9453 Include KPTI status in kernel boot messages

[unleashed.git] / usr / src / uts / i86pc / os / mp_startup.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 1992, 2010, Oracle and/or its affiliates. All rights reserved.
 */
/*
 * Copyright (c) 2010, Intel Corporation.
 * All rights reserved.
 */
/*
 * Copyright 2018 Joyent, Inc.
 * Copyright 2013 Nexenta Systems, Inc.  All rights reserved.
 * Copyright 2018 OmniOS Community Edition (OmniOSce) Association.
 */

#include <sys/types.h>
#include <sys/thread.h>
#include <sys/cpuvar.h>
#include <sys/cpu.h>
#include <sys/t_lock.h>
#include <sys/param.h>
#include <sys/proc.h>
#include <sys/disp.h>
#include <sys/class.h>
#include <sys/cmn_err.h>
#include <sys/debug.h>
#include <sys/note.h>
#include <sys/asm_linkage.h>
#include <sys/x_call.h>
#include <sys/systm.h>
#include <sys/var.h>
#include <sys/vtrace.h>
#include <vm/hat.h>
#include <vm/as.h>
#include <vm/seg_kmem.h>
#include <vm/seg_kp.h>
#include <sys/segments.h>
#include <sys/kmem.h>
#include <sys/stack.h>
#include <sys/smp_impldefs.h>
#include <sys/x86_archext.h>
#include <sys/machsystm.h>
#include <sys/traptrace.h>
#include <sys/clock.h>
#include <sys/cpc_impl.h>
#include <sys/pg.h>
#include <sys/cmt.h>
#include <sys/dtrace.h>
#include <sys/archsystm.h>
#include <sys/fp.h>
#include <sys/reboot.h>
#include <sys/kdi_machimpl.h>
#include <vm/hat_i86.h>
#include <vm/vm_dep.h>
#include <sys/memnode.h>
#include <sys/pci_cfgspace.h>
#include <sys/mach_mmu.h>
#include <sys/sysmacros.h>
#if defined(__xpv)
#include <sys/hypervisor.h>
#endif
#include <sys/cpu_module.h>
#include <sys/ontrap.h>

struct cpu      cpus[1] __aligned(MMU_PAGESIZE);
struct cpu      *cpu[NCPU] = {&cpus[0]};
struct cpu      *cpu_free_list;
cpu_core_t      cpu_core[NCPU];

#define cpu_next_free   cpu_prev

/*
 * Useful for disabling MP bring-up on a MP capable system.
 */
int use_mp = 1;

/*
 * to be set by a PSM to indicate what cpus
 * are sitting around on the system.
 */
cpuset_t mp_cpus;

/*
 * This variable is used by the hat layer to decide whether or not
 * critical sections are needed to prevent race conditions.  For sun4m,
 * this variable is set once enough MP initialization has been done in
 * order to allow cross calls.
 */
int flushes_require_xcalls;

cpuset_t cpu_ready_set;         /* initialized in startup() */

static void mp_startup_boot(void);
static void mp_startup_hotplug(void);

static void cpu_sep_enable(void);
static void cpu_sep_disable(void);
static void cpu_asysc_enable(void);
static void cpu_asysc_disable(void);

/*
 * Init CPU info - get CPU type info for processor_info system call.
 */
void
init_cpu_info(struct cpu *cp)
{
        processor_info_t *pi = &cp->cpu_type_info;

        /*
         * Get clock-frequency property for the CPU.
         */
        pi->pi_clock = cpu_freq;

        /*
         * Current frequency in Hz.
         */
        cp->cpu_curr_clock = cpu_freq_hz;

        /*
         * Supported frequencies.
         */
        if (cp->cpu_supp_freqs == NULL) {
                cpu_set_supp_freqs(cp, NULL);
        }

        (void) strcpy(pi->pi_processor_type, "i386");
        if (fpu_exists)
                (void) strcpy(pi->pi_fputypes, "i387 compatible");

        cp->cpu_idstr = kmem_zalloc(CPU_IDSTRLEN, KM_SLEEP);
        cp->cpu_brandstr = kmem_zalloc(CPU_IDSTRLEN, KM_SLEEP);

        /*
         * If called for the BSP, cp is equal to current CPU.
         * For non-BSPs, cpuid info of cp is not ready yet, so use cpuid info
         * of current CPU as default values for cpu_idstr and cpu_brandstr.
         * They will be corrected in mp_startup_common() after cpuid_pass1()
         * has been invoked on target CPU.
         */
        (void) cpuid_getidstr(CPU, cp->cpu_idstr, CPU_IDSTRLEN);
        (void) cpuid_getbrandstr(CPU, cp->cpu_brandstr, CPU_IDSTRLEN);
}

/*
 * Configure syscall support on this CPU.
 */
/*ARGSUSED*/
void
init_cpu_syscall(struct cpu *cp)
{
        kpreempt_disable();

        if (is_x86_feature(x86_featureset, X86FSET_MSR) &&
            is_x86_feature(x86_featureset, X86FSET_ASYSC)) {
                uint64_t flags;

#if !defined(__xpv)
                /*
                 * The syscall instruction imposes a certain ordering on
                 * segment selectors, so we double-check that ordering
                 * here.
                 */
                CTASSERT(KDS_SEL == KCS_SEL + 8);
                CTASSERT(UDS_SEL == U32CS_SEL + 8);
                CTASSERT(UCS_SEL == U32CS_SEL + 16);
#endif

                /*
                 * Turn syscall/sysret extensions on.
                 */
                cpu_asysc_enable();

                /*
                 * Program the magic registers ..
                 */
                wrmsr(MSR_AMD_STAR,
                    ((uint64_t)(U32CS_SEL << 16 | KCS_SEL)) << 32);
                if (kpti_enable == 1) {
                        wrmsr(MSR_AMD_LSTAR,
                            (uint64_t)(uintptr_t)tr_sys_syscall);
                        wrmsr(MSR_AMD_CSTAR,
                            (uint64_t)(uintptr_t)tr_sys_syscall32);
                } else {
                        wrmsr(MSR_AMD_LSTAR,
                            (uint64_t)(uintptr_t)sys_syscall);
                        wrmsr(MSR_AMD_CSTAR,
                            (uint64_t)(uintptr_t)sys_syscall32);
                }

                /*
                 * This list of flags is masked off the incoming
                 * %rfl when we enter the kernel.
                 */
                flags = PS_IE | PS_T;
                if (is_x86_feature(x86_featureset, X86FSET_SMAP) == B_TRUE)
                        flags |= PS_ACHK;
                wrmsr(MSR_AMD_SFMASK, flags);
        }

        /*
         * On 64-bit kernels on Nocona machines, the 32-bit syscall
         * variant isn't available to 32-bit applications, but sysenter is.
         */
        if (is_x86_feature(x86_featureset, X86FSET_MSR) &&
            is_x86_feature(x86_featureset, X86FSET_SEP)) {

#if !defined(__xpv)
                /*
                 * The sysenter instruction imposes a certain ordering on
                 * segment selectors, so we double-check that ordering
                 * here. See "sysenter" in Intel document 245471-012, "IA-32
                 * Intel Architecture Software Developer's Manual Volume 2:
                 * Instruction Set Reference"
                 */
                CTASSERT(KDS_SEL == KCS_SEL + 8);

                CTASSERT(U32CS_SEL == ((KCS_SEL + 16) | 3));
                CTASSERT(UDS_SEL == U32CS_SEL + 8);
#endif

                cpu_sep_enable();

                /*
                 * resume() sets this value to the base of the threads stack
                 * via a context handler.
                 */
                wrmsr(MSR_INTC_SEP_ESP, 0);

                if (kpti_enable == 1) {
                        wrmsr(MSR_INTC_SEP_EIP,
                            (uint64_t)(uintptr_t)tr_sys_sysenter);
                } else {
                        wrmsr(MSR_INTC_SEP_EIP,
                            (uint64_t)(uintptr_t)sys_sysenter);
                }
        }

        kpreempt_enable();
}

#if !defined(__xpv)
/*
 * Configure per-cpu ID GDT
 */
static void
init_cpu_id_gdt(struct cpu *cp)
{
        /* Write cpu_id into limit field of GDT for usermode retrieval */
#if defined(__amd64)
        set_usegd(&cp->cpu_gdt[GDT_CPUID], SDP_SHORT, NULL, cp->cpu_id,
            SDT_MEMRODA, SEL_UPL, SDP_BYTES, SDP_OP32);
#elif defined(__i386)
        set_usegd(&cp->cpu_gdt[GDT_CPUID], NULL, cp->cpu_id, SDT_MEMRODA,
            SEL_UPL, SDP_BYTES, SDP_OP32);
#endif
}
#endif /* !defined(__xpv) */

