LoongArch: KVM: Implement vcpu interrupt operations

Implement vcpu interrupt operations such as vcpu set irq and vcpu
clear irq, using set_gcsr_estat() to set irq which is parsed by the
irq bitmap.
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>

arch/loongarch/kvm/interrupt.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020-2023 Loongson Technology Corporation Limited
+ */
+
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <asm/kvm_csr.h>
+#include <asm/kvm_vcpu.h>
+
+static unsigned int priority_to_irq[EXCCODE_INT_NUM] = {
+	[INT_TI]	= CPU_TIMER,
+	[INT_IPI]	= CPU_IPI,
+	[INT_SWI0]	= CPU_SIP0,
+	[INT_SWI1]	= CPU_SIP1,
+	[INT_HWI0]	= CPU_IP0,
+	[INT_HWI1]	= CPU_IP1,
+	[INT_HWI2]	= CPU_IP2,
+	[INT_HWI3]	= CPU_IP3,
+	[INT_HWI4]	= CPU_IP4,
+	[INT_HWI5]	= CPU_IP5,
+	[INT_HWI6]	= CPU_IP6,
+	[INT_HWI7]	= CPU_IP7,
+};
+
+static int kvm_irq_deliver(struct kvm_vcpu *vcpu, unsigned int priority)
+{
+	unsigned int irq = 0;
+
+	clear_bit(priority, &vcpu->arch.irq_pending);
+	if (priority < EXCCODE_INT_NUM)
+		irq = priority_to_irq[priority];
+
+	switch (priority) {
+	case INT_TI:
+	case INT_IPI:
+	case INT_SWI0:
+	case INT_SWI1:
+		set_gcsr_estat(irq);
+		break;
+
+	case INT_HWI0 ... INT_HWI7:
+		set_csr_gintc(irq);
+		break;
+
+	default:
+		break;
+	}
+
+	return 1;
+}
+
+static int kvm_irq_clear(struct kvm_vcpu *vcpu, unsigned int priority)
+{
+	unsigned int irq = 0;
+
+	clear_bit(priority, &vcpu->arch.irq_clear);
+	if (priority < EXCCODE_INT_NUM)
+		irq = priority_to_irq[priority];
+
+	switch (priority) {
+	case INT_TI:
+	case INT_IPI:
+	case INT_SWI0:
+	case INT_SWI1:
+		clear_gcsr_estat(irq);
+		break;
+
+	case INT_HWI0 ... INT_HWI7:
+		clear_csr_gintc(irq);
+		break;
+
+	default:
+		break;
+	}
+
+	return 1;
+}
+
+void kvm_deliver_intr(struct kvm_vcpu *vcpu)
+{
+	unsigned int priority;
+	unsigned long *pending = &vcpu->arch.irq_pending;
+	unsigned long *pending_clr = &vcpu->arch.irq_clear;
+
+	if (!(*pending) && !(*pending_clr))
+		return;
+
+	if (*pending_clr) {
+		priority = __ffs(*pending_clr);
+		while (priority <= INT_IPI) {
+			kvm_irq_clear(vcpu, priority);
+			priority = find_next_bit(pending_clr,
+					BITS_PER_BYTE * sizeof(*pending_clr),
+					priority + 1);
+		}
+	}
+
+	if (*pending) {
+		priority = __ffs(*pending);
+		while (priority <= INT_IPI) {
+			kvm_irq_deliver(vcpu, priority);
+			priority = find_next_bit(pending,
+					BITS_PER_BYTE * sizeof(*pending),
+					priority + 1);
+		}
+	}
+}
+
+int kvm_pending_timer(struct kvm_vcpu *vcpu)
+{
+	return test_bit(INT_TI, &vcpu->arch.irq_pending);
+}
+
+/*
+ * Only support illegal instruction or illegal Address Error exception,
+ * Other exceptions are injected by hardware in kvm mode
+ */
+static void _kvm_deliver_exception(struct kvm_vcpu *vcpu,
+				unsigned int code, unsigned int subcode)
+{
+	unsigned long val, vec_size;
+
+	/*
+	 * BADV is added for EXCCODE_ADE exception
+	 *  Use PC register (GVA address) if it is instruction exeception
+	 *  Else use BADV from host side (GPA address) for data exeception
+	 */
+	if (code == EXCCODE_ADE) {
+		if (subcode == EXSUBCODE_ADEF)
+			val = vcpu->arch.pc;
+		else
+			val = vcpu->arch.badv;
+		kvm_write_hw_gcsr(LOONGARCH_CSR_BADV, val);
+	}
+
+	/* Set exception instruction */
+	kvm_write_hw_gcsr(LOONGARCH_CSR_BADI, vcpu->arch.badi);
+
+	/*
+	 * Save CRMD in PRMD
+	 * Set IRQ disabled and PLV0 with CRMD
+	 */
+	val = kvm_read_hw_gcsr(LOONGARCH_CSR_CRMD);
+	kvm_write_hw_gcsr(LOONGARCH_CSR_PRMD, val);
+	val = val & ~(CSR_CRMD_PLV | CSR_CRMD_IE);
+	kvm_write_hw_gcsr(LOONGARCH_CSR_CRMD, val);
+
+	/* Set exception PC address */
+	kvm_write_hw_gcsr(LOONGARCH_CSR_ERA, vcpu->arch.pc);
+
+	/*
+	 * Set exception code
+	 * Exception and interrupt can be inject at the same time
+	 * Hardware will handle exception first and then extern interrupt
+	 * Exception code is Ecode in ESTAT[16:21]
+	 * Interrupt code in ESTAT[0:12]
+	 */
+	val = kvm_read_hw_gcsr(LOONGARCH_CSR_ESTAT);
+	val = (val & ~CSR_ESTAT_EXC) | code;
+	kvm_write_hw_gcsr(LOONGARCH_CSR_ESTAT, val);
+
+	/* Calculate expcetion entry address */
+	val = kvm_read_hw_gcsr(LOONGARCH_CSR_ECFG);
+	vec_size = (val & CSR_ECFG_VS) >> CSR_ECFG_VS_SHIFT;
+	if (vec_size)
+		vec_size = (1 << vec_size) * 4;
+	val =  kvm_read_hw_gcsr(LOONGARCH_CSR_EENTRY);
+	vcpu->arch.pc = val + code * vec_size;
+}
+
+void kvm_deliver_exception(struct kvm_vcpu *vcpu)
+{
+	unsigned int code;
+	unsigned long *pending = &vcpu->arch.exception_pending;
+
+	if (*pending) {
+		code = __ffs(*pending);
+		_kvm_deliver_exception(vcpu, code, vcpu->arch.esubcode);
+		*pending = 0;
+		vcpu->arch.esubcode = 0;
+	}
+}

