sched/headers: Prepare to move signal wakeup & sigpending methods from <linux/sched...

[mirror_ubuntu-artful-kernel.git] / arch / mips / kvm / 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/bitops.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/kdebug.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/vmalloc.h>
#include <linux/sched/signal.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/pgalloc.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 },
        { "msa_fpe",      VCPU_STAT(msa_fpe_exits),      KVM_STAT_VCPU },
        { "fpe",          VCPU_STAT(fpe_exits),          KVM_STAT_VCPU },
        { "msa_disabled", VCPU_STAT(msa_disabled_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_attempted_poll", VCPU_STAT(halt_attempted_poll), KVM_STAT_VCPU },
        { "halt_poll_invalid", VCPU_STAT(halt_poll_invalid), KVM_STAT_VCPU },
        { "halt_wakeup",  VCPU_STAT(halt_wakeup),        KVM_STAT_VCPU },
        {NULL}
};

/*
 * 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;
}

int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
{
        /* Allocate page table to map GPA -> RPA */
        kvm->arch.gpa_mm.pgd = kvm_pgd_alloc();
        if (!kvm->arch.gpa_mm.pgd)
                return -ENOMEM;

        return 0;
}

bool kvm_arch_has_vcpu_debugfs(void)
{
        return false;
}

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

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

        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_free_gpa_pt(struct kvm *kvm)
{
        /* It should always be safe to remove after flushing the whole range */
        WARN_ON(!kvm_mips_flush_gpa_pt(kvm, 0, ~0));
        pgd_free(NULL, kvm->arch.gpa_mm.pgd);
}

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

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;
}

void kvm_arch_flush_shadow_all(struct kvm *kvm)
{
        /* Flush whole GPA */
        kvm_mips_flush_gpa_pt(kvm, 0, ~0);

        /* Let implementation do the rest */
        kvm_mips_callbacks->flush_shadow_all(kvm);
}

void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
                                   struct kvm_memory_slot *slot)
{
        /*
         * The slot has been made invalid (ready for moving or deletion), so we
         * need to ensure that it can no longer be accessed by any guest VCPUs.
         */

        spin_lock(&kvm->mmu_lock);
        /* Flush slot from GPA */
        kvm_mips_flush_gpa_pt(kvm, slot->base_gfn,
                              slot->base_gfn + slot->npages - 1);
        /* Let implementation do the rest */
        kvm_mips_callbacks->flush_shadow_memslot(kvm, slot);
        spin_unlock(&kvm->mmu_lock);
}

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

void kvm_arch_commit_memory_region(struct kvm *kvm,
                                   const struct kvm_userspace_memory_region *mem,
                                   const struct kvm_memory_slot *old,
                                   const struct kvm_memory_slot *new,
                                   enum kvm_mr_change change)
{
        int needs_flush;

        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);

        /*
         * If dirty page logging is enabled, write protect all pages in the slot
         * ready for dirty logging.
         *
         * There is no need to do this in any of the following cases:
         * CREATE:      No dirty mappings will already exist.
         * MOVE/DELETE: The old mappings will already have been cleaned up by
         *              kvm_arch_flush_shadow_memslot()
         */
        if (change == KVM_MR_FLAGS_ONLY &&
            (!(old->flags & KVM_MEM_LOG_DIRTY_PAGES) &&
             new->flags & KVM_MEM_LOG_DIRTY_PAGES)) {
                spin_lock(&kvm->mmu_lock);
                /* Write protect GPA page table entries */
                needs_flush = kvm_mips_mkclean_gpa_pt(kvm, new->base_gfn,
                                        new->base_gfn + new->npages - 1);
                /* Let implementation do the rest */
                if (needs_flush)
                        kvm_mips_callbacks->flush_shadow_memslot(kvm, new);
                spin_unlock(&kvm->mmu_lock);
        }
}

static inline void dump_handler(const char *symbol, void *start, void *end)
{
        u32 *p;

        pr_debug("LEAF(%s)\n", symbol);

        pr_debug("\t.set push\n");
        pr_debug("\t.set noreorder\n");

        for (p = start; p < (u32 *)end; ++p)
                pr_debug("\t.word\t0x%08x\t\t# %p\n", *p, p);

        pr_debug("\t.set\tpop\n");

        pr_debug("\tEND(%s)\n", symbol);
}

struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id)
{
        int err, size;
        void *gebase, *p, *handler, *refill_start, *refill_end;
        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;

