// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2020-2023 Loongson Technology Corporation Limited
 */

#include <linux/err.h>
#include <linux/module.h>
#include <linux/kvm_host.h>
#include <asm/cacheflush.h>
#include <asm/cpufeature.h>
#include <asm/kvm_csr.h>
#include "trace.h"

unsigned long vpid_mask;
struct kvm_world_switch *kvm_loongarch_ops;
static int gcsr_flag[CSR_MAX_NUMS];
static struct kvm_context __percpu *vmcs;

int get_gcsr_flag(int csr)
{
	if (csr < CSR_MAX_NUMS)
		return gcsr_flag[csr];

	return INVALID_GCSR;
}

static inline void set_gcsr_sw_flag(int csr)
{
	if (csr < CSR_MAX_NUMS)
		gcsr_flag[csr] |= SW_GCSR;
}

static inline void set_gcsr_hw_flag(int csr)
{
	if (csr < CSR_MAX_NUMS)
		gcsr_flag[csr] |= HW_GCSR;
}

/*
 * The default value of gcsr_flag[CSR] is 0, and we use this
 * function to set the flag to 1 (SW_GCSR) or 2 (HW_GCSR) if the
 * gcsr is software or hardware. It will be used by get/set_gcsr,
 * if gcsr_flag is HW we should use gcsrrd/gcsrwr to access it,
 * else use software csr to emulate it.
 */
static void kvm_init_gcsr_flag(void)
{
	set_gcsr_hw_flag(LOONGARCH_CSR_CRMD);
	set_gcsr_hw_flag(LOONGARCH_CSR_PRMD);
	set_gcsr_hw_flag(LOONGARCH_CSR_EUEN);
	set_gcsr_hw_flag(LOONGARCH_CSR_MISC);
	set_gcsr_hw_flag(LOONGARCH_CSR_ECFG);
	set_gcsr_hw_flag(LOONGARCH_CSR_ESTAT);
	set_gcsr_hw_flag(LOONGARCH_CSR_ERA);
	set_gcsr_hw_flag(LOONGARCH_CSR_BADV);
	set_gcsr_hw_flag(LOONGARCH_CSR_BADI);
	set_gcsr_hw_flag(LOONGARCH_CSR_EENTRY);
	set_gcsr_hw_flag(LOONGARCH_CSR_TLBIDX);
	set_gcsr_hw_flag(LOONGARCH_CSR_TLBEHI);
	set_gcsr_hw_flag(LOONGARCH_CSR_TLBELO0);
	set_gcsr_hw_flag(LOONGARCH_CSR_TLBELO1);
	set_gcsr_hw_flag(LOONGARCH_CSR_ASID);
	set_gcsr_hw_flag(LOONGARCH_CSR_PGDL);
	set_gcsr_hw_flag(LOONGARCH_CSR_PGDH);
	set_gcsr_hw_flag(LOONGARCH_CSR_PGD);
	set_gcsr_hw_flag(LOONGARCH_CSR_PWCTL0);
	set_gcsr_hw_flag(LOONGARCH_CSR_PWCTL1);
	set_gcsr_hw_flag(LOONGARCH_CSR_STLBPGSIZE);
	set_gcsr_hw_flag(LOONGARCH_CSR_RVACFG);
	set_gcsr_hw_flag(LOONGARCH_CSR_CPUID);
	set_gcsr_hw_flag(LOONGARCH_CSR_PRCFG1);
	set_gcsr_hw_flag(LOONGARCH_CSR_PRCFG2);
	set_gcsr_hw_flag(LOONGARCH_CSR_PRCFG3);
	set_gcsr_hw_flag(LOONGARCH_CSR_KS0);
	set_gcsr_hw_flag(LOONGARCH_CSR_KS1);
	set_gcsr_hw_flag(LOONGARCH_CSR_KS2);
	set_gcsr_hw_flag(LOONGARCH_CSR_KS3);
	set_gcsr_hw_flag(LOONGARCH_CSR_KS4);
	set_gcsr_hw_flag(LOONGARCH_CSR_KS5);
	set_gcsr_hw_flag(LOONGARCH_CSR_KS6);
	set_gcsr_hw_flag(LOONGARCH_CSR_KS7);
	set_gcsr_hw_flag(LOONGARCH_CSR_TMID);
	set_gcsr_hw_flag(LOONGARCH_CSR_TCFG);
	set_gcsr_hw_flag(LOONGARCH_CSR_TVAL);
	set_gcsr_hw_flag(LOONGARCH_CSR_TINTCLR);
	set_gcsr_hw_flag(LOONGARCH_CSR_CNTC);
	set_gcsr_hw_flag(LOONGARCH_CSR_LLBCTL);
	set_gcsr_hw_flag(LOONGARCH_CSR_TLBRENTRY);
	set_gcsr_hw_flag(LOONGARCH_CSR_TLBRBADV);
	set_gcsr_hw_flag(LOONGARCH_CSR_TLBRERA);
	set_gcsr_hw_flag(LOONGARCH_CSR_TLBRSAVE);
	set_gcsr_hw_flag(LOONGARCH_CSR_TLBRELO0);
	set_gcsr_hw_flag(LOONGARCH_CSR_TLBRELO1);
	set_gcsr_hw_flag(LOONGARCH_CSR_TLBREHI);
	set_gcsr_hw_flag(LOONGARCH_CSR_TLBRPRMD);
	set_gcsr_hw_flag(LOONGARCH_CSR_DMWIN0);
	set_gcsr_hw_flag(LOONGARCH_CSR_DMWIN1);
	set_gcsr_hw_flag(LOONGARCH_CSR_DMWIN2);
	set_gcsr_hw_flag(LOONGARCH_CSR_DMWIN3);

