LoongArch: KVM: Add LSX (128bit SIMD) support

This patch adds LSX (128bit SIMD) support for LoongArch KVM.

There will be LSX exception in KVM when guest use the LSX instructions.
KVM will enable LSX and restore the vector registers for guest and then
return to guest to continue running.

Signed-off-by: Tianrui Zhao <zhaotianrui@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

1 files changed, 215 insertions, 5 deletions

diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
index 53fcef8b24a1..80487d177ca4 100644
--- a/arch/loongarch/kvm/vcpu.c
+++ b/arch/loongarch/kvm/vcpu.c
@@ -298,6 +298,69 @@ static int _kvm_setcsr(struct kvm_vcpu *vcpu, unsigned int id, u64 val)
 	return ret;
 }
 
+static int _kvm_get_cpucfg(int id, u64 *v)
+{
+	int ret = 0;
+
+	if (id < 0 && id >= KVM_MAX_CPUCFG_REGS)
+		return -EINVAL;
+
+	switch (id) {
+	case 2:
+		/* Return CPUCFG2 features which have been supported by KVM */
+		*v = CPUCFG2_FP     | CPUCFG2_FPSP  | CPUCFG2_FPDP     |
+		     CPUCFG2_FPVERS | CPUCFG2_LLFTP | CPUCFG2_LLFTPREV |
+		     CPUCFG2_LAM;
+		/*
+		 * If LSX is supported by CPU, it is also supported by KVM,
+		 * as we implement it.
+		 */
+		if (cpu_has_lsx)
+			*v |= CPUCFG2_LSX;
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+	return ret;
+}
+
+static int kvm_check_cpucfg(int id, u64 val)
+{
+	u64 mask;
+	int ret = 0;
+
+	if (id < 0 && id >= KVM_MAX_CPUCFG_REGS)
+		return -EINVAL;
+
+	if (_kvm_get_cpucfg(id, &mask))
+		return ret;
+
+	switch (id) {
+	case 2:
+		/* CPUCFG2 features checking */
+		if (val & ~mask)
+			/* The unsupported features should not be set */
+			ret = -EINVAL;
+		else if (!(val & CPUCFG2_LLFTP))
+			/* The LLFTP must be set, as guest must has a constant timer */
+			ret = -EINVAL;
+		else if ((val & CPUCFG2_FP) && (!(val & CPUCFG2_FPSP) || !(val & CPUCFG2_FPDP)))
+			/* Single and double float point must both be set when enable FP */
+			ret = -EINVAL;
+		else if ((val & CPUCFG2_LSX) && !(val & CPUCFG2_FP))
+			/* FP should be set when enable LSX */
+			ret = -EINVAL;
+		else if ((val & CPUCFG2_LASX) && !(val & CPUCFG2_LSX))
+			/* LSX, FP should be set when enable LASX, and FP has been checked before. */
+			ret = -EINVAL;
+		break;
+	default:
+		break;
+	}
+	return ret;
+}
+
 static int kvm_get_one_reg(struct kvm_vcpu *vcpu,
 		const struct kvm_one_reg *reg, u64 *v)
 {
@@ -367,10 +430,10 @@ static int kvm_set_one_reg(struct kvm_vcpu *vcpu,
 		break;
 	case KVM_REG_LOONGARCH_CPUCFG:
 		id = KVM_GET_IOC_CPUCFG_IDX(reg->id);
-		if (id >= 0 && id < KVM_MAX_CPUCFG_REGS)
-			vcpu->arch.cpucfg[id] = (u32)v;
-		else
-			ret = -EINVAL;
+		ret = kvm_check_cpucfg(id, v);
+		if (ret)
+			break;
+		vcpu->arch.cpucfg[id] = (u32)v;
 		break;
 	case KVM_REG_LOONGARCH_KVM:
 		switch (reg->id) {
@@ -460,10 +523,94 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
 	return -EINVAL;
 }
 
