linux-kernel - [PATCH v2 08/29] LoongArch: KVM: Implement vcpu handle exit interface

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Date:   Mon, 20 Feb 2023 14:57:14 +0800
From:   Tianrui Zhao <zhaotianrui@...ngson.cn>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Huacai Chen <chenhuacai@...nel.org>,
        WANG Xuerui <kernel@...0n.name>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, Jens Axboe <axboe@...nel.dk>,
        Mark Brown <broonie@...nel.org>,
        Alex Deucher <alexander.deucher@....com>,
        Oliver Upton <oliver.upton@...ux.dev>, maobibo@...ngson.cn
Subject: [PATCH v2 08/29] LoongArch: KVM: Implement vcpu handle exit interface

Implement vcpu handle exit interface, getting the exit code by ESTAT
register and using kvm exception vector to handle it.

Signed-off-by: Tianrui Zhao <zhaotianrui@...ngson.cn>
---
 arch/loongarch/kvm/vcpu.c | 86 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 86 insertions(+)

diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
index 571ac8b9d..e08a4faa0 100644
--- a/arch/loongarch/kvm/vcpu.c
+++ b/arch/loongarch/kvm/vcpu.c
@@ -38,6 +38,92 @@ static int _kvm_check_requests(struct kvm_vcpu *vcpu, int cpu)
 	return ret;
 }
 
+/*
+ * Return value is in the form (errcode<<2 | RESUME_FLAG_HOST | RESUME_FLAG_NV)
+ */
+static int _kvm_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu)
+{
+	unsigned long exst = vcpu->arch.host_estat;
+	u32 intr = exst & 0x1fff; /* ignore NMI */
+	u32 exccode = (exst & CSR_ESTAT_EXC) >> CSR_ESTAT_EXC_SHIFT;
+	u32 __user *opc = (u32 __user *) vcpu->arch.pc;
+	int ret = RESUME_GUEST, cpu;
+
+	vcpu->mode = OUTSIDE_GUEST_MODE;
+
+	/* Set a default exit reason */
+	run->exit_reason = KVM_EXIT_UNKNOWN;
+	run->ready_for_interrupt_injection = 1;
+
+	/*
+	 * Set the appropriate status bits based on host CPU features,
+	 * before we hit the scheduler
+	 */
+
+	local_irq_enable();
+
+	kvm_debug("%s: exst: %lx, PC: %p, kvm_run: %p, kvm_vcpu: %p\n",
+			__func__, exst, opc, run, vcpu);
+	trace_kvm_exit(vcpu, exccode);
+	if (exccode) {
+		ret = _kvm_handle_fault(vcpu, exccode);
+	} else {
+		WARN(!intr, "suspicious vm exiting");
+		++vcpu->stat.int_exits;
+
+		if (need_resched())
+			cond_resched();
+
+		ret = RESUME_GUEST;
+	}
+
+	cond_resched();
+
+	local_irq_disable();
+
+	if (ret == RESUME_GUEST)
+		kvm_acquire_timer(vcpu);
+
+	if (!(ret & RESUME_HOST)) {
+		_kvm_deliver_intr(vcpu);
+		/* Only check for signals if not already exiting to userspace */
+		if (signal_pending(current)) {
+			run->exit_reason = KVM_EXIT_INTR;
+			ret = (-EINTR << 2) | RESUME_HOST;
+			++vcpu->stat.signal_exits;
+			trace_kvm_exit(vcpu, KVM_TRACE_EXIT_SIGNAL);
+		}
+	}
+
+	if (ret == RESUME_GUEST) {
+		trace_kvm_reenter(vcpu);
+
+		/*
+		 * Make sure the read of VCPU requests in vcpu_reenter()
+		 * callback is not reordered ahead of the write to vcpu->mode,
+		 * or we could miss a TLB flush request while the requester sees
+		 * the VCPU as outside of guest mode and not needing an IPI.
+		 */
+		smp_store_mb(vcpu->mode, IN_GUEST_MODE);
+
+		cpu = smp_processor_id();
+		_kvm_check_requests(vcpu, cpu);
+		_kvm_check_vmid(vcpu, cpu);
+		vcpu->arch.host_eentry = csr_read64(LOONGARCH_CSR_EENTRY);
+
+		/*
+		 * If FPU are enabled (i.e. the guest's FPU context
+		 * is live), restore FCSR0.
+		 */
+		if (_kvm_guest_has_fpu(&vcpu->arch) &&
+			read_csr_euen() & (CSR_EUEN_FPEN)) {
+			kvm_restore_fcsr(&vcpu->arch.fpu);
+		}
+	}
+
+	return ret;
+}
+
 int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
 {
 	int i;
-- 
2.31.1