// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2021 Western Digital Corporation or its affiliates.
 *
 * Authors:
 *     Atish Patra <atish.patra@wdc.com>
 *     Anup Patel <anup.patel@wdc.com>
 */

#include <linux/errno.h>
#include <linux/err.h>
#include <linux/kvm_host.h>
#include <linux/nospec.h>
#include <linux/uaccess.h>
#include <asm/cpufeature.h>

#ifdef CONFIG_FPU
void kvm_riscv_vcpu_fp_reset(struct kvm_vcpu *vcpu)
{
        struct kvm_cpu_context *cntx = &vcpu->arch.guest_context;

        cntx->sstatus &= ~SR_FS;
        if (riscv_isa_extension_available(vcpu->arch.isa, f) ||
            riscv_isa_extension_available(vcpu->arch.isa, d))
                cntx->sstatus |= SR_FS_INITIAL;
        else
                cntx->sstatus |= SR_FS_OFF;
}

static void kvm_riscv_vcpu_fp_clean(struct kvm_cpu_context *cntx)
{
        cntx->sstatus &= ~SR_FS;
        cntx->sstatus |= SR_FS_CLEAN;
}

void kvm_riscv_vcpu_guest_fp_save(struct kvm_cpu_context *cntx,
                                  const unsigned long *isa)
{
        if ((cntx->sstatus & SR_FS) == SR_FS_DIRTY) {
                if (riscv_isa_extension_available(isa, d))
                        __kvm_riscv_fp_d_save(cntx);
                else if (riscv_isa_extension_available(isa, f))
                        __kvm_riscv_fp_f_save(cntx);
                kvm_riscv_vcpu_fp_clean(cntx);
        }
}

void kvm_riscv_vcpu_guest_fp_restore(struct kvm_cpu_context *cntx,
                                     const unsigned long *isa)
{
        if ((cntx->sstatus & SR_FS) != SR_FS_OFF) {
                if (riscv_isa_extension_available(isa, d))
                        __kvm_riscv_fp_d_restore(cntx);
                else if (riscv_isa_extension_available(isa, f))
                        __kvm_riscv_fp_f_restore(cntx);
                kvm_riscv_vcpu_fp_clean(cntx);
        }
}

void kvm_riscv_vcpu_host_fp_save(struct kvm_cpu_context *cntx)
{
        /* No need to check host sstatus as it can be modified outside */
        if (riscv_isa_extension_available(NULL, d))
                __kvm_riscv_fp_d_save(cntx);
        else if (riscv_isa_extension_available(NULL, f))
                __kvm_riscv_fp_f_save(cntx);
}

void kvm_riscv_vcpu_host_fp_restore(struct kvm_cpu_context *cntx)
{
        if (riscv_isa_extension_available(NULL, d))
                __kvm_riscv_fp_d_restore(cntx);
        else if (riscv_isa_extension_available(NULL, f))
                __kvm_riscv_fp_f_restore(cntx);
}
#endif

int kvm_riscv_vcpu_get_reg_fp(struct kvm_vcpu *vcpu,
                              const struct kvm_one_reg *reg,
                              unsigned long rtype)
{
        struct kvm_cpu_context *cntx = &vcpu->arch.guest_context;
        unsigned long __user *uaddr =
                        (unsigned long __user *)(unsigned long)reg->addr;
        unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
                                            KVM_REG_SIZE_MASK |
                                            rtype);
        void *reg_val;

        if ((rtype == KVM_REG_RISCV_FP_F) &&
            riscv_isa_extension_available(vcpu->arch.isa, f)) {
                if (KVM_REG_SIZE(reg->id) != sizeof(u32))
                        return -EINVAL;
                if (reg_num == KVM_REG_RISCV_FP_F_REG(fcsr))
                        reg_val = &cntx->fp.f.fcsr;
                else if ((KVM_REG_RISCV_FP_F_REG(f[0]) <= reg_num) &&
                          reg_num <= KVM_REG_RISCV_FP_F_REG(f[31])) {
                        reg_num = array_index_nospec(reg_num,
                                        ARRAY_SIZE(cntx->fp.f.f));
                        reg_val = &cntx->fp.f.f[reg_num];
                } else
                        return -ENOENT;
        } else if ((rtype == KVM_REG_RISCV_FP_D) &&
                   riscv_isa_extension_available(vcpu->arch.isa, d)) {
                if (reg_num == KVM_REG_RISCV_FP_D_REG(fcsr)) {
                        if (KVM_REG_SIZE(reg->id) != sizeof(u32))
                                return -EINVAL;
                        reg_val = &cntx->fp.d.fcsr;
                } else if ((KVM_REG_RISCV_FP_D_REG(f[0]) <= reg_num) &&
                           reg_num <= KVM_REG_RISCV_FP_D_REG(f[31])) {
                        if (KVM_REG_SIZE(reg->id) != sizeof(u64))
                                return -EINVAL;
                        reg_num = array_index_nospec(reg_num,
                                        ARRAY_SIZE(cntx->fp.d.f));
                        reg_val = &cntx->fp.d.f[reg_num];
                } else
                        return -ENOENT;
        } else
                return -ENOENT;

        if (copy_to_user(uaddr, reg_val, KVM_REG_SIZE(reg->id)))
                return -EFAULT;

        return 0;
}

int kvm_riscv_vcpu_set_reg_fp(struct kvm_vcpu *vcpu,
                              const struct kvm_one_reg *reg,
                              unsigned long rtype)
{
        struct kvm_cpu_context *cntx = &vcpu->arch.guest_context;
        unsigned long __user *uaddr =
                        (unsigned long __user *)(unsigned long)reg->addr;
        unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
                                            KVM_REG_SIZE_MASK |
                                            rtype);
        void *reg_val;

        if ((rtype == KVM_REG_RISCV_FP_F) &&
            riscv_isa_extension_available(vcpu->arch.isa, f)) {
                if (KVM_REG_SIZE(reg->id) != sizeof(u32))
                        return -EINVAL;
                if (reg_num == KVM_REG_RISCV_FP_F_REG(fcsr))
                        reg_val = &cntx->fp.f.fcsr;
                else if ((KVM_REG_RISCV_FP_F_REG(f[0]) <= reg_num) &&
                          reg_num <= KVM_REG_RISCV_FP_F_REG(f[31])) {
                        reg_num = array_index_nospec(reg_num,
                                        ARRAY_SIZE(cntx->fp.f.f));
                        reg_val = &cntx->fp.f.f[reg_num];
                } else
                        return -ENOENT;
        } else if ((rtype == KVM_REG_RISCV_FP_D) &&
                   riscv_isa_extension_available(vcpu->arch.isa, d)) {
                if (reg_num == KVM_REG_RISCV_FP_D_REG(fcsr)) {
                        if (KVM_REG_SIZE(reg->id) != sizeof(u32))
                                return -EINVAL;
                        reg_val = &cntx->fp.d.fcsr;
                } else if ((KVM_REG_RISCV_FP_D_REG(f[0]) <= reg_num) &&
                           reg_num <= KVM_REG_RISCV_FP_D_REG(f[31])) {
                        if (KVM_REG_SIZE(reg->id) != sizeof(u64))
                                return -EINVAL;
                        reg_num = array_index_nospec(reg_num,
                                        ARRAY_SIZE(cntx->fp.d.f));
                        reg_val = &cntx->fp.d.f[reg_num];
                } else
                        return -ENOENT;
        } else
                return -ENOENT;

        if (copy_from_user(reg_val, uaddr, KVM_REG_SIZE(reg->id)))
                return -EFAULT;

        return 0;
}