FreeBSD/Linux Kernel Cross Reference
sys/x86/x86/cpu_machdep.c

     /*-
      * Copyright (c) 2003 Peter Wemm.
      * Copyright (c) 1992 Terrence R. Lambert.
      * Copyright (c) 1982, 1987, 1990 The Regents of the University of California.
      * All rights reserved.
      *
      * This code is derived from software contributed to Berkeley by
      * William Jolitz.
      *
     * 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.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
     *
     *      from: @(#)machdep.c     7.4 (Berkeley) 6/3/91
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include "opt_acpi.h"
    #include "opt_atpic.h"
    #include "opt_cpu.h"
    #include "opt_ddb.h"
    #include "opt_inet.h"
    #include "opt_isa.h"
    #include "opt_kdb.h"
    #include "opt_kstack_pages.h"
    #include "opt_maxmem.h"
    #include "opt_platform.h"
    #include "opt_sched.h"
    #ifdef __i386__
    #include "opt_apic.h"
    #endif
    
    #include <sys/param.h>
    #include <sys/proc.h>
    #include <sys/systm.h>
    #include <sys/bus.h>
    #include <sys/cpu.h>
    #include <sys/domainset.h>
    #include <sys/kdb.h>
    #include <sys/kernel.h>
    #include <sys/ktr.h>
    #include <sys/lock.h>
    #include <sys/malloc.h>
    #include <sys/mutex.h>
    #include <sys/pcpu.h>
    #include <sys/rwlock.h>
    #include <sys/sched.h>
    #include <sys/smp.h>
    #include <sys/sysctl.h>
    
    #include <machine/clock.h>
    #include <machine/cpu.h>
    #include <machine/cpufunc.h>
    #include <machine/cputypes.h>
    #include <machine/specialreg.h>
    #include <machine/md_var.h>
    #include <machine/tss.h>
    #ifdef SMP
    #include <machine/smp.h>
    #endif
    #ifdef CPU_ELAN
    #include <machine/elan_mmcr.h>
    #endif
    #include <x86/acpica_machdep.h>
    #include <x86/ifunc.h>
    
    #include <vm/vm.h>
    #include <vm/vm_extern.h>
    #include <vm/vm_kern.h>
    #include <vm/vm_page.h>
    #include <vm/vm_map.h>
    #include <vm/vm_object.h>
    #include <vm/vm_pager.h>
   #include <vm/vm_param.h>
   
   #include <isa/isareg.h>
   
   #include <contrib/dev/acpica/include/acpi.h>
   
   #define STATE_RUNNING   0x0
   #define STATE_MWAIT     0x1
   #define STATE_SLEEPING  0x2
   
   #ifdef SMP
   static u_int    cpu_reset_proxyid;
   static volatile u_int   cpu_reset_proxy_active;
   #endif
   
   char bootmethod[16];
   SYSCTL_STRING(_machdep, OID_AUTO, bootmethod, CTLFLAG_RD, bootmethod, 0,
       "System firmware boot method");
   
   struct msr_op_arg {
           u_int msr;
           int op;
           uint64_t arg1;
           uint64_t *res;
   };
   
   static void
   x86_msr_op_one(void *argp)
   {
           struct msr_op_arg *a;
           uint64_t v;
   
           a = argp;
           switch (a->op) {
           case MSR_OP_ANDNOT:
                   v = rdmsr(a->msr);
                   v &= ~a->arg1;
                   wrmsr(a->msr, v);
                   break;
           case MSR_OP_OR:
                   v = rdmsr(a->msr);
                   v |= a->arg1;
                   wrmsr(a->msr, v);
                   break;
           case MSR_OP_WRITE:
                   wrmsr(a->msr, a->arg1);
                   break;
           case MSR_OP_READ:
                   v = rdmsr(a->msr);
                   *a->res = v;
                   break;
           }
   }
   
   #define MSR_OP_EXMODE_MASK      0xf0000000
   #define MSR_OP_OP_MASK          0x000000ff
   #define MSR_OP_GET_CPUID(x)     (((x) & ~MSR_OP_EXMODE_MASK) >> 8)
   
   void
   x86_msr_op(u_int msr, u_int op, uint64_t arg1, uint64_t *res)
   {
           struct thread *td;
           struct msr_op_arg a;
           cpuset_t set;
           u_int exmode;
           int bound_cpu, cpu, i, is_bound;
   
           a.op = op & MSR_OP_OP_MASK;
           MPASS(a.op == MSR_OP_ANDNOT || a.op == MSR_OP_OR ||
               a.op == MSR_OP_WRITE || a.op == MSR_OP_READ);
           exmode = op & MSR_OP_EXMODE_MASK;
           MPASS(exmode == MSR_OP_LOCAL || exmode == MSR_OP_SCHED_ALL ||
               exmode == MSR_OP_SCHED_ONE || exmode == MSR_OP_RENDEZVOUS_ALL ||
               exmode == MSR_OP_RENDEZVOUS_ONE);
           a.msr = msr;
           a.arg1 = arg1;
           a.res = res;
           switch (exmode) {
           case MSR_OP_LOCAL:
                   x86_msr_op_one(&a);
                   break;
           case MSR_OP_SCHED_ALL:
                   td = curthread;
                   thread_lock(td);
                   is_bound = sched_is_bound(td);
                   bound_cpu = td->td_oncpu;
                   CPU_FOREACH(i) {
                           sched_bind(td, i);
                           x86_msr_op_one(&a);
                   }
                   if (is_bound)
                           sched_bind(td, bound_cpu);
                   else
                           sched_unbind(td);
                   thread_unlock(td);
                   break;
           case MSR_OP_SCHED_ONE:
                   td = curthread;
                   cpu = MSR_OP_GET_CPUID(op);
                   thread_lock(td);
                   is_bound = sched_is_bound(td);
                   bound_cpu = td->td_oncpu;
                   if (!is_bound || bound_cpu != cpu)
                           sched_bind(td, cpu);
                   x86_msr_op_one(&a);
                   if (is_bound) {
                           if (bound_cpu != cpu)
                                   sched_bind(td, bound_cpu);
                   } else {
                           sched_unbind(td);
                   }
                   thread_unlock(td);
                   break;
           case MSR_OP_RENDEZVOUS_ALL:
                   smp_rendezvous(smp_no_rendezvous_barrier, x86_msr_op_one,
                       smp_no_rendezvous_barrier, &a);
                   break;
           case MSR_OP_RENDEZVOUS_ONE:
                   cpu = MSR_OP_GET_CPUID(op);
                   CPU_SETOF(cpu, &set);
                   smp_rendezvous_cpus(set, smp_no_rendezvous_barrier,
                       x86_msr_op_one, smp_no_rendezvous_barrier, &a);
                   break;
           }
   }
   
   /*
    * Automatically initialized per CPU errata in cpu_idle_tun below.
    */
   bool mwait_cpustop_broken = false;
   SYSCTL_BOOL(_machdep, OID_AUTO, mwait_cpustop_broken, CTLFLAG_RDTUN,
       &mwait_cpustop_broken, 0,
       "Can not reliably wake MONITOR/MWAIT cpus without interrupts");
   
