mips.c

/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * KVM/MIPS: MIPS specific KVM APIs
 *
 * Copyright (C) 2012  MIPS Technologies, Inc.  All rights reserved.
 * Authors: Sanjay Lal <sanjayl@kymasys.com>
 */

#include <linux/errno.h>
#include <linux/err.h>
#include <linux/kdebug.h>
#include <linux/module.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/bootmem.h>
#include <asm/fpu.h>
#include <asm/page.h>
#include <asm/cacheflush.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>

#include <linux/kvm_host.h>

#include "interrupt.h"
#include "commpage.h"

#define CREATE_TRACE_POINTS
#include "trace.h"

#ifndef VECTORSPACING
#define VECTORSPACING 0x100	/* for EI/VI mode */
#endif

#define VCPU_STAT(x) offsetof(struct kvm_vcpu, stat.x)
struct kvm_stats_debugfs_item debugfs_entries[] = {
	{ "wait",	  VCPU_STAT(wait_exits),	 KVM_STAT_VCPU },
	{ "cache",	  VCPU_STAT(cache_exits),	 KVM_STAT_VCPU },
	{ "signal",	  VCPU_STAT(signal_exits),	 KVM_STAT_VCPU },
	{ "interrupt",	  VCPU_STAT(int_exits),		 KVM_STAT_VCPU },
	{ "cop_unsuable", VCPU_STAT(cop_unusable_exits), KVM_STAT_VCPU },
	{ "tlbmod",	  VCPU_STAT(tlbmod_exits),	 KVM_STAT_VCPU },
	{ "tlbmiss_ld",	  VCPU_STAT(tlbmiss_ld_exits),	 KVM_STAT_VCPU },
	{ "tlbmiss_st",	  VCPU_STAT(tlbmiss_st_exits),	 KVM_STAT_VCPU },
	{ "addrerr_st",	  VCPU_STAT(addrerr_st_exits),	 KVM_STAT_VCPU },
	{ "addrerr_ld",	  VCPU_STAT(addrerr_ld_exits),	 KVM_STAT_VCPU },
	{ "syscall",	  VCPU_STAT(syscall_exits),	 KVM_STAT_VCPU },
	{ "resvd_inst",	  VCPU_STAT(resvd_inst_exits),	 KVM_STAT_VCPU },
	{ "break_inst",	  VCPU_STAT(break_inst_exits),	 KVM_STAT_VCPU },
	{ "trap_inst",	  VCPU_STAT(trap_inst_exits),	 KVM_STAT_VCPU },
	{ "fpe",	  VCPU_STAT(fpe_exits),		 KVM_STAT_VCPU },
	{ "flush_dcache", VCPU_STAT(flush_dcache_exits), KVM_STAT_VCPU },
	{ "halt_successful_poll", VCPU_STAT(halt_successful_poll), KVM_STAT_VCPU },
	{ "halt_wakeup",  VCPU_STAT(halt_wakeup),	 KVM_STAT_VCPU },
	{NULL}
};

static int kvm_mips_reset_vcpu(struct kvm_vcpu *vcpu)
{
	int i;

	for_each_possible_cpu(i) {
		vcpu->arch.guest_kernel_asid[i] = 0;
		vcpu->arch.guest_user_asid[i] = 0;
	}

	return 0;
}

/*
 * XXXKYMA: We are simulatoring a processor that has the WII bit set in
 * Config7, so we are "runnable" if interrupts are pending
 */
int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu)
{
	return !!(vcpu->arch.pending_exceptions);
}

int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu)
{
	return 1;
}

int kvm_arch_hardware_enable(void)
{
	return 0;
}

int kvm_arch_hardware_setup(void)
{
	return 0;
}

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

static void kvm_mips_init_tlbs(struct kvm *kvm)
{
	unsigned long wired;

	/*
	 * Add a wired entry to the TLB, it is used to map the commpage to
	 * the Guest kernel
	 */
	wired = read_c0_wired();
	write_c0_wired(wired + 1);
	mtc0_tlbw_hazard();
	kvm->arch.commpage_tlb = wired;

	kvm_debug("[%d] commpage TLB: %d\n", smp_processor_id(),
		  kvm->arch.commpage_tlb);
}

static void kvm_mips_init_vm_percpu(void *arg)
{
	struct kvm *kvm = (struct kvm *)arg;

	kvm_mips_init_tlbs(kvm);
	kvm_mips_callbacks->vm_init(kvm);

}

int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
{
	if (atomic_inc_return(&kvm_mips_instance) == 1) {
		kvm_debug("%s: 1st KVM instance, setup host TLB parameters\n",
			  __func__);
		on_each_cpu(kvm_mips_init_vm_percpu, kvm, 1);
	}

	return 0;
}

void kvm_mips_free_vcpus(struct kvm *kvm)
{
	unsigned int i;
	struct kvm_vcpu *vcpu;

	/* Put the pages we reserved for the guest pmap */
	for (i = 0; i < kvm->arch.guest_pmap_npages; i++) {
		if (kvm->arch.guest_pmap[i] != KVM_INVALID_PAGE)
			kvm_mips_release_pfn_clean(kvm->arch.guest_pmap[i]);
	}
	kfree(kvm->arch.guest_pmap);

	kvm_for_each_vcpu(i, vcpu, kvm) {
		kvm_arch_vcpu_free(vcpu);
	}

	mutex_lock(&kvm->lock);

	for (i = 0; i < atomic_read(&kvm->online_vcpus); i++)
		kvm->vcpus[i] = NULL;

	atomic_set(&kvm->online_vcpus, 0);

	mutex_unlock(&kvm->lock);
}

static void kvm_mips_uninit_tlbs(void *arg)
{
	/* Restore wired count */
	write_c0_wired(0);
	mtc0_tlbw_hazard();
	/* Clear out all the TLBs */
	kvm_local_flush_tlb_all();
}

void kvm_arch_destroy_vm(struct kvm *kvm)
{
	kvm_mips_free_vcpus(kvm);

	/* If this is the last instance, restore wired count */
	if (atomic_dec_return(&kvm_mips_instance) == 0) {
		kvm_debug("%s: last KVM instance, restoring TLB parameters\n",
			  __func__);
		on_each_cpu(kvm_mips_uninit_tlbs, NULL, 1);
	}
}

