[PATCH 4/7] KVM: PPC: Book3S PR: Don't keep scanning HPTEG after we find a match

Alexander Graf
2013-06-30T01:38:54Z

The loop in kvmppc_mmu_book3s_64_xlate() that looks up a translation
in the guest hashed page table (HPT) keeps going if it finds an
HPTE that matches but doesn't allow access. This is incorrect; it
is different from what the hardware does, and there should never be
more than one matching HPTE anyway. This fixes it to stop when any
matching HPTE is found.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
---
arch/powerpc/kvm/book3s_64_mmu.c | 14 ++------------
1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/kvm/book3s_64_mmu.c b/arch/powerpc/kvm/book3s_64_mmu.c
index b871721..2e93bb5 100644
--- a/arch/powerpc/kvm/book3s_64_mmu.c
+++ b/arch/powerpc/kvm/book3s_64_mmu.c
@@ -167,7 +167,6 @@ static int kvmppc_mmu_book3s_64_xlate(struct kvm_vcpu *vcpu, gva_t eaddr,
int i;
u8 key = 0;
bool found = false;
- bool perm_err = false;
int second = 0;
ulong mp_ea = vcpu->arch.magic_page_ea;

@@ -248,11 +247,6 @@ do_second:
break;
}

- if (!gpte->may_read) {
- perm_err = true;
- continue;
- }
-
dprintk("KVM MMU: Translated 0x%lx [0x%llx] -> 0x%llx "
"-> 0x%lx\n",
eaddr, avpn, gpte->vpage, gpte->raddr);
@@ -281,6 +275,8 @@ do_second:
if (pteg[i+1] != oldr)
copy_to_user((void __user *)ptegp, pteg, sizeof(pteg));

+ if (!gpte->may_read)
+ return -EPERM;
return 0;
} else {
dprintk("KVM MMU: No PTE found (ea=0x%lx sdr1=0x%llx "
@@ -296,13 +292,7 @@ do_second:
}
}

-
no_page_found:
-
-
- if (perm_err)
- return -EPERM;
-
return -ENOENT;

no_seg_found:
--
1.8.1.4