMORY_SLOTS)

@@ -782,8 +780,7 @@ int kvm_get_dirty_log(struct kvm *kvm,
 
 	n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
 
-	for (i = 0; !any && i < n/sizeof(long); ++i)
-		any = memslot->dirty_bitmap[i];
+	any = !bitmap_empty(memslot->dirty_bitmap, memslot->npages);
 
 	r = -EFAULT;
 	if (copy_to_user(log->dirty_bitmap, memslot->dirty_bitmap, n))

Oh, for such a tiny comment.

What I said was just you may be able to use bitmap_empty() instead of

arch/x86/kvm/x86.c int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, · line 2672

Quoted 2 lines

arch/x86/kvm/x86.c +0 -2

-    for (i = 0; !is_dirty && i < n/sizeof(long); i++)
-        is_dirty = memslot->dirty_bitmap[i];

for x86's code too, if your patch for kvm_get_dirty_log() was correct.

Quoted 1 line · Takuya Yoshikawa

Oh, for such a tiny comment.

Your comment is valuable although it's tiny :-)

Quoted 2 lines

What I said was just you may be able to use bitmap_empty() instead of

Quoted 3 lines

arch/x86/kvm/x86.c int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, · line 2672

Quoted 2 lines

arch/x86/kvm/x86.c +0 -2

-    for (i = 0; !is_dirty && i < n/sizeof(long); i++)
-        is_dirty = memslot->dirty_bitmap[i];

for x86's code too, if your patch for kvm_get_dirty_log() was correct.

While i look into x86's code, i found we can direct call kvm_get_dirty_log() in kvm_vm_ioctl_get_dirty_log() to remove some unnecessary code, this is a better cleanup way

Thanks,
Xiao

Ah, probably checking the git log will explain you why it is like that! Marcelo's work? IIRC.

Using bitmap_empty() to see whether memslot->dirty_bitmap is empty

Changlog:
cleanup x86 specific kvm_vm_ioctl_get_dirty_log() and fix a local parameter's type address Takuya Yoshikawa's suggestion

Signed-off-by Xiao Guangrong <[email protected]>

---
 arch/x86/kvm/x86.c  |   17 ++++-------------
 virt/kvm/kvm_main.c |    7 ++-----
 2 files changed, 6 insertions(+), 18 deletions(-)

arch/x86/kvm/x86.c +1 -3

index bcf52d1..e6cbbd4 100644
@@ -2644,22 +2644,17 @@ static int kvm_vm_ioctl_reinject(struct kvm *kvm,
 int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
 				      struct kvm_dirty_log *log)
 {
-	int r, n, i;
+	int r, n, is_dirty = 0;
 	struct kvm_memory_slot *memslot;
-	unsigned long is_dirty = 0;
 	unsigned long *dirty_bitmap = NULL;
 
 	mutex_lock(&kvm->slots_lock);
 
-	r = -EINVAL;

index bcd08b8..b08a7de 100644

virt/kvm/kvm_main.c +1 -3

@@ -767,9 +767,7 @@ int kvm_get_dirty_log(struct kvm *kvm,
 			struct kvm_dirty_log *log, int *is_dirty)
 {
 	struct kvm_memory_slot *memslot;
-	int r, i;
-	int n;
-	unsigned long any = 0;
+	int r, n, any = 0;
 
 	r = -EINVAL;
 	if (log->slot >= KVM_MEMORY_SLOTS)