KVM: arm64: Simplify __kvm_timer_set_cntvoff implementation

Now that this function isn't constrained by the 32bit PCS,
let's simplify it by taking a single 64bit offset instead
of two 32bit parameters.
Signed-off-by: Marc Zyngier <maz@kernel.org>

arch/arm64/include/asm/kvm_asm.h

@@ -64,7 +64,7 @@ extern void __kvm_tlb_flush_vmid_ipa(struct kvm *kvm, phys_addr_t ipa);
 extern void __kvm_tlb_flush_vmid(struct kvm *kvm);
 extern void __kvm_tlb_flush_local_vmid(struct kvm_vcpu *vcpu);
 
-extern void __kvm_timer_set_cntvoff(u32 cntvoff_low, u32 cntvoff_high);
+extern void __kvm_timer_set_cntvoff(u64 cntvoff);
 
 extern int kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu);
 

arch/arm64/kvm/arch_timer.c

@@ -451,17 +451,7 @@ static void timer_restore_state(struct arch_timer_context *ctx)
 
 static void set_cntvoff(u64 cntvoff)
 {
-	u32 low = lower_32_bits(cntvoff);
-	u32 high = upper_32_bits(cntvoff);
-
-	/*
-	 * Since kvm_call_hyp doesn't fully support the ARM PCS especially on
-	 * 32-bit systems, but rather passes register by register shifted one
-	 * place (we put the function address in r0/x0), we cannot simply pass
-	 * a 64-bit value as an argument, but have to split the value in two
-	 * 32-bit halves.
-	 */
-	kvm_call_hyp(__kvm_timer_set_cntvoff, low, high);
+	kvm_call_hyp(__kvm_timer_set_cntvoff, cntvoff);
 }
 
 static inline void set_timer_irq_phys_active(struct arch_timer_context *ctx, bool active)

arch/arm64/kvm/hyp/timer-sr.c

@@ -10,9 +10,8 @@
 
 #include <asm/kvm_hyp.h>
 
-void __hyp_text __kvm_timer_set_cntvoff(u32 cntvoff_low, u32 cntvoff_high)
+void __hyp_text __kvm_timer_set_cntvoff(u64 cntvoff)
 {
-	u64 cntvoff = (u64)cntvoff_high << 32 | cntvoff_low;
 	write_sysreg(cntvoff, cntvoff_el2);
 }