+static int kvm_loongarch_cpucfg_has_attr(struct kvm_vcpu *vcpu,
+					 struct kvm_device_attr *attr)
+{
+	switch (attr->attr) {
+	case 2:
+		return 0;
+	default:
+		return -ENXIO;
+	}
+
+	return -ENXIO;
+}
+
+static int kvm_loongarch_vcpu_has_attr(struct kvm_vcpu *vcpu,
+				       struct kvm_device_attr *attr)
+{
+	int ret = -ENXIO;
+
+	switch (attr->group) {
+	case KVM_LOONGARCH_VCPU_CPUCFG:
+		ret = kvm_loongarch_cpucfg_has_attr(vcpu, attr);
+		break;
+	default:
+		break;
+	}
+
+	return ret;
+}
+
+static int kvm_loongarch_get_cpucfg_attr(struct kvm_vcpu *vcpu,
+					 struct kvm_device_attr *attr)
+{
+	int ret = 0;
+	uint64_t val;
+	uint64_t __user *uaddr = (uint64_t __user *)attr->addr;
+
+	ret = _kvm_get_cpucfg(attr->attr, &val);
+	if (ret)
+		return ret;
+
+	put_user(val, uaddr);
+
+	return ret;
+}
+
+static int kvm_loongarch_vcpu_get_attr(struct kvm_vcpu *vcpu,
+				       struct kvm_device_attr *attr)
+{
+	int ret = -ENXIO;
+
+	switch (attr->group) {
+	case KVM_LOONGARCH_VCPU_CPUCFG:
+		ret = kvm_loongarch_get_cpucfg_attr(vcpu, attr);
+		break;
+	default:
+		break;
+	}
+
+	return ret;
+}
+
+static int kvm_loongarch_cpucfg_set_attr(struct kvm_vcpu *vcpu,
+					 struct kvm_device_attr *attr)
+{
+	return -ENXIO;
+}
+
+static int kvm_loongarch_vcpu_set_attr(struct kvm_vcpu *vcpu,
+				       struct kvm_device_attr *attr)
+{
+	int ret = -ENXIO;
+
+	switch (attr->group) {
+	case KVM_LOONGARCH_VCPU_CPUCFG:
+		ret = kvm_loongarch_cpucfg_set_attr(vcpu, attr);
+		break;
+	default:
+		break;
+	}
+
+	return ret;
+}
+
 long kvm_arch_vcpu_ioctl(struct file *filp,
 			 unsigned int ioctl, unsigned long arg)
 {
 	long r;
+	struct kvm_device_attr attr;
 	void __user *argp = (void __user *)arg;
 	struct kvm_vcpu *vcpu = filp->private_data;
 
@@ -503,6 +650,27 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 		r = kvm_vcpu_ioctl_enable_cap(vcpu, &cap);
 		break;
 	}
+	case KVM_HAS_DEVICE_ATTR: {
+		r = -EFAULT;
+		if (copy_from_user(&attr, argp, sizeof(attr)))
+			break;
+		r = kvm_loongarch_vcpu_has_attr(vcpu, &attr);
+		break;
+	}
+	case KVM_GET_DEVICE_ATTR: {
+		r = -EFAULT;
+		if (copy_from_user(&attr, argp, sizeof(attr)))
+			break;
+		r = kvm_loongarch_vcpu_get_attr(vcpu, &attr);
+		break;
+	}
+	case KVM_SET_DEVICE_ATTR: {
+		r = -EFAULT;
+		if (copy_from_user(&attr, argp, sizeof(attr)))
+			break;
+		r = kvm_loongarch_vcpu_set_attr(vcpu, &attr);
+		break;
+	}
 	default:
 		r = -ENOIOCTLCMD;
 		break;
@@ -550,12 +718,54 @@ void kvm_own_fpu(struct kvm_vcpu *vcpu)
 	preempt_enable();
 }
 
+#ifdef CONFIG_CPU_HAS_LSX
+/* Enable LSX and restore context */
+int kvm_own_lsx(struct kvm_vcpu *vcpu)
+{
+	if (!kvm_guest_has_fpu(&vcpu->arch) || !kvm_guest_has_lsx(&vcpu->arch))
+		return -EINVAL;
+
+	preempt_disable();
+
+	/* Enable LSX for guest */
+	set_csr_euen(CSR_EUEN_LSXEN | CSR_EUEN_FPEN);
+	switch (vcpu->arch.aux_inuse & KVM_LARCH_FPU) {
+	case KVM_LARCH_FPU:
+		/*
+		 * Guest FPU state already loaded,
+		 * only restore upper LSX state
+		 */
+		_restore_lsx_upper(&vcpu->arch.fpu);
+		break;
+	default:
+		/* Neither FP or LSX already active,
+		 * restore full LSX state
+		 */
+		kvm_restore_lsx(&vcpu->arch.fpu);
+		break;
+	}
+
+	trace_kvm_aux(vcpu, KVM_TRACE_AUX_RESTORE, KVM_TRACE_AUX_LSX);
+	vcpu->arch.aux_inuse |= KVM_LARCH_LSX | KVM_LARCH_FPU;
+	preempt_enable();
+
+	return 0;
+}
+#endif
+
 /* Save context and disable FPU */
 void kvm_lose_fpu(struct kvm_vcpu *vcpu)
 {
 	preempt_disable();
 
-	if (vcpu->arch.aux_inuse & KVM_LARCH_FPU) {
+	if (vcpu->arch.aux_inuse & KVM_LARCH_LSX) {
+		kvm_save_lsx(&vcpu->arch.fpu);
+		vcpu->arch.aux_inuse &= ~(KVM_LARCH_LSX | KVM_LARCH_FPU);
+		trace_kvm_aux(vcpu, KVM_TRACE_AUX_SAVE, KVM_TRACE_AUX_LSX);
+
+		/* Disable LSX & FPU */
+		clear_csr_euen(CSR_EUEN_FPEN | CSR_EUEN_LSXEN);
+	} else if (vcpu->arch.aux_inuse & KVM_LARCH_FPU) {
 		kvm_save_fpu(&vcpu->arch.fpu);
 		vcpu->arch.aux_inuse &= ~KVM_LARCH_FPU;
 		trace_kvm_aux(vcpu, KVM_TRACE_AUX_SAVE, KVM_TRACE_AUX_FPU);