LoongArch: KVM: Enable paravirt feature control from VMM

Export kernel paravirt features to user space, so that VMM can control
each single paravirt feature. By default paravirt features will be the
same with kvm supported features if VMM does not set it.

Also a new feature KVM_FEATURE_VIRT_EXTIOI is added which can be set
from user space. This feature indicates that the virt EIOINTC can route
interrupts to 256 vCPUs, rather than 4 vCPUs like with real HW.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

3 files changed, 68 insertions, 26 deletions

diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c
index 34e23a9ed07f..90894f70ff4a 100644
--- a/arch/loongarch/kvm/exit.c
+++ b/arch/loongarch/kvm/exit.c
@@ -50,9 +50,7 @@ static int kvm_emu_cpucfg(struct kvm_vcpu *vcpu, larch_inst inst)
 		vcpu->arch.gprs[rd] = *(unsigned int *)KVM_SIGNATURE;
 		break;
 	case CPUCFG_KVM_FEATURE:
-		ret = KVM_FEATURE_IPI;
-		if (kvm_pvtime_supported())
-			ret |= KVM_FEATURE_STEAL_TIME;
+		ret = vcpu->kvm->arch.pv_features & LOONGARCH_PV_FEAT_MASK;
 		vcpu->arch.gprs[rd] = ret;
 		break;
 	default:
@@ -705,25 +703,22 @@ static long kvm_save_notify(struct kvm_vcpu *vcpu)
 	id   = kvm_read_reg(vcpu, LOONGARCH_GPR_A1);
 	data = kvm_read_reg(vcpu, LOONGARCH_GPR_A2);
 	switch (id) {
-	case KVM_FEATURE_STEAL_TIME:
-		if (!kvm_pvtime_supported())
-			return KVM_HCALL_INVALID_CODE;
-
+	case BIT(KVM_FEATURE_STEAL_TIME):
 		if (data & ~(KVM_STEAL_PHYS_MASK | KVM_STEAL_PHYS_VALID))
 			return KVM_HCALL_INVALID_PARAMETER;
 
 		vcpu->arch.st.guest_addr = data;
 		if (!(data & KVM_STEAL_PHYS_VALID))
-			break;
+			return 0;
 
 		vcpu->arch.st.last_steal = current->sched_info.run_delay;
 		kvm_make_request(KVM_REQ_STEAL_UPDATE, vcpu);
-		break;
+		return 0;
 	default:
-		break;
+		return KVM_HCALL_INVALID_CODE;
 	};
 
-	return 0;
+	return KVM_HCALL_INVALID_CODE;
 };
 
 /*
@@ -797,19 +792,21 @@ static int kvm_send_pv_ipi(struct kvm_vcpu *vcpu)
  */
 static void kvm_handle_service(struct kvm_vcpu *vcpu)
 {
+	long ret = KVM_HCALL_INVALID_CODE;
 	unsigned long func = kvm_read_reg(vcpu, LOONGARCH_GPR_A0);
-	long ret;
 
 	switch (func) {
 	case KVM_HCALL_FUNC_IPI:
-		kvm_send_pv_ipi(vcpu);
-		ret = KVM_HCALL_SUCCESS;
+		if (kvm_guest_has_pv_feature(vcpu, KVM_FEATURE_IPI)) {
+			kvm_send_pv_ipi(vcpu);
+			ret = KVM_HCALL_SUCCESS;
+		}
 		break;
 	case KVM_HCALL_FUNC_NOTIFY:
-		ret = kvm_save_notify(vcpu);
+		if (kvm_guest_has_pv_feature(vcpu, KVM_FEATURE_STEAL_TIME))
+			ret = kvm_save_notify(vcpu);
 		break;
 	default:
-		ret = KVM_HCALL_INVALID_CODE;
 		break;
 	}
 
diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
index 7ed129a231a9..0697b1064251 100644
--- a/arch/loongarch/kvm/vcpu.c
+++ b/arch/loongarch/kvm/vcpu.c
@@ -953,6 +953,8 @@ static int kvm_loongarch_cpucfg_has_attr(struct kvm_vcpu *vcpu,
 	case LOONGARCH_CPUCFG2:
 	case LOONGARCH_CPUCFG6:
 		return 0;
+	case CPUCFG_KVM_FEATURE:
+		return 0;
 	default:
 		return -ENXIO;
 	}
@@ -963,8 +965,8 @@ static int kvm_loongarch_cpucfg_has_attr(struct kvm_vcpu *vcpu,
 static int kvm_loongarch_pvtime_has_attr(struct kvm_vcpu *vcpu,
 					 struct kvm_device_attr *attr)
 {
-	if (!kvm_pvtime_supported() ||
-			attr->attr != KVM_LOONGARCH_VCPU_PVTIME_GPA)
+	if (!kvm_guest_has_pv_feature(vcpu, KVM_FEATURE_STEAL_TIME)
+			|| attr->attr != KVM_LOONGARCH_VCPU_PVTIME_GPA)
 		return -ENXIO;
 
 	return 0;
@@ -996,9 +998,18 @@ static int kvm_loongarch_cpucfg_get_attr(struct kvm_vcpu *vcpu,
 	uint64_t val;
 	uint64_t __user *uaddr = (uint64_t __user *)attr->addr;
 
