[RFC v2 PATCH 12/13] KVM: Introduce kvm_memfd_fallocate_range

[Chao Peng]

It reuses the same code for kvm_memfd_invalidate_range, except using
kvm_map_gfn_range as its handler.

Signed-off-by: Yu Zhang <yu.c.zhang@xxxxxxxxxxxxxxx>
Signed-off-by: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>
---
 include/linux/kvm_host.h |  2 ++
 virt/kvm/kvm_main.c      | 28 +++++++++++++++++++++++++---
 2 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index d841ed877b4b..f1d7856be05b 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1887,5 +1887,7 @@ static inline void kvm_handle_signal_exit(struct kvm_vcpu *vcpu)
 
 int kvm_memfd_invalidate_range(struct kvm *kvm, struct inode *inode,
 			       unsigned long start, unsigned long end);
+int kvm_memfd_fallocate_range(struct kvm *kvm, struct inode *inode,
+			      unsigned long start, unsigned long end);
 
 #endif
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 492c1a99ec63..7eaafc0ae6ab 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -828,8 +828,10 @@ static int kvm_init_mmu_notifier(struct kvm *kvm)
 	return mmu_notifier_register(&kvm->mmu_notifier, current->mm);
 }
 
-int kvm_memfd_invalidate_range(struct kvm *kvm, struct inode *inode,
-			       unsigned long start, unsigned long end)
+int kvm_memfd_handle_range(struct kvm *kvm, struct inode *inode,
+			   unsigned long start, unsigned long end,
+			   gfn_handler_t handler)
+
 {
 	int ret;
 	const struct kvm_useraddr_range useraddr_range = {
@@ -837,7 +839,7 @@ int kvm_memfd_invalidate_range(struct kvm *kvm, struct inode *inode,
 		.end		= end,
 		.inode		= inode,
 		.pte		= __pte(0),
-		.handler	= kvm_unmap_gfn_range,
+		.handler	= handler,
 		.on_lock	= (void *)kvm_null_fn,
 		.flush_on_ret	= true,
 		.may_block	= false,
@@ -858,6 +860,20 @@ int kvm_memfd_invalidate_range(struct kvm *kvm, struct inode *inode,
 	return ret;
 }
 
+int kvm_memfd_invalidate_range(struct kvm *kvm, struct inode *inode,
+			       unsigned long start, unsigned long end)
+{
+	return kvm_memfd_handle_range(kvm, inode, start, end,
+				      kvm_unmap_gfn_range);
+}
+
+int kvm_memfd_fallocate_range(struct kvm *kvm, struct inode *inode,
+			      unsigned long start, unsigned long end)
+{
+	return kvm_memfd_handle_range(kvm, inode, start, end,
+				      kvm_map_gfn_range);
+}
+
 #else  /* !(CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER) */
 
 static int kvm_init_mmu_notifier(struct kvm *kvm)
@@ -871,6 +887,12 @@ int kvm_memfd_invalidate_range(struct kvm *kvm, struct inode *inode,
 	return 0;
 }
 
+int kvm_memfd_fallocate_range(struct kvm *kvm, struct inode *inode,
+			      unsigned long start, unsigned long end)
+{
+	return 0;
+}
+
 #endif /* CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER */
 
 #ifdef CONFIG_HAVE_KVM_PM_NOTIFIER
-- 
2.17.1