/*
 * Multiprocessor initialization.
 *
 * Allocate and initialize the cpu structure, TRAPTRACE buffer, and the
 * startup and idle threads for the specified CPU.
 * Parameter boot is true for boot time operations and is false for CPU
 * DR operations.
 */
static struct cpu *
mp_cpu_configure_common(int cpun, boolean_t boot)
{
        struct cpu *cp;
        kthread_id_t tp;
        caddr_t sp;
        proc_t *procp;
#if !defined(__xpv)
        extern int idle_cpu_prefer_mwait;
        extern void cpu_idle_mwait();
#endif
        extern void idle();
        extern void cpu_idle();

#ifdef TRAPTRACE
        trap_trace_ctl_t *ttc = &trap_trace_ctl[cpun];
#endif

        ASSERT(MUTEX_HELD(&cpu_lock));
        ASSERT(cpun < NCPU && cpu[cpun] == NULL);

        if (cpu_free_list == NULL) {
                cp = kmem_zalloc(sizeof (*cp), KM_SLEEP);
        } else {
                cp = cpu_free_list;
                cpu_free_list = cp->cpu_next_free;
        }

        cp->cpu_m.mcpu_istamp = cpun << 16;

        /* Create per CPU specific threads in the process p0. */
        procp = &p0;

        /*
         * Initialize the dispatcher first.
         */
        disp_cpu_init(cp);

        cpu_vm_data_init(cp);

        /*
         * Allocate and initialize the startup thread for this CPU.
         * Interrupt and process switch stacks get allocated later
         * when the CPU starts running.
         */
        tp = thread_create(NULL, 0, NULL, NULL, 0, procp,
            TS_STOPPED, maxclsyspri);

        /*
         * Set state to TS_ONPROC since this thread will start running
         * as soon as the CPU comes online.
         *
         * All the other fields of the thread structure are setup by
         * thread_create().
         */
        THREAD_ONPROC(tp, cp);
        tp->t_preempt = 1;
        tp->t_bound_cpu = cp;
        tp->t_affinitycnt = 1;
        tp->t_cpu = cp;
        tp->t_disp_queue = cp->cpu_disp;

        /*
         * Setup thread to start in mp_startup_common.
         */
        sp = tp->t_stk;
        tp->t_sp = (uintptr_t)(sp - MINFRAME);
#if defined(__amd64)
        tp->t_sp -= STACK_ENTRY_ALIGN;          /* fake a call */
#endif
        /*
         * Setup thread start entry point for boot or hotplug.
         */
        if (boot) {
                tp->t_pc = (uintptr_t)mp_startup_boot;
        } else {
                tp->t_pc = (uintptr_t)mp_startup_hotplug;
        }

        cp->cpu_id = cpun;
        cp->cpu_self = cp;
        cp->cpu_thread = tp;
        cp->cpu_lwp = NULL;
        cp->cpu_dispthread = tp;
        cp->cpu_dispatch_pri = DISP_PRIO(tp);

        /*
         * cpu_base_spl must be set explicitly here to prevent any blocking
         * operations in mp_startup_common from causing the spl of the cpu
         * to drop to 0 (allowing device interrupts before we're ready) in
         * resume().
         * cpu_base_spl MUST remain at LOCK_LEVEL until the cpu is CPU_READY.
         * As an extra bit of security on DEBUG kernels, this is enforced with
         * an assertion in mp_startup_common() -- before cpu_base_spl is set
         * to its proper value.
         */
        cp->cpu_base_spl = ipltospl(LOCK_LEVEL);

        /*
         * Now, initialize per-CPU idle thread for this CPU.
         */
        tp = thread_create(NULL, PAGESIZE, idle, NULL, 0, procp, TS_ONPROC, -1);

        cp->cpu_idle_thread = tp;

        tp->t_preempt = 1;
        tp->t_bound_cpu = cp;
        tp->t_affinitycnt = 1;
        tp->t_cpu = cp;
        tp->t_disp_queue = cp->cpu_disp;

        /*
         * Bootstrap the CPU's PG data
         */
        pg_cpu_bootstrap(cp);

        /*
         * Perform CPC initialization on the new CPU.
         */
        kcpc_hw_init(cp);

        /*
         * Allocate virtual addresses for cpu_caddr1 and cpu_caddr2
         * for each CPU.
         */
        setup_vaddr_for_ppcopy(cp);

        /*
         * Allocate page for new GDT and initialize from current GDT.
         */
#if !defined(__lint)
        ASSERT((sizeof (*cp->cpu_gdt) * NGDT) <= PAGESIZE);
#endif
        cp->cpu_gdt = kmem_zalloc(PAGESIZE, KM_SLEEP);
        bcopy(CPU->cpu_gdt, cp->cpu_gdt, (sizeof (*cp->cpu_gdt) * NGDT));

#if defined(__i386)
        /*
         * setup kernel %gs.
         */
        set_usegd(&cp->cpu_gdt[GDT_GS], cp, sizeof (struct cpu) -1, SDT_MEMRWA,
            SEL_KPL, 0, 1);
#endif

        /*
         * Allocate pages for the CPU LDT.
         */
        cp->cpu_m.mcpu_ldt = kmem_zalloc(LDT_CPU_SIZE, KM_SLEEP);
        cp->cpu_m.mcpu_ldt_len = 0;

        /*
         * Allocate a per-CPU IDT and initialize the new IDT to the currently
         * runing CPU.
         */
#if !defined(__lint)
        ASSERT((sizeof (*CPU->cpu_idt) * NIDT) <= PAGESIZE);
#endif
        cp->cpu_idt = kmem_alloc(PAGESIZE, KM_SLEEP);
        bcopy(CPU->cpu_idt, cp->cpu_idt, PAGESIZE);

        /*
         * alloc space for cpuid info
         */
        cpuid_alloc_space(cp);
#if !defined(__xpv)
        if (is_x86_feature(x86_featureset, X86FSET_MWAIT) &&
            idle_cpu_prefer_mwait) {
                cp->cpu_m.mcpu_mwait = cpuid_mwait_alloc(cp);
                cp->cpu_m.mcpu_idle_cpu = cpu_idle_mwait;
        } else
#endif
                cp->cpu_m.mcpu_idle_cpu = cpu_idle;

        init_cpu_info(cp);

#if !defined(__xpv)
        init_cpu_id_gdt(cp);
#endif

        /*
         * alloc space for ucode_info
         */
        ucode_alloc_space(cp);
        xc_init_cpu(cp);
        hat_cpu_online(cp);

#ifdef TRAPTRACE
        /*
         * If this is a TRAPTRACE kernel, allocate TRAPTRACE buffers
         */
        ttc->ttc_first = (uintptr_t)kmem_zalloc(trap_trace_bufsize, KM_SLEEP);
        ttc->ttc_next = ttc->ttc_first;
        ttc->ttc_limit = ttc->ttc_first + trap_trace_bufsize;
#endif

        /*
         * Record that we have another CPU.
         */
        /*
         * Initialize the interrupt threads for this CPU
         */
        cpu_intr_alloc(cp, NINTR_THREADS);

        cp->cpu_flags = CPU_OFFLINE | CPU_QUIESCED | CPU_POWEROFF;
        cpu_set_state(cp);

        /*
         * Add CPU to list of available CPUs.  It'll be on the active list
         * after mp_startup_common().
         */
        cpu_add_unit(cp);

        return (cp);
}

/*
 * Undo what was done in mp_cpu_configure_common
 */
static void
mp_cpu_unconfigure_common(struct cpu *cp, int error)
{
        ASSERT(MUTEX_HELD(&cpu_lock));

        /*
         * Remove the CPU from the list of available CPUs.
         */
        cpu_del_unit(cp->cpu_id);

        if (error == ETIMEDOUT) {
                /*
                 * The cpu was started, but never *seemed* to run any
                 * code in the kernel; it's probably off spinning in its
                 * own private world, though with potential references to
                 * our kmem-allocated IDTs and GDTs (for example).
                 *
                 * Worse still, it may actually wake up some time later,
                 * so rather than guess what it might or might not do, we
                 * leave the fundamental data structures intact.
                 */
                cp->cpu_flags = 0;
                return;
        }

        /*
         * At this point, the only threads bound to this CPU should
         * special per-cpu threads: it's idle thread, it's pause threads,
         * and it's interrupt threads.  Clean these up.
         */
        cpu_destroy_bound_threads(cp);
        cp->cpu_idle_thread = NULL;