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

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

int kvm_arch_prepare_memory_region(struct kvm *kvm,
				   struct kvm_memory_slot *memslot,
				   struct kvm_userspace_memory_region *mem,
				   enum kvm_mr_change change)
{
	return 0;
}

void kvm_arch_commit_memory_region(struct kvm *kvm,
				   struct kvm_userspace_memory_region *mem,
				   const struct kvm_memory_slot *old,
				   enum kvm_mr_change change)
{
	unsigned long npages = 0;
	int i;

	kvm_debug("%s: kvm: %p slot: %d, GPA: %llx, size: %llx, QVA: %llx\n",
		  __func__, kvm, mem->slot, mem->guest_phys_addr,
		  mem->memory_size, mem->userspace_addr);

	/* Setup Guest PMAP table */
	if (!kvm->arch.guest_pmap) {
		if (mem->slot == 0)
			npages = mem->memory_size >> PAGE_SHIFT;

		if (npages) {
			kvm->arch.guest_pmap_npages = npages;
			kvm->arch.guest_pmap =
			    kzalloc(npages * sizeof(unsigned long), GFP_KERNEL);

			if (!kvm->arch.guest_pmap) {
				kvm_err("Failed to allocate guest PMAP");
				return;
			}

			kvm_debug("Allocated space for Guest PMAP Table (%ld pages) @ %p\n",
				  npages, kvm->arch.guest_pmap);

			/* Now setup the page table */
			for (i = 0; i < npages; i++)
				kvm->arch.guest_pmap[i] = KVM_INVALID_PAGE;
		}
	}
}

struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
{
	int err, size, offset;
	void *gebase;
	int i;

	struct kvm_vcpu *vcpu = kzalloc(sizeof(struct kvm_vcpu), GFP_KERNEL);

	if (!vcpu) {
		err = -ENOMEM;
		goto out;
	}

	err = kvm_vcpu_init(vcpu, kvm, id);

	if (err)
		goto out_free_cpu;

	kvm_debug("kvm @ %p: create cpu %d at %p\n", kvm, id, vcpu);

	/*
	 * Allocate space for host mode exception handlers that handle
	 * guest mode exits
	 */
	if (cpu_has_veic || cpu_has_vint)
		size = 0x200 + VECTORSPACING * 64;
	else
		size = 0x4000;

	/* Save Linux EBASE */
	vcpu->arch.host_ebase = (void *)read_c0_ebase();

	gebase = kzalloc(ALIGN(size, PAGE_SIZE), GFP_KERNEL);

	if (!gebase) {
		err = -ENOMEM;
		goto out_free_cpu;
	}
	kvm_debug("Allocated %d bytes for KVM Exception Handlers @ %p\n",
		  ALIGN(size, PAGE_SIZE), gebase);

	/* Save new ebase */
	vcpu->arch.guest_ebase = gebase;

	/* Copy L1 Guest Exception handler to correct offset */

	/* TLB Refill, EXL = 0 */
	memcpy(gebase, mips32_exception,
	       mips32_exceptionEnd - mips32_exception);

	/* General Exception Entry point */
	memcpy(gebase + 0x180, mips32_exception,
	       mips32_exceptionEnd - mips32_exception);

	/* For vectored interrupts poke the exception code @ all offsets 0-7 */
	for (i = 0; i < 8; i++) {
		kvm_debug("L1 Vectored handler @ %p\n",
			  gebase + 0x200 + (i * VECTORSPACING));
		memcpy(gebase + 0x200 + (i * VECTORSPACING), mips32_exception,
		       mips32_exceptionEnd - mips32_exception);
	}

	/* General handler, relocate to unmapped space for sanity's sake */
	offset = 0x2000;
	kvm_debug("Installing KVM Exception handlers @ %p, %#x bytes\n",
		  gebase + offset,
		  mips32_GuestExceptionEnd - mips32_GuestException);

	memcpy(gebase + offset, mips32_GuestException,
	       mips32_GuestExceptionEnd - mips32_GuestException);

	/* Invalidate the icache for these ranges */
	local_flush_icache_range((unsigned long)gebase,
				(unsigned long)gebase + ALIGN(size, PAGE_SIZE));

	/*
	 * Allocate comm page for guest kernel, a TLB will be reserved for
	 * mapping GVA @ 0xFFFF8000 to this page
	 */
	vcpu->arch.kseg0_commpage = kzalloc(PAGE_SIZE << 1, GFP_KERNEL);

	if (!vcpu->arch.kseg0_commpage) {
		err = -ENOMEM;
		goto out_free_gebase;
	}

	kvm_debug("Allocated COMM page @ %p\n", vcpu->arch.kseg0_commpage);
	kvm_mips_commpage_init(vcpu);

	/* Init */
	vcpu->arch.last_sched_cpu = -1;

	/* Start off the timer */
	kvm_mips_init_count(vcpu);

	return vcpu;

out_free_gebase:
	kfree(gebase);

out_free_cpu:
	kfree(vcpu);

out:
	return ERR_PTR(err);
}

void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu)
{
	hrtimer_cancel(&vcpu->arch.comparecount_timer);

	kvm_vcpu_uninit(vcpu);

	kvm_mips_dump_stats(vcpu);

	kfree(vcpu->arch.guest_ebase);
	kfree(vcpu->arch.kseg0_commpage);
	kfree(vcpu);
}

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

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

int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
{
	int r = 0;
	sigset_t sigsaved;

	if (vcpu->sigset_active)
		sigprocmask(SIG_SETMASK, &vcpu->sigset, &sigsaved);

	if (vcpu->mmio_needed) {
		if (!vcpu->mmio_is_write)
			kvm_mips_complete_mmio_load(vcpu, run);
		vcpu->mmio_needed = 0;
	}

	lose_fpu(1);

	local_irq_disable();
	/* Check if we have any exceptions/interrupts pending */
	kvm_mips_deliver_interrupts(vcpu,
				    kvm_read_c0_guest_cause(vcpu->arch.cop0));

	kvm_guest_enter();

