KVM: RISC-V: Use kvm_vcpu.srcu_idx, drop RISC-V's unnecessary copy

Use the generic kvm_vcpu's srcu_idx instead of using an indentical field
in RISC-V's version of kvm_vcpu_arch.  Generic KVM very intentionally
does not touch vcpu->srcu_idx, i.e. there's zero chance of running afoul
of common code.
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220415004343.2203171-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/riscv/include/asm/kvm_host.h

@@ -193,9 +193,6 @@ struct kvm_vcpu_arch {
 
 	/* Don't run the VCPU (blocked) */
 	bool pause;
-
-	/* SRCU lock index for in-kernel run loop */
-	int srcu_idx;
 };
 
 static inline void kvm_arch_hardware_unsetup(void) {}

arch/riscv/kvm/vcpu.c

@@ -727,13 +727,13 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 	/* Mark this VCPU ran at least once */
 	vcpu->arch.ran_atleast_once = true;
 
-	vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
+	vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
 
 	/* Process MMIO value returned from user-space */
 	if (run->exit_reason == KVM_EXIT_MMIO) {
 		ret = kvm_riscv_vcpu_mmio_return(vcpu, vcpu->run);
 		if (ret) {
-			srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
+			srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
 			return ret;
 		}
 	}
@@ -742,13 +742,13 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 	if (run->exit_reason == KVM_EXIT_RISCV_SBI) {
 		ret = kvm_riscv_vcpu_sbi_return(vcpu, vcpu->run);
 		if (ret) {
-			srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
+			srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
 			return ret;
 		}
 	}
 
 	if (run->immediate_exit) {
-		srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
+		srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
 		return -EINTR;
 	}
 
@@ -787,7 +787,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 		 */
 		vcpu->mode = IN_GUEST_MODE;
 
-		srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
+		srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
 		smp_mb__after_srcu_read_unlock();
 
 		/*
@@ -805,7 +805,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 			vcpu->mode = OUTSIDE_GUEST_MODE;
 			local_irq_enable();
 			preempt_enable();
-			vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
+			vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
 			continue;
 		}
 
@@ -849,7 +849,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 
 		preempt_enable();
 
-		vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
+		vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
 
 		ret = kvm_riscv_vcpu_exit(vcpu, run, &trap);
 	}
@@ -858,7 +858,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
 
 	vcpu_put(vcpu);
 
-	srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
+	srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
 
 	return ret;
 }

arch/riscv/kvm/vcpu_exit.c

@@ -456,9 +456,9 @@ static int stage2_page_fault(struct kvm_vcpu *vcpu, struct kvm_run *run,
 void kvm_riscv_vcpu_wfi(struct kvm_vcpu *vcpu)
 {
 	if (!kvm_arch_vcpu_runnable(vcpu)) {
-		srcu_read_unlock(&vcpu->kvm->srcu, vcpu->arch.srcu_idx);
+		srcu_read_unlock(&vcpu->kvm->srcu, vcpu->srcu_idx);
 		kvm_vcpu_halt(vcpu);
-		vcpu->arch.srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
+		vcpu->srcu_idx = srcu_read_lock(&vcpu->kvm->srcu);
 		kvm_clear_request(KVM_REQ_UNHALT, vcpu);
 	}
 }