linux-kernel - [PATCH v20 25/30] LoongArch: KVM: Implement handle fpu exception

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Message-Id: <20230831083020.2187109-26-zhaotianrui@loongson.cn>
Date:   Thu, 31 Aug 2023 16:30:15 +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 25/30] LoongArch: KVM: Implement handle fpu exception

Implement handle fpu exception, using kvm_own_fpu to enable fpu for
guest.

Reviewed-by: Bibo Mao <maobibo@...ngson.cn>
Signed-off-by: Tianrui Zhao <zhaotianrui@...ngson.cn>
---
 arch/loongarch/kvm/exit.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c
index 491d1c39a9..f9c7951261 100644
--- a/arch/loongarch/kvm/exit.c
+++ b/arch/loongarch/kvm/exit.c
@@ -628,3 +628,29 @@ static int _kvm_handle_read_fault(struct kvm_vcpu *vcpu)
 {
 	return _kvm_handle_mmu_fault(vcpu, false);
 }
+
+/**
+ * _kvm_handle_fpu_disabled() - Guest used fpu however it is disabled at host
+ * @vcpu:	Virtual CPU context.
+ *
+ * Handle when the guest attempts to use fpu which hasn't been allowed
+ * by the root context.
+ */
+static int _kvm_handle_fpu_disabled(struct kvm_vcpu *vcpu)
+{
+	struct kvm_run *run = vcpu->run;
+
+	/*
+	 * If guest FPU not present, the FPU operation should have been
+	 * treated as a reserved instruction!
+	 * If FPU already in use, we shouldn't get this at all.
+	 */
+	if (WARN_ON(vcpu->arch.aux_inuse & KVM_LARCH_FPU)) {
+		kvm_err("%s internal error\n", __func__);
+		run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
+		return RESUME_HOST;
+	}
+
+	kvm_own_fpu(vcpu);
+	return RESUME_GUEST;
+}
-- 
2.27.0