   /*
    * Flush the D-cache for non-DMA I/O so that the I-cache can
    * be made coherent later.
    */
   void
   cpu_flush_dcache(void *ptr, size_t len)
   {
           /* Not applicable */
   }
   
   void
   acpi_cpu_c1(void)
   {
   
           __asm __volatile("sti; hlt");
   }
   
   /*
    * Use mwait to pause execution while waiting for an interrupt or
    * another thread to signal that there is more work.
    *
    * NOTE: Interrupts will cause a wakeup; however, this function does
    * not enable interrupt handling. The caller is responsible to enable
    * interrupts.
    */
   void
   acpi_cpu_idle_mwait(uint32_t mwait_hint)
   {
           int *state;
           uint64_t v;
   
           /*
            * A comment in Linux patch claims that 'CPUs run faster with
            * speculation protection disabled. All CPU threads in a core
            * must disable speculation protection for it to be
            * disabled. Disable it while we are idle so the other
            * hyperthread can run fast.'
            *
            * XXXKIB.  Software coordination mode should be supported,
            * but all Intel CPUs provide hardware coordination.
            */
   
           state = &PCPU_PTR(monitorbuf)->idle_state;
           KASSERT(atomic_load_int(state) == STATE_SLEEPING,
               ("cpu_mwait_cx: wrong monitorbuf state"));
           atomic_store_int(state, STATE_MWAIT);
           if (PCPU_GET(ibpb_set) || hw_ssb_active) {
                   v = rdmsr(MSR_IA32_SPEC_CTRL);
                   wrmsr(MSR_IA32_SPEC_CTRL, v & ~(IA32_SPEC_CTRL_IBRS |
                       IA32_SPEC_CTRL_STIBP | IA32_SPEC_CTRL_SSBD));
           } else {
                   v = 0;
           }
           cpu_monitor(state, 0, 0);
           if (atomic_load_int(state) == STATE_MWAIT)
                   cpu_mwait(MWAIT_INTRBREAK, mwait_hint);
   
           /*
            * SSB cannot be disabled while we sleep, or rather, if it was
            * disabled, the sysctl thread will bind to our cpu to tweak
            * MSR.
            */
           if (v != 0)
                   wrmsr(MSR_IA32_SPEC_CTRL, v);
   
           /*
            * We should exit on any event that interrupts mwait, because
            * that event might be a wanted interrupt.
            */
           atomic_store_int(state, STATE_RUNNING);
   }
   
   /* Get current clock frequency for the given cpu id. */
   int
   cpu_est_clockrate(int cpu_id, uint64_t *rate)
   {
           uint64_t tsc1, tsc2;
           uint64_t acnt, mcnt, perf;
           register_t reg;
   
           if (pcpu_find(cpu_id) == NULL || rate == NULL)
                   return (EINVAL);
   #ifdef __i386__
           if ((cpu_feature & CPUID_TSC) == 0)
                   return (EOPNOTSUPP);
   #endif
   
           /*
            * If TSC is P-state invariant and APERF/MPERF MSRs do not exist,
            * DELAY(9) based logic fails.
            */
           if (tsc_is_invariant && !tsc_perf_stat)
                   return (EOPNOTSUPP);
   
   #ifdef SMP
           if (smp_cpus > 1) {
                   /* Schedule ourselves on the indicated cpu. */
                   thread_lock(curthread);
                   sched_bind(curthread, cpu_id);
                   thread_unlock(curthread);
           }
   #endif
   
           /* Calibrate by measuring a short delay. */
           reg = intr_disable();
           if (tsc_is_invariant) {
                   wrmsr(MSR_MPERF, 0);
                   wrmsr(MSR_APERF, 0);
                   tsc1 = rdtsc();
                   DELAY(1000);
                   mcnt = rdmsr(MSR_MPERF);
                   acnt = rdmsr(MSR_APERF);
                   tsc2 = rdtsc();
                   intr_restore(reg);
                   perf = 1000 * acnt / mcnt;
                   *rate = (tsc2 - tsc1) * perf;
           } else {
                   tsc1 = rdtsc();
                   DELAY(1000);
                   tsc2 = rdtsc();
                   intr_restore(reg);
                   *rate = (tsc2 - tsc1) * 1000;
           }
   
   #ifdef SMP
           if (smp_cpus > 1) {
                   thread_lock(curthread);
                   sched_unbind(curthread);
                   thread_unlock(curthread);
           }
   #endif
   
           return (0);
   }
   
   /*
    * Shutdown the CPU as much as possible
    */
   void
   cpu_halt(void)
   {
           for (;;)
                   halt();
   }
   
   static void
   cpu_reset_real(void)
   {
           struct region_descriptor null_idt;
           int b;
   
           disable_intr();
   #ifdef CPU_ELAN
           if (elan_mmcr != NULL)
                   elan_mmcr->RESCFG = 1;
   #endif
   #ifdef __i386__
           if (cpu == CPU_GEODE1100) {
                   /* Attempt Geode's own reset */
                   outl(0xcf8, 0x80009044ul);
                   outl(0xcfc, 0xf);
           }
   #endif
   #if !defined(BROKEN_KEYBOARD_RESET)
           /*
            * Attempt to do a CPU reset via the keyboard controller,
            * do not turn off GateA20, as any machine that fails
            * to do the reset here would then end up in no man's land.
            */
           outb(IO_KBD + 4, 0xFE);
           DELAY(500000);  /* wait 0.5 sec to see if that did it */
   #endif
   
           /*
            * Attempt to force a reset via the Reset Control register at
            * I/O port 0xcf9.  Bit 2 forces a system reset when it
            * transitions from 0 to 1.  Bit 1 selects the type of reset
            * to attempt: 0 selects a "soft" reset, and 1 selects a
            * "hard" reset.  We try a "hard" reset.  The first write sets
            * bit 1 to select a "hard" reset and clears bit 2.  The
            * second write forces a 0 -> 1 transition in bit 2 to trigger
            * a reset.
            */
           outb(0xcf9, 0x2);
           outb(0xcf9, 0x6);
           DELAY(500000);  /* wait 0.5 sec to see if that did it */
   
           /*
            * Attempt to force a reset via the Fast A20 and Init register
            * at I/O port 0x92.  Bit 1 serves as an alternate A20 gate.
            * Bit 0 asserts INIT# when set to 1.  We are careful to only
            * preserve bit 1 while setting bit 0.  We also must clear bit
            * 0 before setting it if it isn't already clear.
            */
           b = inb(0x92);
           if (b != 0xff) {
                   if ((b & 0x1) != 0)
                           outb(0x92, b & 0xfe);
                   outb(0x92, b | 0x1);
                   DELAY(500000);  /* wait 0.5 sec to see if that did it */
           }
   
           printf("No known reset method worked, attempting CPU shutdown\n");
           DELAY(1000000); /* wait 1 sec for printf to complete */
   
           /* Wipe the IDT. */
           null_idt.rd_limit = 0;
           null_idt.rd_base = 0;
           lidt(&null_idt);
   
           /* "good night, sweet prince .... <THUNK!>" */
           breakpoint();
   