arch/loongarch/kvm/vcpu.c

@@ -458,6 +458,44 @@ void kvm_lose_fpu(struct kvm_vcpu *vcpu)
 	preempt_enable();
 }
 
+int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu, struct kvm_interrupt *irq)
+{
+	int intr = (int)irq->irq;
+
+	if (intr > 0)
+		kvm_queue_irq(vcpu, intr);
+	else if (intr < 0)
+		kvm_dequeue_irq(vcpu, -intr);
+	else {
+		kvm_err("%s: invalid interrupt ioctl %d\n", __func__, irq->irq);
+		return -EINVAL;
+	}
+
+	kvm_vcpu_kick(vcpu);
+
+	return 0;
+}
+
+long kvm_arch_vcpu_async_ioctl(struct file *filp,
+			       unsigned int ioctl, unsigned long arg)
+{
+	void __user *argp = (void __user *)arg;
+	struct kvm_vcpu *vcpu = filp->private_data;
+
+	if (ioctl == KVM_INTERRUPT) {
+		struct kvm_interrupt irq;
+
+		if (copy_from_user(&irq, argp, sizeof(irq)))
+			return -EFAULT;
+
+		kvm_debug("[%d] %s: irq: %d\n", vcpu->vcpu_id, __func__, irq.irq);
+
+		return kvm_vcpu_ioctl_interrupt(vcpu, &irq);
+	}
+
+	return -ENOIOCTLCMD;
+}
+
 int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id)
 {
 	return 0;