[v4,2/6] target/arm/kvm: Make uncalled stubs explicitly unreachable

Commit Message

Andrew Jones Oct. 1, 2020, 6:17 a.m. UTC

When we compile without KVM support !defined(CONFIG_KVM) we generate
stubs for functions that the linker will still encounter. Sometimes
these stubs can be executed safely and are placed in paths where they
get executed with or without KVM. Other functions should never be
called without KVM. Those functions should be guarded by kvm_enabled(),
but should also be robust to refactoring mistakes. Putting a
g_assert_not_reached() in the function should help. Additionally,
the g_assert_not_reached() calls may actually help the linker remove
some code.

We remove the stubs for kvm_arm_get/put_virtual_time(), as they aren't
necessary at all - the only caller is in kvm.c

Reviewed-by: Eric Auger <[e-mail]>
Signed-off-by: Andrew Jones <[e-mail]>
---
 target/arm/kvm_arm.h | 51 +++++++++++++++++++++++++++-----------------
 1 file changed, 32 insertions(+), 19 deletions(-)

Patch

diff --git a/target/arm/kvm_arm.h b/target/arm/kvm_arm.h
index bc178eeb84c0..f513702176a7 100644
--- a/target/arm/kvm_arm.h
+++ b/target/arm/kvm_arm.h
@@ -344,18 +344,10 @@  int kvm_arm_set_irq(int cpu, int irqtype, int irq, int level);
 
 #else
 
-static inline void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu)
-{
-    /*
-     * This should never actually be called in the "not KVM" case,
-     * but set up the fields to indicate an error anyway.
-     */
-    cpu->kvm_target = QEMU_KVM_ARM_TARGET_NONE;
-    cpu->host_cpu_probe_failed = true;
-}
-
-static inline void kvm_arm_add_vcpu_properties(Object *obj) {}
-
+/*
+ * It's safe to call these functions without KVM support.
+ * They should either do nothing or return "not supported".
+ */
 static inline bool kvm_arm_aarch32_supported(void)
 {
     return false;
@@ -371,23 +363,44 @@  static inline bool kvm_arm_sve_supported(void)
     return false;
 }
 
+/*
+ * These functions should never actually be called without KVM support.
+ */
+static inline void kvm_arm_set_cpu_features_from_host(ARMCPU *cpu)
+{
+    g_assert_not_reached();
+}
+
+static inline void kvm_arm_add_vcpu_properties(Object *obj)
+{
+    g_assert_not_reached();
+}
+
 static inline int kvm_arm_get_max_vm_ipa_size(MachineState *ms)
 {
-    return -ENOENT;
+    g_assert_not_reached();
 }
 
 static inline int kvm_arm_vgic_probe(void)
 {
-    return 0;
+    g_assert_not_reached();
 }
 
-static inline void kvm_arm_pmu_set_irq(CPUState *cs, int irq) {}
-static inline void kvm_arm_pmu_init(CPUState *cs) {}
+static inline void kvm_arm_pmu_set_irq(CPUState *cs, int irq)
+{
+    g_assert_not_reached();
+}
 
-static inline void kvm_arm_sve_get_vls(CPUState *cs, unsigned long *map) {}
+static inline void kvm_arm_pmu_init(CPUState *cs)
+{
+    g_assert_not_reached();
+}
+
+static inline void kvm_arm_sve_get_vls(CPUState *cs, unsigned long *map)
+{
+    g_assert_not_reached();
+}
 
-static inline void kvm_arm_get_virtual_time(CPUState *cs) {}
-static inline void kvm_arm_put_virtual_time(CPUState *cs) {}
 #endif
 
 static inline const char *gic_class_name(void)