	/* Disable hardware page table walking while in guest */
	htw_stop();

	r = __kvm_mips_vcpu_run(run, vcpu);

	/* Re-enable HTW before enabling interrupts */
	htw_start();

	kvm_guest_exit();
	local_irq_enable();

	if (vcpu->sigset_active)
		sigprocmask(SIG_SETMASK, &sigsaved, NULL);

	return r;
}

int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu,
			     struct kvm_mips_interrupt *irq)
{
	int intr = (int)irq->irq;
	struct kvm_vcpu *dvcpu = NULL;

	if (intr == 3 || intr == -3 || intr == 4 || intr == -4)
		kvm_debug("%s: CPU: %d, INTR: %d\n", __func__, irq->cpu,
			  (int)intr);

	if (irq->cpu == -1)
		dvcpu = vcpu;
	else
		dvcpu = vcpu->kvm->vcpus[irq->cpu];

	if (intr == 2 || intr == 3 || intr == 4) {
		kvm_mips_callbacks->queue_io_int(dvcpu, irq);

	} else if (intr == -2 || intr == -3 || intr == -4) {
		kvm_mips_callbacks->dequeue_io_int(dvcpu, irq);
	} else {
		kvm_err("%s: invalid interrupt ioctl (%d:%d)\n", __func__,
			irq->cpu, irq->irq);
		return -EINVAL;
	}

	dvcpu->arch.wait = 0;

	if (waitqueue_active(&dvcpu->wq))
		wake_up_interruptible(&dvcpu->wq);

	return 0;
}

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

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

static u64 kvm_mips_get_one_regs[] = {
	KVM_REG_MIPS_R0,
	KVM_REG_MIPS_R1,
	KVM_REG_MIPS_R2,
	KVM_REG_MIPS_R3,
	KVM_REG_MIPS_R4,
	KVM_REG_MIPS_R5,
	KVM_REG_MIPS_R6,
	KVM_REG_MIPS_R7,
	KVM_REG_MIPS_R8,
	KVM_REG_MIPS_R9,
	KVM_REG_MIPS_R10,
	KVM_REG_MIPS_R11,
	KVM_REG_MIPS_R12,
	KVM_REG_MIPS_R13,
	KVM_REG_MIPS_R14,
	KVM_REG_MIPS_R15,
	KVM_REG_MIPS_R16,
	KVM_REG_MIPS_R17,
	KVM_REG_MIPS_R18,
	KVM_REG_MIPS_R19,
	KVM_REG_MIPS_R20,
	KVM_REG_MIPS_R21,
	KVM_REG_MIPS_R22,
	KVM_REG_MIPS_R23,
	KVM_REG_MIPS_R24,
	KVM_REG_MIPS_R25,
	KVM_REG_MIPS_R26,
	KVM_REG_MIPS_R27,
	KVM_REG_MIPS_R28,
	KVM_REG_MIPS_R29,
	KVM_REG_MIPS_R30,
	KVM_REG_MIPS_R31,

	KVM_REG_MIPS_HI,
	KVM_REG_MIPS_LO,
	KVM_REG_MIPS_PC,

	KVM_REG_MIPS_CP0_INDEX,
	KVM_REG_MIPS_CP0_CONTEXT,
	KVM_REG_MIPS_CP0_USERLOCAL,
	KVM_REG_MIPS_CP0_PAGEMASK,
	KVM_REG_MIPS_CP0_WIRED,
	KVM_REG_MIPS_CP0_HWRENA,
	KVM_REG_MIPS_CP0_BADVADDR,
	KVM_REG_MIPS_CP0_COUNT,
	KVM_REG_MIPS_CP0_ENTRYHI,
	KVM_REG_MIPS_CP0_COMPARE,
	KVM_REG_MIPS_CP0_STATUS,
	KVM_REG_MIPS_CP0_CAUSE,
	KVM_REG_MIPS_CP0_EPC,
	KVM_REG_MIPS_CP0_PRID,
	KVM_REG_MIPS_CP0_CONFIG,
	KVM_REG_MIPS_CP0_CONFIG1,
	KVM_REG_MIPS_CP0_CONFIG2,
	KVM_REG_MIPS_CP0_CONFIG3,
	KVM_REG_MIPS_CP0_CONFIG4,
	KVM_REG_MIPS_CP0_CONFIG5,
	KVM_REG_MIPS_CP0_CONFIG7,
	KVM_REG_MIPS_CP0_ERROREPC,

	KVM_REG_MIPS_COUNT_CTL,
	KVM_REG_MIPS_COUNT_RESUME,
	KVM_REG_MIPS_COUNT_HZ,
};

static int kvm_mips_get_reg(struct kvm_vcpu *vcpu,
			    const struct kvm_one_reg *reg)
{
	struct mips_coproc *cop0 = vcpu->arch.cop0;
	struct mips_fpu_struct *fpu = &vcpu->arch.fpu;
	int ret;
	s64 v;
	unsigned int idx;

	switch (reg->id) {
	/* General purpose registers */
	case KVM_REG_MIPS_R0 ... KVM_REG_MIPS_R31:
		v = (long)vcpu->arch.gprs[reg->id - KVM_REG_MIPS_R0];
		break;
	case KVM_REG_MIPS_HI:
		v = (long)vcpu->arch.hi;
		break;
	case KVM_REG_MIPS_LO:
		v = (long)vcpu->arch.lo;
		break;
	case KVM_REG_MIPS_PC:
		v = (long)vcpu->arch.pc;
		break;

