/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2026, Netflix, Inc.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/* Support for the AMD IBS */

#include <sys/param.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/pcpu.h>
#include <sys/pmc.h>
#include <sys/pmckern.h>
#include <sys/pmclog.h>
#include <sys/smp.h>
#include <sys/systm.h>

#include <machine/cpu.h>
#include <machine/cpufunc.h>
#include <machine/md_var.h>
#include <machine/specialreg.h>

#define IBS_STOP_ITER           50 /* Stopping iterations */

/* AMD IBS PMCs */
struct ibs_descr {
        struct pmc_descr pm_descr;  /* "base class" */
};

/*
 * Globals
 */
static uint64_t ibs_features;

/*
 * Per-processor information
 */
#define IBS_CPU_RUNNING         1
#define IBS_CPU_STOPPING        2
#define IBS_CPU_STOPPED         3

struct ibs_cpu {
        int             pc_status;
        struct pmc_hw   pc_ibspmcs[IBS_NPMCS];
};
static struct ibs_cpu **ibs_pcpu;

/*
 * Read a PMC value from the MSR.
 */
static int
ibs_read_pmc(int cpu, int ri, struct pmc *pm, pmc_value_t *v)
{

        KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
            ("[ibs,%d] illegal CPU value %d", __LINE__, cpu));
        KASSERT(ri >= 0 && ri < IBS_NPMCS,
            ("[ibs,%d] illegal row-index %d", __LINE__, ri));
        KASSERT(ibs_pcpu[cpu],
            ("[ibs,%d] null per-cpu, cpu %d", __LINE__, cpu));

        /* read the IBS ctl */
        switch (ri) {
        case IBS_PMC_FETCH:
                *v = rdmsr(IBS_FETCH_CTL);
                break;
        case IBS_PMC_OP:
                *v = rdmsr(IBS_OP_CTL);
                break;
        }

        PMCDBG2(MDP, REA, 2, "ibs-read id=%d -> %jd", ri, *v);

        return (0);
}

/*
 * Write a PMC MSR.
 */
static int
ibs_write_pmc(int cpu, int ri, struct pmc *pm, pmc_value_t v)
{

        KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
            ("[ibs,%d] illegal CPU value %d", __LINE__, cpu));
        KASSERT(ri >= 0 && ri < IBS_NPMCS,
            ("[ibs,%d] illegal row-index %d", __LINE__, ri));

        PMCDBG3(MDP, WRI, 1, "ibs-write cpu=%d ri=%d v=%jx", cpu, ri, v);

        return (0);
}

/*
 * Configure hardware PMC according to the configuration recorded in 'pm'.
 */
static int
ibs_config_pmc(int cpu, int ri, struct pmc *pm)
{
        struct pmc_hw *phw;

        PMCDBG3(MDP, CFG, 1, "cpu=%d ri=%d pm=%p", cpu, ri, pm);

        KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
            ("[ibs,%d] illegal CPU value %d", __LINE__, cpu));
        KASSERT(ri >= 0 && ri < IBS_NPMCS,
            ("[ibs,%d] illegal row-index %d", __LINE__, ri));

        phw = &ibs_pcpu[cpu]->pc_ibspmcs[ri];

        KASSERT(pm == NULL || phw->phw_pmc == NULL,
            ("[ibs,%d] pm=%p phw->pm=%p hwpmc not unconfigured",
                __LINE__, pm, phw->phw_pmc));

        phw->phw_pmc = pm;

        return (0);
}

/*
 * Retrieve a configured PMC pointer from hardware state.
 */
static int
ibs_get_config(int cpu, int ri, struct pmc **ppm)
{

        *ppm = ibs_pcpu[cpu]->pc_ibspmcs[ri].phw_pmc;

        return (0);
}

/*
 * Check if a given PMC allocation is feasible.
 */
static int
ibs_allocate_pmc(int cpu __unused, int ri, struct pmc *pm,
    const struct pmc_op_pmcallocate *a)
{
        uint64_t caps, config;

        KASSERT(ri >= 0 && ri < IBS_NPMCS,
            ("[ibs,%d] illegal row index %d", __LINE__, ri));

