LoongArch: KVM: Implement handle idle exception

Implement kvm handle LoongArch vcpu idle exception, using kvm_vcpu_block
to emulate it.

Reviewed-by: Bibo Mao <maobibo@loongson.cn>
Tested-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Tianrui Zhao <zhaotianrui@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

1 files changed, 20 insertions, 0 deletions

diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c
index 7e729dd9e915..d4d7e74f72af 100644
--- a/arch/loongarch/kvm/exit.c
+++ b/arch/loongarch/kvm/exit.c
@@ -194,3 +194,23 @@ int kvm_complete_iocsr_read(struct kvm_vcpu *vcpu, struct kvm_run *run)
 
 	return er;
 }
+
+int kvm_emu_idle(struct kvm_vcpu *vcpu)
+{
+	++vcpu->stat.idle_exits;
+	trace_kvm_exit_idle(vcpu, KVM_TRACE_EXIT_IDLE);
+
+	if (!kvm_arch_vcpu_runnable(vcpu)) {
+		/*
+		 * Switch to the software timer before halt-polling/blocking as
+		 * the guest's timer may be a break event for the vCPU, and the
+		 * hypervisor timer runs only when the CPU is in guest mode.
+		 * Switch before halt-polling so that KVM recognizes an expired
+		 * timer before blocking.
+		 */
+		kvm_save_timer(vcpu);
+		kvm_vcpu_block(vcpu);
+	}
+
+	return EMULATE_DONE;
+}