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

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

        /*
         * Check new ebase actually fits in CP0_EBase. The lack of a write gate
         * limits us to the low 512MB of physical address space. If the memory
         * we allocate is out of range, just give up now.
         */
        if (!cpu_has_ebase_wg && virt_to_phys(gebase) >= 0x20000000) {
                kvm_err("CP0_EBase.WG required for guest exception base %pK\n",
                        gebase);
                err = -ENOMEM;
                goto out_free_gebase;
        }

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

        /* Build guest exception vectors dynamically in unmapped memory */
        handler = gebase + 0x2000;

        /* TLB refill */
        refill_start = gebase;
        refill_end = kvm_mips_build_tlb_refill_exception(refill_start, handler);

        /* General Exception Entry point */
        kvm_mips_build_exception(gebase + 0x180, handler);

        /* 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));
                kvm_mips_build_exception(gebase + 0x200 + i * VECTORSPACING,
                                         handler);
        }

        /* General exit handler */
        p = handler;
        p = kvm_mips_build_exit(p);

        /* Guest entry routine */
        vcpu->arch.vcpu_run = p;
        p = kvm_mips_build_vcpu_run(p);

        /* Dump the generated code */
        pr_debug("#include <asm/asm.h>\n");
        pr_debug("#include <asm/regdef.h>\n");
        pr_debug("\n");
        dump_handler("kvm_vcpu_run", vcpu->arch.vcpu_run, p);
        dump_handler("kvm_tlb_refill", refill_start, refill_end);
        dump_handler("kvm_gen_exc", gebase + 0x180, gebase + 0x200);
        dump_handler("kvm_exit", gebase + 0x2000, vcpu->arch.vcpu_run);

        /* Invalidate the icache for these ranges */
        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_uninit_cpu:
        kvm_vcpu_uninit(vcpu);

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);

        kvm_mmu_free_memory_caches(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 = -EINTR;
        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;
        }

        if (run->immediate_exit)
                goto out;

        lose_fpu(1);

        local_irq_disable();
        guest_enter_irqoff();
        trace_kvm_enter(vcpu);

        /*
         * Make sure the read of VCPU requests in vcpu_run() callback is not
         * reordered ahead of the write to vcpu->mode, or we could miss a TLB
         * flush request while the requester sees the VCPU as outside of guest
         * mode and not needing an IPI.
         */
        smp_store_mb(vcpu->mode, IN_GUEST_MODE);

        r = kvm_mips_callbacks->vcpu_run(run, vcpu);

        trace_kvm_out(vcpu);
        guest_exit_irqoff();
        local_irq_enable();

out:
        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 (swait_active(&dvcpu->wq))
                swake_up(&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,

#ifndef CONFIG_CPU_MIPSR6
        KVM_REG_MIPS_HI,
        KVM_REG_MIPS_LO,
#endif
        KVM_REG_MIPS_PC,
};

static u64 kvm_mips_get_one_regs_fpu[] = {
        KVM_REG_MIPS_FCR_IR,
        KVM_REG_MIPS_FCR_CSR,
};

static u64 kvm_mips_get_one_regs_msa[] = {
        KVM_REG_MIPS_MSA_IR,
        KVM_REG_MIPS_MSA_CSR,
};

static unsigned long kvm_mips_num_regs(struct kvm_vcpu *vcpu)
{
        unsigned long ret;

        ret = ARRAY_SIZE(kvm_mips_get_one_regs);
        if (kvm_mips_guest_can_have_fpu(&vcpu->arch)) {
                ret += ARRAY_SIZE(kvm_mips_get_one_regs_fpu) + 48;
                /* odd doubles */
                if (boot_cpu_data.fpu_id & MIPS_FPIR_F64)
                        ret += 16;
        }
        if (kvm_mips_guest_can_have_msa(&vcpu->arch))
                ret += ARRAY_SIZE(kvm_mips_get_one_regs_msa) + 32;
        ret += kvm_mips_callbacks->num_regs(vcpu);