        /*
         * Free the interrupt stack.
         */
        segkp_release(segkp,
            cp->cpu_intr_stack - (INTR_STACK_SIZE - SA(MINFRAME)));
        cp->cpu_intr_stack = NULL;

#ifdef TRAPTRACE
        /*
         * Discard the trap trace buffer
         */
        {
                trap_trace_ctl_t *ttc = &trap_trace_ctl[cp->cpu_id];

                kmem_free((void *)ttc->ttc_first, trap_trace_bufsize);
                ttc->ttc_first = NULL;
        }
#endif

        hat_cpu_offline(cp);

        ucode_free_space(cp);

        /* Free CPU ID string and brand string. */
        if (cp->cpu_idstr) {
                kmem_free(cp->cpu_idstr, CPU_IDSTRLEN);
                cp->cpu_idstr = NULL;
        }
        if (cp->cpu_brandstr) {
                kmem_free(cp->cpu_brandstr, CPU_IDSTRLEN);
                cp->cpu_brandstr = NULL;
        }

#if !defined(__xpv)
        if (cp->cpu_m.mcpu_mwait != NULL) {
                cpuid_mwait_free(cp);
                cp->cpu_m.mcpu_mwait = NULL;
        }
#endif
        cpuid_free_space(cp);

        if (cp->cpu_idt != CPU->cpu_idt)
                kmem_free(cp->cpu_idt, PAGESIZE);
        cp->cpu_idt = NULL;

        kmem_free(cp->cpu_m.mcpu_ldt, LDT_CPU_SIZE);
        cp->cpu_m.mcpu_ldt = NULL;
        cp->cpu_m.mcpu_ldt_len = 0;

        kmem_free(cp->cpu_gdt, PAGESIZE);
        cp->cpu_gdt = NULL;

        if (cp->cpu_supp_freqs != NULL) {
                size_t len = strlen(cp->cpu_supp_freqs) + 1;
                kmem_free(cp->cpu_supp_freqs, len);
                cp->cpu_supp_freqs = NULL;
        }

        teardown_vaddr_for_ppcopy(cp);

        kcpc_hw_fini(cp);

        cp->cpu_dispthread = NULL;
        cp->cpu_thread = NULL;  /* discarded by cpu_destroy_bound_threads() */

        cpu_vm_data_destroy(cp);

        xc_fini_cpu(cp);
        disp_cpu_fini(cp);

        ASSERT(cp != CPU0);
        bzero(cp, sizeof (*cp));
        cp->cpu_next_free = cpu_free_list;
        cpu_free_list = cp;
}

/*
 * Apply workarounds for known errata, and warn about those that are absent.
 *
 * System vendors occasionally create configurations which contain different
 * revisions of the CPUs that are almost but not exactly the same.  At the
 * time of writing, this meant that their clock rates were the same, their
 * feature sets were the same, but the required workaround were -not-
 * necessarily the same.  So, this routine is invoked on -every- CPU soon
 * after starting to make sure that the resulting system contains the most
 * pessimal set of workarounds needed to cope with *any* of the CPUs in the
 * system.
 *
 * workaround_errata is invoked early in mlsetup() for CPU 0, and in
 * mp_startup_common() for all slave CPUs. Slaves process workaround_errata
 * prior to acknowledging their readiness to the master, so this routine will
 * never be executed by multiple CPUs in parallel, thus making updates to
 * global data safe.
 *
 * These workarounds are based on Rev 3.57 of the Revision Guide for
 * AMD Athlon(tm) 64 and AMD Opteron(tm) Processors, August 2005.
 */

#if defined(OPTERON_ERRATUM_88)
int opteron_erratum_88;         /* if non-zero -> at least one cpu has it */
#endif

#if defined(OPTERON_ERRATUM_91)
int opteron_erratum_91;         /* if non-zero -> at least one cpu has it */
#endif

#if defined(OPTERON_ERRATUM_93)
int opteron_erratum_93;         /* if non-zero -> at least one cpu has it */
#endif

#if defined(OPTERON_ERRATUM_95)
int opteron_erratum_95;         /* if non-zero -> at least one cpu has it */
#endif

#if defined(OPTERON_ERRATUM_100)
int opteron_erratum_100;        /* if non-zero -> at least one cpu has it */
#endif

#if defined(OPTERON_ERRATUM_108)
int opteron_erratum_108;        /* if non-zero -> at least one cpu has it */
#endif

#if defined(OPTERON_ERRATUM_109)
int opteron_erratum_109;        /* if non-zero -> at least one cpu has it */
#endif

#if defined(OPTERON_ERRATUM_121)
int opteron_erratum_121;        /* if non-zero -> at least one cpu has it */
#endif

#if defined(OPTERON_ERRATUM_122)
int opteron_erratum_122;        /* if non-zero -> at least one cpu has it */
#endif

#if defined(OPTERON_ERRATUM_123)
int opteron_erratum_123;        /* if non-zero -> at least one cpu has it */
#endif

#if defined(OPTERON_ERRATUM_131)
int opteron_erratum_131;        /* if non-zero -> at least one cpu has it */
#endif

#if defined(OPTERON_WORKAROUND_6336786)
int opteron_workaround_6336786; /* non-zero -> WA relevant and applied */
int opteron_workaround_6336786_UP = 0;  /* Not needed for UP */
#endif

#if defined(OPTERON_WORKAROUND_6323525)
int opteron_workaround_6323525; /* if non-zero -> at least one cpu has it */
#endif

#if defined(OPTERON_ERRATUM_298)
int opteron_erratum_298;
#endif

#if defined(OPTERON_ERRATUM_721)
int opteron_erratum_721;
#endif

static void
workaround_warning(cpu_t *cp, uint_t erratum)
{
        cmn_err(CE_WARN, "cpu%d: no workaround for erratum %u",
            cp->cpu_id, erratum);
}

static void
workaround_applied(uint_t erratum)
{
        if (erratum > 1000000)
                cmn_err(CE_CONT, "?workaround applied for cpu issue #%d\n",
                    erratum);
        else
                cmn_err(CE_CONT, "?workaround applied for cpu erratum #%d\n",
                    erratum);
}

static void
msr_warning(cpu_t *cp, const char *rw, uint_t msr, int error)
{
        cmn_err(CE_WARN, "cpu%d: couldn't %smsr 0x%x, error %d",
            cp->cpu_id, rw, msr, error);
}

/*
 * Determine the number of nodes in a Hammer / Greyhound / Griffin family
 * system.
 */
static uint_t
opteron_get_nnodes(void)
{
        static uint_t nnodes = 0;

        if (nnodes == 0) {
#ifdef  DEBUG
                uint_t family;

                /*
                 * This routine uses a PCI config space based mechanism
                 * for retrieving the number of nodes in the system.
                 * Device 24, function 0, offset 0x60 as used here is not
                 * AMD processor architectural, and may not work on processor
                 * families other than those listed below.
                 *
                 * Callers of this routine must ensure that we're running on
                 * a processor which supports this mechanism.
                 * The assertion below is meant to catch calls on unsupported
                 * processors.
                 */
                family = cpuid_getfamily(CPU);
                ASSERT(family == 0xf || family == 0x10 || family == 0x11);
#endif  /* DEBUG */

                /*
                 * Obtain the number of nodes in the system from
                 * bits [6:4] of the Node ID register on node 0.
                 *
                 * The actual node count is NodeID[6:4] + 1
                 *
                 * The Node ID register is accessed via function 0,
                 * offset 0x60. Node 0 is device 24.
                 */
                nnodes = ((pci_getl_func(0, 24, 0, 0x60) & 0x70) >> 4) + 1;
        }
        return (nnodes);
}

uint_t
do_erratum_298(struct cpu *cpu)
{
        static int      osvwrc = -3;
        extern int      osvw_opteron_erratum(cpu_t *, uint_t);