        /* check class match */
        if (a->pm_class != PMC_CLASS_IBS)
                return (EINVAL);
        if (a->pm_md.pm_ibs.ibs_type != ri)
                return (EINVAL);

        caps = pm->pm_caps;

        PMCDBG2(MDP, ALL, 1, "ibs-allocate ri=%d caps=0x%x", ri, caps);

        if ((caps & PMC_CAP_SYSTEM) == 0)
                return (EINVAL);

        config = a->pm_md.pm_ibs.ibs_ctl;
        pm->pm_md.pm_ibs.ibs_ctl = config;

        PMCDBG2(MDP, ALL, 2, "ibs-allocate ri=%d -> config=0x%x", ri, config);

        return (0);
}

/*
 * Release machine dependent state associated with a PMC.  This is a
 * no-op on this architecture.
 */
static int
ibs_release_pmc(int cpu, int ri, struct pmc *pmc __unused)
{
        struct pmc_hw *phw __diagused;

        KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
            ("[ibs,%d] illegal CPU value %d", __LINE__, cpu));
        KASSERT(ri >= 0 && ri < IBS_NPMCS,
            ("[ibs,%d] illegal row-index %d", __LINE__, ri));

        PMCDBG1(MDP, ALL, 1, "ibs-release ri=%d", ri);

        phw = &ibs_pcpu[cpu]->pc_ibspmcs[ri];

        KASSERT(phw->phw_pmc == NULL,
            ("[ibs,%d] PHW pmc %p non-NULL", __LINE__, phw->phw_pmc));

        return (0);
}

/*
 * Start a PMC.
 */
static int
ibs_start_pmc(int cpu __diagused, int ri, struct pmc *pm)
{
        uint64_t config;

        KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
            ("[ibs,%d] illegal CPU value %d", __LINE__, cpu));
        KASSERT(ri >= 0 && ri < IBS_NPMCS,
            ("[ibs,%d] illegal row-index %d", __LINE__, ri));

        PMCDBG2(MDP, STA, 1, "ibs-start cpu=%d ri=%d", cpu, ri);

        /*
         * This is used to handle spurious NMIs.  All that matters is that it
         * is not in the stopping state.
         */
        atomic_store_int(&ibs_pcpu[cpu]->pc_status, IBS_CPU_RUNNING);

        /*
         * Turn on the ENABLE bit.  Zeroing out the control register eliminates
         * stale valid bits from spurious NMIs and it resets the counter.
         */
        switch (ri) {
        case IBS_PMC_FETCH:
                wrmsr(IBS_FETCH_CTL, 0);
                config = pm->pm_md.pm_ibs.ibs_ctl | IBS_FETCH_CTL_ENABLE;
                wrmsr(IBS_FETCH_CTL, config);
                break;
        case IBS_PMC_OP:
                wrmsr(IBS_OP_CTL, 0);
                config = pm->pm_md.pm_ibs.ibs_ctl | IBS_OP_CTL_ENABLE;
                wrmsr(IBS_OP_CTL, config);
                break;
        }

        return (0);
}

/*
 * Stop a PMC.
 */
static int
ibs_stop_pmc(int cpu __diagused, int ri, struct pmc *pm)
{
        int i;
        uint64_t config;

        KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
            ("[ibs,%d] illegal CPU value %d", __LINE__, cpu));
        KASSERT(ri >= 0 && ri < IBS_NPMCS,
            ("[ibs,%d] illegal row-index %d", __LINE__, ri));

        PMCDBG1(MDP, STO, 1, "ibs-stop ri=%d", ri);

        /*
         * Turn off the ENABLE bit, but unfortunately there are a few quirks
         * that generate excess NMIs.  Workaround #420 in the Revision Guide
         * for AMD Family 10h Processors 41322 Rev. 3.92 March 2012. requires
         * that we clear the count before clearing enable.
         *
         * Even after clearing the counter spurious NMIs are still possible so
         * we use a per-CPU atomic variable to notify the interrupt handler we
         * are stopping and discard spurious NMIs.  We then retry clearing the
         * control register for 50us.  This gives us enough time and ensures
         * that the valid bit is not accidently stuck after a spurious NMI.
         */
        config = pm->pm_md.pm_ibs.ibs_ctl;