-	ret = _kvm_get_cpucfg_mask(attr->attr, &val);
-	if (ret)
-		return ret;
+	switch (attr->attr) {
+	case 0 ... (KVM_MAX_CPUCFG_REGS - 1):
+		ret = _kvm_get_cpucfg_mask(attr->attr, &val);
+		if (ret)
+			return ret;
+		break;
+	case CPUCFG_KVM_FEATURE:
+		val = vcpu->kvm->arch.pv_features & LOONGARCH_PV_FEAT_MASK;
+		break;
+	default:
+		return -ENXIO;
+	}
 
 	put_user(val, uaddr);
 
@@ -1011,8 +1022,8 @@ static int kvm_loongarch_pvtime_get_attr(struct kvm_vcpu *vcpu,
 	u64 gpa;
 	u64 __user *user = (u64 __user *)attr->addr;
 
-	if (!kvm_pvtime_supported() ||
-			attr->attr != KVM_LOONGARCH_VCPU_PVTIME_GPA)
+	if (!kvm_guest_has_pv_feature(vcpu, KVM_FEATURE_STEAL_TIME)
+			|| attr->attr != KVM_LOONGARCH_VCPU_PVTIME_GPA)
 		return -ENXIO;
 
 	gpa = vcpu->arch.st.guest_addr;
@@ -1044,7 +1055,28 @@ static int kvm_loongarch_vcpu_get_attr(struct kvm_vcpu *vcpu,
 static int kvm_loongarch_cpucfg_set_attr(struct kvm_vcpu *vcpu,
 					 struct kvm_device_attr *attr)
 {
-	return -ENXIO;
+	u64 val, valid;
+	u64 __user *user = (u64 __user *)attr->addr;
+	struct kvm *kvm = vcpu->kvm;
+
+	switch (attr->attr) {
+	case CPUCFG_KVM_FEATURE:
+		if (get_user(val, user))
+			return -EFAULT;
+
+		valid = LOONGARCH_PV_FEAT_MASK;
+		if (val & ~valid)
+			return -EINVAL;
+
+		/* All vCPUs need set the same PV features */
+		if ((kvm->arch.pv_features & LOONGARCH_PV_FEAT_UPDATED)
+				&& ((kvm->arch.pv_features & valid) != val))
+			return -EINVAL;
+		kvm->arch.pv_features = val | LOONGARCH_PV_FEAT_UPDATED;
+		return 0;
+	default:
+		return -ENXIO;
+	}
 }
 
 static int kvm_loongarch_pvtime_set_attr(struct kvm_vcpu *vcpu,
@@ -1054,8 +1086,8 @@ static int kvm_loongarch_pvtime_set_attr(struct kvm_vcpu *vcpu,
 	u64 gpa, __user *user = (u64 __user *)attr->addr;
 	struct kvm *kvm = vcpu->kvm;
 
-	if (!kvm_pvtime_supported() ||
-			attr->attr != KVM_LOONGARCH_VCPU_PVTIME_GPA)
+	if (!kvm_guest_has_pv_feature(vcpu, KVM_FEATURE_STEAL_TIME)
+			|| attr->attr != KVM_LOONGARCH_VCPU_PVTIME_GPA)
 		return -ENXIO;
 
 	if (get_user(gpa, user))
diff --git a/arch/loongarch/kvm/vm.c b/arch/loongarch/kvm/vm.c
index e0d267aec7a4..4ba734aaef87 100644
--- a/arch/loongarch/kvm/vm.c
+++ b/arch/loongarch/kvm/vm.c
@@ -5,6 +5,7 @@
 
 #include <linux/kvm_host.h>
 #include <asm/kvm_mmu.h>
+#include <asm/kvm_vcpu.h>
 
 const struct _kvm_stats_desc kvm_vm_stats_desc[] = {
 	KVM_GENERIC_VM_STATS(),
@@ -39,6 +40,12 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 	spin_lock_init(&kvm->arch.phyid_map_lock);
 
 	kvm_init_vmcs(kvm);
+
+	/* Enable all PV features by default */
+	kvm->arch.pv_features = BIT(KVM_FEATURE_IPI);
+	if (kvm_pvtime_supported())
+		kvm->arch.pv_features |= BIT(KVM_FEATURE_STEAL_TIME);
+
 	kvm->arch.gpa_size = BIT(cpu_vabits - 1);
 	kvm->arch.root_level = CONFIG_PGTABLE_LEVELS - 1;
 	kvm->arch.invalid_ptes[0] = 0;
@@ -126,6 +133,12 @@ static int kvm_vm_feature_has_attr(struct kvm *kvm, struct kvm_device_attr *attr
 		if (cpu_has_pmp)
 			return 0;
 		return -ENXIO;
+	case KVM_LOONGARCH_VM_FEAT_PV_IPI:
+		return 0;
+	case KVM_LOONGARCH_VM_FEAT_PV_STEALTIME:
+		if (kvm_pvtime_supported())
+			return 0;
+		return -ENXIO;
 	default:
 		return -ENXIO;
 	}