        /*
         * L2 Eviction May Occur During Processor Operation To Set
         * Accessed or Dirty Bit.
         */
        if (osvwrc == -3) {
                osvwrc = osvw_opteron_erratum(cpu, 298);
        } else {
                /* osvw return codes should be consistent for all cpus */
                ASSERT(osvwrc == osvw_opteron_erratum(cpu, 298));
        }

        switch (osvwrc) {
        case 0:         /* erratum is not present: do nothing */
                break;
        case 1:         /* erratum is present: BIOS workaround applied */
                /*
                 * check if workaround is actually in place and issue warning
                 * if not.
                 */
                if (((rdmsr(MSR_AMD_HWCR) & AMD_HWCR_TLBCACHEDIS) == 0) ||
                    ((rdmsr(MSR_AMD_BU_CFG) & AMD_BU_CFG_E298) == 0)) {
#if defined(OPTERON_ERRATUM_298)
                        opteron_erratum_298++;
#else
                        workaround_warning(cpu, 298);
                        return (1);
#endif
                }
                break;
        case -1:        /* cannot determine via osvw: check cpuid */
                if ((cpuid_opteron_erratum(cpu, 298) > 0) &&
                    (((rdmsr(MSR_AMD_HWCR) & AMD_HWCR_TLBCACHEDIS) == 0) ||
                    ((rdmsr(MSR_AMD_BU_CFG) & AMD_BU_CFG_E298) == 0))) {
#if defined(OPTERON_ERRATUM_298)
                        opteron_erratum_298++;
#else
                        workaround_warning(cpu, 298);
                        return (1);
#endif
                }
                break;
        }
        return (0);
}

uint_t
workaround_errata(struct cpu *cpu)
{
        uint_t missing = 0;

        ASSERT(cpu == CPU);

        /*LINTED*/
        if (cpuid_opteron_erratum(cpu, 88) > 0) {
                /*
                 * SWAPGS May Fail To Read Correct GS Base
                 */
#if defined(OPTERON_ERRATUM_88)
                /*
                 * The workaround is an mfence in the relevant assembler code
                 */
                opteron_erratum_88++;
#else
                workaround_warning(cpu, 88);
                missing++;
#endif
        }

        if (cpuid_opteron_erratum(cpu, 91) > 0) {
                /*
                 * Software Prefetches May Report A Page Fault
                 */
#if defined(OPTERON_ERRATUM_91)
                /*
                 * fix is in trap.c
                 */
                opteron_erratum_91++;
#else
                workaround_warning(cpu, 91);
                missing++;
#endif
        }

        if (cpuid_opteron_erratum(cpu, 93) > 0) {
                /*
                 * RSM Auto-Halt Restart Returns to Incorrect RIP
                 */
#if defined(OPTERON_ERRATUM_93)
                /*
                 * fix is in trap.c
                 */
                opteron_erratum_93++;
#else
                workaround_warning(cpu, 93);
                missing++;
#endif
        }

        /*LINTED*/
        if (cpuid_opteron_erratum(cpu, 95) > 0) {
                /*
                 * RET Instruction May Return to Incorrect EIP
                 */
#if defined(OPTERON_ERRATUM_95)
#if defined(_LP64)
                /*
                 * Workaround this by ensuring that 32-bit user code and
                 * 64-bit kernel code never occupy the same address
                 * range mod 4G.
                 */
                if (_userlimit32 > 0xc0000000ul)
                        *(uintptr_t *)&_userlimit32 = 0xc0000000ul;

                /*LINTED*/
                ASSERT((uint32_t)COREHEAP_BASE == 0xc0000000u);
                opteron_erratum_95++;
#endif  /* _LP64 */
#else
                workaround_warning(cpu, 95);
                missing++;
#endif
        }

        if (cpuid_opteron_erratum(cpu, 100) > 0) {
                /*
                 * Compatibility Mode Branches Transfer to Illegal Address
                 */
#if defined(OPTERON_ERRATUM_100)
                /*
                 * fix is in trap.c
                 */
                opteron_erratum_100++;
#else
                workaround_warning(cpu, 100);
                missing++;
#endif
        }

        /*LINTED*/
        if (cpuid_opteron_erratum(cpu, 108) > 0) {
                /*
                 * CPUID Instruction May Return Incorrect Model Number In
                 * Some Processors
                 */
#if defined(OPTERON_ERRATUM_108)
                /*
                 * (Our cpuid-handling code corrects the model number on
                 * those processors)
                 */
#else
                workaround_warning(cpu, 108);
                missing++;
#endif
        }

        /*LINTED*/
        if (cpuid_opteron_erratum(cpu, 109) > 0) do {
                /*
                 * Certain Reverse REP MOVS May Produce Unpredictable Behavior
                 */
#if defined(OPTERON_ERRATUM_109)
                /*
                 * The "workaround" is to print a warning to upgrade the BIOS
                 */
                uint64_t value;
                const uint_t msr = MSR_AMD_PATCHLEVEL;
                int err;

                if ((err = checked_rdmsr(msr, &value)) != 0) {
                        msr_warning(cpu, "rd", msr, err);
                        workaround_warning(cpu, 109);
                        missing++;
                }
                if (value == 0)
                        opteron_erratum_109++;
#else
                workaround_warning(cpu, 109);
                missing++;
#endif
        /*CONSTANTCONDITION*/
        } while (0);

        /*LINTED*/
        if (cpuid_opteron_erratum(cpu, 121) > 0) {
                /*
                 * Sequential Execution Across Non_Canonical Boundary Caused
                 * Processor Hang
                 */
#if defined(OPTERON_ERRATUM_121)
#if defined(_LP64)
                /*
                 * Erratum 121 is only present in long (64 bit) mode.
                 * Workaround is to include the page immediately before the
                 * va hole to eliminate the possibility of system hangs due to
                 * sequential execution across the va hole boundary.
                 */
                if (opteron_erratum_121)
                        opteron_erratum_121++;
                else {
                        if (hole_start) {
                                hole_start -= PAGESIZE;
                        } else {
                                /*
                                 * hole_start not yet initialized by
                                 * mmu_init. Initialize hole_start
                                 * with value to be subtracted.
                                 */
                                hole_start = PAGESIZE;
                        }
                        opteron_erratum_121++;
                }
#endif  /* _LP64 */
#else
                workaround_warning(cpu, 121);
                missing++;
#endif
        }

        /*LINTED*/
        if (cpuid_opteron_erratum(cpu, 122) > 0) do {
                /*
                 * TLB Flush Filter May Cause Coherency Problem in
                 * Multiprocessor Systems
                 */
#if defined(OPTERON_ERRATUM_122)
                uint64_t value;
                const uint_t msr = MSR_AMD_HWCR;
                int error;

                /*
                 * Erratum 122 is only present in MP configurations (multi-core
                 * or multi-processor).
                 */
#if defined(__xpv)
                if (!DOMAIN_IS_INITDOMAIN(xen_info))
                        break;
                if (!opteron_erratum_122 && xpv_nr_phys_cpus() == 1)
                        break;
#else
                if (!opteron_erratum_122 && opteron_get_nnodes() == 1 &&
                    cpuid_get_ncpu_per_chip(cpu) == 1)
                        break;
#endif
                /* disable TLB Flush Filter */

                if ((error = checked_rdmsr(msr, &value)) != 0) {
                        msr_warning(cpu, "rd", msr, error);
                        workaround_warning(cpu, 122);
                        missing++;
                } else {
                        value |= (uint64_t)AMD_HWCR_FFDIS;
                        if ((error = checked_wrmsr(msr, value)) != 0) {
                                msr_warning(cpu, "wr", msr, error);
                                workaround_warning(cpu, 122);
                                missing++;
                        }
                }
                opteron_erratum_122++;
#else
                workaround_warning(cpu, 122);
                missing++;
#endif
        /*CONSTANTCONDITION*/
        } while (0);

        /*LINTED*/
        if (cpuid_opteron_erratum(cpu, 123) > 0) do {
                /*
                 * Bypassed Reads May Cause Data Corruption of System Hang in
                 * Dual Core Processors
                 */
#if defined(OPTERON_ERRATUM_123)
                uint64_t value;
                const uint_t msr = MSR_AMD_PATCHLEVEL;
                int err;

                /*
                 * Erratum 123 applies only to multi-core cpus.
                 */
                if (cpuid_get_ncpu_per_chip(cpu) < 2)
                        break;
#if defined(__xpv)
                if (!DOMAIN_IS_INITDOMAIN(xen_info))
                        break;
#endif
                /*
                 * The "workaround" is to print a warning to upgrade the BIOS
                 */
                if ((err = checked_rdmsr(msr, &value)) != 0) {
                        msr_warning(cpu, "rd", msr, err);
                        workaround_warning(cpu, 123);
                        missing++;
                }
                if (value == 0)
                        opteron_erratum_123++;
#else
                workaround_warning(cpu, 123);
                missing++;

#endif
        /*CONSTANTCONDITION*/
        } while (0);

        /*LINTED*/
        if (cpuid_opteron_erratum(cpu, 131) > 0) do {
                /*
                 * Multiprocessor Systems with Four or More Cores May Deadlock
                 * Waiting for a Probe Response
                 */
#if defined(OPTERON_ERRATUM_131)
                uint64_t nbcfg;
                const uint_t msr = MSR_AMD_NB_CFG;
                const uint64_t wabits =
                    AMD_NB_CFG_SRQ_HEARTBEAT | AMD_NB_CFG_SRQ_SPR;
                int error;

