// SPDX-License-Identifier: GPL-2.0-only
/*
 *
 * Copyright IBM Corp. 2007
 * Copyright 2011 Freescale Semiconductor, Inc.
 *
 * Authors: Hollis Blanchard <hollisb@us.ibm.com>
 */

#include <linux/jiffies.h>
#include <linux/hrtimer.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/kvm_host.h>
#include <linux/clockchips.h>

#include <asm/reg.h>
#include <asm/time.h>
#include <asm/byteorder.h>
#include <asm/kvm_ppc.h>
#include <asm/disassemble.h>
#include <asm/ppc-opcode.h>
#include "timing.h"
#include "trace.h"

void kvmppc_emulate_dec(struct kvm_vcpu *vcpu)
{
        unsigned long dec_nsec;
        unsigned long long dec_time;

        pr_debug("mtDEC: %lx\n", vcpu->arch.dec);
        hrtimer_try_to_cancel(&vcpu->arch.dec_timer);

#ifdef CONFIG_PPC_BOOK3S
        /* mtdec lowers the interrupt line when positive. */
        kvmppc_core_dequeue_dec(vcpu);
#endif

#ifdef CONFIG_BOOKE
        /* On BOOKE, DEC = 0 is as good as decrementer not enabled */
        if (vcpu->arch.dec == 0)
                return;
#endif

        /*
         * The decrementer ticks at the same rate as the timebase, so
         * that's how we convert the guest DEC value to the number of
         * host ticks.
         */

        dec_time = vcpu->arch.dec;
        /*
         * Guest timebase ticks at the same frequency as host timebase.
         * So use the host timebase calculations for decrementer emulation.
         */
        dec_time = tb_to_ns(dec_time);
        dec_nsec = do_div(dec_time, NSEC_PER_SEC);
        hrtimer_start(&vcpu->arch.dec_timer,
                ktime_set(dec_time, dec_nsec), HRTIMER_MODE_REL);
        vcpu->arch.dec_jiffies = get_tb();
}

u32 kvmppc_get_dec(struct kvm_vcpu *vcpu, u64 tb)
{
        u64 jd = tb - vcpu->arch.dec_jiffies;

#ifdef CONFIG_BOOKE
        if (vcpu->arch.dec < jd)
                return 0;
#endif

        return vcpu->arch.dec - jd;
}

static int kvmppc_emulate_mtspr(struct kvm_vcpu *vcpu, int sprn, int rs)
{
        enum emulation_result emulated = EMULATE_DONE;
        ulong spr_val = kvmppc_get_gpr(vcpu, rs);

        switch (sprn) {
        case SPRN_SRR0:
                kvmppc_set_srr0(vcpu, spr_val);
                break;
        case SPRN_SRR1:
                kvmppc_set_srr1(vcpu, spr_val);
                break;

        /* XXX We need to context-switch the timebase for
         * watchdog and FIT. */
        case SPRN_TBWL: break;
        case SPRN_TBWU: break;

        case SPRN_DEC:
                vcpu->arch.dec = (u32) spr_val;
                kvmppc_emulate_dec(vcpu);
                break;

        case SPRN_SPRG0:
                kvmppc_set_sprg0(vcpu, spr_val);
                break;
        case SPRN_SPRG1:
                kvmppc_set_sprg1(vcpu, spr_val);
                break;
        case SPRN_SPRG2:
                kvmppc_set_sprg2(vcpu, spr_val);
                break;
        case SPRN_SPRG3:
                kvmppc_set_sprg3(vcpu, spr_val);
                break;

        /* PIR can legally be written, but we ignore it */
        case SPRN_PIR: break;

        default:
                emulated = vcpu->kvm->arch.kvm_ops->emulate_mtspr(vcpu, sprn,
                                                                  spr_val);
                if (emulated == EMULATE_FAIL)
                        printk(KERN_INFO "mtspr: unknown spr "
                                "0x%x\n", sprn);
                break;
        }

        kvmppc_set_exit_type(vcpu, EMULATED_MTSPR_EXITS);

        return emulated;
}

static int kvmppc_emulate_mfspr(struct kvm_vcpu *vcpu, int sprn, int rt)
{
        enum emulation_result emulated = EMULATE_DONE;
        ulong spr_val = 0;

        switch (sprn) {
        case SPRN_SRR0:
                spr_val = kvmppc_get_srr0(vcpu);
                break;
        case SPRN_SRR1:
                spr_val = kvmppc_get_srr1(vcpu);
                break;
        case SPRN_PVR:
                spr_val = vcpu->arch.pvr;
                break;
        case SPRN_PIR:
                spr_val = vcpu->vcpu_id;
                break;