	/* Floating point registers */
	case KVM_REG_MIPS_FPR_32(0) ... KVM_REG_MIPS_FPR_32(31):
		if (!kvm_mips_guest_has_fpu(&vcpu->arch))
			return -EINVAL;
		idx = reg->id - KVM_REG_MIPS_FPR_32(0);
		/* Odd singles in top of even double when FR=0 */
		if (kvm_read_c0_guest_status(cop0) & ST0_FR)
			v = get_fpr32(&fpu->fpr[idx], 0);
		else
			v = get_fpr32(&fpu->fpr[idx & ~1], idx & 1);
		break;
	case KVM_REG_MIPS_FPR_64(0) ... KVM_REG_MIPS_FPR_64(31):
		if (!kvm_mips_guest_has_fpu(&vcpu->arch))
			return -EINVAL;
		idx = reg->id - KVM_REG_MIPS_FPR_64(0);
		/* Can't access odd doubles in FR=0 mode */
		if (idx & 1 && !(kvm_read_c0_guest_status(cop0) & ST0_FR))
			return -EINVAL;
		v = get_fpr64(&fpu->fpr[idx], 0);
		break;
	case KVM_REG_MIPS_FCR_IR:
		if (!kvm_mips_guest_has_fpu(&vcpu->arch))
			return -EINVAL;
		v = boot_cpu_data.fpu_id;
		break;
	case KVM_REG_MIPS_FCR_CSR:
		if (!kvm_mips_guest_has_fpu(&vcpu->arch))
			return -EINVAL;
		v = fpu->fcr31;
		break;

	/* Co-processor 0 registers */
	case KVM_REG_MIPS_CP0_INDEX:
		v = (long)kvm_read_c0_guest_index(cop0);
		break;
	case KVM_REG_MIPS_CP0_CONTEXT:
		v = (long)kvm_read_c0_guest_context(cop0);
		break;
	case KVM_REG_MIPS_CP0_USERLOCAL:
		v = (long)kvm_read_c0_guest_userlocal(cop0);
		break;
	case KVM_REG_MIPS_CP0_PAGEMASK:
		v = (long)kvm_read_c0_guest_pagemask(cop0);
		break;
	case KVM_REG_MIPS_CP0_WIRED:
		v = (long)kvm_read_c0_guest_wired(cop0);
		break;
	case KVM_REG_MIPS_CP0_HWRENA:
		v = (long)kvm_read_c0_guest_hwrena(cop0);
		break;
	case KVM_REG_MIPS_CP0_BADVADDR:
		v = (long)kvm_read_c0_guest_badvaddr(cop0);
		break;
	case KVM_REG_MIPS_CP0_ENTRYHI:
		v = (long)kvm_read_c0_guest_entryhi(cop0);
		break;
	case KVM_REG_MIPS_CP0_COMPARE:
		v = (long)kvm_read_c0_guest_compare(cop0);
		break;
	case KVM_REG_MIPS_CP0_STATUS:
		v = (long)kvm_read_c0_guest_status(cop0);
		break;
	case KVM_REG_MIPS_CP0_CAUSE:
		v = (long)kvm_read_c0_guest_cause(cop0);
		break;
	case KVM_REG_MIPS_CP0_EPC:
		v = (long)kvm_read_c0_guest_epc(cop0);
		break;
	case KVM_REG_MIPS_CP0_PRID:
		v = (long)kvm_read_c0_guest_prid(cop0);
		break;
	case KVM_REG_MIPS_CP0_CONFIG:
		v = (long)kvm_read_c0_guest_config(cop0);
		break;
	case KVM_REG_MIPS_CP0_CONFIG1:
		v = (long)kvm_read_c0_guest_config1(cop0);
		break;
	case KVM_REG_MIPS_CP0_CONFIG2:
		v = (long)kvm_read_c0_guest_config2(cop0);
		break;
	case KVM_REG_MIPS_CP0_CONFIG3:
		v = (long)kvm_read_c0_guest_config3(cop0);
		break;
	case KVM_REG_MIPS_CP0_CONFIG4:
		v = (long)kvm_read_c0_guest_config4(cop0);
		break;
	case KVM_REG_MIPS_CP0_CONFIG5:
		v = (long)kvm_read_c0_guest_config5(cop0);
		break;
	case KVM_REG_MIPS_CP0_CONFIG7:
		v = (long)kvm_read_c0_guest_config7(cop0);
		break;
	case KVM_REG_MIPS_CP0_ERROREPC:
		v = (long)kvm_read_c0_guest_errorepc(cop0);
		break;
	/* registers to be handled specially */
	case KVM_REG_MIPS_CP0_COUNT:
	case KVM_REG_MIPS_COUNT_CTL:
	case KVM_REG_MIPS_COUNT_RESUME:
	case KVM_REG_MIPS_COUNT_HZ:
		ret = kvm_mips_callbacks->get_one_reg(vcpu, reg, &v);
		if (ret)
			return ret;
		break;
	default:
		return -EINVAL;
	}
	if ((reg->id & KVM_REG_SIZE_MASK) == KVM_REG_SIZE_U64) {
		u64 __user *uaddr64 = (u64 __user *)(long)reg->addr;

		return put_user(v, uaddr64);
	} else if ((reg->id & KVM_REG_SIZE_MASK) == KVM_REG_SIZE_U32) {
		u32 __user *uaddr32 = (u32 __user *)(long)reg->addr;
		u32 v32 = (u32)v;

		return put_user(v32, uaddr32);
	} else {
		return -EINVAL;
	}
}

static int kvm_mips_set_reg(struct kvm_vcpu *vcpu,
			    const struct kvm_one_reg *reg)
{
	struct mips_coproc *cop0 = vcpu->arch.cop0;
	struct mips_fpu_struct *fpu = &vcpu->arch.fpu;
	s64 v;
	unsigned int idx;

	if ((reg->id & KVM_REG_SIZE_MASK) == KVM_REG_SIZE_U64) {
		u64 __user *uaddr64 = (u64 __user *)(long)reg->addr;

		if (get_user(v, uaddr64) != 0)
			return -EFAULT;
	} else if ((reg->id & KVM_REG_SIZE_MASK) == KVM_REG_SIZE_U32) {
		u32 __user *uaddr32 = (u32 __user *)(long)reg->addr;
		s32 v32;

		if (get_user(v32, uaddr32) != 0)
			return -EFAULT;
		v = (s64)v32;
	} else {
		return -EINVAL;
	}

	switch (reg->id) {
	/* General purpose registers */
	case KVM_REG_MIPS_R0:
		/* Silently ignore requests to set $0 */
		break;
	case KVM_REG_MIPS_R1 ... KVM_REG_MIPS_R31:
		vcpu->arch.gprs[reg->id - KVM_REG_MIPS_R0] = v;
		break;
	case KVM_REG_MIPS_HI:
		vcpu->arch.hi = v;
		break;
	case KVM_REG_MIPS_LO:
		vcpu->arch.lo = v;
		break;
	case KVM_REG_MIPS_PC:
		vcpu->arch.pc = v;
		break;