                /*
                 * Erratum 131 applies to any system with four or more cores.
                 */
                if (opteron_erratum_131)
                        break;
#if defined(__xpv)
                if (!DOMAIN_IS_INITDOMAIN(xen_info))
                        break;
                if (xpv_nr_phys_cpus() < 4)
                        break;
#else
                if (opteron_get_nnodes() * cpuid_get_ncpu_per_chip(cpu) < 4)
                        break;
#endif
                /*
                 * Print a warning if neither of the workarounds for
                 * erratum 131 is present.
                 */
                if ((error = checked_rdmsr(msr, &nbcfg)) != 0) {
                        msr_warning(cpu, "rd", msr, error);
                        workaround_warning(cpu, 131);
                        missing++;
                } else if ((nbcfg & wabits) == 0) {
                        opteron_erratum_131++;
                } else {
                        /* cannot have both workarounds set */
                        ASSERT((nbcfg & wabits) != wabits);
                }
#else
                workaround_warning(cpu, 131);
                missing++;
#endif
        /*CONSTANTCONDITION*/
        } while (0);

        /*
         * This isn't really an erratum, but for convenience the
         * detection/workaround code lives here and in cpuid_opteron_erratum.
         */
        if (cpuid_opteron_erratum(cpu, 6336786) > 0) {
#if defined(OPTERON_WORKAROUND_6336786)
                /*
                 * Disable C1-Clock ramping on multi-core/multi-processor
                 * K8 platforms to guard against TSC drift.
                 */
                if (opteron_workaround_6336786) {
                        opteron_workaround_6336786++;
#if defined(__xpv)
                } else if ((DOMAIN_IS_INITDOMAIN(xen_info) &&
                    xpv_nr_phys_cpus() > 1) ||
                    opteron_workaround_6336786_UP) {
                        /*
                         * XXPV Hmm.  We can't walk the Northbridges on
                         *      the hypervisor; so just complain and drive
                         *      on.  This probably needs to be fixed in
                         *      the hypervisor itself.
                         */
                        opteron_workaround_6336786++;
                        workaround_warning(cpu, 6336786);
#else   /* __xpv */
                } else if ((opteron_get_nnodes() *
                    cpuid_get_ncpu_per_chip(cpu) > 1) ||
                    opteron_workaround_6336786_UP) {

                        uint_t  node, nnodes;
                        uint8_t data;

                        nnodes = opteron_get_nnodes();
                        for (node = 0; node < nnodes; node++) {
                                /*
                                 * Clear PMM7[1:0] (function 3, offset 0x87)
                                 * Northbridge device is the node id + 24.
                                 */
                                data = pci_getb_func(0, node + 24, 3, 0x87);
                                data &= 0xFC;
                                pci_putb_func(0, node + 24, 3, 0x87, data);
                        }
                        opteron_workaround_6336786++;
#endif  /* __xpv */
                }
#else
                workaround_warning(cpu, 6336786);
                missing++;
#endif
        }

        /*LINTED*/
        /*
         * Mutex primitives don't work as expected.
         */
        if (cpuid_opteron_erratum(cpu, 6323525) > 0) {
#if defined(OPTERON_WORKAROUND_6323525)
                /*
                 * This problem only occurs with 2 or more cores. If bit in
                 * MSR_AMD_BU_CFG set, then not applicable. The workaround
                 * is to patch the semaphone routines with the lfence
                 * instruction to provide necessary load memory barrier with
                 * possible subsequent read-modify-write ops.
                 *
                 * It is too early in boot to call the patch routine so
                 * set erratum variable to be done in startup_end().
                 */
                if (opteron_workaround_6323525) {
                        opteron_workaround_6323525++;
#if defined(__xpv)
                } else if (is_x86_feature(x86_featureset, X86FSET_SSE2)) {
                        if (DOMAIN_IS_INITDOMAIN(xen_info)) {
                                /*
                                 * XXPV Use dom0_msr here when extended
                                 *      operations are supported?
                                 */
                                if (xpv_nr_phys_cpus() > 1)
                                        opteron_workaround_6323525++;
                        } else {
                                /*
                                 * We have no way to tell how many physical
                                 * cpus there are, or even if this processor
                                 * has the problem, so enable the workaround
                                 * unconditionally (at some performance cost).
                                 */
                                opteron_workaround_6323525++;
                        }
#else   /* __xpv */
                } else if (is_x86_feature(x86_featureset, X86FSET_SSE2) &&
                    ((opteron_get_nnodes() *
                    cpuid_get_ncpu_per_chip(cpu)) > 1)) {
                        if ((xrdmsr(MSR_AMD_BU_CFG) & (UINT64_C(1) << 33)) == 0)
                                opteron_workaround_6323525++;
#endif  /* __xpv */
                }
#else
                workaround_warning(cpu, 6323525);
                missing++;
#endif
        }

        missing += do_erratum_298(cpu);

        if (cpuid_opteron_erratum(cpu, 721) > 0) {
#if defined(OPTERON_ERRATUM_721)
                on_trap_data_t otd;

                if (!on_trap(&otd, OT_DATA_ACCESS))
                        wrmsr(MSR_AMD_DE_CFG,
                            rdmsr(MSR_AMD_DE_CFG) | AMD_DE_CFG_E721);
                no_trap();

                opteron_erratum_721++;
#else
                workaround_warning(cpu, 721);
                missing++;
#endif
        }

#ifdef __xpv
        return (0);
#else
        return (missing);
#endif
}

void
workaround_errata_end()
{
#if defined(OPTERON_ERRATUM_88)
        if (opteron_erratum_88)
                workaround_applied(88);
#endif
#if defined(OPTERON_ERRATUM_91)
        if (opteron_erratum_91)
                workaround_applied(91);
#endif
#if defined(OPTERON_ERRATUM_93)
        if (opteron_erratum_93)
                workaround_applied(93);
#endif
#if defined(OPTERON_ERRATUM_95)
        if (opteron_erratum_95)
                workaround_applied(95);
#endif
#if defined(OPTERON_ERRATUM_100)
        if (opteron_erratum_100)
                workaround_applied(100);
#endif
#if defined(OPTERON_ERRATUM_108)
        if (opteron_erratum_108)
                workaround_applied(108);
#endif
#if defined(OPTERON_ERRATUM_109)
        if (opteron_erratum_109) {
                cmn_err(CE_WARN,
                    "BIOS microcode patch for AMD Athlon(tm) 64/Opteron(tm)"
                    " processor\nerratum 109 was not detected; updating your"
                    " system's BIOS to a version\ncontaining this"
                    " microcode patch is HIGHLY recommended or erroneous"
                    " system\noperation may occur.\n");
        }
#endif
#if defined(OPTERON_ERRATUM_121)
        if (opteron_erratum_121)
                workaround_applied(121);
#endif
#if defined(OPTERON_ERRATUM_122)
        if (opteron_erratum_122)
                workaround_applied(122);
#endif
#if defined(OPTERON_ERRATUM_123)
        if (opteron_erratum_123) {
                cmn_err(CE_WARN,
                    "BIOS microcode patch for AMD Athlon(tm) 64/Opteron(tm)"
                    " processor\nerratum 123 was not detected; updating your"
                    " system's BIOS to a version\ncontaining this"
                    " microcode patch is HIGHLY recommended or erroneous"
                    " system\noperation may occur.\n");
        }
#endif
#if defined(OPTERON_ERRATUM_131)
        if (opteron_erratum_131) {
                cmn_err(CE_WARN,
                    "BIOS microcode patch for AMD Athlon(tm) 64/Opteron(tm)"
                    " processor\nerratum 131 was not detected; updating your"
                    " system's BIOS to a version\ncontaining this"
                    " microcode patch is HIGHLY recommended or erroneous"
                    " system\noperation may occur.\n");
        }
#endif
#if defined(OPTERON_WORKAROUND_6336786)
        if (opteron_workaround_6336786)
                workaround_applied(6336786);
#endif
#if defined(OPTERON_WORKAROUND_6323525)
        if (opteron_workaround_6323525)
                workaround_applied(6323525);
#endif
#if defined(OPTERON_ERRATUM_298)
        if (opteron_erratum_298) {
                cmn_err(CE_WARN,
                    "BIOS microcode patch for AMD 64/Opteron(tm)"
                    " processor\nerratum 298 was not detected; updating your"
                    " system's BIOS to a version\ncontaining this"
                    " microcode patch is HIGHLY recommended or erroneous"
                    " system\noperation may occur.\n");
        }
#endif
#if defined(OPTERON_ERRATUM_721)
        if (opteron_erratum_721)
                workaround_applied(721);
#endif
}