           /* NOTREACHED */
           while(1);
   }
   
   #ifdef SMP
   static void
   cpu_reset_proxy(void)
   {
   
           cpu_reset_proxy_active = 1;
           while (cpu_reset_proxy_active == 1)
                   ia32_pause(); /* Wait for other cpu to see that we've started */
   
           printf("cpu_reset_proxy: Stopped CPU %d\n", cpu_reset_proxyid);
           DELAY(1000000);
           cpu_reset_real();
   }
   #endif
   
   void
   cpu_reset(void)
   {
   #ifdef SMP
           struct monitorbuf *mb;
           cpuset_t map;
           u_int cnt;
   
           if (smp_started) {
                   map = all_cpus;
                   CPU_CLR(PCPU_GET(cpuid), &map);
                   CPU_ANDNOT(&map, &map, &stopped_cpus);
                   if (!CPU_EMPTY(&map)) {
                           printf("cpu_reset: Stopping other CPUs\n");
                           stop_cpus(map);
                   }
   
                   if (PCPU_GET(cpuid) != 0) {
                           cpu_reset_proxyid = PCPU_GET(cpuid);
                           cpustop_restartfunc = cpu_reset_proxy;
                           cpu_reset_proxy_active = 0;
                           printf("cpu_reset: Restarting BSP\n");
   
                           /* Restart CPU #0. */
                           CPU_SETOF(0, &started_cpus);
                           mb = &pcpu_find(0)->pc_monitorbuf;
                           atomic_store_int(&mb->stop_state,
                               MONITOR_STOPSTATE_RUNNING);
   
                           cnt = 0;
                           while (cpu_reset_proxy_active == 0 && cnt < 10000000) {
                                   ia32_pause();
                                   cnt++;  /* Wait for BSP to announce restart */
                           }
                           if (cpu_reset_proxy_active == 0) {
                                   printf("cpu_reset: Failed to restart BSP\n");
                           } else {
                                   cpu_reset_proxy_active = 2;
                                   while (1)
                                           ia32_pause();
                                   /* NOTREACHED */
                           }
                   }
           }
   #endif
           cpu_reset_real();
           /* NOTREACHED */
   }
   
   bool
   cpu_mwait_usable(void)
   {
   
           return ((cpu_feature2 & CPUID2_MON) != 0 && ((cpu_mon_mwait_flags &
               (CPUID5_MON_MWAIT_EXT | CPUID5_MWAIT_INTRBREAK)) ==
               (CPUID5_MON_MWAIT_EXT | CPUID5_MWAIT_INTRBREAK)));
   }
   
   void (*cpu_idle_hook)(sbintime_t) = NULL;       /* ACPI idle hook. */
   
   int cpu_amdc1e_bug = 0;                 /* AMD C1E APIC workaround required. */
   
   static int      idle_mwait = 1;         /* Use MONITOR/MWAIT for short idle. */
   SYSCTL_INT(_machdep, OID_AUTO, idle_mwait, CTLFLAG_RWTUN, &idle_mwait,
       0, "Use MONITOR/MWAIT for short idle");
   
   static bool
   cpu_idle_enter(int *statep, int newstate)
   {
           KASSERT(atomic_load_int(statep) == STATE_RUNNING,
               ("%s: state %d", __func__, atomic_load_int(statep)));
   
           /*
            * A fence is needed to prevent reordering of the load in
            * sched_runnable() with this store to the idle state word.  Without it,
            * cpu_idle_wakeup() can observe the state as STATE_RUNNING after having
            * added load to the queue, and elide an IPI.  Then, sched_runnable()
            * can observe tdq_load == 0, so the CPU ends up idling with pending
            * work.  tdq_notify() similarly ensures that a prior update to tdq_load
            * is visible before calling cpu_idle_wakeup().
            */
           atomic_store_int(statep, newstate);
   #if defined(SCHED_ULE) && defined(SMP)
           atomic_thread_fence_seq_cst();
   #endif
   
           /*
            * Since we may be in a critical section from cpu_idle(), if
            * an interrupt fires during that critical section we may have
            * a pending preemption.  If the CPU halts, then that thread
            * may not execute until a later interrupt awakens the CPU.
            * To handle this race, check for a runnable thread after
            * disabling interrupts and immediately return if one is
            * found.  Also, we must absolutely guarentee that hlt is
            * the next instruction after sti.  This ensures that any
            * interrupt that fires after the call to disable_intr() will
            * immediately awaken the CPU from hlt.  Finally, please note
            * that on x86 this works fine because of interrupts enabled only
            * after the instruction following sti takes place, while IF is set
            * to 1 immediately, allowing hlt instruction to acknowledge the
            * interrupt.
            */
           disable_intr();
           if (sched_runnable()) {
                   enable_intr();
                   atomic_store_int(statep, STATE_RUNNING);
                   return (false);
           } else {
                   return (true);
           }
   }
   
   static void
   cpu_idle_exit(int *statep)
   {
           atomic_store_int(statep, STATE_RUNNING);
   }
   
   static void
   cpu_idle_acpi(sbintime_t sbt)
   {
           int *state;
   
           state = &PCPU_PTR(monitorbuf)->idle_state;
           if (cpu_idle_enter(state, STATE_SLEEPING)) {
                   if (cpu_idle_hook)
                           cpu_idle_hook(sbt);
                   else
                           acpi_cpu_c1();
                   cpu_idle_exit(state);
           }
   }
   
   static void
   cpu_idle_hlt(sbintime_t sbt)
   {
           int *state;
   
           state = &PCPU_PTR(monitorbuf)->idle_state;
           if (cpu_idle_enter(state, STATE_SLEEPING)) {
                   acpi_cpu_c1();
                   atomic_store_int(state, STATE_RUNNING);
           }
   }
   
   static void
   cpu_idle_mwait(sbintime_t sbt)
   {
           int *state;
   
           state = &PCPU_PTR(monitorbuf)->idle_state;
           if (cpu_idle_enter(state, STATE_MWAIT)) {
                   cpu_monitor(state, 0, 0);
                   if (atomic_load_int(state) == STATE_MWAIT)
                           __asm __volatile("sti; mwait" : : "a" (MWAIT_C1), "c" (0));
                   else
                           enable_intr();
                   cpu_idle_exit(state);
           }
   }
   
   static void
   cpu_idle_spin(sbintime_t sbt)
   {
           int *state;
           int i;
   
           state = &PCPU_PTR(monitorbuf)->idle_state;
           atomic_store_int(state, STATE_RUNNING);
   
           /*
            * The sched_runnable() call is racy but as long as there is
            * a loop missing it one time will have just a little impact if any 
            * (and it is much better than missing the check at all).
            */
           for (i = 0; i < 1000; i++) {
                   if (sched_runnable())
                           return;
                   cpu_spinwait();
           }
   }
   
   void (*cpu_idle_fn)(sbintime_t) = cpu_idle_acpi;
   
   void
   cpu_idle(int busy)
   {
           uint64_t msr;
           sbintime_t sbt = -1;
   
           CTR1(KTR_SPARE2, "cpu_idle(%d)", busy);
   
           /* If we are busy - try to use fast methods. */
           if (busy) {
                   if ((cpu_feature2 & CPUID2_MON) && idle_mwait) {
                           cpu_idle_mwait(busy);
                           goto out;
                   }
           }
   
           /* If we have time - switch timers into idle mode. */
           if (!busy) {
                   critical_enter();
                   sbt = cpu_idleclock();
           }
   