        /* Note: mftb and TBRL/TBWL are user-accessible, so
         * the guest can always access the real TB anyways.
         * In fact, we probably will never see these traps. */
        case SPRN_TBWL:
                spr_val = get_tb() >> 32;
                break;
        case SPRN_TBWU:
                spr_val = get_tb();
                break;

        case SPRN_SPRG0:
                spr_val = kvmppc_get_sprg0(vcpu);
                break;
        case SPRN_SPRG1:
                spr_val = kvmppc_get_sprg1(vcpu);
                break;
        case SPRN_SPRG2:
                spr_val = kvmppc_get_sprg2(vcpu);
                break;
        case SPRN_SPRG3:
                spr_val = kvmppc_get_sprg3(vcpu);
                break;
        /* Note: SPRG4-7 are user-readable, so we don't get
         * a trap. */

        case SPRN_DEC:
                spr_val = kvmppc_get_dec(vcpu, get_tb());
                break;
        default:
                emulated = vcpu->kvm->arch.kvm_ops->emulate_mfspr(vcpu, sprn,
                                                                  &spr_val);
                if (unlikely(emulated == EMULATE_FAIL)) {
                        printk(KERN_INFO "mfspr: unknown spr "
                                "0x%x\n", sprn);
                }
                break;
        }

        if (emulated == EMULATE_DONE)
                kvmppc_set_gpr(vcpu, rt, spr_val);
        kvmppc_set_exit_type(vcpu, EMULATED_MFSPR_EXITS);

        return emulated;
}

/* XXX Should probably auto-generate instruction decoding for a particular core
 * from opcode tables in the future. */
int kvmppc_emulate_instruction(struct kvm_vcpu *vcpu)
{
        u32 inst;
        ppc_inst_t pinst;
        int rs, rt, sprn;
        enum emulation_result emulated;
        int advance = 1;

        /* this default type might be overwritten by subcategories */
        kvmppc_set_exit_type(vcpu, EMULATED_INST_EXITS);

        emulated = kvmppc_get_last_inst(vcpu, INST_GENERIC, &pinst);
        inst = ppc_inst_val(pinst);
        if (emulated != EMULATE_DONE)
                return emulated;

        pr_debug("Emulating opcode %d / %d\n", get_op(inst), get_xop(inst));

        rs = get_rs(inst);
        rt = get_rt(inst);
        sprn = get_sprn(inst);

        switch (get_op(inst)) {
        case OP_TRAP:
#ifdef CONFIG_PPC_BOOK3S
        case OP_TRAP_64:
                kvmppc_core_queue_program(vcpu, SRR1_PROGTRAP);
#else
                kvmppc_core_queue_program(vcpu,
                                          vcpu->arch.shared->esr | ESR_PTR);
#endif
                advance = 0;
                break;

        case 31:
                switch (get_xop(inst)) {

                case OP_31_XOP_TRAP:
#ifdef CONFIG_64BIT
                case OP_31_XOP_TRAP_64:
#endif
#ifdef CONFIG_PPC_BOOK3S
                        kvmppc_core_queue_program(vcpu, SRR1_PROGTRAP);
#else
                        kvmppc_core_queue_program(vcpu,
                                        vcpu->arch.shared->esr | ESR_PTR);
#endif
                        advance = 0;
                        break;

                case OP_31_XOP_MFSPR:
                        emulated = kvmppc_emulate_mfspr(vcpu, sprn, rt);
                        if (emulated == EMULATE_AGAIN) {
                                emulated = EMULATE_DONE;
                                advance = 0;
                        }
                        break;

                case OP_31_XOP_MTSPR:
                        emulated = kvmppc_emulate_mtspr(vcpu, sprn, rs);
                        if (emulated == EMULATE_AGAIN) {
                                emulated = EMULATE_DONE;
                                advance = 0;
                        }
                        break;

                case OP_31_XOP_TLBSYNC:
                        break;

                default:
                        /* Attempt core-specific emulation below. */
                        emulated = EMULATE_FAIL;
                }
                break;

        case 0:
                /*
                 * Instruction with primary opcode 0. Based on PowerISA
                 * these are illegal instructions.
                 */
                if (inst == KVMPPC_INST_SW_BREAKPOINT) {
                        vcpu->run->exit_reason = KVM_EXIT_DEBUG;
                        vcpu->run->debug.arch.status = 0;
                        vcpu->run->debug.arch.address = kvmppc_get_pc(vcpu);
                        emulated = EMULATE_EXIT_USER;
                        advance = 0;
                } else
                        emulated = EMULATE_FAIL;

                break;

        default:
                emulated = EMULATE_FAIL;
        }

        if (emulated == EMULATE_FAIL) {
                emulated = vcpu->kvm->arch.kvm_ops->emulate_op(vcpu, inst,
                                                               &advance);
                if (emulated == EMULATE_AGAIN) {
                        advance = 0;
                } else if (emulated == EMULATE_FAIL) {
                        advance = 0;
                        printk(KERN_ERR "Couldn't emulate instruction 0x%08x "
                               "(op %d xop %d)\n", inst, get_op(inst), get_xop(inst));
                }
        }

        trace_kvm_ppc_instr(inst, kvmppc_get_pc(vcpu), emulated);

        /* Advance past emulated instruction. */
        /*
         * If this ever handles prefixed instructions, the 4
         * will need to become ppc_inst_len(pinst) instead.
         */
        if (advance)
                kvmppc_set_pc(vcpu, kvmppc_get_pc(vcpu) + 4);

        return emulated;
}
EXPORT_SYMBOL_GPL(kvmppc_emulate_instruction);