/*
 * The procset_slave and procset_master are used to synchronize
 * between the control CPU and the target CPU when starting CPUs.
 */
static cpuset_t procset_slave, procset_master;

static void
mp_startup_wait(cpuset_t *sp, processorid_t cpuid)
{
        cpuset_t tempset;

        for (tempset = *sp; !CPU_IN_SET(tempset, cpuid);
            tempset = *(volatile cpuset_t *)sp) {
                SMT_PAUSE();
        }
        CPUSET_ATOMIC_DEL(*(cpuset_t *)sp, cpuid);
}

static void
mp_startup_signal(cpuset_t *sp, processorid_t cpuid)
{
        cpuset_t tempset;

        CPUSET_ATOMIC_ADD(*(cpuset_t *)sp, cpuid);
        for (tempset = *sp; CPU_IN_SET(tempset, cpuid);
            tempset = *(volatile cpuset_t *)sp) {
                SMT_PAUSE();
        }
}

int
mp_start_cpu_common(cpu_t *cp, boolean_t boot)
{
        _NOTE(ARGUNUSED(boot));

        void *ctx;
        int delays;
        int error = 0;
        cpuset_t tempset;
        processorid_t cpuid;
#ifndef __xpv
        extern void cpupm_init(cpu_t *);
#endif

        ASSERT(cp != NULL);
        cpuid = cp->cpu_id;
        ctx = mach_cpucontext_alloc(cp);
        if (ctx == NULL) {
                cmn_err(CE_WARN,
                    "cpu%d: failed to allocate context", cp->cpu_id);
                return (EAGAIN);
        }
        error = mach_cpu_start(cp, ctx);
        if (error != 0) {
                cmn_err(CE_WARN,
                    "cpu%d: failed to start, error %d", cp->cpu_id, error);
                mach_cpucontext_free(cp, ctx, error);
                return (error);
        }

        for (delays = 0, tempset = procset_slave; !CPU_IN_SET(tempset, cpuid);
            delays++) {
                if (delays == 500) {
                        /*
                         * After five seconds, things are probably looking
                         * a bit bleak - explain the hang.
                         */
                        cmn_err(CE_NOTE, "cpu%d: started, "
                            "but not running in the kernel yet", cpuid);
                } else if (delays > 2000) {
                        /*
                         * We waited at least 20 seconds, bail ..
                         */
                        error = ETIMEDOUT;
                        cmn_err(CE_WARN, "cpu%d: timed out", cpuid);
                        mach_cpucontext_free(cp, ctx, error);
                        return (error);
                }

                /*
                 * wait at least 10ms, then check again..
                 */
                delay(USEC_TO_TICK_ROUNDUP(10000));
                tempset = *((volatile cpuset_t *)&procset_slave);
        }
        CPUSET_ATOMIC_DEL(procset_slave, cpuid);

        mach_cpucontext_free(cp, ctx, 0);

#ifndef __xpv
        if (tsc_gethrtime_enable)
                tsc_sync_master(cpuid);
#endif

        if (dtrace_cpu_init != NULL) {
                (*dtrace_cpu_init)(cpuid);
        }

        /*
         * During CPU DR operations, the cpu_lock is held by current
         * (the control) thread. We can't release the cpu_lock here
         * because that will break the CPU DR logic.
         * On the other hand, CPUPM and processor group initialization
         * routines need to access the cpu_lock. So we invoke those
         * routines here on behalf of mp_startup_common().
         *
         * CPUPM and processor group initialization routines depend
         * on the cpuid probing results. Wait for mp_startup_common()
         * to signal that cpuid probing is done.
         */
        mp_startup_wait(&procset_slave, cpuid);
#ifndef __xpv
        cpupm_init(cp);
#endif
        (void) pg_cpu_init(cp, B_FALSE);
        cpu_set_state(cp);
        mp_startup_signal(&procset_master, cpuid);

        return (0);
}

/*
 * Start a single cpu, assuming that the kernel context is available
 * to successfully start another cpu.
 *
 * (For example, real mode code is mapped into the right place
 * in memory and is ready to be run.)
 */
int
start_cpu(processorid_t who)
{
        cpu_t *cp;
        int error = 0;
        cpuset_t tempset;

        ASSERT(who != 0);

        /*
         * Check if there's at least a Mbyte of kmem available
         * before attempting to start the cpu.
         */
        if (kmem_avail() < 1024 * 1024) {
                /*
                 * Kick off a reap in case that helps us with
                 * later attempts ..
                 */
                kmem_reap();
                return (ENOMEM);
        }

        /*
         * First configure cpu.
         */
        cp = mp_cpu_configure_common(who, B_TRUE);
        ASSERT(cp != NULL);

        /*
         * Then start cpu.
         */
        error = mp_start_cpu_common(cp, B_TRUE);
        if (error != 0) {
                mp_cpu_unconfigure_common(cp, error);
                return (error);
        }

        mutex_exit(&cpu_lock);
        tempset = cpu_ready_set;
        while (!CPU_IN_SET(tempset, who)) {
                drv_usecwait(1);
                tempset = *((volatile cpuset_t *)&cpu_ready_set);
        }
        mutex_enter(&cpu_lock);

        return (0);
}

void
start_other_cpus(int cprboot)
{
        _NOTE(ARGUNUSED(cprboot));

        uint_t who;
        uint_t bootcpuid = 0;

        /*
         * Initialize our own cpu_info.
         */
        init_cpu_info(CPU);

#if !defined(__xpv)
        init_cpu_id_gdt(CPU);
#endif

        cmn_err(CE_CONT, "?cpu%d: %s\n", CPU->cpu_id, CPU->cpu_idstr);
        cmn_err(CE_CONT, "?cpu%d: %s\n", CPU->cpu_id, CPU->cpu_brandstr);

        /*
         * KPTI initialisation happens very early in boot, before logging is
         * set up. Output a status message now as the boot CPU comes online.
         */
        cmn_err(CE_CONT, "?KPTI %s (PCID %s, INVPCID %s)\n",
            kpti_enable ? "enabled" : "disabled",
            x86_use_pcid == 1 ? "in use" :
            (is_x86_feature(x86_featureset, X86FSET_PCID) ? "disabled" :
            "not supported"),
            x86_use_pcid == 1 && x86_use_invpcid == 1 ? "in use" :
            (is_x86_feature(x86_featureset, X86FSET_INVPCID) ? "disabled" :
            "not supported"));

        /*
         * Initialize our syscall handlers
         */
        init_cpu_syscall(CPU);

        /*
         * Take the boot cpu out of the mp_cpus set because we know
         * it's already running.  Add it to the cpu_ready_set for
         * precisely the same reason.
         */
        CPUSET_DEL(mp_cpus, bootcpuid);
        CPUSET_ADD(cpu_ready_set, bootcpuid);

        /*
         * skip the rest of this if
         * . only 1 cpu dectected and system isn't hotplug-capable
         * . not using MP
         */
        if ((CPUSET_ISNULL(mp_cpus) && plat_dr_support_cpu() == 0) ||
            use_mp == 0) {
                if (use_mp == 0)
                        cmn_err(CE_CONT, "?***** Not in MP mode\n");
                goto done;
        }

        /*
         * perform such initialization as is needed
         * to be able to take CPUs on- and off-line.
         */
        cpu_pause_init();

        xc_init_cpu(CPU);               /* initialize processor crosscalls */

        if (mach_cpucontext_init() != 0)
                goto done;

        flushes_require_xcalls = 1;

        /*
         * We lock our affinity to the master CPU to ensure that all slave CPUs
         * do their TSC syncs with the same CPU.
         */
        affinity_set(CPU_CURRENT);

        for (who = 0; who < NCPU; who++) {
                if (!CPU_IN_SET(mp_cpus, who))
                        continue;
                ASSERT(who != bootcpuid);

                mutex_enter(&cpu_lock);
                if (start_cpu(who) != 0)
                        CPUSET_DEL(mp_cpus, who);
                cpu_state_change_notify(who, CPU_SETUP);
                mutex_exit(&cpu_lock);
        }

