[PATCH v2 3/4] KVM: cleanup: remove kvm_get_dirty_log()

[Takuya Yoshikawa <yoshikawa.takuya@xxxxxxxxxxxxx>]

kvm_get_dirty_log() is a helper function for kvm_vm_ioctl_get_dirty_log() which
is currently used by ia64 and ppc and the following is what it is doing:

  - sanity checks
  - bitmap scan to check if the slot is dirty
  - copy_to_user()

Considering the fact that x86 is not using this anymore and sanity checks must
be done before kvm_ia64_sync_dirty_log(), we can say that this is not working
for code sharing effectively. So we just remove this.

Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@xxxxxxxxxxxxx>
---
 arch/ia64/kvm/kvm-ia64.c  |   20 ++++++++++++++------
 arch/powerpc/kvm/book3s.c |   29 ++++++++++++++++++++++-------
 include/linux/kvm_host.h  |    2 --
 virt/kvm/kvm_main.c       |   34 ----------------------------------
 4 files changed, 36 insertions(+), 49 deletions(-)

diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 5cb5865..da0c133 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -1818,10 +1818,10 @@ static void kvm_ia64_sync_dirty_log(struct kvm *kvm,
 int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
 		struct kvm_dirty_log *log)
 {
-	int r;
+	int r, i;
 	unsigned long n;
 	struct kvm_memory_slot *memslot;
-	int is_dirty = 0;
+	unsigned long is_dirty = 0;
 
 	mutex_lock(&kvm->slots_lock);
 
@@ -1835,15 +1835,23 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
 		goto out;
 
 	kvm_ia64_sync_dirty_log(kvm, memslot);
-	r = kvm_get_dirty_log(kvm, log, &is_dirty);
-	if (r)
-		goto out;
+
+	n = kvm_dirty_bitmap_bytes(memslot);
+
+	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) {
 		kvm_flush_remote_tlbs(kvm);
-		n = kvm_dirty_bitmap_bytes(memslot);
+		r = -EFAULT;
+		if (copy_to_user(log->dirty_bitmap, memslot->dirty_bitmap, n))
+			goto out;
 		memset(memslot->dirty_bitmap, 0, n);
+	} else {
+		r = -EFAULT;
+		if (clear_user(log->dirty_bitmap, n))
+			goto out;
 	}
 	r = 0;
 out:
diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
index 801d9f3..bea6f7c 100644
--- a/arch/powerpc/kvm/book3s.c
+++ b/arch/powerpc/kvm/book3s.c
@@ -1185,28 +1185,43 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
 	struct kvm_memory_slot *memslot;
 	struct kvm_vcpu *vcpu;
 	ulong ga, ga_end;
-	int is_dirty = 0;
-	int r;
+	unsigned long is_dirty = 0;
+	int r, i;
 	unsigned long n;
 
 	mutex_lock(&kvm->slots_lock);
 
-	r = kvm_get_dirty_log(kvm, log, &is_dirty);
-	if (r)
+	r = -EINVAL;
+	if (log->slot >= KVM_MEMORY_SLOTS)
+		goto out;
+
+	memslot = &kvm->memslots->memslots[log->slot];
+	r = -ENOENT;
+	if (!memslot->dirty_bitmap)
 		goto out;
 
+	n = kvm_dirty_bitmap_bytes(memslot);
+
+	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) {
-		memslot = &kvm->memslots->memslots[log->slot];
-
 		ga = memslot->base_gfn << PAGE_SHIFT;
 		ga_end = ga + (memslot->npages << PAGE_SHIFT);
 
 		kvm_for_each_vcpu(n, vcpu, kvm)
 			kvmppc_mmu_pte_pflush(vcpu, ga, ga_end);
 
-		n = kvm_dirty_bitmap_bytes(memslot);
+		r = -EFAULT;
+		if (copy_to_user(log->dirty_bitmap, memslot->dirty_bitmap, n))
+			goto out;
+
 		memset(memslot->dirty_bitmap, 0, n);
+	} else {
+		r = -EFAULT;
+		if (clear_user(log->dirty_bitmap, n))
+			goto out;
 	}
 
 	r = 0;
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index e796326..b51e6b2 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -336,8 +336,6 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 
 int kvm_dev_ioctl_check_extension(long ext);
 
-int kvm_get_dirty_log(struct kvm *kvm,
-			struct kvm_dirty_log *log, int *is_dirty);
 int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
 				struct kvm_dirty_log *log);
 
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 74f7319..8859049 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -773,40 +773,6 @@ int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
 	return kvm_set_memory_region(kvm, mem, user_alloc);
 }
 
-int kvm_get_dirty_log(struct kvm *kvm,
-			struct kvm_dirty_log *log, int *is_dirty)
-{
-	struct kvm_memory_slot *memslot;
-	int r, i;
-	unsigned long n;
-	unsigned long any = 0;
-
-	r = -EINVAL;
-	if (log->slot >= KVM_MEMORY_SLOTS)
-		goto out;
-
-	memslot = &kvm->memslots->memslots[log->slot];
-	r = -ENOENT;
-	if (!memslot->dirty_bitmap)
-		goto out;
-
-	n = kvm_dirty_bitmap_bytes(memslot);
-
-	for (i = 0; !any && i < n/sizeof(long); ++i)
-		any = memslot->dirty_bitmap[i];
-
-	r = -EFAULT;
-	if (copy_to_user(log->dirty_bitmap, memslot->dirty_bitmap, n))
-		goto out;
-
-	if (any)
-		*is_dirty = 1;
-
-	r = 0;
-out:
-	return r;
-}
-
 void kvm_disable_largepages(void)
 {
 	largepages_enabled = false;
-- 
1.7.0.4

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