        return ret;
}

static int kvm_mips_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *indices)
{
        u64 index;
        unsigned int i;

        if (copy_to_user(indices, kvm_mips_get_one_regs,
                         sizeof(kvm_mips_get_one_regs)))
                return -EFAULT;
        indices += ARRAY_SIZE(kvm_mips_get_one_regs);

        if (kvm_mips_guest_can_have_fpu(&vcpu->arch)) {
                if (copy_to_user(indices, kvm_mips_get_one_regs_fpu,
                                 sizeof(kvm_mips_get_one_regs_fpu)))
                        return -EFAULT;
                indices += ARRAY_SIZE(kvm_mips_get_one_regs_fpu);

                for (i = 0; i < 32; ++i) {
                        index = KVM_REG_MIPS_FPR_32(i);
                        if (copy_to_user(indices, &index, sizeof(index)))
                                return -EFAULT;
                        ++indices;

                        /* skip odd doubles if no F64 */
                        if (i & 1 && !(boot_cpu_data.fpu_id & MIPS_FPIR_F64))
                                continue;

                        index = KVM_REG_MIPS_FPR_64(i);
                        if (copy_to_user(indices, &index, sizeof(index)))
                                return -EFAULT;
                        ++indices;
                }
        }

        if (kvm_mips_guest_can_have_msa(&vcpu->arch)) {
                if (copy_to_user(indices, kvm_mips_get_one_regs_msa,
                                 sizeof(kvm_mips_get_one_regs_msa)))
                        return -EFAULT;
                indices += ARRAY_SIZE(kvm_mips_get_one_regs_msa);

                for (i = 0; i < 32; ++i) {
                        index = KVM_REG_MIPS_VEC_128(i);
                        if (copy_to_user(indices, &index, sizeof(index)))
                                return -EFAULT;
                        ++indices;
                }
        }

        return kvm_mips_callbacks->copy_reg_indices(vcpu, indices);
}

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;
        s64 vs[2];
        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;
#ifndef CONFIG_CPU_MIPSR6
        case KVM_REG_MIPS_HI:
                v = (long)vcpu->arch.hi;
                break;
        case KVM_REG_MIPS_LO:
                v = (long)vcpu->arch.lo;
                break;
#endif
        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;

        /* MIPS SIMD Architecture (MSA) registers */
        case KVM_REG_MIPS_VEC_128(0) ... KVM_REG_MIPS_VEC_128(31):
                if (!kvm_mips_guest_has_msa(&vcpu->arch))
                        return -EINVAL;
                /* Can't access MSA registers in FR=0 mode */
                if (!(kvm_read_c0_guest_status(cop0) & ST0_FR))
                        return -EINVAL;
                idx = reg->id - KVM_REG_MIPS_VEC_128(0);
#ifdef CONFIG_CPU_LITTLE_ENDIAN
                /* least significant byte first */
                vs[0] = get_fpr64(&fpu->fpr[idx], 0);
                vs[1] = get_fpr64(&fpu->fpr[idx], 1);
#else
                /* most significant byte first */
                vs[0] = get_fpr64(&fpu->fpr[idx], 1);
                vs[1] = get_fpr64(&fpu->fpr[idx], 0);
#endif
                break;
        case KVM_REG_MIPS_MSA_IR:
                if (!kvm_mips_guest_has_msa(&vcpu->arch))
                        return -EINVAL;
                v = boot_cpu_data.msa_id;
                break;
        case KVM_REG_MIPS_MSA_CSR:
                if (!kvm_mips_guest_has_msa(&vcpu->arch))
                        return -EINVAL;
                v = fpu->msacsr;
                break;

        /* registers to be handled specially */
        default:
                ret = kvm_mips_callbacks->get_one_reg(vcpu, reg, &v);
                if (ret)
                        return ret;
                break;
        }
        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 if ((reg->id & KVM_REG_SIZE_MASK) == KVM_REG_SIZE_U128) {
                void __user *uaddr = (void __user *)(long)reg->addr;

                return copy_to_user(uaddr, vs, 16) ? -EFAULT : 0;
        } 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;
        s64 vs[2];
        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 if ((reg->id & KVM_REG_SIZE_MASK) == KVM_REG_SIZE_U128) {
                void __user *uaddr = (void __user *)(long)reg->addr;

                return copy_from_user(vs, uaddr, 16) ? -EFAULT : 0;
        } 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;
#ifndef CONFIG_CPU_MIPSR6
        case KVM_REG_MIPS_HI:
                vcpu->arch.hi = v;
                break;
        case KVM_REG_MIPS_LO:
                vcpu->arch.lo = v;
                break;
#endif
        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;

