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>

7 files changed, 15 insertions, 17 deletions

diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 24cb5f66787d..96ebab7a1959 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -230,8 +230,8 @@ int kvm_arch_set_memory_region(struct kvm *kvm,
 
 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)
 {
         return 0;
 }
diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
index 43701f0c0f71..5c2b07e8c3d6 100644
--- a/arch/ia64/kvm/kvm-ia64.c
+++ b/arch/ia64/kvm/kvm-ia64.c
@@ -1560,8 +1560,8 @@ int kvm_arch_create_memslot(struct kvm_memory_slot *slot, unsigned long npages)
 
 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)
 {
         unsigned long i;
         unsigned long pfn;
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 22b33159fbc4..8aa51cd67c28 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -412,8 +412,8 @@ int kvm_arch_create_memslot(struct kvm_memory_slot *slot, unsigned long npages)
 
 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)
 {
         return kvmppc_core_prepare_memory_region(kvm, memslot, mem);
 }
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 07ac302ce246..4288780c86b8 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -974,8 +974,8 @@ int kvm_arch_create_memslot(struct kvm_memory_slot *slot, unsigned long npages)
 /* Section: memory related */
 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)
 {
         /* A few sanity checks. We can have exactly one memory slot which has
            to start at guest virtual zero and which has to be located at a
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);
 
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 8eaf61f7b02d..caa72cf7e8e7 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -479,8 +479,8 @@ void kvm_arch_free_memslot(struct kvm_memory_slot *free,
 int kvm_arch_create_memslot(struct kvm_memory_slot *slot, unsigned long npages);
 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);
 void kvm_arch_commit_memory_region(struct kvm *kvm,
                                 struct kvm_userspace_memory_region *mem,
                                 struct kvm_memory_slot old);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index c7979ed41923..8f85bae862c7 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -856,7 +856,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
                 slots = old_memslots;
         }
 
-        r = kvm_arch_prepare_memory_region(kvm, &new, old, mem);
+        r = kvm_arch_prepare_memory_region(kvm, &new, mem, change);
         if (r)
                 goto out_slots;