           /* Apply AMD APIC timer C1E workaround. */
           if (cpu_amdc1e_bug && cpu_disable_c3_sleep) {
                   msr = rdmsr(MSR_AMDK8_IPM);
                   if ((msr & (AMDK8_SMIONCMPHALT | AMDK8_C1EONCMPHALT)) != 0)
                           wrmsr(MSR_AMDK8_IPM, msr & ~(AMDK8_SMIONCMPHALT |
                               AMDK8_C1EONCMPHALT));
           }
   
           /* Call main idle method. */
           cpu_idle_fn(sbt);
   
           /* Switch timers back into active mode. */
           if (!busy) {
                   cpu_activeclock();
                   critical_exit();
           }
   out:
           CTR1(KTR_SPARE2, "cpu_idle(%d) done", busy);
   }
   
   static int cpu_idle_apl31_workaround;
   SYSCTL_INT(_machdep, OID_AUTO, idle_apl31, CTLFLAG_RW,
       &cpu_idle_apl31_workaround, 0,
       "Apollo Lake APL31 MWAIT bug workaround");
   
   int
   cpu_idle_wakeup(int cpu)
   {
           struct monitorbuf *mb;
           int *state;
   
           mb = &pcpu_find(cpu)->pc_monitorbuf;
           state = &mb->idle_state;
           switch (atomic_load_int(state)) {
           case STATE_SLEEPING:
                   return (0);
           case STATE_MWAIT:
                   atomic_store_int(state, STATE_RUNNING);
                   return (cpu_idle_apl31_workaround ? 0 : 1);
           case STATE_RUNNING:
                   return (1);
           default:
                   panic("bad monitor state");
                   return (1);
           }
   }
   
   /*
    * Ordered by speed/power consumption.
    */
   static struct {
           void    *id_fn;
           char    *id_name;
           int     id_cpuid2_flag;
   } idle_tbl[] = {
           { .id_fn = cpu_idle_spin, .id_name = "spin" },
           { .id_fn = cpu_idle_mwait, .id_name = "mwait",
               .id_cpuid2_flag = CPUID2_MON },
           { .id_fn = cpu_idle_hlt, .id_name = "hlt" },
           { .id_fn = cpu_idle_acpi, .id_name = "acpi" },
   };
   
   static int
   idle_sysctl_available(SYSCTL_HANDLER_ARGS)
   {
           char *avail, *p;
           int error;
           int i;
   
           avail = malloc(256, M_TEMP, M_WAITOK);
           p = avail;
           for (i = 0; i < nitems(idle_tbl); i++) {
                   if (idle_tbl[i].id_cpuid2_flag != 0 &&
                       (cpu_feature2 & idle_tbl[i].id_cpuid2_flag) == 0)
                           continue;
                   if (strcmp(idle_tbl[i].id_name, "acpi") == 0 &&
                       cpu_idle_hook == NULL)
                           continue;
                   p += sprintf(p, "%s%s", p != avail ? ", " : "",
                       idle_tbl[i].id_name);
           }
           error = sysctl_handle_string(oidp, avail, 0, req);
           free(avail, M_TEMP);
           return (error);
   }
   
   SYSCTL_PROC(_machdep, OID_AUTO, idle_available,
       CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE,
       0, 0, idle_sysctl_available, "A",
       "list of available idle functions");
   
   static bool
   cpu_idle_selector(const char *new_idle_name)
   {
           int i;
   
           for (i = 0; i < nitems(idle_tbl); i++) {
                   if (idle_tbl[i].id_cpuid2_flag != 0 &&
                       (cpu_feature2 & idle_tbl[i].id_cpuid2_flag) == 0)
                           continue;
                   if (strcmp(idle_tbl[i].id_name, "acpi") == 0 &&
                       cpu_idle_hook == NULL)
                           continue;
                   if (strcmp(idle_tbl[i].id_name, new_idle_name))
                           continue;
                   cpu_idle_fn = idle_tbl[i].id_fn;
                   if (bootverbose)
                           printf("CPU idle set to %s\n", idle_tbl[i].id_name);
                   return (true);
           }
           return (false);
   }
   
   static int
   cpu_idle_sysctl(SYSCTL_HANDLER_ARGS)
   {
           char buf[16], *p;
           int error, i;
   
           p = "unknown";
           for (i = 0; i < nitems(idle_tbl); i++) {
                   if (idle_tbl[i].id_fn == cpu_idle_fn) {
                           p = idle_tbl[i].id_name;
                           break;
                   }
           }
           strncpy(buf, p, sizeof(buf));
           error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
           if (error != 0 || req->newptr == NULL)
                   return (error);
           return (cpu_idle_selector(buf) ? 0 : EINVAL);
   }
   
   SYSCTL_PROC(_machdep, OID_AUTO, idle,
       CTLTYPE_STRING | CTLFLAG_RW | CTLFLAG_MPSAFE,
       0, 0, cpu_idle_sysctl, "A",
       "currently selected idle function");
   
   static void
   cpu_idle_tun(void *unused __unused)
   {
           char tunvar[16];
   
           if (TUNABLE_STR_FETCH("machdep.idle", tunvar, sizeof(tunvar)))
                   cpu_idle_selector(tunvar);
           else if (cpu_vendor_id == CPU_VENDOR_AMD &&
               CPUID_TO_FAMILY(cpu_id) == 0x17 && CPUID_TO_MODEL(cpu_id) == 0x1) {
                   /* Ryzen erratas 1057, 1109. */
                   cpu_idle_selector("hlt");
                   idle_mwait = 0;
                   mwait_cpustop_broken = true;
           }
   
           if (cpu_vendor_id == CPU_VENDOR_INTEL &&
               CPUID_TO_FAMILY(cpu_id) == 0x6 && CPUID_TO_MODEL(cpu_id) == 0x5c) {
                   /*
                    * Apollo Lake errata APL31 (public errata APL30).
                    * Stores to the armed address range may not trigger
                    * MWAIT to resume execution.  OS needs to use
                    * interrupts to wake processors from MWAIT-induced
                    * sleep states.
                    */
                   cpu_idle_apl31_workaround = 1;
                   mwait_cpustop_broken = true;
           }
           TUNABLE_INT_FETCH("machdep.idle_apl31", &cpu_idle_apl31_workaround);
   }
   SYSINIT(cpu_idle_tun, SI_SUB_CPU, SI_ORDER_MIDDLE, cpu_idle_tun, NULL);
   
   static int panic_on_nmi = 0xff;
   SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RWTUN,
       &panic_on_nmi, 0,
       "Panic on NMI: 1 = H/W failure; 2 = unknown; 0xff = all");
   int nmi_is_broadcast = 1;
   SYSCTL_INT(_machdep, OID_AUTO, nmi_is_broadcast, CTLFLAG_RWTUN,
       &nmi_is_broadcast, 0,
       "Chipset NMI is broadcast");
   int (*apei_nmi)(void);
   
   void
   nmi_call_kdb(u_int cpu, u_int type, struct trapframe *frame)
   {
           bool claimed = false;
   