        /* MIPS SIMD Architecture (MSA) registers */
        case KVM_REG_MIPS_VEC_128(0) ... KVM_REG_MIPS_VEC_128(31):
                if (!kvm_mips_guest_has_msa(&vcpu->arch))
                        return -EINVAL;
                idx = reg->id - KVM_REG_MIPS_VEC_128(0);
#ifdef CONFIG_CPU_LITTLE_ENDIAN
                /* least significant byte first */
                set_fpr64(&fpu->fpr[idx], 0, vs[0]);
                set_fpr64(&fpu->fpr[idx], 1, vs[1]);
#else
                /* most significant byte first */
                set_fpr64(&fpu->fpr[idx], 1, vs[0]);
                set_fpr64(&fpu->fpr[idx], 0, vs[1]);
#endif
                break;
        case KVM_REG_MIPS_MSA_IR:
                if (!kvm_mips_guest_has_msa(&vcpu->arch))
                        return -EINVAL;
                /* Read-only */
                break;
        case KVM_REG_MIPS_MSA_CSR:
                if (!kvm_mips_guest_has_msa(&vcpu->arch))
                        return -EINVAL;
                fpu->msacsr = v;
                break;

        /* registers to be handled specially */
        default:
                return kvm_mips_callbacks->set_one_reg(vcpu, reg, v);
        }
        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;
        case KVM_CAP_MIPS_MSA:
                vcpu->arch.msa_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;
                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_mips_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_mips_copy_reg_indices(vcpu, user_list->reg);
        }
        case KVM_INTERRUPT:
                {
                        struct kvm_mips_interrupt irq;

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

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

/**
 * kvm_vm_ioctl_get_dirty_log - get and clear the log of dirty pages in a slot
 * @kvm: kvm instance
 * @log: slot id and address to which we copy the log
 *
 * Steps 1-4 below provide general overview of dirty page logging. See
 * kvm_get_dirty_log_protect() function description for additional details.
 *
 * We call kvm_get_dirty_log_protect() to handle steps 1-3, upon return we
 * always flush the TLB (step 4) even if previous step failed  and the dirty
 * bitmap may be corrupt. Regardless of previous outcome the KVM logging API
 * does not preclude user space subsequent dirty log read. Flushing TLB ensures
 * writes will be marked dirty for next log read.
 *
 *   1. Take a snapshot of the bit and clear it if needed.
 *   2. Write protect the corresponding page.
 *   3. Copy the snapshot to the userspace.
 *   4. Flush TLB's if needed.
 */
int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log)
{
        struct kvm_memslots *slots;
        struct kvm_memory_slot *memslot;
        bool is_dirty = false;
        int r;

        mutex_lock(&kvm->slots_lock);

        r = kvm_get_dirty_log_protect(kvm, log, &is_dirty);

        if (is_dirty) {
                slots = kvm_memslots(kvm);
                memslot = id_to_memslot(slots, log->slot);

                /* Let implementation handle TLB/GVA invalidation */
                kvm_mips_callbacks->flush_shadow_memslot(kvm, memslot);
        }

