[PATCH 02/14] arm64: KVM: Allow for direct call of HYP functions when using VHE

Christoffer Dall
2019-01-24T14:00:20Z

From: Marc Zyngier <marc.zyngier@arm.com>

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>
---
arch/arm64/include/asm/kvm_host.h | 32 +++++++++++++++++++++++++++++--
1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index e54cb7c88a4e..8b7702bdb219 100644
--- 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);
--
2.18.0