LoongArch: KVM: Get VM PMU capability from HW GCFG register

Now VM PMU capability comes from host PMU capability directly, instead
bit 23 of HW GCFG CSR register also show PMU capability for VM. It will
be better if it comes from HW GCFG CSR register rather than just host
PMU capability, especially when LVZ feature is emulated in TCG mode, in
which case without PMU capability.

Signed-off-by: Bibo Mao <[e-mail]>
Signed-off-by: Huacai Chen <[e-mail]>

arch/loongarch/include/asm/kvm_host.h

···
 	struct kvm_phyid_map  *phyid_map;
 	/* Enabled PV features */
 	unsigned long pv_features;
+	/* Supported KVM features */
+	unsigned long kvm_features;
 
 	s64 time_offset;
 	struct kvm_context __percpu *vmcs;
···
 static inline int kvm_get_pmu_num(struct kvm_vcpu_arch *arch)
 {
 	return (arch->cpucfg[6] & CPUCFG6_PMNUM) >> CPUCFG6_PMNUM_SHIFT;
+}
+
+/* Check whether KVM support this feature (VMM may disable it) */
+static inline bool kvm_vm_support(struct kvm_arch *arch, int feature)
+{
+	return !!(arch->kvm_features & BIT_ULL(feature));
 }
 
 bool kvm_arch_pmi_in_guest(struct kvm_vcpu *vcpu);

arch/loongarch/include/asm/loongarch.h

···
 #define  CSR_GCFG_GPERF_SHIFT		24
 #define  CSR_GCFG_GPERF_WIDTH		3
 #define  CSR_GCFG_GPERF			(_ULCAST_(0x7) << CSR_GCFG_GPERF_SHIFT)
+#define  CSR_GCFG_GPMP_SHIFT		23
+#define  CSR_GCFG_GPMP			(_ULCAST_(0x1) << CSR_GCFG_GPMP_SHIFT)
 #define  CSR_GCFG_GCI_SHIFT		20
 #define  CSR_GCFG_GCI_WIDTH		2
 #define  CSR_GCFG_GCI			(_ULCAST_(0x3) << CSR_GCFG_GCI_SHIFT)

arch/loongarch/kvm/vm.c

···
 #include <linux/kvm_host.h>
 #include <asm/kvm_mmu.h>
 #include <asm/kvm_vcpu.h>
+#include <asm/kvm_csr.h>
 #include <asm/kvm_eiointc.h>
 #include <asm/kvm_pch_pic.h>
 
···
 	.data_offset = sizeof(struct kvm_stats_header) + KVM_STATS_NAME_SIZE +
 					sizeof(kvm_vm_stats_desc),
 };
+
+static void kvm_vm_init_features(struct kvm *kvm)
+{
+	unsigned long val;
+
+	val = read_csr_gcfg();
+	if (val & CSR_GCFG_GPMP)
+		kvm->arch.kvm_features |= BIT(KVM_LOONGARCH_VM_FEAT_PMU);
+
+	/* Enable all PV features by default */
+	kvm->arch.pv_features = BIT(KVM_FEATURE_IPI);
+	kvm->arch.kvm_features = BIT(KVM_LOONGARCH_VM_FEAT_PV_IPI);
+	if (kvm_pvtime_supported()) {
+		kvm->arch.pv_features |= BIT(KVM_FEATURE_STEAL_TIME);
+		kvm->arch.kvm_features |= BIT(KVM_LOONGARCH_VM_FEAT_PV_STEALTIME);
+	}
+}
 
 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_vm_init_features(kvm);
 
 	/*
 	 * cpu_vabits means user address space only (a half of total).
···
 		if (cpu_has_lbt_mips)
 			return 0;
 		return -ENXIO;
-	case KVM_LOONGARCH_VM_FEAT_PMU:
-		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;
 	case KVM_LOONGARCH_VM_FEAT_PTW:
 		if (cpu_has_ptw)
+			return 0;
+		return -ENXIO;
+	case KVM_LOONGARCH_VM_FEAT_PMU:
+	case KVM_LOONGARCH_VM_FEAT_PV_IPI:
+	case KVM_LOONGARCH_VM_FEAT_PV_STEALTIME:
+		if (kvm_vm_support(&kvm->arch, attr->attr))
 			return 0;
 		return -ENXIO;
 	default: