On 19.04.2010, at 03:07, Alexander Graf wrote:
>
> On 19.04.2010, at 03:01, Jim Paris wrote:
>
>> Alexander Graf wrote:
>>> We have a condition in the ppc64 host mmu code that should never occur.
>>> Unfortunately, it just did happen to me and I was rather puzzled on why,
>>> because BUG_ON doesn't tell me anything useful.
>>>
>>> So let's add some more debug output in case this goes wrong. Also change
>>> BUG to WARN, since I don't want to reboot every time I mess something up.
>>>
>>> Signed-off-by: Alexander Graf <agraf@xxxxxxx>
>>> ---
>>> arch/powerpc/kvm/book3s_64_mmu_host.c | 9 +++++++--
>>> 1 files changed, 7 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/arch/powerpc/kvm/book3s_64_mmu_host.c b/arch/powerpc/kvm/book3s_64_mmu_host.c
>>> index 41af12f..5bf91a7 100644
>>> --- a/arch/powerpc/kvm/book3s_64_mmu_host.c
>>> +++ b/arch/powerpc/kvm/book3s_64_mmu_host.c
>>> @@ -231,10 +231,15 @@ int kvmppc_mmu_map_page(struct kvm_vcpu *vcpu, struct kvmppc_pte *orig_pte)
>>> vcpu->arch.mmu.esid_to_vsid(vcpu, orig_pte->eaddr >> SID_SHIFT, &vsid);
>>> map = find_sid_vsid(vcpu, vsid);
>>> if (!map) {
>>> - kvmppc_mmu_map_segment(vcpu, orig_pte->eaddr);
>>> + ret = kvmppc_mmu_map_segment(vcpu, orig_pte->eaddr);
>>> + WARN_ON(ret < 0);
>>> map = find_sid_vsid(vcpu, vsid);
>>> }
>>> - BUG_ON(!map);
>>> + if (!map) {
>>> + printk(KERN_ERR "KVM: Segment map for 0x%llx (0x%lx) failed\n",
>>> + vsid, orig_pte->eaddr);
>>> + WARN();
>>
>> Return here, otherwise dereferencing map in the next line will crash anyway...
>
> Very true. In fact, I certainly remember me putting a return and a WARN_ON(true) because WARN() gave me a warning here. I wonder where that code went ... hrm ...
> Either way, thanks for looking over this patch!
Ugh - I messed up my patch rebasing. The hunk to put the return there is included in 6/8.
Oh well, I don't think that's enough of a bummer for a resubmit. Avi, please apply this set nevertheless.
Alex
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