	/* Floating point registers */
	case KVM_REG_MIPS_FPR_32(0) ... KVM_REG_MIPS_FPR_32(31):
		if (!kvm_mips_guest_has_fpu(&vcpu->arch))
			return -EINVAL;
		idx = reg->id - KVM_REG_MIPS_FPR_32(0);
		/* Odd singles in top of even double when FR=0 */
		if (kvm_read_c0_guest_status(cop0) & ST0_FR)
			set_fpr32(&fpu->fpr[idx], 0, v);
		else
			set_fpr32(&fpu->fpr[idx & ~1], idx & 1, v);
		break;
	case KVM_REG_MIPS_FPR_64(0) ... KVM_REG_MIPS_FPR_64(31):
		if (!kvm_mips_guest_has_fpu(&vcpu->arch))
			return -EINVAL;
		idx = reg->id - KVM_REG_MIPS_FPR_64(0);
		/* Can't access odd doubles in FR=0 mode */
		if (idx & 1 && !(kvm_read_c0_guest_status(cop0) & ST0_FR))
			return -EINVAL;
		set_fpr64(&fpu->fpr[idx], 0, v);
		break;
	case KVM_REG_MIPS_FCR_IR:
		if (!kvm_mips_guest_has_fpu(&vcpu->arch))
			return -EINVAL;
		/* Read-only */
		break;
	case KVM_REG_MIPS_FCR_CSR:
		if (!kvm_mips_guest_has_fpu(&vcpu->arch))
			return -EINVAL;
		fpu->fcr31 = v;
		break;

	/* Co-processor 0 registers */
	case KVM_REG_MIPS_CP0_INDEX:
		kvm_write_c0_guest_index(cop0, v);
		break;
	case KVM_REG_MIPS_CP0_CONTEXT:
		kvm_write_c0_guest_context(cop0, v);
		break;
	case KVM_REG_MIPS_CP0_USERLOCAL:
		kvm_write_c0_guest_userlocal(cop0, v);
		break;
	case KVM_REG_MIPS_CP0_PAGEMASK:
		kvm_write_c0_guest_pagemask(cop0, v);
		break;
	case KVM_REG_MIPS_CP0_WIRED:
		kvm_write_c0_guest_wired(cop0, v);
		break;
	case KVM_REG_MIPS_CP0_HWRENA:
		kvm_write_c0_guest_hwrena(cop0, v);
		break;
	case KVM_REG_MIPS_CP0_BADVADDR:
		kvm_write_c0_guest_badvaddr(cop0, v);
		break;
	case KVM_REG_MIPS_CP0_ENTRYHI:
		kvm_write_c0_guest_entryhi(cop0, v);
		break;
	case KVM_REG_MIPS_CP0_STATUS:
		kvm_write_c0_guest_status(cop0, v);
		break;
	case KVM_REG_MIPS_CP0_EPC:
		kvm_write_c0_guest_epc(cop0, v);
		break;
	case KVM_REG_MIPS_CP0_PRID:
		kvm_write_c0_guest_prid(cop0, v);
		break;
	case KVM_REG_MIPS_CP0_ERROREPC:
		kvm_write_c0_guest_errorepc(cop0, v);
		break;
	/* registers to be handled specially */
	case KVM_REG_MIPS_CP0_COUNT:
	case KVM_REG_MIPS_CP0_COMPARE:
	case KVM_REG_MIPS_CP0_CAUSE:
	case KVM_REG_MIPS_CP0_CONFIG:
	case KVM_REG_MIPS_CP0_CONFIG1:
	case KVM_REG_MIPS_CP0_CONFIG2:
	case KVM_REG_MIPS_CP0_CONFIG3:
	case KVM_REG_MIPS_CP0_CONFIG4:
	case KVM_REG_MIPS_CP0_CONFIG5:
	case KVM_REG_MIPS_COUNT_CTL:
	case KVM_REG_MIPS_COUNT_RESUME:
	case KVM_REG_MIPS_COUNT_HZ:
		return kvm_mips_callbacks->set_one_reg(vcpu, reg, v);
	default:
		return -EINVAL;
	}
	return 0;
}

static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
				     struct kvm_enable_cap *cap)
{
	int r = 0;

	if (!kvm_vm_ioctl_check_extension(vcpu->kvm, cap->cap))
		return -EINVAL;
	if (cap->flags)
		return -EINVAL;
	if (cap->args[0])
		return -EINVAL;

	switch (cap->cap) {
	case KVM_CAP_MIPS_FPU:
		vcpu->arch.fpu_enabled = true;
		break;
	default:
		r = -EINVAL;
		break;
	}

	return r;
}

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;
	long r;

	switch (ioctl) {
	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_mips_set_reg(vcpu, &reg);
		else
			return kvm_mips_get_reg(vcpu, &reg);
	}
	case KVM_GET_REG_LIST: {
		struct kvm_reg_list __user *user_list = argp;
		u64 __user *reg_dest;
		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 = ARRAY_SIZE(kvm_mips_get_one_regs);
		if (copy_to_user(user_list, &reg_list, sizeof(reg_list)))
			return -EFAULT;
		if (n < reg_list.n)
			return -E2BIG;
		reg_dest = user_list->reg;
		if (copy_to_user(reg_dest, kvm_mips_get_one_regs,
				 sizeof(kvm_mips_get_one_regs)))
			return -EFAULT;
		return 0;
	}
	case KVM_NMI:
		/* Treat the NMI as a CPU reset */
		r = kvm_mips_reset_vcpu(vcpu);
		break;
	case KVM_INTERRUPT:
		{
			struct kvm_mips_interrupt irq;

			r = -EFAULT;
			if (copy_from_user(&irq, argp, sizeof(irq)))
				goto out;

			kvm_debug("[%d] %s: irq: %d\n", vcpu->vcpu_id, __func__,
				  irq.irq);

			r = kvm_vcpu_ioctl_interrupt(vcpu, &irq);
			break;
		}
	case KVM_ENABLE_CAP: {
		struct kvm_enable_cap cap;

		r = -EFAULT;
		if (copy_from_user(&cap, argp, sizeof(cap)))
			goto out;
		r = kvm_vcpu_ioctl_enable_cap(vcpu, &cap);
		break;
	}
	default:
		r = -ENOIOCTLCMD;
	}

out:
	return r;
}

/* Get (and clear) the dirty memory log for a memory slot. */
int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
{
	struct kvm_memory_slot *memslot;
	unsigned long ga, ga_end;
	int is_dirty = 0;
	int r;
	unsigned long n;

	mutex_lock(&kvm->slots_lock);

	r = kvm_get_dirty_log(kvm, log, &is_dirty);
	if (r)
		goto out;

