/*
   * 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 <asm/cputype.h>
  #include <asm/uaccess.h>
  #include <asm/kvm.h>
  #include <asm/kvm_asm.h>
  #include <asm/kvm_emulate.h>
  #include <asm/kvm_coproc.h>
  
  #define VM_STAT(x) { #x, offsetof(struct kvm, stat.x), KVM_STAT_VM }
  #define VCPU_STAT(x) { #x, offsetof(struct kvm_vcpu, stat.x), KVM_STAT_VCPU }
  
  struct kvm_stats_debugfs_item debugfs_entries[] = {
  	{ NULL }
  };
  
  int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
  {
  	return 0;
  }
  
  static u64 core_reg_offset_from_id(u64 id)
  {
  	return id & ~(KVM_REG_ARCH_MASK | KVM_REG_SIZE_MASK | KVM_REG_ARM_CORE);
  }
  
  static int get_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
  {
  	u32 __user *uaddr = (u32 __user *)(long)reg->addr;
  	struct kvm_regs *regs = &vcpu->arch.regs;
  	u64 off;
  
  	if (KVM_REG_SIZE(reg->id) != 4)
  		return -ENOENT;
  
  	/* Our ID is an index into the kvm_regs struct. */
  	off = core_reg_offset_from_id(reg->id);
  	if (off >= sizeof(*regs) / KVM_REG_SIZE(reg->id))
  		return -ENOENT;
  
  	return put_user(((u32 *)regs)[off], uaddr);
  }
  
  static int set_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
  {
  	u32 __user *uaddr = (u32 __user *)(long)reg->addr;
  	struct kvm_regs *regs = &vcpu->arch.regs;
  	u64 off, val;
  
  	if (KVM_REG_SIZE(reg->id) != 4)
  		return -ENOENT;
  
  	/* Our ID is an index into the kvm_regs struct. */
  	off = core_reg_offset_from_id(reg->id);
  	if (off >= sizeof(*regs) / KVM_REG_SIZE(reg->id))
  		return -ENOENT;
  
  	if (get_user(val, uaddr) != 0)
  		return -EFAULT;
  
  	if (off == KVM_REG_ARM_CORE_REG(usr_regs.ARM_cpsr)) {
  		unsigned long mode = val & MODE_MASK;
  		switch (mode) {
  		case USR_MODE:
  		case FIQ_MODE:
  		case IRQ_MODE:
  		case SVC_MODE:
  		case ABT_MODE:
  		case UND_MODE:
  			break;
  		default:
  			return -EINVAL;
  		}
  	}
  
  	((u32 *)regs)[off] = val;
  	return 0;
  }
  
  int kvm_arch_vcpu_ioctl_get_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
  {
  	return -EINVAL;
  }
  
  int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
  {
  	return -EINVAL;
  }
  
  #ifndef CONFIG_KVM_ARM_TIMER
  
  #define NUM_TIMER_REGS 0
  
  static int copy_timer_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
  {
  	return 0;
  }
  
  static bool is_timer_reg(u64 index)
  {
  	return false;
  }
  
  int kvm_arm_timer_set_reg(struct kvm_vcpu *vcpu, u64 regid, u64 value)
  {
  	return 0;
  }
  
  u64 kvm_arm_timer_get_reg(struct kvm_vcpu *vcpu, u64 regid)
  {
  	return 0;
  }
  
  #else
  
  #define NUM_TIMER_REGS 3
  
  static bool is_timer_reg(u64 index)
  {
  	switch (index) {
  	case KVM_REG_ARM_TIMER_CTL:
  	case KVM_REG_ARM_TIMER_CNT:
  	case KVM_REG_ARM_TIMER_CVAL:
  		return true;
  	}
  	return false;
  }
  
  static int copy_timer_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
  {
  	if (put_user(KVM_REG_ARM_TIMER_CTL, uindices))
  		return -EFAULT;
  	uindices++;
  	if (put_user(KVM_REG_ARM_TIMER_CNT, uindices))
  		return -EFAULT;
  	uindices++;
  	if (put_user(KVM_REG_ARM_TIMER_CVAL, uindices))
  		return -EFAULT;
  
  	return 0;
  }
  
  #endif
  
  static int set_timer_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
  {
  	void __user *uaddr = (void __user *)(long)reg->addr;
  	u64 val;
  	int ret;
  
  	ret = copy_from_user(&val, uaddr, KVM_REG_SIZE(reg->id));
  	if (ret != 0)
  		return ret;
  
  	return kvm_arm_timer_set_reg(vcpu, reg->id, val);
  }
  
  static int get_timer_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
  {
  	void __user *uaddr = (void __user *)(long)reg->addr;
  	u64 val;
  
  	val = kvm_arm_timer_get_reg(vcpu, reg->id);
  	return copy_to_user(uaddr, &val, KVM_REG_SIZE(reg->id));
  }
  
  static unsigned long num_core_regs(void)
  {
  	return sizeof(struct kvm_regs) / sizeof(u32);
  }
  