   #ifdef DEV_ISA
           /* machine/parity/power fail/"kitchen sink" faults */
           if (isa_nmi(frame->tf_err)) {
                   claimed = true;
                   if ((panic_on_nmi & 1) != 0)
                           panic("NMI indicates hardware failure");
           }
   #endif /* DEV_ISA */
   
           /* ACPI Platform Error Interfaces callback. */
           if (apei_nmi != NULL && (*apei_nmi)())
                   claimed = true;
   
           /*
            * NMIs can be useful for debugging.  They can be hooked up to a
            * pushbutton, usually on an ISA, PCI, or PCIe card.  They can also be
            * generated by an IPMI BMC, either manually or in response to a
            * watchdog timeout.  For example, see the "power diag" command in
            * ports/sysutils/ipmitool.  They can also be generated by a
            * hypervisor; see "bhyvectl --inject-nmi".
            */
   
   #ifdef KDB
           if (!claimed && (panic_on_nmi & 2) != 0) {
                   if (debugger_on_panic) {
                           printf("NMI/cpu%d ... going to debugger\n", cpu);
                           claimed = kdb_trap(type, 0, frame);
                   }
           }
   #endif /* KDB */
   
           if (!claimed && panic_on_nmi != 0)
                   panic("NMI");
   }
   
   void
   nmi_handle_intr(u_int type, struct trapframe *frame)
   {
   
   #ifdef SMP
           if (nmi_is_broadcast) {
                   nmi_call_kdb_smp(type, frame);
                   return;
           }
   #endif
           nmi_call_kdb(PCPU_GET(cpuid), type, frame);
   }
   
   static int hw_ibrs_active;
   int hw_ibrs_ibpb_active;
   int hw_ibrs_disable = 1;
   
   SYSCTL_INT(_hw, OID_AUTO, ibrs_active, CTLFLAG_RD, &hw_ibrs_active, 0,
       "Indirect Branch Restricted Speculation active");
   
   SYSCTL_NODE(_machdep_mitigations, OID_AUTO, ibrs,
       CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
       "Indirect Branch Restricted Speculation active");
   
   SYSCTL_INT(_machdep_mitigations_ibrs, OID_AUTO, active, CTLFLAG_RD,
       &hw_ibrs_active, 0, "Indirect Branch Restricted Speculation active");
   
   void
   hw_ibrs_recalculate(bool for_all_cpus)
   {
           if ((cpu_ia32_arch_caps & IA32_ARCH_CAP_IBRS_ALL) != 0) {
                   x86_msr_op(MSR_IA32_SPEC_CTRL, (for_all_cpus ?
                       MSR_OP_RENDEZVOUS_ALL : MSR_OP_LOCAL) |
                       (hw_ibrs_disable != 0 ? MSR_OP_ANDNOT : MSR_OP_OR),
                       IA32_SPEC_CTRL_IBRS, NULL);
                   hw_ibrs_active = hw_ibrs_disable == 0;
                   hw_ibrs_ibpb_active = 0;
           } else {
                   hw_ibrs_active = hw_ibrs_ibpb_active = (cpu_stdext_feature3 &
                       CPUID_STDEXT3_IBPB) != 0 && !hw_ibrs_disable;
           }
   }
   
   static int
   hw_ibrs_disable_handler(SYSCTL_HANDLER_ARGS)
   {
           int error, val;
   
           val = hw_ibrs_disable;
           error = sysctl_handle_int(oidp, &val, 0, req);
           if (error != 0 || req->newptr == NULL)
                   return (error);
           hw_ibrs_disable = val != 0;
           hw_ibrs_recalculate(true);
           return (0);
   }
   SYSCTL_PROC(_hw, OID_AUTO, ibrs_disable, CTLTYPE_INT | CTLFLAG_RWTUN |
       CTLFLAG_NOFETCH | CTLFLAG_MPSAFE, NULL, 0, hw_ibrs_disable_handler, "I",
       "Disable Indirect Branch Restricted Speculation");
   
   SYSCTL_PROC(_machdep_mitigations_ibrs, OID_AUTO, disable, CTLTYPE_INT |
       CTLFLAG_RWTUN | CTLFLAG_NOFETCH | CTLFLAG_MPSAFE, NULL, 0,
       hw_ibrs_disable_handler, "I",
       "Disable Indirect Branch Restricted Speculation");
   
   int hw_ssb_active;
   int hw_ssb_disable;
   
   SYSCTL_INT(_hw, OID_AUTO, spec_store_bypass_disable_active, CTLFLAG_RD,
       &hw_ssb_active, 0,
       "Speculative Store Bypass Disable active");
   
   SYSCTL_NODE(_machdep_mitigations, OID_AUTO, ssb,
       CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
       "Speculative Store Bypass Disable active");
   
   SYSCTL_INT(_machdep_mitigations_ssb, OID_AUTO, active, CTLFLAG_RD,
       &hw_ssb_active, 0, "Speculative Store Bypass Disable active");
   
   static void
   hw_ssb_set(bool enable, bool for_all_cpus)
   {
   
           if ((cpu_stdext_feature3 & CPUID_STDEXT3_SSBD) == 0) {
                   hw_ssb_active = 0;
                   return;
           }
           hw_ssb_active = enable;
           x86_msr_op(MSR_IA32_SPEC_CTRL,
               (enable ? MSR_OP_OR : MSR_OP_ANDNOT) |
               (for_all_cpus ? MSR_OP_SCHED_ALL : MSR_OP_LOCAL),
               IA32_SPEC_CTRL_SSBD, NULL);
   }
   
   void
   hw_ssb_recalculate(bool all_cpus)
   {
   
           switch (hw_ssb_disable) {
           default:
                   hw_ssb_disable = 0;
                   /* FALLTHROUGH */
           case 0: /* off */
                   hw_ssb_set(false, all_cpus);
                   break;
           case 1: /* on */
                   hw_ssb_set(true, all_cpus);
                   break;
           case 2: /* auto */
                  hw_ssb_set((cpu_ia32_arch_caps & IA32_ARCH_CAP_SSB_NO) != 0 ?
                      false : true, all_cpus);
                  break;
          }
  }
  
  static int
  hw_ssb_disable_handler(SYSCTL_HANDLER_ARGS)
  {
          int error, val;
  
          val = hw_ssb_disable;
          error = sysctl_handle_int(oidp, &val, 0, req);
          if (error != 0 || req->newptr == NULL)
                  return (error);
          hw_ssb_disable = val;
          hw_ssb_recalculate(true);
          return (0);
  }
  SYSCTL_PROC(_hw, OID_AUTO, spec_store_bypass_disable, CTLTYPE_INT |
      CTLFLAG_RWTUN | CTLFLAG_NOFETCH | CTLFLAG_MPSAFE, NULL, 0,
      hw_ssb_disable_handler, "I",
      "Speculative Store Bypass Disable (0 - off, 1 - on, 2 - auto)");
  
  SYSCTL_PROC(_machdep_mitigations_ssb, OID_AUTO, disable, CTLTYPE_INT |
      CTLFLAG_RWTUN | CTLFLAG_NOFETCH | CTLFLAG_MPSAFE, NULL, 0,
      hw_ssb_disable_handler, "I",
      "Speculative Store Bypass Disable (0 - off, 1 - on, 2 - auto)");
  
  int hw_mds_disable;
  
