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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: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Reported-by: Jan Kiszka <jan.kiszka@web.de>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Takuya Yoshikawa 2011-04-28 07:08:36 +09:00 committed by Avi Kivity
parent b74323dc2b
commit 8f74d8e168
1 changed files with 15 additions and 1 deletions
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16
arch/x86/kvm/paging_tmpl.h
View File

@ -115,6 +115,20 @@ static unsigned FNAME(gpte_access)(struct kvm_vcpu *vcpu, pt_element_t gpte)
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
*/
@ -185,7 +199,7 @@ static int FNAME(walk_addr_generic)(struct guest_walker *walker,
}
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;
break;
}