kvm: arm/arm64: Fold VHE entry/exit work into kvm_vcpu_run_vhe()

With VHE, running a vCPU always requires the sequence:

1. kvm_arm_vhe_guest_enter();
2. kvm_vcpu_run_vhe();
3. kvm_arm_vhe_guest_exit()

... and as we invoke this from the shared arm/arm64 KVM code, 32-bit arm
has to provide stubs for all three functions.

To simplify the common code, and make it easier to make further
modifications to the arm64-specific portions in the near future, let's
fold kvm_arm_vhe_guest_enter() and kvm_arm_vhe_guest_exit() into
kvm_vcpu_run_vhe().

The 32-bit stubs for kvm_arm_vhe_guest_enter() and
kvm_arm_vhe_guest_exit() are removed, as they are no longer used. The
32-bit stub for kvm_vcpu_run_vhe() is left as-is.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: mrutland-arm

arch/arm/include/asm/kvm_host.h

@@ -394,9 +394,6 @@ static inline void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu) {}
 static inline void kvm_vcpu_pmu_restore_guest(struct kvm_vcpu *vcpu) {}
 static inline void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu) {}
 
-static inline void kvm_arm_vhe_guest_enter(void) {}
-static inline void kvm_arm_vhe_guest_exit(void) {}
-
 #define KVM_BP_HARDEN_UNKNOWN		-1
 #define KVM_BP_HARDEN_WA_NEEDED		0
 #define KVM_BP_HARDEN_NOT_REQUIRED	1

arch/arm64/include/asm/kvm_host.h

@@ -628,38 +628,6 @@ static inline void kvm_set_pmu_events(u32 set, struct perf_event_attr *attr) {}
 static inline void kvm_clr_pmu_events(u32 clr) {}
 #endif
 
-static inline void kvm_arm_vhe_guest_enter(void)
-{
-	local_daif_mask();
-
-	/*
-	 * Having IRQs masked via PMR when entering the guest means the GIC
-	 * will not signal the CPU of interrupts of lower priority, and the
-	 * only way to get out will be via guest exceptions.
-	 * Naturally, we want to avoid this.
-	 *
-	 * local_daif_mask() already sets GIC_PRIO_PSR_I_SET, we just need a
-	 * dsb to ensure the redistributor is forwards EL2 IRQs to the CPU.
-	 */
-	pmr_sync();
-}
-
-static inline void kvm_arm_vhe_guest_exit(void)
-{
-	/*
-	 * local_daif_restore() takes care to properly restore PSTATE.DAIF
-	 * and the GIC PMR if the host is using IRQ priorities.
-	 */
-	local_daif_restore(DAIF_PROCCTX_NOIRQ);
-
-	/*
-	 * When we exit from the guest we change a number of CPU configuration
-	 * parameters, such as traps.  Make sure these changes take effect
-	 * before running the host or additional guests.
-	 */
-	isb();
-}
-
 #define KVM_BP_HARDEN_UNKNOWN		-1
 #define KVM_BP_HARDEN_WA_NEEDED		0
 #define KVM_BP_HARDEN_NOT_REQUIRED	1

arch/arm64/kvm/hyp/switch.c

@@ -617,7 +617,7 @@ static void __hyp_text __pmu_switch_to_host(struct kvm_cpu_context *host_ctxt)
 }
 
 /* Switch to the guest for VHE systems running in EL2 */
-int kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
+static int __kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
 {
 	struct kvm_cpu_context *host_ctxt;
 	struct kvm_cpu_context *guest_ctxt;
@@ -670,7 +670,42 @@ int kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
 
 	return exit_code;
 }
-NOKPROBE_SYMBOL(kvm_vcpu_run_vhe);
+NOKPROBE_SYMBOL(__kvm_vcpu_run_vhe);
+
+int kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
+{
+	int ret;
+
+	local_daif_mask();
+
+	/*
+	 * Having IRQs masked via PMR when entering the guest means the GIC
+	 * will not signal the CPU of interrupts of lower priority, and the
+	 * only way to get out will be via guest exceptions.
+	 * Naturally, we want to avoid this.
+	 *
+	 * local_daif_mask() already sets GIC_PRIO_PSR_I_SET, we just need a
+	 * dsb to ensure the redistributor is forwards EL2 IRQs to the CPU.
+	 */
+	pmr_sync();
+
+	ret = __kvm_vcpu_run_vhe(vcpu);
+
+	/*
+	 * local_daif_restore() takes care to properly restore PSTATE.DAIF
+	 * and the GIC PMR if the host is using IRQ priorities.
+	 */
+	local_daif_restore(DAIF_PROCCTX_NOIRQ);
+
+	/*
+	 * When we exit from the guest we change a number of CPU configuration
+	 * parameters, such as traps.  Make sure these changes take effect
+	 * before running the host or additional guests.
+	 */
+	isb();
+
+	return ret;
+}
 
 /* Switch to the guest for legacy non-VHE systems */
 int __hyp_text __kvm_vcpu_run_nvhe(struct kvm_vcpu *vcpu)

virt/kvm/arm/arm.c

@@ -797,9 +797,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
 		guest_enter_irqoff();
 
 		if (has_vhe()) {
-			kvm_arm_vhe_guest_enter();
 			ret = kvm_vcpu_run_vhe(vcpu);
-			kvm_arm_vhe_guest_exit();
 		} else {
 			ret = kvm_call_hyp_ret(__kvm_vcpu_run_nvhe, vcpu);
 		}