	set_gcsr_sw_flag(LOONGARCH_CSR_IMPCTL1);
	set_gcsr_sw_flag(LOONGARCH_CSR_IMPCTL2);
	set_gcsr_sw_flag(LOONGARCH_CSR_MERRCTL);
	set_gcsr_sw_flag(LOONGARCH_CSR_MERRINFO1);
	set_gcsr_sw_flag(LOONGARCH_CSR_MERRINFO2);
	set_gcsr_sw_flag(LOONGARCH_CSR_MERRENTRY);
	set_gcsr_sw_flag(LOONGARCH_CSR_MERRERA);
	set_gcsr_sw_flag(LOONGARCH_CSR_MERRSAVE);
	set_gcsr_sw_flag(LOONGARCH_CSR_CTAG);
	set_gcsr_sw_flag(LOONGARCH_CSR_DEBUG);
	set_gcsr_sw_flag(LOONGARCH_CSR_DERA);
	set_gcsr_sw_flag(LOONGARCH_CSR_DESAVE);

	set_gcsr_sw_flag(LOONGARCH_CSR_FWPC);
	set_gcsr_sw_flag(LOONGARCH_CSR_FWPS);
	set_gcsr_sw_flag(LOONGARCH_CSR_MWPC);
	set_gcsr_sw_flag(LOONGARCH_CSR_MWPS);

	set_gcsr_sw_flag(LOONGARCH_CSR_DB0ADDR);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB0MASK);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB0CTRL);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB0ASID);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB1ADDR);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB1MASK);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB1CTRL);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB1ASID);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB2ADDR);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB2MASK);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB2CTRL);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB2ASID);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB3ADDR);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB3MASK);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB3CTRL);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB3ASID);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB4ADDR);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB4MASK);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB4CTRL);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB4ASID);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB5ADDR);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB5MASK);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB5CTRL);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB5ASID);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB6ADDR);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB6MASK);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB6CTRL);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB6ASID);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB7ADDR);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB7MASK);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB7CTRL);
	set_gcsr_sw_flag(LOONGARCH_CSR_DB7ASID);

	set_gcsr_sw_flag(LOONGARCH_CSR_IB0ADDR);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB0MASK);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB0CTRL);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB0ASID);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB1ADDR);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB1MASK);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB1CTRL);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB1ASID);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB2ADDR);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB2MASK);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB2CTRL);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB2ASID);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB3ADDR);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB3MASK);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB3CTRL);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB3ASID);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB4ADDR);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB4MASK);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB4CTRL);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB4ASID);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB5ADDR);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB5MASK);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB5CTRL);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB5ASID);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB6ADDR);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB6MASK);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB6CTRL);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB6ASID);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB7ADDR);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB7MASK);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB7CTRL);
	set_gcsr_sw_flag(LOONGARCH_CSR_IB7ASID);

	set_gcsr_sw_flag(LOONGARCH_CSR_PERFCTRL0);
	set_gcsr_sw_flag(LOONGARCH_CSR_PERFCNTR0);
	set_gcsr_sw_flag(LOONGARCH_CSR_PERFCTRL1);
	set_gcsr_sw_flag(LOONGARCH_CSR_PERFCNTR1);
	set_gcsr_sw_flag(LOONGARCH_CSR_PERFCTRL2);
	set_gcsr_sw_flag(LOONGARCH_CSR_PERFCNTR2);
	set_gcsr_sw_flag(LOONGARCH_CSR_PERFCTRL3);
	set_gcsr_sw_flag(LOONGARCH_CSR_PERFCNTR3);
}

static void kvm_update_vpid(struct kvm_vcpu *vcpu, int cpu)
{
	unsigned long vpid;
	struct kvm_context *context;

	context = per_cpu_ptr(vcpu->kvm->arch.vmcs, cpu);
	vpid = context->vpid_cache + 1;
	if (!(vpid & vpid_mask)) {
		/* finish round of vpid loop */
		if (unlikely(!vpid))
			vpid = vpid_mask + 1;

