LoongArch: KVM: Implement kvm hardware enable, disable interface

Implement kvm hardware enable, disable interface, setting the
guest config register to enable virtualization features when called
the interface.
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/main.c

@@ -249,6 +249,68 @@ void kvm_check_vpid(struct kvm_vcpu *vcpu)
 	change_csr_gstat(vpid_mask << CSR_GSTAT_GID_SHIFT, vpid);
 }
 
+void kvm_init_vmcs(struct kvm *kvm)
+{
+	kvm->arch.vmcs = vmcs;
+}
+
+long kvm_arch_dev_ioctl(struct file *filp,
+			unsigned int ioctl, unsigned long arg)
+{
+	return -ENOIOCTLCMD;
+}
+
+int kvm_arch_hardware_enable(void)
+{
+	unsigned long env, gcfg = 0;
+
+	env = read_csr_gcfg();
+
+	/* First init gcfg, gstat, gintc, gtlbc. All guest use the same config */
+	write_csr_gcfg(0);
+	write_csr_gstat(0);
+	write_csr_gintc(0);
+	clear_csr_gtlbc(CSR_GTLBC_USETGID | CSR_GTLBC_TOTI);
+
+	/*
+	 * Enable virtualization features granting guest direct control of
+	 * certain features:
+	 * GCI=2:       Trap on init or unimplement cache instruction.
+	 * TORU=0:      Trap on Root Unimplement.
+	 * CACTRL=1:    Root control cache.
+	 * TOP=0:       Trap on Previlege.
+	 * TOE=0:       Trap on Exception.
+	 * TIT=0:       Trap on Timer.
+	 */
+	if (env & CSR_GCFG_GCIP_ALL)
+		gcfg |= CSR_GCFG_GCI_SECURE;
+	if (env & CSR_GCFG_MATC_ROOT)
+		gcfg |= CSR_GCFG_MATC_ROOT;
+
+	gcfg |= CSR_GCFG_TIT;
+	write_csr_gcfg(gcfg);
+
+	kvm_flush_tlb_all();
+
+	/* Enable using TGID  */
+	set_csr_gtlbc(CSR_GTLBC_USETGID);
+	kvm_debug("GCFG:%lx GSTAT:%lx GINTC:%lx GTLBC:%lx",
+		  read_csr_gcfg(), read_csr_gstat(), read_csr_gintc(), read_csr_gtlbc());
+
+	return 0;
+}
+
+void kvm_arch_hardware_disable(void)
+{
+	write_csr_gcfg(0);
+	write_csr_gstat(0);
+	write_csr_gintc(0);
+	clear_csr_gtlbc(CSR_GTLBC_USETGID | CSR_GTLBC_TOTI);
+
+	/* Flush any remaining guest TLB entries */
+	kvm_flush_tlb_all();
+}
+
 static int kvm_loongarch_env_init(void)
 {
 	int cpu, order;