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:

> Am 21.08.2013 um 16:59 schrieb "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>:
>
>> Alexander Graf <agraf@suse.de> writes:
>> 
>> 
>> ....
>> 
>>>> 
>>>> On HV KVM yes, that would be the end of the list, but PR KVM could
>>>> give you entry 0 containing esid==0 and vsid==0 followed by valid
>>>> entries.  Perhaps the best approach is to ignore any entries with
>>>> SLB_ESID_V clear.
>>> 
>>> That means we don't clear entries we don't receive from the kernel because they're V=0 but which were V=1 before. Which with the current code is probably already broken.
>>> 
>>> So yes, clear all cached entries first (to make sure we have no stale
>>> ones), then loop through all and only add entries with V=1 should fix
>>> everything for PR as well as HV.
>> 
>> This is more or less what the patch is doing. The kernel already
>> does memset of all the slb entries. The only difference is we don't
>> depend on the slb index in the return value. Instead we just use the
>> array index as the slb index. Do we really need to make sure the slb
>> index remain same ?
>
> Yes, otherwise get/set change SLB numbering which the guest doesn't
> expect.

how about 

diff --git a/target-ppc/kvm.c b/target-ppc/kvm.c
index 30a870e..313f866 100644
--- a/target-ppc/kvm.c
+++ b/target-ppc/kvm.c
@@ -1033,9 +1033,21 @@ int kvm_arch_get_registers(CPUState *cs)
 
         /* Sync SLB */
 #ifdef TARGET_PPC64
+        /*
+         * 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.
+         * Zero out the SLB array invalidating all the entries
+         */
+        memset(env->slb, 0, 64 * sizeof(ppc_slb_t));
         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;
+            target_ulong rs = sregs.u.s.ppc64.slb[i].slbv;
+            /*
+             * Only restore valid entries
+             */
+            if (rb & SLB_ESID_V)
+                ppc_store_slb(env, rb, rs);
         }
 #endif