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>

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index f7181a407be184a0d277f8338b1ebfba6261e37e..12de42c789a2a183640a61eafe8042aa8dfd3ce3 100644 (file)
--- 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 453e98e251dafd839d8c151cd21f922b98001a6d..ab2c77c9ecef925c60e6eabe095241a5664a65fa 100644 (file)
--- 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 */