        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:
        case KVM_CAP_READONLY_MEM:
        case KVM_CAP_SYNC_MMU:
        case KVM_CAP_IMMEDIATE_EXIT:
                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;
        case KVM_CAP_MIPS_FPU:
                /* We don't handle systems with inconsistent cpu_has_fpu */
                r = !!raw_cpu_has_fpu;
                break;
        case KVM_CAP_MIPS_MSA:
                /*
                 * We don't support MSA vector partitioning yet:
                 * 1) It would require explicit support which can't be tested
                 *    yet due to lack of support in current hardware.
                 * 2) It extends the state that would need to be saved/restored
                 *    by e.g. QEMU for migration.
                 *
                 * When vector partitioning hardware becomes available, support
                 * could be added by requiring a flag when enabling
                 * KVM_CAP_MIPS_MSA capability to indicate that userland knows
                 * to save/restore the appropriate extra state.
                 */
                r = cpu_has_msa && !(boot_cpu_data.msa_id & MSA_IR_WRPF);
                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 (swait_active(&vcpu->wq))
                swake_up(&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)
{
        int err;

        err = kvm_mips_callbacks->vcpu_init(vcpu);
        if (err)
                return err;

        hrtimer_init(&vcpu->arch.comparecount_timer, CLOCK_MONOTONIC,
                     HRTIMER_MODE_REL);
        vcpu->arch.comparecount_timer.function = kvm_mips_comparecount_wakeup;
        return 0;
}

void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu)
{
        kvm_mips_callbacks->vcpu_uninit(vcpu);
}

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)
{
        u32 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)
{
        u32 cause = vcpu->arch.host_cp0_cause;
        u32 exccode = (cause >> CAUSEB_EXCCODE) & 0x1f;
        u32 __user *opc = (u32 __user *) vcpu->arch.pc;
        unsigned long badvaddr = vcpu->arch.host_cp0_badvaddr;
        enum emulation_result er = EMULATE_DONE;
        u32 inst;
        int ret = RESUME_GUEST;

        vcpu->mode = OUTSIDE_GUEST_MODE;

        /* 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);
        trace_kvm_exit(vcpu, exccode);

        /*
         * 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 EXCCODE_INT:
                kvm_debug("[%d]EXCCODE_INT @ %p\n", vcpu->vcpu_id, opc);

                ++vcpu->stat.int_exits;

                if (need_resched())
                        cond_resched();

                ret = RESUME_GUEST;
                break;

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

                ++vcpu->stat.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 EXCCODE_MOD:
                ++vcpu->stat.tlbmod_exits;
                ret = kvm_mips_callbacks->handle_tlb_mod(vcpu);
                break;

        case EXCCODE_TLBS:
                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;
                ret = kvm_mips_callbacks->handle_tlb_st_miss(vcpu);
                break;

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

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

        case EXCCODE_ADES:
                ++vcpu->stat.addrerr_st_exits;
                ret = kvm_mips_callbacks->handle_addr_err_st(vcpu);
                break;

        case EXCCODE_ADEL:
                ++vcpu->stat.addrerr_ld_exits;
                ret = kvm_mips_callbacks->handle_addr_err_ld(vcpu);
                break;

        case EXCCODE_SYS:
                ++vcpu->stat.syscall_exits;
                ret = kvm_mips_callbacks->handle_syscall(vcpu);
                break;

        case EXCCODE_RI:
                ++vcpu->stat.resvd_inst_exits;
                ret = kvm_mips_callbacks->handle_res_inst(vcpu);
                break;

        case EXCCODE_BP:
                ++vcpu->stat.break_inst_exits;
                ret = kvm_mips_callbacks->handle_break(vcpu);
                break;

        case EXCCODE_TR:
                ++vcpu->stat.trap_inst_exits;
                ret = kvm_mips_callbacks->handle_trap(vcpu);
                break;

        case EXCCODE_MSAFPE:
                ++vcpu->stat.msa_fpe_exits;
                ret = kvm_mips_callbacks->handle_msa_fpe(vcpu);
                break;

        case EXCCODE_FPE:
                ++vcpu->stat.fpe_exits;
                ret = kvm_mips_callbacks->handle_fpe(vcpu);
                break;

        case EXCCODE_MSADIS:
                ++vcpu->stat.msa_disabled_exits;
                ret = kvm_mips_callbacks->handle_msa_disabled(vcpu);
                break;

        default:
                if (cause & CAUSEF_BD)
                        opc += 1;
                inst = 0;
                kvm_get_badinstr(opc, vcpu, &inst);
                kvm_err("Exception Code: %d, not yet handled, @ PC: %p, inst: 0x%08x  BadVaddr: %#lx Status: %#lx\n",
                        exccode, opc, inst, 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, KVM_TRACE_EXIT_SIGNAL);
                }
        }

        if (ret == RESUME_GUEST) {
                trace_kvm_reenter(vcpu);

