RISC-V: KVM: Implement stage2 page table programming

This patch implements all required functions for programming
the stage2 page table for each Guest/VM.

At high-level, the flow of stage2 related functions is similar
from KVM ARM/ARM64 implementation but the stage2 page table
format is quite different for KVM RISC-V.

[jiangyifei: stage2 dirty log support]
Signed-off-by: Yifei Jiang <jiangyifei@huawei.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Palmer Dabbelt <palmerdabbelt@google.com>

arch/riscv/include/asm/kvm_host.h

@@ -70,6 +70,13 @@ struct kvm_mmio_decode {
 	int return_handled;
 };
 
+#define KVM_MMU_PAGE_CACHE_NR_OBJS	32
+
+struct kvm_mmu_page_cache {
+	int nobjs;
+	void *objects[KVM_MMU_PAGE_CACHE_NR_OBJS];
+};
+
 struct kvm_cpu_trap {
 	unsigned long sepc;
 	unsigned long scause;
@@ -171,6 +178,9 @@ struct kvm_vcpu_arch {
 	/* MMIO instruction details */
 	struct kvm_mmio_decode mmio_decode;
 
+	/* Cache pages needed to program page tables with spinlock held */
+	struct kvm_mmu_page_cache mmu_page_cache;
+
 	/* VCPU power-off state */
 	bool power_off;
 
@@ -198,6 +208,8 @@ void kvm_riscv_stage2_flush_cache(struct kvm_vcpu *vcpu);
 int kvm_riscv_stage2_alloc_pgd(struct kvm *kvm);
 void kvm_riscv_stage2_free_pgd(struct kvm *kvm);
 void kvm_riscv_stage2_update_hgatp(struct kvm_vcpu *vcpu);
+void kvm_riscv_stage2_mode_detect(void);
+unsigned long kvm_riscv_stage2_mode(void);
 
 void kvm_riscv_stage2_vmid_detect(void);
 unsigned long kvm_riscv_stage2_vmid_bits(void);

arch/riscv/kvm/Kconfig

@@ -23,6 +23,7 @@ config KVM
 	select PREEMPT_NOTIFIERS
 	select ANON_INODES
 	select KVM_MMIO
+	select KVM_GENERIC_DIRTYLOG_READ_PROTECT
 	select HAVE_KVM_VCPU_ASYNC_IOCTL
 	select HAVE_KVM_EVENTFD
 	select SRCU

arch/riscv/kvm/main.c

@@ -64,6 +64,8 @@ void kvm_arch_hardware_disable(void)
 
 int kvm_arch_init(void *opaque)
 {
+	const char *str;
+
 	if (!riscv_isa_extension_available(NULL, h)) {
 		kvm_info("hypervisor extension not available\n");
 		return -ENODEV;
@@ -79,10 +81,27 @@ int kvm_arch_init(void *opaque)
 		return -ENODEV;
 	}
 
+	kvm_riscv_stage2_mode_detect();
+
 	kvm_riscv_stage2_vmid_detect();
 
 	kvm_info("hypervisor extension available\n");
 
+	switch (kvm_riscv_stage2_mode()) {
+	case HGATP_MODE_SV32X4:
+		str = "Sv32x4";
+		break;
+	case HGATP_MODE_SV39X4:
+		str = "Sv39x4";
+		break;
+	case HGATP_MODE_SV48X4:
+		str = "Sv48x4";
+		break;
+	default:
+		return -ENODEV;
+	}
+	kvm_info("using %s G-stage page table format\n", str);
+
 	kvm_info("VMID %ld bits available\n", kvm_riscv_stage2_vmid_bits());
 
 	return 0;

arch/riscv/kvm/vm.c

@@ -27,12 +27,6 @@ const struct kvm_stats_header kvm_vm_stats_header = {
 		       sizeof(kvm_vm_stats_desc),
 };
 
-int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
-{
-	/* TODO: To be added later. */
-	return -EOPNOTSUPP;
-}
-
 int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 {
 	int r;