linux-kernel - [PATCH v20 22/30] LoongArch: KVM: Implement handle idle exception

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Message-Id: <20230831083020.2187109-23-zhaotianrui@loongson.cn>
Date:   Thu, 31 Aug 2023 16:30:12 +0800
From:   Tianrui Zhao <zhaotianrui@...ngson.cn>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Huacai Chen <chenhuacai@...nel.org>,
        WANG Xuerui <kernel@...0n.name>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        loongarch@...ts.linux.dev, Jens Axboe <axboe@...nel.dk>,
        Mark Brown <broonie@...nel.org>,
        Alex Deucher <alexander.deucher@....com>,
        Oliver Upton <oliver.upton@...ux.dev>, maobibo@...ngson.cn,
        Xi Ruoyao <xry111@...111.site>, zhaotianrui@...ngson.cn
Subject: [PATCH v20 22/30] 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@...ngson.cn>
Signed-off-by: Tianrui Zhao <zhaotianrui@...ngson.cn>
---
 arch/loongarch/kvm/exit.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c
index 32edd915eb..30748238c7 100644
--- a/arch/loongarch/kvm/exit.c
+++ b/arch/loongarch/kvm/exit.c
@@ -188,3 +188,23 @@ 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;
+}
-- 
2.27.0