OpenE2K/qemu-e2k
13
4
Fork 0
Code Issues 4 Pull Requests Projects 2 Releases Activity

s390x/cpumodel: fix segmentation fault when baselining models

Browse Source 
Usually, when baselining two CPU models, whereby one of them has base
CPU features disabled (e.g. z14-base,msa=off), we fallback to an older
model that did not have these features in the base model. We always try to
create a "sane" CPU model (as far as possible), and one part of it is that
removing base features is no good and to be avoided.

Now, if we disable base features that were part of a z900, we're out of
luck. We won't find a CPU model and QEMU will segfault. This is a
scenario that should never happen in real life, but it can be used to
crash QEMU.

So let's properly report an error if we baseline e.g.:

{ "execute": "query-cpu-model-baseline",
  "arguments" : { "modela": { "name": "z14-base", "props": {"esan3" : false}},
                  "modelb": { "name": "z14"}} }

Instead of segfaulting.

Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20180718092330.19465-1-david@redhat.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Cornelia Huck <cohuck@redhat.com>
This commit is contained in:
David Hildenbrand 2018-07-18 11:23:30 +02:00 committed by Cornelia Huck
parent ea6abffa8a
commit 677ff32db1
1 changed files with 8 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
target/s390x/cpu_models.c
View File

@ -716,6 +716,14 @@ CpuModelBaselineInfo *arch_query_cpu_model_baseline(CpuModelInfo *infoa,
model.def = s390_find_cpu_def(cpu_type, max_gen, max_gen_ga, model.def = s390_find_cpu_def(cpu_type, max_gen, max_gen_ga,
model.features); model.features);
/* models without early base features (esan3) are bad */
if (!model.def) {
error_setg(errp, "No compatible CPU model could be created as"
" important base features are disabled");
return NULL;
}
/* strip off features not part of the max model */ /* strip off features not part of the max model */
bitmap_and(model.features, model.features, model.def->full_feat, bitmap_and(model.features, model.features, model.def->full_feat,
S390_FEAT_MAX); S390_FEAT_MAX);