        /* Free the space allocated to hold the microcode file */
        ucode_cleanup();

        affinity_clear();

        mach_cpucontext_fini();

done:
        if (get_hwenv() == HW_NATIVE)
                workaround_errata_end();
        cmi_post_mpstartup();

        if (use_mp && ncpus != boot_max_ncpus) {
                cmn_err(CE_NOTE,
                    "System detected %d cpus, but "
                    "only %d cpu(s) were enabled during boot.",
                    boot_max_ncpus, ncpus);
                cmn_err(CE_NOTE,
                    "Use \"boot-ncpus\" parameter to enable more CPU(s). "
                    "See eeprom(1M).");
        }
}

int
mp_cpu_configure(int cpuid)
{
        cpu_t *cp;

        if (use_mp == 0 || plat_dr_support_cpu() == 0) {
                return (ENOTSUP);
        }

        cp = cpu_get(cpuid);
        if (cp != NULL) {
                return (EALREADY);
        }

        /*
         * Check if there's at least a Mbyte of kmem available
         * before attempting to start the cpu.
         */
        if (kmem_avail() < 1024 * 1024) {
                /*
                 * Kick off a reap in case that helps us with
                 * later attempts ..
                 */
                kmem_reap();
                return (ENOMEM);
        }

        cp = mp_cpu_configure_common(cpuid, B_FALSE);
        ASSERT(cp != NULL && cpu_get(cpuid) == cp);

        return (cp != NULL ? 0 : EAGAIN);
}

int
mp_cpu_unconfigure(int cpuid)
{
        cpu_t *cp;

        if (use_mp == 0 || plat_dr_support_cpu() == 0) {
                return (ENOTSUP);
        } else if (cpuid < 0 || cpuid >= max_ncpus) {
                return (EINVAL);
        }

        cp = cpu_get(cpuid);
        if (cp == NULL) {
                return (ENODEV);
        }
        mp_cpu_unconfigure_common(cp, 0);

        return (0);
}

/*
 * Startup function for 'other' CPUs (besides boot cpu).
 * Called from real_mode_start.
 *
 * WARNING: until CPU_READY is set, mp_startup_common and routines called by
 * mp_startup_common should not call routines (e.g. kmem_free) that could call
 * hat_unload which requires CPU_READY to be set.
 */
static void
mp_startup_common(boolean_t boot)
{
        cpu_t *cp = CPU;
        uchar_t new_x86_featureset[BT_SIZEOFMAP(NUM_X86_FEATURES)];
        extern void cpu_event_init_cpu(cpu_t *);

        /*
         * We need to get TSC on this proc synced (i.e., any delta
         * from cpu0 accounted for) as soon as we can, because many
         * many things use gethrtime/pc_gethrestime, including
         * interrupts, cmn_err, etc.  Before we can do that, we want to
         * clear TSC if we're on a buggy Sandy/Ivy Bridge CPU, so do that
         * right away.
         */
        bzero(new_x86_featureset, BT_SIZEOFMAP(NUM_X86_FEATURES));
        cpuid_pass1(cp, new_x86_featureset);

        if (boot && get_hwenv() == HW_NATIVE &&
            cpuid_getvendor(CPU) == X86_VENDOR_Intel &&
            cpuid_getfamily(CPU) == 6 &&
            (cpuid_getmodel(CPU) == 0x2d || cpuid_getmodel(CPU) == 0x3e) &&
            is_x86_feature(new_x86_featureset, X86FSET_TSC)) {
                (void) wrmsr(REG_TSC, 0UL);
        }

        /* Let the control CPU continue into tsc_sync_master() */
        mp_startup_signal(&procset_slave, cp->cpu_id);

#ifndef __xpv
        if (tsc_gethrtime_enable)
                tsc_sync_slave();
#endif

        /*
         * Once this was done from assembly, but it's safer here; if
         * it blocks, we need to be able to swtch() to and from, and
         * since we get here by calling t_pc, we need to do that call
         * before swtch() overwrites it.
         */
        (void) (*ap_mlsetup)();

#ifndef __xpv
        /*
         * Program this cpu's PAT
         */
        pat_sync();
#endif

        /*
         * Set up TSC_AUX to contain the cpuid for this processor
         * for the rdtscp instruction.
         */
        if (is_x86_feature(x86_featureset, X86FSET_TSCP))
                (void) wrmsr(MSR_AMD_TSCAUX, cp->cpu_id);

        /*
         * Initialize this CPU's syscall handlers
         */
        init_cpu_syscall(cp);

        /*
         * Enable interrupts with spl set to LOCK_LEVEL. LOCK_LEVEL is the
         * highest level at which a routine is permitted to block on
         * an adaptive mutex (allows for cpu poke interrupt in case
         * the cpu is blocked on a mutex and halts). Setting LOCK_LEVEL blocks
         * device interrupts that may end up in the hat layer issuing cross
         * calls before CPU_READY is set.
         */
        splx(ipltospl(LOCK_LEVEL));
        sti();

        /*
         * Do a sanity check to make sure this new CPU is a sane thing
         * to add to the collection of processors running this system.
         *
         * XXX  Clearly this needs to get more sophisticated, if x86
         * systems start to get built out of heterogenous CPUs; as is
         * likely to happen once the number of processors in a configuration
         * gets large enough.
         */
        if (compare_x86_featureset(x86_featureset, new_x86_featureset) ==
            B_FALSE) {
                cmn_err(CE_CONT, "cpu%d: featureset\n", cp->cpu_id);
                print_x86_featureset(new_x86_featureset);
                cmn_err(CE_WARN, "cpu%d feature mismatch", cp->cpu_id);
        }

        /*
         * There exists a small subset of systems which expose differing
         * MWAIT/MONITOR support between CPUs.  If MWAIT support is absent from
         * the boot CPU, but is found on a later CPU, the system continues to
         * operate as if no MWAIT support is available.
         *
         * The reverse case, where MWAIT is available on the boot CPU but not
         * on a subsequently initialized CPU, is not presently allowed and will
         * result in a panic.
         */
        if (is_x86_feature(x86_featureset, X86FSET_MWAIT) !=
            is_x86_feature(new_x86_featureset, X86FSET_MWAIT)) {
                if (!is_x86_feature(x86_featureset, X86FSET_MWAIT)) {
                        remove_x86_feature(new_x86_featureset, X86FSET_MWAIT);
                } else {
                        panic("unsupported mixed cpu mwait support detected");
                }
        }

        /*
         * We could be more sophisticated here, and just mark the CPU
         * as "faulted" but at this point we'll opt for the easier
         * answer of dying horribly.  Provided the boot cpu is ok,
         * the system can be recovered by booting with use_mp set to zero.
         */
        if (workaround_errata(cp) != 0)
                panic("critical workaround(s) missing for cpu%d", cp->cpu_id);

        /*
         * We can touch cpu_flags here without acquiring the cpu_lock here
         * because the cpu_lock is held by the control CPU which is running
         * mp_start_cpu_common().
         * Need to clear CPU_QUIESCED flag before calling any function which
         * may cause thread context switching, such as kmem_alloc() etc.
         * The idle thread checks for CPU_QUIESCED flag and loops for ever if
         * it's set. So the startup thread may have no chance to switch back
         * again if it's switched away with CPU_QUIESCED set.
         */
        cp->cpu_flags &= ~(CPU_POWEROFF | CPU_QUIESCED);

        enable_pcid();

        /*
         * Setup this processor for XSAVE.
         */
        if (fp_save_mech == FP_XSAVE) {
                xsave_setup_msr(cp);
        }

        cpuid_pass2(cp);
        cpuid_pass3(cp);
        cpuid_pass4(cp, NULL);

        /*
         * Correct cpu_idstr and cpu_brandstr on target CPU after
         * cpuid_pass1() is done.
         */
        (void) cpuid_getidstr(cp, cp->cpu_idstr, CPU_IDSTRLEN);
        (void) cpuid_getbrandstr(cp, cp->cpu_brandstr, CPU_IDSTRLEN);

        cp->cpu_flags |= CPU_RUNNING | CPU_READY | CPU_EXISTS;

        post_startup_cpu_fixups();

        cpu_event_init_cpu(cp);

        /*
         * Enable preemption here so that contention for any locks acquired
         * later in mp_startup_common may be preempted if the thread owning
         * those locks is continuously executing on other CPUs (for example,
         * this CPU must be preemptible to allow other CPUs to pause it during
         * their startup phases).  It's safe to enable preemption here because
         * the CPU state is pretty-much fully constructed.
         */
        curthread->t_preempt = 0;

        /* The base spl should still be at LOCK LEVEL here */
        ASSERT(cp->cpu_base_spl == ipltospl(LOCK_LEVEL));
        set_base_spl();         /* Restore the spl to its proper value */

        pghw_physid_create(cp);
        /*
         * Delegate initialization tasks, which need to access the cpu_lock,
         * to mp_start_cpu_common() because we can't acquire the cpu_lock here
         * during CPU DR operations.
         */
        mp_startup_signal(&procset_slave, cp->cpu_id);
        mp_startup_wait(&procset_master, cp->cpu_id);
        pg_cmt_cpu_startup(cp);

        if (boot) {
                mutex_enter(&cpu_lock);
                cp->cpu_flags &= ~CPU_OFFLINE;
                cpu_enable_intr(cp);
                cpu_add_active(cp);
                mutex_exit(&cpu_lock);
        }

