KVM: Unmap kernel-allocated memory on slot destruction

kvm_vm_ioctl_set_memory_region() is able to remove memory in addition to
adding it.  Therefore when using kernel swapping support for old userspaces,
we need to munmap the memory if the user request to remove it

Signed-off-by: Izik Eidus <izike@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

2 files changed, 15 insertions, 0 deletions

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index f7181a407be1..12de42c789a2 100644
--- a/drivers/kvm/kvm.h
+++ b/drivers/kvm/kvm.h
@@ -353,6 +353,7 @@ struct kvm_memory_slot {
         unsigned long *rmap;
         unsigned long *dirty_bitmap;
         unsigned long userspace_addr;
+        int user_alloc;
 };
 
 struct kvm {
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 453e98e251da..ab2c77c9ecef 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -713,6 +713,7 @@ static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
 
                 memset(new.rmap, 0, npages * sizeof(*new.rmap));
 
+                new.user_alloc = user_alloc;
                 if (user_alloc)
                         new.userspace_addr = mem->userspace_addr;
                 else {
@@ -727,6 +728,19 @@ static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm,
                         if (IS_ERR((void *)new.userspace_addr))
                                 goto out_unlock;
                 }
+        } else {
+                if (!old.user_alloc && old.rmap) {
+                        int ret;
+
+                        down_write(&current->mm->mmap_sem);
+                        ret = do_munmap(current->mm, old.userspace_addr,
+                                        old.npages * PAGE_SIZE);
+                        up_write(&current->mm->mmap_sem);
+                        if (ret < 0)
+                                printk(KERN_WARNING
+                                       "kvm_vm_ioctl_set_memory_region: "
+                                       "failed to munmap memory\n");
+                }
         }
 
         /* Allocate page dirty bitmap if needed */