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>

1 files changed, 14 insertions, 0 deletions

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 */