	/* If nothing is dirty, don't bother messing with page tables. */
	if (is_dirty) {
		memslot = &kvm->memslots->memslots[log->slot];

		ga = memslot->base_gfn << PAGE_SHIFT;
		ga_end = ga + (memslot->npages << PAGE_SHIFT);

		kvm_info("%s: dirty, ga: %#lx, ga_end %#lx\n", __func__, ga,
			 ga_end);

		n = kvm_dirty_bitmap_bytes(memslot);
		memset(memslot->dirty_bitmap, 0, n);
	}

	r = 0;
out:
	mutex_unlock(&kvm->slots_lock);
	return r;

}

long kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
{
	long r;

	switch (ioctl) {
	default:
		r = -ENOIOCTLCMD;
	}

	return r;
}

int kvm_arch_init(void *opaque)
{
	if (kvm_mips_callbacks) {
		kvm_err("kvm: module already exists\n");
		return -EEXIST;
	}

	return kvm_mips_emulation_init(&kvm_mips_callbacks);
}

void kvm_arch_exit(void)
{
	kvm_mips_callbacks = NULL;
}

int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,
				  struct kvm_sregs *sregs)
{
	return -ENOIOCTLCMD;
}

int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu,
				  struct kvm_sregs *sregs)
{
	return -ENOIOCTLCMD;
}

void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu)
{
}

int kvm_arch_vcpu_ioctl_get_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
{
	return -ENOIOCTLCMD;
}

int kvm_arch_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
{
	return -ENOIOCTLCMD;
}

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

int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
{
	int r;

	switch (ext) {
	case KVM_CAP_ONE_REG:
	case KVM_CAP_ENABLE_CAP:
		r = 1;
		break;
	case KVM_CAP_COALESCED_MMIO:
		r = KVM_COALESCED_MMIO_PAGE_OFFSET;
		break;
	case KVM_CAP_MIPS_FPU:
		r = !!cpu_has_fpu;
		break;
	default:
		r = 0;
		break;
	}
	return r;
}

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

int kvm_arch_vcpu_dump_regs(struct kvm_vcpu *vcpu)
{
	int i;
	struct mips_coproc *cop0;

	if (!vcpu)
		return -1;

	kvm_debug("VCPU Register Dump:\n");
	kvm_debug("\tpc = 0x%08lx\n", vcpu->arch.pc);
	kvm_debug("\texceptions: %08lx\n", vcpu->arch.pending_exceptions);

	for (i = 0; i < 32; i += 4) {
		kvm_debug("\tgpr%02d: %08lx %08lx %08lx %08lx\n", i,
		       vcpu->arch.gprs[i],
		       vcpu->arch.gprs[i + 1],
		       vcpu->arch.gprs[i + 2], vcpu->arch.gprs[i + 3]);
	}
	kvm_debug("\thi: 0x%08lx\n", vcpu->arch.hi);
	kvm_debug("\tlo: 0x%08lx\n", vcpu->arch.lo);

	cop0 = vcpu->arch.cop0;
	kvm_debug("\tStatus: 0x%08lx, Cause: 0x%08lx\n",
		  kvm_read_c0_guest_status(cop0),
		  kvm_read_c0_guest_cause(cop0));

	kvm_debug("\tEPC: 0x%08lx\n", kvm_read_c0_guest_epc(cop0));

	return 0;
}

int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
{
	int i;

	for (i = 1; i < ARRAY_SIZE(vcpu->arch.gprs); i++)
		vcpu->arch.gprs[i] = regs->gpr[i];
	vcpu->arch.gprs[0] = 0; /* zero is special, and cannot be set. */
	vcpu->arch.hi = regs->hi;
	vcpu->arch.lo = regs->lo;
	vcpu->arch.pc = regs->pc;

	return 0;
}

int kvm_arch_vcpu_ioctl_get_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(vcpu->arch.gprs); i++)
		regs->gpr[i] = vcpu->arch.gprs[i];

	regs->hi = vcpu->arch.hi;
	regs->lo = vcpu->arch.lo;
	regs->pc = vcpu->arch.pc;

	return 0;
}

static void kvm_mips_comparecount_func(unsigned long data)
{
	struct kvm_vcpu *vcpu = (struct kvm_vcpu *)data;

	kvm_mips_callbacks->queue_timer_int(vcpu);

	vcpu->arch.wait = 0;
	if (waitqueue_active(&vcpu->wq))
		wake_up_interruptible(&vcpu->wq);
}

/* low level hrtimer wake routine */
static enum hrtimer_restart kvm_mips_comparecount_wakeup(struct hrtimer *timer)
{
	struct kvm_vcpu *vcpu;

	vcpu = container_of(timer, struct kvm_vcpu, arch.comparecount_timer);
	kvm_mips_comparecount_func((unsigned long) vcpu);
	return kvm_mips_count_timeout(vcpu);
}

int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
{
	kvm_mips_callbacks->vcpu_init(vcpu);
	hrtimer_init(&vcpu->arch.comparecount_timer, CLOCK_MONOTONIC,
		     HRTIMER_MODE_REL);
	vcpu->arch.comparecount_timer.function = kvm_mips_comparecount_wakeup;
	return 0;
}

int kvm_arch_vcpu_ioctl_translate(struct kvm_vcpu *vcpu,
				  struct kvm_translation *tr)
{
	return 0;
}

