Re: [PATCH] target-ppc: Update slb array with correct index values.

["Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>]

Alexander Graf <agraf@suse.de> writes:

> On 11.08.2013, at 20:16, Aneesh Kumar K.V wrote:
>
>> From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
>> 
>> Without this, a value of rb=0 and rs=0, result in us replacing the 0th index
>> 
>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
>
> Wrong mailing list again ;).

Will post the series again with updated commit message to the qemu list.

>
>> ---
>> target-ppc/kvm.c | 14 ++++++++++++--
>> 1 file changed, 12 insertions(+), 2 deletions(-)
>> 
>> diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
>> index 30a870e..5d4e613 100644
>> --- a/target-ppc/kvm.c
>> +++ b/target-ppc/kvm.c
>> @@ -1034,8 +1034,18 @@ int kvm_arch_get_registers(CPUState *cs)
>>         /* Sync SLB */
>> #ifdef TARGET_PPC64
>>         for (i = 0; i < 64; i++) {
>> -            ppc_store_slb(env, sregs.u.s.ppc64.slb[i].slbe,
>> -                               sregs.u.s.ppc64.slb[i].slbv);
>> +            target_ulong rb  = sregs.u.s.ppc64.slb[i].slbe;
>> +            /*
>> +             * KVM_GET_SREGS doesn't retun slb entry with slot information
>> +             * same as index. So don't depend on the slot information in
>> +             * the returned value.
>
> This is the generating code in book3s_pr.c:
>
>         if (vcpu->arch.hflags & BOOK3S_HFLAG_SLB) {
>                 for (i = 0; i < 64; i++) {
>                         sregs->u.s.ppc64.slb[i].slbe = vcpu->arch.slb[i].orige | i;
>                         sregs->u.s.ppc64.slb[i].slbv = vcpu->arch.slb[i].origv;
>                 }
>
> Where exactly did you see broken slbe entries?
>

I noticed this when adding support for guest memory dumping via qemu gdb
server. Now the array we get would look like below

slbe0 slbv0
slbe1 slbv1
0000  00000
0000  00000

Once we get an array like that when we hit the third value we will
replace the 0th entry, that is [slbe0 slbv0]. That resulted in failed
translation of the address by qemu gdb server. 


-aneesh