                /*
                 * Make sure the read of VCPU requests in vcpu_reenter()
                 * callback is not reordered ahead of the write to vcpu->mode,
                 * or we could miss a TLB flush request while the requester sees
                 * the VCPU as outside of guest mode and not needing an IPI.
                 */
                smp_store_mb(vcpu->mode, IN_GUEST_MODE);

                kvm_mips_callbacks->vcpu_reenter(run, vcpu);

                /*
                 * If FPU / MSA are enabled (i.e. the guest's FPU / MSA context
                 * is live), restore FCR31 / MSACSR.
                 *
                 * This should be before returning to the guest exception
                 * vector, as it may well cause an [MSA] 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);

                if (kvm_mips_guest_has_msa(&vcpu->arch) &&
                    read_c0_config5() & MIPS_CONF5_MSAEN)
                        __kvm_restore_msacsr(&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();

        sr = kvm_read_c0_guest_status(cop0);

        /*
         * If MSA state is already live, it is undefined how it interacts with
         * FR=0 FPU state, and we don't want to hit reserved instruction
         * exceptions trying to save the MSA state later when CU=1 && FR=1, so
         * play it safe and save it first.
         *
         * In theory we shouldn't ever hit this case since kvm_lose_fpu() should
         * get called when guest CU1 is set, however we can't trust the guest
         * not to clobber the status register directly via the commpage.
         */
        if (cpu_has_msa && sr & ST0_CU1 && !(sr & ST0_FR) &&
            vcpu->arch.aux_inuse & KVM_MIPS_AUX_MSA)
                kvm_lose_fpu(vcpu);

        /*
         * Enable FPU for guest
         * We set FR and FRE according to guest context
         */
        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.aux_inuse & KVM_MIPS_AUX_FPU)) {
                __kvm_restore_fpu(&vcpu->arch);
                vcpu->arch.aux_inuse |= KVM_MIPS_AUX_FPU;
                trace_kvm_aux(vcpu, KVM_TRACE_AUX_RESTORE, KVM_TRACE_AUX_FPU);
        } else {
                trace_kvm_aux(vcpu, KVM_TRACE_AUX_ENABLE, KVM_TRACE_AUX_FPU);
        }

        preempt_enable();
}

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

        preempt_disable();

        /*
         * Enable FPU if enabled in guest, since we're restoring FPU context
         * anyway. We set FR and FRE according to guest context.
         */
        if (kvm_mips_guest_has_fpu(&vcpu->arch)) {
                sr = kvm_read_c0_guest_status(cop0);

                /*
                 * If FR=0 FPU state is already live, it is undefined how it
                 * interacts with MSA state, so play it safe and save it first.
                 */
                if (!(sr & ST0_FR) &&
                    (vcpu->arch.aux_inuse & (KVM_MIPS_AUX_FPU |
                                KVM_MIPS_AUX_MSA)) == KVM_MIPS_AUX_FPU)
                        kvm_lose_fpu(vcpu);

                change_c0_status(ST0_CU1 | ST0_FR, sr);
                if (sr & ST0_CU1 && cpu_has_fre) {
                        cfg5 = kvm_read_c0_guest_config5(cop0);
                        change_c0_config5(MIPS_CONF5_FRE, cfg5);
                }
        }

        /* Enable MSA for guest */
        set_c0_config5(MIPS_CONF5_MSAEN);
        enable_fpu_hazard();

        switch (vcpu->arch.aux_inuse & (KVM_MIPS_AUX_FPU | KVM_MIPS_AUX_MSA)) {
        case KVM_MIPS_AUX_FPU:
                /*
                 * Guest FPU state already loaded, only restore upper MSA state
                 */
                __kvm_restore_msa_upper(&vcpu->arch);
                vcpu->arch.aux_inuse |= KVM_MIPS_AUX_MSA;
                trace_kvm_aux(vcpu, KVM_TRACE_AUX_RESTORE, KVM_TRACE_AUX_MSA);
                break;
        case 0:
                /* Neither FPU or MSA already active, restore full MSA state */
                __kvm_restore_msa(&vcpu->arch);
                vcpu->arch.aux_inuse |= KVM_MIPS_AUX_MSA;
                if (kvm_mips_guest_has_fpu(&vcpu->arch))
                        vcpu->arch.aux_inuse |= KVM_MIPS_AUX_FPU;
                trace_kvm_aux(vcpu, KVM_TRACE_AUX_RESTORE,
                              KVM_TRACE_AUX_FPU_MSA);
                break;
        default:
                trace_kvm_aux(vcpu, KVM_TRACE_AUX_ENABLE, KVM_TRACE_AUX_MSA);
                break;
        }