  /*
   * Handler for Microarchitectural Data Sampling issues.  Really not a
   * pointer to C function: on amd64 the code must not change any CPU
   * architectural state except possibly %rflags. Also, it is always
   * called with interrupts disabled.
   */
  void mds_handler_void(void);
  void mds_handler_verw(void);
  void mds_handler_ivb(void);
  void mds_handler_bdw(void);
  void mds_handler_skl_sse(void);
  void mds_handler_skl_avx(void);
  void mds_handler_skl_avx512(void);
  void mds_handler_silvermont(void);
  void (*mds_handler)(void) = mds_handler_void;
  
  static int
  sysctl_hw_mds_disable_state_handler(SYSCTL_HANDLER_ARGS)
  {
          const char *state;
  
          if (mds_handler == mds_handler_void)
                  state = "inactive";
          else if (mds_handler == mds_handler_verw)
                  state = "VERW";
          else if (mds_handler == mds_handler_ivb)
                  state = "software IvyBridge";
          else if (mds_handler == mds_handler_bdw)
                  state = "software Broadwell";
          else if (mds_handler == mds_handler_skl_sse)
                  state = "software Skylake SSE";
          else if (mds_handler == mds_handler_skl_avx)
                  state = "software Skylake AVX";
          else if (mds_handler == mds_handler_skl_avx512)
                  state = "software Skylake AVX512";
          else if (mds_handler == mds_handler_silvermont)
                  state = "software Silvermont";
          else
                  state = "unknown";
          return (SYSCTL_OUT(req, state, strlen(state)));
  }
  
  SYSCTL_PROC(_hw, OID_AUTO, mds_disable_state,
      CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
      sysctl_hw_mds_disable_state_handler, "A",
      "Microarchitectural Data Sampling Mitigation state");
  
  SYSCTL_NODE(_machdep_mitigations, OID_AUTO, mds,
      CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
      "Microarchitectural Data Sampling Mitigation state");
  
  SYSCTL_PROC(_machdep_mitigations_mds, OID_AUTO, state,
      CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
      sysctl_hw_mds_disable_state_handler, "A",
      "Microarchitectural Data Sampling Mitigation state");
  
  _Static_assert(__offsetof(struct pcpu, pc_mds_tmp) % 64 == 0, "MDS AVX512");
  
  void
  hw_mds_recalculate(void)
  {
          struct pcpu *pc;
          vm_offset_t b64;
          u_long xcr0;
          int i;
  
          /*
           * Allow user to force VERW variant even if MD_CLEAR is not
           * reported.  For instance, hypervisor might unknowingly
           * filter the cap out.
           * For the similar reasons, and for testing, allow to enable
           * mitigation even when MDS_NO cap is set.
           */
          if (cpu_vendor_id != CPU_VENDOR_INTEL || hw_mds_disable == 0 ||
              ((cpu_ia32_arch_caps & IA32_ARCH_CAP_MDS_NO) != 0 &&
              hw_mds_disable == 3)) {
                  mds_handler = mds_handler_void;
          } else if (((cpu_stdext_feature3 & CPUID_STDEXT3_MD_CLEAR) != 0 &&
              hw_mds_disable == 3) || hw_mds_disable == 1) {
                  mds_handler = mds_handler_verw;
          } else if (CPUID_TO_FAMILY(cpu_id) == 0x6 &&
              (CPUID_TO_MODEL(cpu_id) == 0x2e || CPUID_TO_MODEL(cpu_id) == 0x1e ||
              CPUID_TO_MODEL(cpu_id) == 0x1f || CPUID_TO_MODEL(cpu_id) == 0x1a ||
              CPUID_TO_MODEL(cpu_id) == 0x2f || CPUID_TO_MODEL(cpu_id) == 0x25 ||
              CPUID_TO_MODEL(cpu_id) == 0x2c || CPUID_TO_MODEL(cpu_id) == 0x2d ||
              CPUID_TO_MODEL(cpu_id) == 0x2a || CPUID_TO_MODEL(cpu_id) == 0x3e ||
              CPUID_TO_MODEL(cpu_id) == 0x3a) &&
              (hw_mds_disable == 2 || hw_mds_disable == 3)) {
                  /*
                   * Nehalem, SandyBridge, IvyBridge
                   */
                  CPU_FOREACH(i) {
                          pc = pcpu_find(i);
                          if (pc->pc_mds_buf == NULL) {
                                  pc->pc_mds_buf = malloc_domainset(672, M_TEMP,
                                      DOMAINSET_PREF(pc->pc_domain), M_WAITOK);
                                  bzero(pc->pc_mds_buf, 16);
                          }
                  }
                  mds_handler = mds_handler_ivb;
          } else if (CPUID_TO_FAMILY(cpu_id) == 0x6 &&
              (CPUID_TO_MODEL(cpu_id) == 0x3f || CPUID_TO_MODEL(cpu_id) == 0x3c ||
              CPUID_TO_MODEL(cpu_id) == 0x45 || CPUID_TO_MODEL(cpu_id) == 0x46 ||
              CPUID_TO_MODEL(cpu_id) == 0x56 || CPUID_TO_MODEL(cpu_id) == 0x4f ||
              CPUID_TO_MODEL(cpu_id) == 0x47 || CPUID_TO_MODEL(cpu_id) == 0x3d) &&
              (hw_mds_disable == 2 || hw_mds_disable == 3)) {
                  /*
                   * Haswell, Broadwell
                   */
                  CPU_FOREACH(i) {
                          pc = pcpu_find(i);
                          if (pc->pc_mds_buf == NULL) {
                                  pc->pc_mds_buf = malloc_domainset(1536, M_TEMP,
                                      DOMAINSET_PREF(pc->pc_domain), M_WAITOK);
                                  bzero(pc->pc_mds_buf, 16);
                          }
                  }
                  mds_handler = mds_handler_bdw;
          } else if (CPUID_TO_FAMILY(cpu_id) == 0x6 &&
              ((CPUID_TO_MODEL(cpu_id) == 0x55 && (cpu_id &
              CPUID_STEPPING) <= 5) ||
              CPUID_TO_MODEL(cpu_id) == 0x4e || CPUID_TO_MODEL(cpu_id) == 0x5e ||
              (CPUID_TO_MODEL(cpu_id) == 0x8e && (cpu_id &
              CPUID_STEPPING) <= 0xb) ||
              (CPUID_TO_MODEL(cpu_id) == 0x9e && (cpu_id &
              CPUID_STEPPING) <= 0xc)) &&
              (hw_mds_disable == 2 || hw_mds_disable == 3)) {
                  /*
                   * Skylake, KabyLake, CoffeeLake, WhiskeyLake,
                   * CascadeLake
                   */
                  CPU_FOREACH(i) {
                          pc = pcpu_find(i);
                          if (pc->pc_mds_buf == NULL) {
                                  pc->pc_mds_buf = malloc_domainset(6 * 1024,
                                      M_TEMP, DOMAINSET_PREF(pc->pc_domain),
                                      M_WAITOK);
                                  b64 = (vm_offset_t)malloc_domainset(64 + 63,
                                      M_TEMP, DOMAINSET_PREF(pc->pc_domain),
                                      M_WAITOK);
                                  pc->pc_mds_buf64 = (void *)roundup2(b64, 64);
                                  bzero(pc->pc_mds_buf64, 64);
                          }
                  }
                  xcr0 = rxcr(0);
                  if ((xcr0 & XFEATURE_ENABLED_ZMM_HI256) != 0 &&
                      (cpu_stdext_feature & CPUID_STDEXT_AVX512DQ) != 0)
                          mds_handler = mds_handler_skl_avx512;
                  else if ((xcr0 & XFEATURE_ENABLED_AVX) != 0 &&
                      (cpu_feature2 & CPUID2_AVX) != 0)
                          mds_handler = mds_handler_skl_avx;
                  else
                          mds_handler = mds_handler_skl_sse;
          } else if (CPUID_TO_FAMILY(cpu_id) == 0x6 &&
              ((CPUID_TO_MODEL(cpu_id) == 0x37 ||
              CPUID_TO_MODEL(cpu_id) == 0x4a ||
              CPUID_TO_MODEL(cpu_id) == 0x4c ||
              CPUID_TO_MODEL(cpu_id) == 0x4d ||
              CPUID_TO_MODEL(cpu_id) == 0x5a ||
              CPUID_TO_MODEL(cpu_id) == 0x5d ||
              CPUID_TO_MODEL(cpu_id) == 0x6e ||
              CPUID_TO_MODEL(cpu_id) == 0x65 ||
              CPUID_TO_MODEL(cpu_id) == 0x75 ||
              CPUID_TO_MODEL(cpu_id) == 0x1c ||
              CPUID_TO_MODEL(cpu_id) == 0x26 ||
              CPUID_TO_MODEL(cpu_id) == 0x27 ||
              CPUID_TO_MODEL(cpu_id) == 0x35 ||
              CPUID_TO_MODEL(cpu_id) == 0x36 ||
              CPUID_TO_MODEL(cpu_id) == 0x7a))) {
                  /* Silvermont, Airmont */
                  CPU_FOREACH(i) {
                          pc = pcpu_find(i);
                          if (pc->pc_mds_buf == NULL)
                                  pc->pc_mds_buf = malloc(256, M_TEMP, M_WAITOK);
                  }
                  mds_handler = mds_handler_silvermont;
          } else {
                  hw_mds_disable = 0;
                  mds_handler = mds_handler_void;
          }
  }
  
