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Commit 6ff5894c authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Avi Kivity
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KVM: Enable 32bit dirty log pointers on 64bit host 



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: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarAlexander Graf <agraf@suse.de>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent afbcf7ab

virt/kvm/kvm_main.c

+50 −1
Original line number Diff line number Diff line
@@ -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,

};