        /* Enable interrupts */
        (void) spl0();

        /*
         * Fill out cpu_ucode_info.  Update microcode if necessary.
         */
        ucode_check(cp);

#ifndef __xpv
        {
                /*
                 * Set up the CPU module for this CPU.  This can't be done
                 * before this CPU is made CPU_READY, because we may (in
                 * heterogeneous systems) need to go load another CPU module.
                 * The act of attempting to load a module may trigger a
                 * cross-call, which will ASSERT unless this cpu is CPU_READY.
                 */
                cmi_hdl_t hdl;

                if ((hdl = cmi_init(CMI_HDL_NATIVE, cmi_ntv_hwchipid(CPU),
                    cmi_ntv_hwcoreid(CPU), cmi_ntv_hwstrandid(CPU))) != NULL) {
                        if (is_x86_feature(x86_featureset, X86FSET_MCA))
                                cmi_mca_init(hdl);
                        cp->cpu_m.mcpu_cmi_hdl = hdl;
                }
        }
#endif /* __xpv */

        if (boothowto & RB_DEBUG)
                kdi_cpu_init();

        /*
         * Setting the bit in cpu_ready_set must be the last operation in
         * processor initialization; the boot CPU will continue to boot once
         * it sees this bit set for all active CPUs.
         */
        CPUSET_ATOMIC_ADD(cpu_ready_set, cp->cpu_id);

        (void) mach_cpu_create_device_node(cp, NULL);

        cmn_err(CE_CONT, "?cpu%d: %s\n", cp->cpu_id, cp->cpu_idstr);
        cmn_err(CE_CONT, "?cpu%d: %s\n", cp->cpu_id, cp->cpu_brandstr);
        cmn_err(CE_CONT, "?cpu%d initialization complete - online\n",
            cp->cpu_id);

        /*
         * Now we are done with the startup thread, so free it up.
         */
        thread_exit();
        panic("mp_startup: cannot return");
        /*NOTREACHED*/
}

/*
 * Startup function for 'other' CPUs at boot time (besides boot cpu).
 */
static void
mp_startup_boot(void)
{
        mp_startup_common(B_TRUE);
}

/*
 * Startup function for hotplug CPUs at runtime.
 */
void
mp_startup_hotplug(void)
{
        mp_startup_common(B_FALSE);
}

/*
 * Start CPU on user request.
 */
/* ARGSUSED */
int
mp_cpu_start(struct cpu *cp)
{
        ASSERT(MUTEX_HELD(&cpu_lock));
        return (0);
}

/*
 * Stop CPU on user request.
 */
int
mp_cpu_stop(struct cpu *cp)
{
        extern int cbe_psm_timer_mode;
        ASSERT(MUTEX_HELD(&cpu_lock));

#ifdef __xpv
        /*
         * We can't offline vcpu0.
         */
        if (cp->cpu_id == 0)
                return (EBUSY);
#endif

        /*
         * If TIMER_PERIODIC mode is used, CPU0 is the one running it;
         * can't stop it.  (This is true only for machines with no TSC.)
         */

        if ((cbe_psm_timer_mode == TIMER_PERIODIC) && (cp->cpu_id == 0))
                return (EBUSY);

        return (0);
}

/*
 * Take the specified CPU out of participation in interrupts.
 */
int
cpu_disable_intr(struct cpu *cp)
{
        if (psm_disable_intr(cp->cpu_id) != DDI_SUCCESS)
                return (EBUSY);

        cp->cpu_flags &= ~CPU_ENABLE;
        return (0);
}

/*
 * Allow the specified CPU to participate in interrupts.
 */
void
cpu_enable_intr(struct cpu *cp)
{
        ASSERT(MUTEX_HELD(&cpu_lock));
        cp->cpu_flags |= CPU_ENABLE;
        psm_enable_intr(cp->cpu_id);
}

void
mp_cpu_faulted_enter(struct cpu *cp)
{
#ifdef __xpv
        _NOTE(ARGUNUSED(cp));
#else
        cmi_hdl_t hdl = cp->cpu_m.mcpu_cmi_hdl;

        if (hdl != NULL) {
                cmi_hdl_hold(hdl);
        } else {
                hdl = cmi_hdl_lookup(CMI_HDL_NATIVE, cmi_ntv_hwchipid(cp),
                    cmi_ntv_hwcoreid(cp), cmi_ntv_hwstrandid(cp));
        }
        if (hdl != NULL) {
                cmi_faulted_enter(hdl);
                cmi_hdl_rele(hdl);
        }
#endif
}

void
mp_cpu_faulted_exit(struct cpu *cp)
{
#ifdef __xpv
        _NOTE(ARGUNUSED(cp));
#else
        cmi_hdl_t hdl = cp->cpu_m.mcpu_cmi_hdl;

        if (hdl != NULL) {
                cmi_hdl_hold(hdl);
        } else {
                hdl = cmi_hdl_lookup(CMI_HDL_NATIVE, cmi_ntv_hwchipid(cp),
                    cmi_ntv_hwcoreid(cp), cmi_ntv_hwstrandid(cp));
        }
        if (hdl != NULL) {
                cmi_faulted_exit(hdl);
                cmi_hdl_rele(hdl);
        }
#endif
}

/*
 * The following two routines are used as context operators on threads belonging
 * to processes with a private LDT (see sysi86).  Due to the rarity of such
 * processes, these routines are currently written for best code readability and
 * organization rather than speed.  We could avoid checking x86_featureset at
 * every context switch by installing different context ops, depending on
 * x86_featureset, at LDT creation time -- one for each combination of fast
 * syscall features.
 */

/*ARGSUSED*/
void
cpu_fast_syscall_disable(void *arg)
{
        if (is_x86_feature(x86_featureset, X86FSET_MSR) &&
            is_x86_feature(x86_featureset, X86FSET_SEP))
                cpu_sep_disable();
        if (is_x86_feature(x86_featureset, X86FSET_MSR) &&
            is_x86_feature(x86_featureset, X86FSET_ASYSC))
                cpu_asysc_disable();
}

/*ARGSUSED*/
void
cpu_fast_syscall_enable(void *arg)
{
        if (is_x86_feature(x86_featureset, X86FSET_MSR) &&
            is_x86_feature(x86_featureset, X86FSET_SEP))
                cpu_sep_enable();
        if (is_x86_feature(x86_featureset, X86FSET_MSR) &&
            is_x86_feature(x86_featureset, X86FSET_ASYSC))
                cpu_asysc_enable();
}

static void
cpu_sep_enable(void)
{
        ASSERT(is_x86_feature(x86_featureset, X86FSET_SEP));
        ASSERT(curthread->t_preempt || getpil() >= LOCK_LEVEL);

        wrmsr(MSR_INTC_SEP_CS, (uint64_t)(uintptr_t)KCS_SEL);
}

static void
cpu_sep_disable(void)
{
        ASSERT(is_x86_feature(x86_featureset, X86FSET_SEP));
        ASSERT(curthread->t_preempt || getpil() >= LOCK_LEVEL);

        /*
         * Setting the SYSENTER_CS_MSR register to 0 causes software executing
         * the sysenter or sysexit instruction to trigger a #gp fault.
         */
        wrmsr(MSR_INTC_SEP_CS, 0);
}

static void
cpu_asysc_enable(void)
{
        ASSERT(is_x86_feature(x86_featureset, X86FSET_ASYSC));
        ASSERT(curthread->t_preempt || getpil() >= LOCK_LEVEL);

        wrmsr(MSR_AMD_EFER, rdmsr(MSR_AMD_EFER) |
            (uint64_t)(uintptr_t)AMD_EFER_SCE);
}

static void
cpu_asysc_disable(void)
{
        ASSERT(is_x86_feature(x86_featureset, X86FSET_ASYSC));
        ASSERT(curthread->t_preempt || getpil() >= LOCK_LEVEL);

        /*
         * Turn off the SCE (syscall enable) bit in the EFER register. Software
         * executing syscall or sysret with this bit off will incur a #ud trap.
         */
        wrmsr(MSR_AMD_EFER, rdmsr(MSR_AMD_EFER) &
            ~((uint64_t)(uintptr_t)AMD_EFER_SCE));
}