LoongArch: KVM: Implement virtual machine tlb operations

Implement LoongArch virtual machine tlb operations such as flush tlb by
specific gpa parameter and flush all of the virtual machine's tlbs.
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/tlb.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020-2023 Loongson Technology Corporation Limited
+ */
+
+#include <linux/kvm_host.h>
+#include <asm/tlb.h>
+#include <asm/kvm_csr.h>
+
+/*
+ * kvm_flush_tlb_all() - Flush all root TLB entries for guests.
+ *
+ * Invalidate all entries including GVA-->GPA and GPA-->HPA mappings.
+ */
+void kvm_flush_tlb_all(void)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	invtlb_all(INVTLB_ALLGID, 0, 0);
+	local_irq_restore(flags);
+}
+
+void kvm_flush_tlb_gpa(struct kvm_vcpu *vcpu, unsigned long gpa)
+{
+	unsigned long flags;
+
+	local_irq_save(flags);
+	gpa &= (PAGE_MASK << 1);
+	invtlb(INVTLB_GID_ADDR, read_csr_gstat() & CSR_GSTAT_GID, gpa);
+	local_irq_restore(flags);
+}