arm64: KVM: Allow for direct call of HYP functions when using VHE

When running VHE, there is no need to jump via some stub to perform
a "HYP" function call, as there is a single address space.

Let's thus change kvm_call_hyp() and co to perform a direct call
in this case. Although this results in a bit of code expansion,
it allows the compiler to check for type compatibility, something
that we are missing so far.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index e54cb7c88a4e87e183b71bce2f7aef8c433e6804..8b7702bdb219ab84115ad97018ed644d5ce417de 100644 (file)
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -370,8 +370,36 @@ void kvm_arm_halt_guest(struct kvm *kvm);
 void kvm_arm_resume_guest(struct kvm *kvm);
 
 u64 __kvm_call_hyp(void *hypfn, ...);
-#define kvm_call_hyp(f, ...) __kvm_call_hyp(kvm_ksym_ref(f), ##__VA_ARGS__)
-#define kvm_call_hyp_ret(f, ...) kvm_call_hyp(f, ##__VA_ARGS__)
+
+/*
+ * The couple of isb() below are there to guarantee the same behaviour
+ * on VHE as on !VHE, where the eret to EL1 acts as a context
+ * synchronization event.
+ */
+#define kvm_call_hyp(f, ...)                                           \
+       do {                                                            \
+               if (has_vhe()) {                                        \
+                       f(__VA_ARGS__);                                 \
+                       isb();                                          \
+               } else {                                                \
+                       __kvm_call_hyp(kvm_ksym_ref(f), ##__VA_ARGS__); \
+               }                                                       \
+       } while(0)
+
+#define kvm_call_hyp_ret(f, ...)                                       \
+       ({                                                              \
+               typeof(f(__VA_ARGS__)) ret;                             \
+                                                                       \
+               if (has_vhe()) {                                        \
+                       ret = f(__VA_ARGS__);                           \
+                       isb();                                          \
+               } else {                                                \
+                       ret = __kvm_call_hyp(kvm_ksym_ref(f),           \
+                                            ##__VA_ARGS__);            \
+               }                                                       \
+                                                                       \
+               ret;                                                    \
+       })
 
 void force_vm_exit(const cpumask_t *mask);
 void kvm_mmu_wp_memory_region(struct kvm *kvm, int slot);