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Commit 8f74d8e1 authored by Takuya Yoshikawa's avatar Takuya Yoshikawa Committed by Avi Kivity
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KVM: MMU: Fix 64-bit paging breakage on x86_32 



Fix regression introduced by
  commit e30d2a170506830d5eef5e9d7990c5aedf1b0a51
  KVM: MMU: Optimize guest page table walk

On x86_32, get_user() does not support 64-bit values and we fail to
build KVM at the point of 64-bit paging.

This patch fixes this by using get_user() twice for that condition.

Signed-off-by: default avatarTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Reported-by: default avatarJan Kiszka <jan.kiszka@web.de>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent b74323dc

arch/x86/kvm/paging_tmpl.h

+15 −1
Original line number Original line Diff line number Diff line
@@ -115,6 +115,20 @@ static unsigned FNAME(gpte_access)(struct kvm_vcpu *vcpu, pt_element_t gpte) 
	return access;

	return access;

}

}





static int FNAME(read_gpte)(pt_element_t *pte, pt_element_t __user *ptep_user)

{

#if defined(CONFIG_X86_32) && (PTTYPE == 64)

	u32 *p = (u32 *)pte;

	u32 __user *p_user = (u32 __user *)ptep_user;



	if (unlikely(get_user(*p, p_user)))

		return -EFAULT;

	return get_user(*(p + 1), p_user + 1);

#else

	return get_user(*pte, ptep_user);

#endif

}



/*

/*

 * Fetch a guest pte for a guest virtual address

 * Fetch a guest pte for a guest virtual address

 */

 */
@@ -185,7 +199,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker, 
		}

		}





		ptep_user = (pt_element_t __user *)((void *)host_addr + offset);

		ptep_user = (pt_element_t __user *)((void *)host_addr + offset);

		if (unlikely(get_user(pte, ptep_user))) {

		if (unlikely(FNAME(read_gpte)(&pte, ptep_user))) {

			present = false;

			present = false;

			break;

			break;

		}

		}