        atomic_store_int(&ibs_pcpu[cpu]->pc_status, IBS_CPU_STOPPING);

        switch (ri) {
        case IBS_PMC_FETCH:
                wrmsr(IBS_FETCH_CTL, config & ~IBS_FETCH_CTL_MAXCNTMASK);
                DELAY(1);
                config &= ~IBS_FETCH_CTL_ENABLE;
                wrmsr(IBS_FETCH_CTL, config);
                break;
        case IBS_PMC_OP:
                wrmsr(IBS_FETCH_CTL, config & ~IBS_FETCH_CTL_MAXCNTMASK);
                DELAY(1);
                config &= ~IBS_OP_CTL_ENABLE;
                wrmsr(IBS_OP_CTL, config);
                break;
        }

        for (i = 0; i < IBS_STOP_ITER; i++) {
                DELAY(1);

                switch (ri) {
                case IBS_PMC_FETCH:
                        wrmsr(IBS_FETCH_CTL, 0);
                        break;
                case IBS_PMC_OP:
                        wrmsr(IBS_OP_CTL, 0);
                        break;
                }
        }

        atomic_store_int(&ibs_pcpu[cpu]->pc_status, IBS_CPU_STOPPED);

        return (0);
}

static void
pmc_ibs_process_fetch(struct pmc *pm, struct trapframe *tf, uint64_t config)
{
        struct pmc_multipart mpd;

        if (pm == NULL)
                return;

        if (pm->pm_state != PMC_STATE_RUNNING)
                return;

        memset(&mpd, 0, sizeof(mpd));

        mpd.pl_type = PMC_CC_MULTIPART_IBS_FETCH;
        mpd.pl_length = 4;
        mpd.pl_mpdata[PMC_MPIDX_FETCH_CTL] = config;
        if (ibs_features) {
                mpd.pl_mpdata[PMC_MPIDX_FETCH_EXTCTL] = rdmsr(IBS_FETCH_EXTCTL);
        }
        mpd.pl_mpdata[PMC_MPIDX_FETCH_CTL] = config;
        mpd.pl_mpdata[PMC_MPIDX_FETCH_LINADDR] = rdmsr(IBS_FETCH_LINADDR);
        if ((config & IBS_FETCH_CTL_PHYSADDRVALID) != 0) {
                mpd.pl_mpdata[PMC_MPIDX_FETCH_PHYSADDR] =
                    rdmsr(IBS_FETCH_PHYSADDR);
        }

        pmc_process_interrupt_mp(PMC_HR, pm, tf, &mpd);
}

static void
pmc_ibs_process_op(struct pmc *pm, struct trapframe *tf, uint64_t config)
{
        struct pmc_multipart mpd;

        if (pm == NULL)
                return;

        if (pm->pm_state != PMC_STATE_RUNNING)
                return;

        memset(&mpd, 0, sizeof(mpd));

        mpd.pl_type = PMC_CC_MULTIPART_IBS_OP;
        mpd.pl_length = 8;
        mpd.pl_mpdata[PMC_MPIDX_OP_CTL] = config;
        mpd.pl_mpdata[PMC_MPIDX_OP_RIP] = rdmsr(IBS_OP_RIP);
        mpd.pl_mpdata[PMC_MPIDX_OP_DATA] = rdmsr(IBS_OP_DATA);
        mpd.pl_mpdata[PMC_MPIDX_OP_DATA2] = rdmsr(IBS_OP_DATA2);
        mpd.pl_mpdata[PMC_MPIDX_OP_DATA3] = rdmsr(IBS_OP_DATA3);
        mpd.pl_mpdata[PMC_MPIDX_OP_DC_LINADDR] = rdmsr(IBS_OP_DC_LINADDR);
        mpd.pl_mpdata[PMC_MPIDX_OP_DC_PHYSADDR] = rdmsr(IBS_OP_DC_PHYSADDR);

        pmc_process_interrupt_mp(PMC_HR, pm, tf, &mpd);

        wrmsr(IBS_OP_CTL, pm->pm_md.pm_ibs.ibs_ctl | IBS_OP_CTL_ENABLE);
}

/*
 * Interrupt handler.  This function needs to return '1' if the
 * interrupt was this CPU's PMCs or '0' otherwise.  It is not allowed
 * to sleep or do anything a 'fast' interrupt handler is not allowed
 * to do.
 */
int
pmc_ibs_intr(struct trapframe *tf)
{
        struct ibs_cpu *pac;
        struct pmc *pm;
        int retval, cpu;
        uint64_t config;

        cpu = curcpu;
        KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
            ("[ibs,%d] out of range CPU %d", __LINE__, cpu));

