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KVM: Enable 32bit dirty log pointers on 64bit host

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With big endian userspace, we can't quite figure out if a pointer
is 32 bit (shifted >> 32) or 64 bit when we read a 64 bit pointer.

This is what happens with dirty logging. To get the pointer interpreted
correctly, we thus need Arnd's patch to implement a compat layer for
the ioctl:

A better way to do this is to add a separate compat_ioctl() method that
converts this for you.

Based on initial patch from Arnd Bergmann.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Arnd Bergmann 2009-10-22 14:19:27 +02:00 committed by Avi Kivity
parent afbcf7ab8d
commit 6ff5894cdf
1 changed files with 50 additions and 1 deletions
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51
virt/kvm/kvm_main.c
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@ -43,6 +43,7 @@
#include <linux/swap.h>
#include <linux/bitops.h>
#include <linux/spinlock.h>
#include <linux/compat.h>
#include <asm/processor.h>
#include <asm/io.h>
@ -1542,6 +1543,52 @@ static long kvm_vm_ioctl(struct file *filp,
return r;
}
#ifdef CONFIG_COMPAT
struct compat_kvm_dirty_log {
__u32 slot;
__u32 padding1;
union {
compat_uptr_t dirty_bitmap; /* one bit per page */
__u64 padding2;
};
};
static long kvm_vm_compat_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg)
{
struct kvm *kvm = filp->private_data;
int r;
if (kvm->mm != current->mm)
return -EIO;
switch (ioctl) {
case KVM_GET_DIRTY_LOG: {
struct compat_kvm_dirty_log compat_log;
struct kvm_dirty_log log;
r = -EFAULT;
if (copy_from_user(&compat_log, (void __user *)arg,
sizeof(compat_log)))
goto out;
log.slot = compat_log.slot;
log.padding1 = compat_log.padding1;
log.padding2 = compat_log.padding2;
log.dirty_bitmap = compat_ptr(compat_log.dirty_bitmap);
r = kvm_vm_ioctl_get_dirty_log(kvm, &log);
if (r)
goto out;
break;
}
default:
r = kvm_vm_ioctl(filp, ioctl, arg);
}
out:
return r;
}
#endif
static int kvm_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct page *page[1];
@ -1576,7 +1623,9 @@ static int kvm_vm_mmap(struct file *file, struct vm_area_struct *vma)
static struct file_operations kvm_vm_fops = {
.release = kvm_vm_release,
.unlocked_ioctl = kvm_vm_ioctl,
.compat_ioctl = kvm_vm_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = kvm_vm_compat_ioctl,
#endif
.mmap = kvm_vm_mmap,
};