        preempt_enable();
}
#endif

/* Drop FPU & MSA without saving it */
void kvm_drop_fpu(struct kvm_vcpu *vcpu)
{
        preempt_disable();
        if (cpu_has_msa && vcpu->arch.aux_inuse & KVM_MIPS_AUX_MSA) {
                disable_msa();
                trace_kvm_aux(vcpu, KVM_TRACE_AUX_DISCARD, KVM_TRACE_AUX_MSA);
                vcpu->arch.aux_inuse &= ~KVM_MIPS_AUX_MSA;
        }
        if (vcpu->arch.aux_inuse & KVM_MIPS_AUX_FPU) {
                clear_c0_status(ST0_CU1 | ST0_FR);
                trace_kvm_aux(vcpu, KVM_TRACE_AUX_DISCARD, KVM_TRACE_AUX_FPU);
                vcpu->arch.aux_inuse &= ~KVM_MIPS_AUX_FPU;
        }
        preempt_enable();
}

/* Save and disable FPU & MSA */
void kvm_lose_fpu(struct kvm_vcpu *vcpu)
{
        /*
         * FPU & MSA get 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 (cpu_has_msa && vcpu->arch.aux_inuse & KVM_MIPS_AUX_MSA) {
                set_c0_config5(MIPS_CONF5_MSAEN);
                enable_fpu_hazard();

                __kvm_save_msa(&vcpu->arch);
                trace_kvm_aux(vcpu, KVM_TRACE_AUX_SAVE, KVM_TRACE_AUX_FPU_MSA);

                /* Disable MSA & FPU */
                disable_msa();
                if (vcpu->arch.aux_inuse & KVM_MIPS_AUX_FPU) {
                        clear_c0_status(ST0_CU1 | ST0_FR);
                        disable_fpu_hazard();
                }
                vcpu->arch.aux_inuse &= ~(KVM_MIPS_AUX_FPU | KVM_MIPS_AUX_MSA);
        } else if (vcpu->arch.aux_inuse & KVM_MIPS_AUX_FPU) {
                set_c0_status(ST0_CU1);
                enable_fpu_hazard();

                __kvm_save_fpu(&vcpu->arch);
                vcpu->arch.aux_inuse &= ~KVM_MIPS_AUX_FPU;
                trace_kvm_aux(vcpu, KVM_TRACE_AUX_SAVE, KVM_TRACE_AUX_FPU);

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

/*
 * Step over a specific ctc1 to FCSR and a specific ctcmsa to MSACSR which are
 * used to restore guest FCSR/MSACSR state and may trigger a "harmless" FP/MSAFP
 * 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 and MSAFPE */
        if (cmd != DIE_FP && cmd != DIE_MSAFP)
                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;
        case DIE_MSAFP:
                /* match 2nd/3rd instruction in __kvm_restore_msacsr */
                if (!cpu_has_msa ||
                    pc < (unsigned long)&__kvm_restore_msacsr + 4 ||
                    pc > (unsigned long)&__kvm_restore_msacsr + 8)
                        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,
};

static int __init kvm_mips_init(void)
{
        int ret;

        ret = kvm_mips_entry_setup();
        if (ret)
                return ret;

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

        if (ret)
                return ret;

        register_die_notifier(&kvm_mips_csr_die_notifier);

        return 0;
}

static void __exit kvm_mips_exit(void)
{
        kvm_exit();

        unregister_die_notifier(&kvm_mips_csr_die_notifier);
}

module_init(kvm_mips_init);
module_exit(kvm_mips_exit);

EXPORT_TRACEPOINT_SYMBOL(kvm_exit);