/*
 * Copyright (C) 2012 - Virtual Open Systems and Columbia University
 * Author: Christoffer Dall <c.dall@virtualopensystems.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2, as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

#include <linux/errno.h>
#include <linux/err.h>
#include <linux/kvm_host.h>
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/mman.h>
#include <linux/sched.h>
#include <trace/events/kvm.h>

#define CREATE_TRACE_POINTS
#include "trace.h"

#include <asm/unified.h>
#include <asm/uaccess.h>
#include <asm/ptrace.h>
#include <asm/mman.h>
#include <asm/cputype.h>
#include <asm/tlbflush.h>
#include <asm/virt.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_asm.h>
#include <asm/kvm_mmu.h>

#ifdef REQUIRES_VIRT
__asm__(".arch_extension	virt");
#endif

static DEFINE_PER_CPU(unsigned long, kvm_arm_hyp_stack_page);
static struct vfp_hard_struct __percpu *kvm_host_vfp_state;
static unsigned long hyp_default_vectors;


int kvm_arch_hardware_enable(void *garbage)
{
	return 0;
}

int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
{
	return kvm_vcpu_exiting_guest_mode(vcpu) == IN_GUEST_MODE;
}

void kvm_arch_hardware_disable(void *garbage)
{
}

int kvm_arch_hardware_setup(void)
{
	return 0;
}

void kvm_arch_hardware_unsetup(void)
{
}

void kvm_arch_check_processor_compat(void *rtn)
{
	*(int *)rtn = 0;
}

void kvm_arch_sync_events(struct kvm *kvm)
{
}

/**
 * kvm_arch_init_vm - initializes a VM data structure
 * @kvm:	pointer to the KVM struct
 */
int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
{
	int ret = 0;

	if (type)
		return -EINVAL;

	ret = kvm_alloc_stage2_pgd(kvm);
	if (ret)
		goto out_fail_alloc;

	ret = create_hyp_mappings(kvm, kvm + 1);
	if (ret)
		goto out_free_stage2_pgd;

	/* Mark the initial VMID generation invalid */
	kvm->arch.vmid_gen = 0;

	return ret;
out_free_stage2_pgd:
	kvm_free_stage2_pgd(kvm);
out_fail_alloc:
	return ret;
}

int kvm_arch_vcpu_fault(struct kvm_vcpu *vcpu, struct vm_fault *vmf)
{
	return VM_FAULT_SIGBUS;
}

void kvm_arch_free_memslot(struct kvm_memory_slot *free,
			   struct kvm_memory_slot *dont)
{
}

int kvm_arch_create_memslot(struct kvm_memory_slot *slot, unsigned long npages)
{
	return 0;
}

/**
 * kvm_arch_destroy_vm - destroy the VM data structure
 * @kvm:	pointer to the KVM struct
 */
void kvm_arch_destroy_vm(struct kvm *kvm)
{
	int i;

	kvm_free_stage2_pgd(kvm);

	for (i = 0; i < KVM_MAX_VCPUS; ++i) {
		if (kvm->vcpus[i]) {
			kvm_arch_vcpu_free(kvm->vcpus[i]);
			kvm->vcpus[i] = NULL;
		}
	}
}

int kvm_dev_ioctl_check_extension(long ext)
{
	int r;
	switch (ext) {
	case KVM_CAP_USER_MEMORY:
	case KVM_CAP_SYNC_MMU:
	case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
	case KVM_CAP_ONE_REG:
		r = 1;
		break;
	case KVM_CAP_COALESCED_MMIO:
		r = KVM_COALESCED_MMIO_PAGE_OFFSET;
		break;
	case KVM_CAP_NR_VCPUS:
		r = num_online_cpus();
		break;
	case KVM_CAP_MAX_VCPUS:
		r = KVM_MAX_VCPUS;
		break;
	default:
		r = 0;
		break;
	}
	return r;
}

long kvm_arch_dev_ioctl(struct file *filp,
			unsigned int ioctl, unsigned long arg)
{
	return -EINVAL;
}

int kvm_arch_set_memory_region(struct kvm *kvm,
			       struct kvm_userspace_memory_region *mem,
			       struct kvm_memory_slot old,
			       int user_alloc)
{
	return 0;
}

int kvm_arch_prepare_memory_region(struct kvm *kvm,
				   struct kvm_memory_slot *memslot,
				   struct kvm_memory_slot old,
				   struct kvm_userspace_memory_region *mem,
				   int user_alloc)
{
	return 0;
}

void kvm_arch_commit_memory_region(struct kvm *kvm,
				   struct kvm_userspace_memory_region *mem,
				   struct kvm_memory_slot old,
				   int user_alloc)
{
}

