KVM: set_memory_region: Refactor prepare_memory_region()

This patch drops the parameter old, a copy of the old memory slot, and
adds a new parameter named change to know the change being requested.

This not only cleans up the code but also removes extra copying of the
memory slot structure.

Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 4 insertions, 6 deletions

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 26216bb4403f..7198234fa088 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6906,23 +6906,21 @@ out_free:
 
 int kvm_arch_prepare_memory_region(struct kvm *kvm,
                                 struct kvm_memory_slot *memslot,
-                                struct kvm_memory_slot old,
-                                struct kvm_userspace_memory_region *mem)
+                                struct kvm_userspace_memory_region *mem,
+                                enum kvm_mr_change change)
 {
-        int npages = memslot->npages;
-
         /*
          * Only private memory slots need to be mapped here since
          * KVM_SET_MEMORY_REGION ioctl is no longer supported.
          */
-        if ((memslot->id >= KVM_USER_MEM_SLOTS) && npages && !old.npages) {
+        if ((memslot->id >= KVM_USER_MEM_SLOTS) && (change == KVM_MR_CREATE)) {
                 unsigned long userspace_addr;
 
                 /*
                  * MAP_SHARED to prevent internal slot pages from being moved
                  * by fork()/COW.
                  */
-                userspace_addr = vm_mmap(NULL, 0, npages * PAGE_SIZE,
+                userspace_addr = vm_mmap(NULL, 0, memslot->npages * PAGE_SIZE,
                                          PROT_READ | PROT_WRITE,
                                          MAP_SHARED | MAP_ANONYMOUS, 0);