        PMCDBG3(MDP, INT, 1, "cpu=%d tf=%p um=%d", cpu, tf, TRAPF_USERMODE(tf));

        retval = 0;

        pac = ibs_pcpu[cpu];

        config = rdmsr(IBS_FETCH_CTL);
        if ((config & IBS_FETCH_CTL_VALID) != 0) {
                pm = pac->pc_ibspmcs[IBS_PMC_FETCH].phw_pmc;

                retval = 1;

                pmc_ibs_process_fetch(pm, tf, config);
        }

        config = rdmsr(IBS_OP_CTL);
        if ((retval == 0) && ((config & IBS_OP_CTL_VALID) != 0)) {
                pm = pac->pc_ibspmcs[IBS_PMC_OP].phw_pmc;

                retval = 1;

                pmc_ibs_process_op(pm, tf, config);
        }

        if (retval == 0) {
                // Lets check for a stray NMI when stopping
                if (atomic_load_int(&pac->pc_status) == IBS_CPU_STOPPING) {
                        return (1);
                }
        }


        if (retval)
                counter_u64_add(pmc_stats.pm_intr_processed, 1);
        else
                counter_u64_add(pmc_stats.pm_intr_ignored, 1);

        PMCDBG1(MDP, INT, 2, "retval=%d", retval);

        return (retval);
}

/*
 * Describe a PMC.
 */
static int
ibs_describe(int cpu, int ri, struct pmc_info *pi, struct pmc **ppmc)
{
        struct pmc_hw *phw;

        KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
            ("[ibs,%d] illegal CPU %d", __LINE__, cpu));
        KASSERT(ri >= 0 && ri < IBS_NPMCS,
            ("[ibs,%d] row-index %d out of range", __LINE__, ri));

        phw = &ibs_pcpu[cpu]->pc_ibspmcs[ri];

        if (ri == IBS_PMC_FETCH) {
                strlcpy(pi->pm_name, "IBS-FETCH", sizeof(pi->pm_name));
                pi->pm_class = PMC_CLASS_IBS;
                pi->pm_enabled = true;
                *ppmc          = phw->phw_pmc;
        } else {
                strlcpy(pi->pm_name, "IBS-OP", sizeof(pi->pm_name));
                pi->pm_class = PMC_CLASS_IBS;
                pi->pm_enabled = true;
                *ppmc          = phw->phw_pmc;
        }

        return (0);
}

/*
 * Processor-dependent initialization.
 */
static int
ibs_pcpu_init(struct pmc_mdep *md, int cpu)
{
        struct ibs_cpu *pac;
        struct pmc_cpu *pc;
        struct pmc_hw  *phw;
        int first_ri, n;

        KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
            ("[ibs,%d] insane cpu number %d", __LINE__, cpu));

        PMCDBG1(MDP, INI, 1, "ibs-init cpu=%d", cpu);

        ibs_pcpu[cpu] = pac = malloc(sizeof(struct ibs_cpu), M_PMC,
            M_WAITOK | M_ZERO);

        /*
         * Set the content of the hardware descriptors to a known
         * state and initialize pointers in the MI per-cpu descriptor.
         */
        pc = pmc_pcpu[cpu];
        first_ri = md->pmd_classdep[PMC_MDEP_CLASS_INDEX_IBS].pcd_ri;