void kvm_arch_flush_shadow_all(struct kvm *kvm)
{
}

void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
				   struct kvm_memory_slot *slot)
{
}

struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
{
	int err;
	struct kvm_vcpu *vcpu;

	vcpu = kmem_cache_zalloc(kvm_vcpu_cache, GFP_KERNEL);
	if (!vcpu) {
		err = -ENOMEM;
		goto out;
	}

	err = kvm_vcpu_init(vcpu, kvm, id);
	if (err)
		goto free_vcpu;

	err = create_hyp_mappings(vcpu, vcpu + 1);
	if (err)
		goto vcpu_uninit;

	return vcpu;
vcpu_uninit:
	kvm_vcpu_uninit(vcpu);
free_vcpu:
	kmem_cache_free(kvm_vcpu_cache, vcpu);
out:
	return ERR_PTR(err);
}

int kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
{
	return 0;
}

void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu)
{
	kvm_mmu_free_memory_caches(vcpu);
	kmem_cache_free(kvm_vcpu_cache, vcpu);
}

void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu)
{
	kvm_arch_vcpu_free(vcpu);
}

int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
{
	return 0;
}

int __attribute_const__ kvm_target_cpu(void)
{
	unsigned long implementor = read_cpuid_implementor();
	unsigned long part_number = read_cpuid_part_number();

	if (implementor != ARM_CPU_IMP_ARM)
		return -EINVAL;

	switch (part_number) {
	case ARM_CPU_PART_CORTEX_A15:
		return KVM_ARM_TARGET_CORTEX_A15;
	default:
		return -EINVAL;
	}
}

int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
{
	return 0;
}

void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu)
{
}

void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
{
}

void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
{
}

int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
					struct kvm_guest_debug *dbg)
{
	return -EINVAL;
}


int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,
				    struct kvm_mp_state *mp_state)
{
	return -EINVAL;
}

int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu,
				    struct kvm_mp_state *mp_state)
{
	return -EINVAL;
}

int kvm_arch_vcpu_runnable(struct kvm_vcpu *v)
{
	return 0;
}

int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
	return -EINVAL;
}

long kvm_arch_vcpu_ioctl(struct file *filp,
			 unsigned int ioctl, unsigned long arg)
{
	struct kvm_vcpu *vcpu = filp->private_data;
	void __user *argp = (void __user *)arg;

	switch (ioctl) {
	case KVM_ARM_VCPU_INIT: {
		struct kvm_vcpu_init init;

		if (copy_from_user(&init, argp, sizeof(init)))
			return -EFAULT;

		return kvm_vcpu_set_target(vcpu, &init);

	}
	case KVM_SET_ONE_REG:
	case KVM_GET_ONE_REG: {
		struct kvm_one_reg reg;
		if (copy_from_user(&reg, argp, sizeof(reg)))
			return -EFAULT;
		if (ioctl == KVM_SET_ONE_REG)
			return kvm_arm_set_reg(vcpu, &reg);
		else
			return kvm_arm_get_reg(vcpu, &reg);
	}
	case KVM_GET_REG_LIST: {
		struct kvm_reg_list __user *user_list = argp;
		struct kvm_reg_list reg_list;
		unsigned n;

		if (copy_from_user(&reg_list, user_list, sizeof(reg_list)))
			return -EFAULT;
		n = reg_list.n;
		reg_list.n = kvm_arm_num_regs(vcpu);
		if (copy_to_user(user_list, &reg_list, sizeof(reg_list)))
			return -EFAULT;
		if (n < reg_list.n)
			return -E2BIG;
		return kvm_arm_copy_reg_indices(vcpu, user_list->reg);
	}
	default:
		return -EINVAL;
	}
}

int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
{
	return -EINVAL;
}

long kvm_arch_vm_ioctl(struct file *filp,
		       unsigned int ioctl, unsigned long arg)
{
	return -EINVAL;
}

static void cpu_init_hyp_mode(void *vector)
{
	unsigned long long pgd_ptr;
	unsigned long pgd_low, pgd_high;
	unsigned long hyp_stack_ptr;
	unsigned long stack_page;
	unsigned long vector_ptr;

	/* Switch from the HYP stub to our own HYP init vector */
	__hyp_set_vectors((unsigned long)vector);

	pgd_ptr = (unsigned long long)kvm_mmu_get_httbr();
	pgd_low = (pgd_ptr & ((1ULL << 32) - 1));
	pgd_high = (pgd_ptr >> 32ULL);
	stack_page = __get_cpu_var(kvm_arm_hyp_stack_page);
	hyp_stack_ptr = stack_page + PAGE_SIZE;
	vector_ptr = (unsigned long)__kvm_hyp_vector;