  static void
  hw_mds_recalculate_boot(void *arg __unused)
  {
  
          hw_mds_recalculate();
  }
  SYSINIT(mds_recalc, SI_SUB_SMP, SI_ORDER_ANY, hw_mds_recalculate_boot, NULL);
  
  static int
  sysctl_mds_disable_handler(SYSCTL_HANDLER_ARGS)
  {
          int error, val;
  
          val = hw_mds_disable;
          error = sysctl_handle_int(oidp, &val, 0, req);
          if (error != 0 || req->newptr == NULL)
                  return (error);
          if (val < 0 || val > 3)
                  return (EINVAL);
          hw_mds_disable = val;
          hw_mds_recalculate();
          return (0);
  }
  
  SYSCTL_PROC(_hw, OID_AUTO, mds_disable, CTLTYPE_INT |
      CTLFLAG_RWTUN | CTLFLAG_NOFETCH | CTLFLAG_MPSAFE, NULL, 0,
      sysctl_mds_disable_handler, "I",
      "Microarchitectural Data Sampling Mitigation "
      "(0 - off, 1 - on VERW, 2 - on SW, 3 - on AUTO)");
  
  SYSCTL_PROC(_machdep_mitigations_mds, OID_AUTO, disable, CTLTYPE_INT |
      CTLFLAG_RWTUN | CTLFLAG_NOFETCH | CTLFLAG_MPSAFE, NULL, 0,
      sysctl_mds_disable_handler, "I",
      "Microarchitectural Data Sampling Mitigation "
      "(0 - off, 1 - on VERW, 2 - on SW, 3 - on AUTO)");
  
  /*
   * Intel Transactional Memory Asynchronous Abort Mitigation
   * CVE-2019-11135
   */
  int x86_taa_enable;
  int x86_taa_state;
  enum {
          TAA_NONE        = 0,    /* No mitigation enabled */
          TAA_TSX_DISABLE = 1,    /* Disable TSX via MSR */
          TAA_VERW        = 2,    /* Use VERW mitigation */
          TAA_AUTO        = 3,    /* Automatically select the mitigation */
  
          /* The states below are not selectable by the operator */
  
          TAA_TAA_UC      = 4,    /* Mitigation present in microcode */
          TAA_NOT_PRESENT = 5     /* TSX is not present */
  };
  
  static void
  taa_set(bool enable, bool all)
  {
  
          x86_msr_op(MSR_IA32_TSX_CTRL,
              (enable ? MSR_OP_OR : MSR_OP_ANDNOT) |
              (all ? MSR_OP_RENDEZVOUS_ALL : MSR_OP_LOCAL),
              IA32_TSX_CTRL_RTM_DISABLE | IA32_TSX_CTRL_TSX_CPUID_CLEAR,
              NULL);
  }
  
  void
  x86_taa_recalculate(void)
  {
          static int taa_saved_mds_disable = 0;
          int taa_need = 0, taa_state = 0;
          int mds_disable = 0, need_mds_recalc = 0;
  
          /* Check CPUID.07h.EBX.HLE and RTM for the presence of TSX */
          if ((cpu_stdext_feature & CPUID_STDEXT_HLE) == 0 ||
              (cpu_stdext_feature & CPUID_STDEXT_RTM) == 0) {
                  /* TSX is not present */
                  x86_taa_state = TAA_NOT_PRESENT;
                  return;
          }
  
          /* Check to see what mitigation options the CPU gives us */
          if (cpu_ia32_arch_caps & IA32_ARCH_CAP_TAA_NO) {
                  /* CPU is not suseptible to TAA */
                  taa_need = TAA_TAA_UC;
          } else if (cpu_ia32_arch_caps & IA32_ARCH_CAP_TSX_CTRL) {
                  /*
                   * CPU can turn off TSX.  This is the next best option
                   * if TAA_NO hardware mitigation isn't present
                   */
                  taa_need = TAA_TSX_DISABLE;
          } else {
                  /* No TSX/TAA specific remedies are available. */
                  if (x86_taa_enable == TAA_TSX_DISABLE) {
                          if (bootverbose)
                                  printf("TSX control not available\n");
                          return;
                  } else
                          taa_need = TAA_VERW;
          }
  
          /* Can we automatically take action, or are we being forced? */
          if (x86_taa_enable == TAA_AUTO)
                  taa_state = taa_need;
          else
                  taa_state = x86_taa_enable;
  
          /* No state change, nothing to do */
          if (taa_state == x86_taa_state) {
                  if (bootverbose)
                          printf("No TSX change made\n");
                  return;
          }
  
          /* Does the MSR need to be turned on or off? */
          if (taa_state == TAA_TSX_DISABLE)
                  taa_set(true, true);
          else if (x86_taa_state == TAA_TSX_DISABLE)
                  taa_set(false, true);
  