/* Initial guest state */
int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
{
	return kvm_mips_callbacks->vcpu_setup(vcpu);
}

static void kvm_mips_set_c0_status(void)
{
	uint32_t status = read_c0_status();

	if (cpu_has_dsp)
		status |= (ST0_MX);

	write_c0_status(status);
	ehb();
}

/*
 * Return value is in the form (errcode<<2 | RESUME_FLAG_HOST | RESUME_FLAG_NV)
 */
int kvm_mips_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu)
{
	uint32_t cause = vcpu->arch.host_cp0_cause;
	uint32_t exccode = (cause >> CAUSEB_EXCCODE) & 0x1f;
	uint32_t __user *opc = (uint32_t __user *) vcpu->arch.pc;
	unsigned long badvaddr = vcpu->arch.host_cp0_badvaddr;
	enum emulation_result er = EMULATE_DONE;
	int ret = RESUME_GUEST;

	/* re-enable HTW before enabling interrupts */
	htw_start();

	/* Set a default exit reason */
	run->exit_reason = KVM_EXIT_UNKNOWN;
	run->ready_for_interrupt_injection = 1;

	/*
	 * Set the appropriate status bits based on host CPU features,
	 * before we hit the scheduler
	 */
	kvm_mips_set_c0_status();

	local_irq_enable();

	kvm_debug("kvm_mips_handle_exit: cause: %#x, PC: %p, kvm_run: %p, kvm_vcpu: %p\n",
			cause, opc, run, vcpu);

	/*
	 * Do a privilege check, if in UM most of these exit conditions end up
	 * causing an exception to be delivered to the Guest Kernel
	 */
	er = kvm_mips_check_privilege(cause, opc, run, vcpu);
	if (er == EMULATE_PRIV_FAIL) {
		goto skip_emul;
	} else if (er == EMULATE_FAIL) {
		run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
		ret = RESUME_HOST;
		goto skip_emul;
	}

	switch (exccode) {
	case T_INT:
		kvm_debug("[%d]T_INT @ %p\n", vcpu->vcpu_id, opc);

		++vcpu->stat.int_exits;
		trace_kvm_exit(vcpu, INT_EXITS);

		if (need_resched())
			cond_resched();

		ret = RESUME_GUEST;
		break;

	case T_COP_UNUSABLE:
		kvm_debug("T_COP_UNUSABLE: @ PC: %p\n", opc);

		++vcpu->stat.cop_unusable_exits;
		trace_kvm_exit(vcpu, COP_UNUSABLE_EXITS);
		ret = kvm_mips_callbacks->handle_cop_unusable(vcpu);
		/* XXXKYMA: Might need to return to user space */
		if (run->exit_reason == KVM_EXIT_IRQ_WINDOW_OPEN)
			ret = RESUME_HOST;
		break;

	case T_TLB_MOD:
		++vcpu->stat.tlbmod_exits;
		trace_kvm_exit(vcpu, TLBMOD_EXITS);
		ret = kvm_mips_callbacks->handle_tlb_mod(vcpu);
		break;

	case T_TLB_ST_MISS:
		kvm_debug("TLB ST fault:  cause %#x, status %#lx, PC: %p, BadVaddr: %#lx\n",
			  cause, kvm_read_c0_guest_status(vcpu->arch.cop0), opc,
			  badvaddr);

		++vcpu->stat.tlbmiss_st_exits;
		trace_kvm_exit(vcpu, TLBMISS_ST_EXITS);
		ret = kvm_mips_callbacks->handle_tlb_st_miss(vcpu);
		break;

	case T_TLB_LD_MISS:
		kvm_debug("TLB LD fault: cause %#x, PC: %p, BadVaddr: %#lx\n",
			  cause, opc, badvaddr);

		++vcpu->stat.tlbmiss_ld_exits;
		trace_kvm_exit(vcpu, TLBMISS_LD_EXITS);
		ret = kvm_mips_callbacks->handle_tlb_ld_miss(vcpu);
		break;

	case T_ADDR_ERR_ST:
		++vcpu->stat.addrerr_st_exits;
		trace_kvm_exit(vcpu, ADDRERR_ST_EXITS);
		ret = kvm_mips_callbacks->handle_addr_err_st(vcpu);
		break;

	case T_ADDR_ERR_LD:
		++vcpu->stat.addrerr_ld_exits;
		trace_kvm_exit(vcpu, ADDRERR_LD_EXITS);
		ret = kvm_mips_callbacks->handle_addr_err_ld(vcpu);
		break;

	case T_SYSCALL:
		++vcpu->stat.syscall_exits;
		trace_kvm_exit(vcpu, SYSCALL_EXITS);
		ret = kvm_mips_callbacks->handle_syscall(vcpu);
		break;

	case T_RES_INST:
		++vcpu->stat.resvd_inst_exits;
		trace_kvm_exit(vcpu, RESVD_INST_EXITS);
		ret = kvm_mips_callbacks->handle_res_inst(vcpu);
		break;

	case T_BREAK:
		++vcpu->stat.break_inst_exits;
		trace_kvm_exit(vcpu, BREAK_INST_EXITS);
		ret = kvm_mips_callbacks->handle_break(vcpu);
		break;

	case T_TRAP:
		++vcpu->stat.trap_inst_exits;
		trace_kvm_exit(vcpu, TRAP_INST_EXITS);
		ret = kvm_mips_callbacks->handle_trap(vcpu);
		break;

	case T_FPE:
		++vcpu->stat.fpe_exits;
		trace_kvm_exit(vcpu, FPE_EXITS);
		ret = kvm_mips_callbacks->handle_fpe(vcpu);
		break;

	case T_MSADIS:
		ret = kvm_mips_callbacks->handle_msa_disabled(vcpu);
		break;

	default:
		kvm_err("Exception Code: %d, not yet handled, @ PC: %p, inst: 0x%08x  BadVaddr: %#lx Status: %#lx\n",
			exccode, opc, kvm_get_inst(opc, vcpu), badvaddr,
			kvm_read_c0_guest_status(vcpu->arch.cop0));
		kvm_arch_vcpu_dump_regs(vcpu);
		run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
		ret = RESUME_HOST;
		break;