	/*
	 * Call initialization code, and switch to the full blown
	 * HYP code. The init code doesn't need to preserve these registers as
	 * r1-r3 and r12 are already callee save according to the AAPCS.
	 * Note that we slightly misuse the prototype by casing the pgd_low to
	 * a void *.
	 */
	kvm_call_hyp((void *)pgd_low, pgd_high, hyp_stack_ptr, vector_ptr);
}

/**
 * Inits Hyp-mode on all online CPUs
 */
static int init_hyp_mode(void)
{
	phys_addr_t init_phys_addr;
	int cpu;
	int err = 0;

	/*
	 * Allocate Hyp PGD and setup Hyp identity mapping
	 */
	err = kvm_mmu_init();
	if (err)
		goto out_err;

	/*
	 * It is probably enough to obtain the default on one
	 * CPU. It's unlikely to be different on the others.
	 */
	hyp_default_vectors = __hyp_get_vectors();

	/*
	 * Allocate stack pages for Hypervisor-mode
	 */
	for_each_possible_cpu(cpu) {
		unsigned long stack_page;

		stack_page = __get_free_page(GFP_KERNEL);
		if (!stack_page) {
			err = -ENOMEM;
			goto out_free_stack_pages;
		}

		per_cpu(kvm_arm_hyp_stack_page, cpu) = stack_page;
	}

	/*
	 * Execute the init code on each CPU.
	 *
	 * Note: The stack is not mapped yet, so don't do anything else than
	 * initializing the hypervisor mode on each CPU using a local stack
	 * space for temporary storage.
	 */
	init_phys_addr = virt_to_phys(__kvm_hyp_init);
	for_each_online_cpu(cpu) {
		smp_call_function_single(cpu, cpu_init_hyp_mode,
					 (void *)(long)init_phys_addr, 1);
	}

	/*
	 * Unmap the identity mapping
	 */
	kvm_clear_hyp_idmap();

	/*
	 * Map the Hyp-code called directly from the host
	 */
	err = create_hyp_mappings(__kvm_hyp_code_start, __kvm_hyp_code_end);
	if (err) {
		kvm_err("Cannot map world-switch code\n");
		goto out_free_mappings;
	}

	/*
	 * Map the Hyp stack pages
	 */
	for_each_possible_cpu(cpu) {
		char *stack_page = (char *)per_cpu(kvm_arm_hyp_stack_page, cpu);
		err = create_hyp_mappings(stack_page, stack_page + PAGE_SIZE);

		if (err) {
			kvm_err("Cannot map hyp stack\n");
			goto out_free_mappings;
		}
	}

	/*
	 * Map the host VFP structures
	 */
	kvm_host_vfp_state = alloc_percpu(struct vfp_hard_struct);
	if (!kvm_host_vfp_state) {
		err = -ENOMEM;
		kvm_err("Cannot allocate host VFP state\n");
		goto out_free_mappings;
	}

	for_each_possible_cpu(cpu) {
		struct vfp_hard_struct *vfp;

		vfp = per_cpu_ptr(kvm_host_vfp_state, cpu);
		err = create_hyp_mappings(vfp, vfp + 1);

		if (err) {
			kvm_err("Cannot map host VFP state: %d\n", err);
			goto out_free_vfp;
		}
	}

	kvm_info("Hyp mode initialized successfully\n");
	return 0;
out_free_vfp:
	free_percpu(kvm_host_vfp_state);
out_free_mappings:
	free_hyp_pmds();
out_free_stack_pages:
	for_each_possible_cpu(cpu)
		free_page(per_cpu(kvm_arm_hyp_stack_page, cpu));
out_err:
	kvm_err("error initializing Hyp mode: %d\n", err);
	return err;
}

/**
 * Initialize Hyp-mode and memory mappings on all CPUs.
 */
int kvm_arch_init(void *opaque)
{
	int err;

	if (!is_hyp_mode_available()) {
		kvm_err("HYP mode not available\n");
		return -ENODEV;
	}

	if (kvm_target_cpu() < 0) {
		kvm_err("Target CPU not supported!\n");
		return -ENODEV;
	}

	err = init_hyp_mode();
	if (err)
		goto out_err;

	return 0;
out_err:
	return err;
}

/* NOP: Compiling as a module not supported */
void kvm_arch_exit(void)
{
}

static int arm_init(void)
{
	int rc = kvm_init(NULL, sizeof(struct kvm_vcpu), 0, THIS_MODULE);
	return rc;
}

module_init(arm_init);