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| author | Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp> | 2011-05-07 07:31:36 (GMT) |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2011-05-22 12:47:54 (GMT) |
| commit | 12cb814f3bb35736420cc6bfc9fed7b6a9d3a828 (patch) | |
| tree | 86371ff3cc2a2e9e08211cd20c464b8efbabb1d6 /arch/x86 | |
| parent | 5ce941ee4258b836cf818d2ac159d8cf3ebad648 (diff) | |
| download | linux-12cb814f3bb35736420cc6bfc9fed7b6a9d3a828.tar.xz | |
KVM: MMU: Clean up gpte reading with copy_from_user()
When we optimized walk_addr_generic() by not using the generic guest
memory reader, we replaced copy_from_user() with get_user():
commit e30d2a170506830d5eef5e9d7990c5aedf1b0a51
KVM: MMU: Optimize guest page table walk
commit 15e2ac9a43d4d7d08088e404fddf2533a8e7d52e
KVM: MMU: Fix 64-bit paging breakage on x86_32
But as Andi pointed out later, copy_from_user() does the same as
get_user() as long as we give a constant size to it.
So we use copy_from_user() to clean up the code.
The only, noticeable, regression introduced by this is 64-bit gpte
reading on x86_32 hosts needed for PAE guests.
But this can be mitigated by implementing 8-byte get_user() for x86_32,
if needed.
Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kvm/paging_tmpl.h | 16 |
1 files changed, 1 insertions, 15 deletions
diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h index 52450a6..88ca456 100644 --- a/arch/x86/kvm/paging_tmpl.h +++ b/arch/x86/kvm/paging_tmpl.h @@ -115,20 +115,6 @@ 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 */ @@ -199,7 +185,7 @@ walk: } ptep_user = (pt_element_t __user *)((void *)host_addr + offset); - if (unlikely(FNAME(read_gpte)(&pte, ptep_user))) { + if (unlikely(copy_from_user(&pte, ptep_user, sizeof(pte)))) { present = false; break; } |