	}

skip_emul:
	local_irq_disable();

	if (er == EMULATE_DONE && !(ret & RESUME_HOST))
		kvm_mips_deliver_interrupts(vcpu, cause);

	if (!(ret & RESUME_HOST)) {
		/* Only check for signals if not already exiting to userspace */
		if (signal_pending(current)) {
			run->exit_reason = KVM_EXIT_INTR;
			ret = (-EINTR << 2) | RESUME_HOST;
			++vcpu->stat.signal_exits;
			trace_kvm_exit(vcpu, SIGNAL_EXITS);
		}
	}

	if (ret == RESUME_GUEST) {
		/*
		 * If FPU is enabled (i.e. the guest's FPU context is live),
		 * restore FCR31.
		 *
		 * This should be before returning to the guest exception
		 * vector, as it may well cause an FP exception if there are
		 * pending exception bits unmasked. (see
		 * kvm_mips_csr_die_notifier() for how that is handled).
		 */
		if (kvm_mips_guest_has_fpu(&vcpu->arch) &&
		    read_c0_status() & ST0_CU1)
			__kvm_restore_fcsr(&vcpu->arch);
	}

	/* Disable HTW before returning to guest or host */
	htw_stop();

	return ret;
}

/* Enable FPU for guest and restore context */
void kvm_own_fpu(struct kvm_vcpu *vcpu)
{
	struct mips_coproc *cop0 = vcpu->arch.cop0;
	unsigned int sr, cfg5;

	preempt_disable();

	/*
	 * Enable FPU for guest
	 * We set FR and FRE according to guest context
	 */
	sr = kvm_read_c0_guest_status(cop0);
	change_c0_status(ST0_CU1 | ST0_FR, sr);
	if (cpu_has_fre) {
		cfg5 = kvm_read_c0_guest_config5(cop0);
		change_c0_config5(MIPS_CONF5_FRE, cfg5);
	}
	enable_fpu_hazard();

	/* If guest FPU state not active, restore it now */
	if (!(vcpu->arch.fpu_inuse & KVM_MIPS_FPU_FPU)) {
		__kvm_restore_fpu(&vcpu->arch);
		vcpu->arch.fpu_inuse |= KVM_MIPS_FPU_FPU;
	}

	preempt_enable();
}

/* Drop FPU without saving it */
void kvm_drop_fpu(struct kvm_vcpu *vcpu)
{
	preempt_disable();
	if (vcpu->arch.fpu_inuse & KVM_MIPS_FPU_FPU) {
		clear_c0_status(ST0_CU1 | ST0_FR);
		vcpu->arch.fpu_inuse &= ~KVM_MIPS_FPU_FPU;
	}
	preempt_enable();
}

/* Save and disable FPU */
void kvm_lose_fpu(struct kvm_vcpu *vcpu)
{
	/*
	 * FPU gets disabled in root context (hardware) when it is disabled in
	 * guest context (software), but the register state in the hardware may
	 * still be in use. This is why we explicitly re-enable the hardware
	 * before saving.
	 */

	preempt_disable();
	if (vcpu->arch.fpu_inuse & KVM_MIPS_FPU_FPU) {
		set_c0_status(ST0_CU1);
		enable_fpu_hazard();

		__kvm_save_fpu(&vcpu->arch);
		vcpu->arch.fpu_inuse &= ~KVM_MIPS_FPU_FPU;

		/* Disable FPU */
		clear_c0_status(ST0_CU1 | ST0_FR);
	}
	preempt_enable();
}

/*
 * Step over a specific ctc1 to FCSR which is used to restore guest FCSR state
 * and may trigger a "harmless" FP exception if cause bits are set in the value
 * being written.
 */
static int kvm_mips_csr_die_notify(struct notifier_block *self,
				   unsigned long cmd, void *ptr)
{
	struct die_args *args = (struct die_args *)ptr;
	struct pt_regs *regs = args->regs;
	unsigned long pc;

	/* Only interested in FPE */
	if (cmd != DIE_FP)
		return NOTIFY_DONE;

	/* Return immediately if guest context isn't active */
	if (!(current->flags & PF_VCPU))
		return NOTIFY_DONE;

	/* Should never get here from user mode */
	BUG_ON(user_mode(regs));

	pc = instruction_pointer(regs);
	switch (cmd) {
	case DIE_FP:
		/* match 2nd instruction in __kvm_restore_fcsr */
		if (pc != (unsigned long)&__kvm_restore_fcsr + 4)
			return NOTIFY_DONE;
		break;
	}

	/* Move PC forward a little and continue executing */
	instruction_pointer(regs) += 4;

	return NOTIFY_STOP;
}

static struct notifier_block kvm_mips_csr_die_notifier = {
	.notifier_call = kvm_mips_csr_die_notify,
};

int __init kvm_mips_init(void)
{
	int ret;

	ret = kvm_init(NULL, sizeof(struct kvm_vcpu), 0, THIS_MODULE);

	if (ret)
		return ret;

	register_die_notifier(&kvm_mips_csr_die_notifier);

	/*
	 * On MIPS, kernel modules are executed from "mapped space", which
	 * requires TLBs. The TLB handling code is statically linked with
	 * the rest of the kernel (tlb.c) to avoid the possibility of
	 * double faulting. The issue is that the TLB code references
	 * routines that are part of the the KVM module, which are only
	 * available once the module is loaded.
	 */
	kvm_mips_gfn_to_pfn = gfn_to_pfn;
	kvm_mips_release_pfn_clean = kvm_release_pfn_clean;
	kvm_mips_is_error_pfn = is_error_pfn;

	return 0;
}

void __exit kvm_mips_exit(void)
{
	kvm_exit();

	kvm_mips_gfn_to_pfn = NULL;
	kvm_mips_release_pfn_clean = NULL;
	kvm_mips_is_error_pfn = NULL;

	unregister_die_notifier(&kvm_mips_csr_die_notifier);
}

module_init(kvm_mips_init);
module_exit(kvm_mips_exit);

EXPORT_TRACEPOINT_SYMBOL(kvm_exit);