        KASSERT(pc != NULL, ("[ibs,%d] NULL per-cpu pointer", __LINE__));

        for (n = 0, phw = pac->pc_ibspmcs; n < IBS_NPMCS; n++, phw++) {
                phw->phw_state = PMC_PHW_FLAG_IS_ENABLED |
                    PMC_PHW_CPU_TO_STATE(cpu) | PMC_PHW_INDEX_TO_STATE(n);
                phw->phw_pmc = NULL;
                pc->pc_hwpmcs[n + first_ri] = phw;
        }

        return (0);
}

/*
 * Processor-dependent cleanup prior to the KLD being unloaded.
 */
static int
ibs_pcpu_fini(struct pmc_mdep *md, int cpu)
{
        struct ibs_cpu *pac;
        struct pmc_cpu *pc;
        int first_ri, i;

        KASSERT(cpu >= 0 && cpu < pmc_cpu_max(),
            ("[ibs,%d] insane cpu number (%d)", __LINE__, cpu));

        PMCDBG1(MDP, INI, 1, "ibs-cleanup cpu=%d", cpu);

        /*
         * Turn off IBS.
         */
        wrmsr(IBS_FETCH_CTL, 0);
        wrmsr(IBS_OP_CTL, 0);

        /*
         * Free up allocated space.
         */
        if ((pac = ibs_pcpu[cpu]) == NULL)
                return (0);

        ibs_pcpu[cpu] = NULL;

        pc = pmc_pcpu[cpu];
        KASSERT(pc != NULL, ("[ibs,%d] NULL per-cpu state", __LINE__));

        first_ri = md->pmd_classdep[PMC_MDEP_CLASS_INDEX_IBS].pcd_ri;

        /*
         * Reset pointers in the MI 'per-cpu' state.
         */
        for (i = 0; i < IBS_NPMCS; i++)
                pc->pc_hwpmcs[i + first_ri] = NULL;

        free(pac, M_PMC);

        return (0);
}

/*
 * Initialize ourselves.
 */
int
pmc_ibs_initialize(struct pmc_mdep *pmc_mdep, int ncpus)
{
        u_int regs[4];
        struct pmc_classdep *pcd;

        /*
         * Allocate space for pointers to PMC HW descriptors and for
         * the MDEP structure used by MI code.
         */
        ibs_pcpu = malloc(sizeof(struct ibs_cpu *) * pmc_cpu_max(), M_PMC,
            M_WAITOK | M_ZERO);

        /* Initialize AMD IBS handling. */
        pcd = &pmc_mdep->pmd_classdep[PMC_MDEP_CLASS_INDEX_IBS];

        pcd->pcd_caps           = IBS_PMC_CAPS;
        pcd->pcd_class          = PMC_CLASS_IBS;
        pcd->pcd_num            = IBS_NPMCS;
        pcd->pcd_ri             = pmc_mdep->pmd_npmc;
        pcd->pcd_width          = 0;

        pcd->pcd_allocate_pmc   = ibs_allocate_pmc;
        pcd->pcd_config_pmc     = ibs_config_pmc;
        pcd->pcd_describe       = ibs_describe;
        pcd->pcd_get_config     = ibs_get_config;
        pcd->pcd_pcpu_fini      = ibs_pcpu_fini;
        pcd->pcd_pcpu_init      = ibs_pcpu_init;
        pcd->pcd_release_pmc    = ibs_release_pmc;
        pcd->pcd_start_pmc      = ibs_start_pmc;
        pcd->pcd_stop_pmc       = ibs_stop_pmc;
        pcd->pcd_read_pmc       = ibs_read_pmc;
        pcd->pcd_write_pmc      = ibs_write_pmc;

        pmc_mdep->pmd_npmc      += IBS_NPMCS;

        if (cpu_exthigh >= CPUID_IBSID) {
                do_cpuid(CPUID_IBSID, regs);
                ibs_features = regs[0];
        } else {
                ibs_features = 0;
        }

        PMCDBG0(MDP, INI, 0, "ibs-initialize");

        return (0);
}

/*
 * Finalization code for AMD CPUs.
 */
void
pmc_ibs_finalize(struct pmc_mdep *md)
{
        PMCDBG0(MDP, INI, 1, "ibs-finalize");

        for (int i = 0; i < pmc_cpu_max(); i++)
                KASSERT(ibs_pcpu[i] == NULL,
                    ("[ibs,%d] non-null pcpu cpu %d", __LINE__, i));

        free(ibs_pcpu, M_PMC);
        ibs_pcpu = NULL;
}