          /* Does MDS need to be set to turn on VERW? */
          if (taa_state == TAA_VERW) {
                  taa_saved_mds_disable = hw_mds_disable;
                  mds_disable = hw_mds_disable = 1;
                  need_mds_recalc = 1;
          } else if (x86_taa_state == TAA_VERW) {
                  mds_disable = hw_mds_disable = taa_saved_mds_disable;
                  need_mds_recalc = 1;
          }
          if (need_mds_recalc) {
                  hw_mds_recalculate();
                  if (mds_disable != hw_mds_disable) {
                          if (bootverbose)
                                  printf("Cannot change MDS state for TAA\n");
                          /* Don't update our state */
                          return;
                  }
          }
  
          x86_taa_state = taa_state;
          return;
  }
  
  static void
  taa_recalculate_boot(void * arg __unused)
  {
  
          x86_taa_recalculate();
  }
  SYSINIT(taa_recalc, SI_SUB_SMP, SI_ORDER_ANY, taa_recalculate_boot, NULL);
  
  SYSCTL_NODE(_machdep_mitigations, OID_AUTO, taa,
      CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
      "TSX Asynchronous Abort Mitigation");
  
  static int
  sysctl_taa_handler(SYSCTL_HANDLER_ARGS)
  {
          int error, val;
  
          val = x86_taa_enable;
          error = sysctl_handle_int(oidp, &val, 0, req);
          if (error != 0 || req->newptr == NULL)
                  return (error);
          if (val < TAA_NONE || val > TAA_AUTO)
                  return (EINVAL);
          x86_taa_enable = val;
          x86_taa_recalculate();
          return (0);
  }
  
  SYSCTL_PROC(_machdep_mitigations_taa, OID_AUTO, enable, CTLTYPE_INT |
      CTLFLAG_RWTUN | CTLFLAG_NOFETCH | CTLFLAG_MPSAFE, NULL, 0,
      sysctl_taa_handler, "I",
      "TAA Mitigation enablement control "
      "(0 - off, 1 - disable TSX, 2 - VERW, 3 - on AUTO)");
  
  static int
  sysctl_taa_state_handler(SYSCTL_HANDLER_ARGS)
  {
          const char *state;
  
          switch (x86_taa_state) {
          case TAA_NONE:
                  state = "inactive";
                  break;
          case TAA_TSX_DISABLE:
                  state = "TSX disabled";
                  break;
          case TAA_VERW:
                  state = "VERW";
                  break;
          case TAA_TAA_UC:
                  state = "Mitigated in microcode";
                  break;
          case TAA_NOT_PRESENT:
                  state = "TSX not present";
                  break;
          default:
                  state = "unknown";
          }
  
          return (SYSCTL_OUT(req, state, strlen(state)));
  }
  
  SYSCTL_PROC(_machdep_mitigations_taa, OID_AUTO, state,
      CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
      sysctl_taa_state_handler, "A",
      "TAA Mitigation state");
  
  int __read_frequently cpu_flush_rsb_ctxsw;
  SYSCTL_INT(_machdep_mitigations, OID_AUTO, flush_rsb_ctxsw,
      CTLFLAG_RW | CTLFLAG_NOFETCH, &cpu_flush_rsb_ctxsw, 0,
      "Flush Return Stack Buffer on context switch");
  
  SYSCTL_NODE(_machdep_mitigations, OID_AUTO, rngds,
      CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
      "MCU Optimization, disable RDSEED mitigation");
  
  int x86_rngds_mitg_enable = 1;
  void
  x86_rngds_mitg_recalculate(bool all_cpus)
  {
          if ((cpu_stdext_feature3 & CPUID_STDEXT3_MCUOPT) == 0)
                  return;
          x86_msr_op(MSR_IA32_MCU_OPT_CTRL,
              (x86_rngds_mitg_enable ? MSR_OP_OR : MSR_OP_ANDNOT) |
              (all_cpus ? MSR_OP_RENDEZVOUS_ALL : MSR_OP_LOCAL),
              IA32_RNGDS_MITG_DIS, NULL);
  }
  
  static int
  sysctl_rngds_mitg_enable_handler(SYSCTL_HANDLER_ARGS)
  {
          int error, val;
  
          val = x86_rngds_mitg_enable;
          error = sysctl_handle_int(oidp, &val, 0, req);
          if (error != 0 || req->newptr == NULL)
                  return (error);
          x86_rngds_mitg_enable = val;
          x86_rngds_mitg_recalculate(true);
          return (0);
  }
  SYSCTL_PROC(_machdep_mitigations_rngds, OID_AUTO, enable, CTLTYPE_INT |
      CTLFLAG_RWTUN | CTLFLAG_NOFETCH | CTLFLAG_MPSAFE, NULL, 0,
      sysctl_rngds_mitg_enable_handler, "I",
      "MCU Optimization, disabling RDSEED mitigation control "
      "(0 - mitigation disabled (RDSEED optimized), 1 - mitigation enabled)");
  
  static int
  sysctl_rngds_state_handler(SYSCTL_HANDLER_ARGS)
  {
          const char *state;
  
          if ((cpu_stdext_feature3 & CPUID_STDEXT3_MCUOPT) == 0) {
                  state = "Not applicable";
          } else if (x86_rngds_mitg_enable == 0) {
                  state = "RDSEED not serialized";
          } else {
                  state = "Mitigated";
          }
          return (SYSCTL_OUT(req, state, strlen(state)));
  }
  SYSCTL_PROC(_machdep_mitigations_rngds, OID_AUTO, state,
      CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
      sysctl_rngds_state_handler, "A",
      "MCU Optimization state");
  
  /*
   * Enable and restore kernel text write permissions.
   * Callers must ensure that disable_wp()/restore_wp() are executed
   * without rescheduling on the same core.
   */
  bool
  disable_wp(void)
  {
          u_int cr0;
  
          cr0 = rcr0();
          if ((cr0 & CR0_WP) == 0)
                  return (false);
          load_cr0(cr0 & ~CR0_WP);
          return (true);
  }
  
  void
  restore_wp(bool old_wp)
  {
  
          if (old_wp)
                  load_cr0(rcr0() | CR0_WP);
  }
  
  bool
  acpi_get_fadt_bootflags(uint16_t *flagsp)
  {
  #ifdef DEV_ACPI
          ACPI_TABLE_FADT *fadt;
          vm_paddr_t physaddr;
  
          physaddr = acpi_find_table(ACPI_SIG_FADT);
          if (physaddr == 0)
                  return (false);
          fadt = acpi_map_table(physaddr, ACPI_SIG_FADT);
          if (fadt == NULL)
                  return (false);
          *flagsp = fadt->BootFlags;
          acpi_unmap_table(fadt);
          return (true);
  #else
          return (false);
  #endif
  }
  
  DEFINE_IFUNC(, uint64_t, rdtsc_ordered, (void))
  {
          bool cpu_is_amd = cpu_vendor_id == CPU_VENDOR_AMD ||
              cpu_vendor_id == CPU_VENDOR_HYGON;
  
          if ((amd_feature & AMDID_RDTSCP) != 0)
                  return (rdtscp);
          else if ((cpu_feature & CPUID_SSE2) != 0)
                  return (cpu_is_amd ? rdtsc_ordered_mfence :
                      rdtsc_ordered_lfence);
          else
                  return (rdtsc);
  }

Cache object: 8b16f4aaadea30733ce5bd009a1b015d