  /**
   * kvm_arm_num_regs - how many registers do we present via KVM_GET_ONE_REG
   *
   * This is for all registers.
   */
  unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu)
  {
  	return num_core_regs() + kvm_arm_num_coproc_regs(vcpu)
  		+ NUM_TIMER_REGS;
  }
  
  /**
   * kvm_arm_copy_reg_indices - get indices of all registers.
   *
   * We do core registers right here, then we apppend coproc regs.
   */
  int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
  {
  	unsigned int i;
  	const u64 core_reg = KVM_REG_ARM | KVM_REG_SIZE_U32 | KVM_REG_ARM_CORE;
  	int ret;
  
  	for (i = 0; i < sizeof(struct kvm_regs)/sizeof(u32); i++) {
  		if (put_user(core_reg | i, uindices))
  			return -EFAULT;
  		uindices++;
  	}
  
  	ret = copy_timer_indices(vcpu, uindices);
  	if (ret)
  		return ret;
  	uindices += NUM_TIMER_REGS;
  
  	return kvm_arm_copy_coproc_indices(vcpu, uindices);
  }
  
  int kvm_arm_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
  {
  	/* We currently use nothing arch-specific in upper 32 bits */
  	if ((reg->id & ~KVM_REG_SIZE_MASK) >> 32 != KVM_REG_ARM >> 32)
  		return -EINVAL;
  
  	/* Register group 16 means we want a core register. */
  	if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_CORE)
  		return get_core_reg(vcpu, reg);
  
  	if (is_timer_reg(reg->id))
  		return get_timer_reg(vcpu, reg);
  
  	return kvm_arm_coproc_get_reg(vcpu, reg);
  }
  
  int kvm_arm_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
  {
  	/* We currently use nothing arch-specific in upper 32 bits */
  	if ((reg->id & ~KVM_REG_SIZE_MASK) >> 32 != KVM_REG_ARM >> 32)
  		return -EINVAL;
  
  	/* Register group 16 means we set a core register. */
  	if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_CORE)
  		return set_core_reg(vcpu, reg);
  
  	if (is_timer_reg(reg->id))
  		return set_timer_reg(vcpu, reg);
  
  	return kvm_arm_coproc_set_reg(vcpu, reg);
  }
  
  int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,
  				  struct kvm_sregs *sregs)
  {
  	return -EINVAL;
  }
  
  int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
  				  struct kvm_sregs *sregs)
  {
  	return -EINVAL;
  }
  
  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_A7:
  		return KVM_ARM_TARGET_CORTEX_A7;
  	case ARM_CPU_PART_CORTEX_A15:
  		return KVM_ARM_TARGET_CORTEX_A15;
  	default:
  		return -EINVAL;
  	}
  }
  
  int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
  			const struct kvm_vcpu_init *init)
  {
  	unsigned int i;
  
  	/* We can only cope with guest==host and only on A15/A7 (for now). */
  	if (init->target != kvm_target_cpu())
  		return -EINVAL;
  
  	vcpu->arch.target = init->target;
  	bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES);
  
  	/* -ENOENT for unknown features, -EINVAL for invalid combinations. */
  	for (i = 0; i < sizeof(init->features) * 8; i++) {
  		if (test_bit(i, (void *)init->features)) {
  			if (i >= KVM_VCPU_MAX_FEATURES)
  				return -ENOENT;
  			set_bit(i, vcpu->arch.features);
  		}
  	}
  
  	/* Now we know what it is, we can reset it. */
  	return kvm_reset_vcpu(vcpu);
  }
  
  int kvm_vcpu_preferred_target(struct kvm_vcpu_init *init)
  {
  	int target = kvm_target_cpu();
  
  	if (target < 0)
  		return -ENODEV;
  
  	memset(init, 0, sizeof(*init));
  
  	/*
  	 * For now, we don't return any features.
  	 * In future, we might use features to return target
  	 * specific features available for the preferred
  	 * target type.
  	 */
  	init->target = (__u32)target;
  
  	return 0;
  }
  
  int kvm_arch_vcpu_ioctl_get_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
  {
  	return -EINVAL;
  }
  
  int kvm_arch_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
  {
  	return -EINVAL;
  }
  
  int kvm_arch_vcpu_ioctl_translate(struct kvm_vcpu *vcpu,
  				  struct kvm_translation *tr)
  {
  	return -EINVAL;
  }