From ea20aeab55e8ec61cb9500d5a44d82a9f95e41b3 Mon Sep 17 00:00:00 2001
From: Liang Yan <lyan@suse.com>
Date: Fri, 7 Feb 2020 14:04:21 +0000
Subject: [PATCH] target/arm/monitor: query-cpu-model-expansion crashed qemu
 when using machine type none

Commit e19afd566781 mentioned that target-arm only supports queryable
cpu models 'max', 'host', and the current type when KVM is in use.
The logic works well until using machine type none.

For machine type none, cpu_type will be null if cpu option is not
set by command line, strlen(cpu_type) will terminate process.
So We add a check above it.

This won't affect i386 and s390x since they do not use current_cpu.

Signed-off-by: Liang Yan <lyan@suse.com>
Message-id: 20200203134251.12986-1-lyan@suse.com
Reviewed-by: Andrew Jones <drjones@redhat.com>
Tested-by: Andrew Jones <drjones@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
(cherry-picked from commit 0999a4ba8718aa96105b978d3567fc7e90244c7e)
Signed-off-by: Peng Liang <liangpeng10@huawei.com>
---
 target/arm/monitor.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/target/arm/monitor.c b/target/arm/monitor.c
index 560970de7f..e2b1d117a4 100644
--- a/target/arm/monitor.c
+++ b/target/arm/monitor.c
@@ -131,17 +131,20 @@ CpuModelExpansionInfo *qmp_query_cpu_model_expansion(CpuModelExpansionType type,
     }
 
     if (kvm_enabled()) {
-        const char *cpu_type = current_machine->cpu_type;
-        int len = strlen(cpu_type) - strlen(ARM_CPU_TYPE_SUFFIX);
         bool supported = false;
 
         if (!strcmp(model->name, "host") || !strcmp(model->name, "max")) {
             /* These are kvmarm's recommended cpu types */
             supported = true;
-        } else if (strlen(model->name) == len &&
-                   !strncmp(model->name, cpu_type, len)) {
-            /* KVM is enabled and we're using this type, so it works. */
-            supported = true;
+        } else if (current_machine->cpu_type) {
+            const char *cpu_type = current_machine->cpu_type;
+            int len = strlen(cpu_type) - strlen(ARM_CPU_TYPE_SUFFIX);
+
+            if (strlen(model->name) == len &&
+                !strncmp(model->name, cpu_type, len)) {
+                /* KVM is enabled and we're using this type, so it works. */
+                supported = true;
+            }
         }
         if (!supported) {
             error_setg(errp, "We cannot guarantee the CPU type '%s' works "
-- 
2.23.0