		++vpid; /* vpid 0 reserved for root */

		/* start new vpid cycle */
		kvm_flush_tlb_all();
	}

	context->vpid_cache = vpid;
	vcpu->arch.vpid = vpid;
}

void kvm_check_vpid(struct kvm_vcpu *vcpu)
{
	int cpu;
	bool migrated;
	unsigned long ver, old, vpid;
	struct kvm_context *context;

	cpu = smp_processor_id();
	/*
	 * Are we entering guest context on a different CPU to last time?
	 * If so, the vCPU's guest TLB state on this CPU may be stale.
	 */
	context = per_cpu_ptr(vcpu->kvm->arch.vmcs, cpu);
	migrated = (vcpu->cpu != cpu);

	/*
	 * Check if our vpid is of an older version
	 *
	 * We also discard the stored vpid if we've executed on
	 * another CPU, as the guest mappings may have changed without
	 * hypervisor knowledge.
	 */
	ver = vcpu->arch.vpid & ~vpid_mask;
	old = context->vpid_cache  & ~vpid_mask;
	if (migrated || (ver != old)) {
		kvm_update_vpid(vcpu, cpu);
		trace_kvm_vpid_change(vcpu, vcpu->arch.vpid);
		vcpu->cpu = cpu;
	}

	/* Restore GSTAT(0x50).vpid */
	vpid = (vcpu->arch.vpid & vpid_mask) << CSR_GSTAT_GID_SHIFT;
	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;

	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;
	void *addr;
	struct kvm_context *context;

	vmcs = alloc_percpu(struct kvm_context);
	if (!vmcs) {
		pr_err("kvm: failed to allocate percpu kvm_context\n");
		return -ENOMEM;
	}

	kvm_loongarch_ops = kzalloc(sizeof(*kvm_loongarch_ops), GFP_KERNEL);
	if (!kvm_loongarch_ops) {
		free_percpu(vmcs);
		vmcs = NULL;
		return -ENOMEM;
	}

	/*
	 * PGD register is shared between root kernel and kvm hypervisor.
	 * So world switch entry should be in DMW area rather than TLB area
	 * to avoid page fault reenter.
	 *
	 * In future if hardware pagetable walking is supported, we won't
	 * need to copy world switch code to DMW area.
	 */
	order = get_order(kvm_exception_size + kvm_enter_guest_size);
	addr = (void *)__get_free_pages(GFP_KERNEL, order);
	if (!addr) {
		free_percpu(vmcs);
		vmcs = NULL;
		kfree(kvm_loongarch_ops);
		kvm_loongarch_ops = NULL;
		return -ENOMEM;
	}

	memcpy(addr, kvm_exc_entry, kvm_exception_size);
	memcpy(addr + kvm_exception_size, kvm_enter_guest, kvm_enter_guest_size);
	flush_icache_range((unsigned long)addr, (unsigned long)addr + kvm_exception_size + kvm_enter_guest_size);
	kvm_loongarch_ops->exc_entry = addr;
	kvm_loongarch_ops->enter_guest = addr + kvm_exception_size;
	kvm_loongarch_ops->page_order = order;

	vpid_mask = read_csr_gstat();
	vpid_mask = (vpid_mask & CSR_GSTAT_GIDBIT) >> CSR_GSTAT_GIDBIT_SHIFT;
	if (vpid_mask)
		vpid_mask = GENMASK(vpid_mask - 1, 0);

	for_each_possible_cpu(cpu) {
		context = per_cpu_ptr(vmcs, cpu);
		context->vpid_cache = vpid_mask + 1;
		context->last_vcpu = NULL;
	}

	kvm_init_gcsr_flag();

	return 0;
}

static void kvm_loongarch_env_exit(void)
{
	unsigned long addr;

	if (vmcs)
		free_percpu(vmcs);

	if (kvm_loongarch_ops) {
		if (kvm_loongarch_ops->exc_entry) {
			addr = (unsigned long)kvm_loongarch_ops->exc_entry;
			free_pages(addr, kvm_loongarch_ops->page_order);
		}
		kfree(kvm_loongarch_ops);
	}
}

static int kvm_loongarch_init(void)
{
	int r;

	if (!cpu_has_lvz) {
		kvm_info("Hardware virtualization not available\n");
		return -ENODEV;
	}
	r = kvm_loongarch_env_init();
	if (r)
		return r;

	return kvm_init(sizeof(struct kvm_vcpu), 0, THIS_MODULE);
}

static void kvm_loongarch_exit(void)
{
	kvm_exit();
	kvm_loongarch_env_exit();
}

module_init(kvm_loongarch_init);
module_exit(kvm_loongarch_exit);

#ifdef MODULE
static const struct cpu_feature kvm_feature[] = {
	{ .feature = cpu_feature(LOONGARCH_LVZ) },
	{},
};
MODULE_DEVICE_TABLE(cpu, kvm_feature);
#endif