KVM: Unmap kernel-allocated memory on slot destruction

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Gitweb:     
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=80b14b5b32cb0a98234283daf9b5a6643e1a1ef3
Commit:     80b14b5b32cb0a98234283daf9b5a6643e1a1ef3
Parent:     5f43238d036fb30e73563e81e42d9c6f1de5551a
Author:     Izik Eidus <[EMAIL PROTECTED]>
AuthorDate: Thu Oct 25 11:54:04 2007 +0200
Committer:  Avi Kivity <[EMAIL PROTECTED]>
CommitDate: Wed Jan 30 17:52:55 2008 +0200

    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 <[EMAIL PROTECTED]>
    Signed-off-by: Avi Kivity <[EMAIL PROTECTED]>
---
 drivers/kvm/kvm.h      |    1 +
 drivers/kvm/kvm_main.c |   14 ++++++++++++++
 2 files changed, 15 insertions(+), 0 deletions(-)

diff --git a/drivers/kvm/kvm.h b/drivers/kvm/kvm.h
index f7181a4..12de42c 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 453e98e..ab2c77c 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 */
-
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