1 /*-
2  * Copyright (c) 1982, 1986 The Regents of the University of California.
3  * Copyright (c) 1989, 1990 William Jolitz
4  * Copyright (c) 1994 John Dyson
5  * Copyright (c) 2008-2018 The DragonFly Project.
6  * All rights reserved.
7  *
8  * This code is derived from software contributed to Berkeley by
9  * the Systems Programming Group of the University of Utah Computer
10  * Science Department, and William Jolitz.
11  *
12  * Redistribution and use in source and binary forms, with or without
13  * modification, are permitted provided that the following conditions
14  * are met:
15  * 1. Redistributions of source code must retain the above copyright
16  *    notice, this list of conditions and the following disclaimer.
17  * 2. Redistributions in binary form must reproduce the above copyright
18  *    notice, this list of conditions and the following disclaimer in the
19  *    documentation and/or other materials provided with the distribution.
20  * 3. All advertising materials mentioning features or use of this software
21  *    must display the following acknowledgement:
22  *	This product includes software developed by the University of
23  *	California, Berkeley and its contributors.
24  * 4. Neither the name of the University nor the names of its contributors
25  *    may be used to endorse or promote products derived from this software
26  *    without specific prior written permission.
27  *
28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38  * SUCH DAMAGE.
39  *
40  *	from: @(#)vm_machdep.c	7.3 (Berkeley) 5/13/91
41  *	Utah $Hdr: vm_machdep.c 1.16.1.1 89/06/23$
42  * $FreeBSD: src/sys/i386/i386/vm_machdep.c,v 1.132.2.9 2003/01/25 19:02:23 dillon Exp $
43  */
44 
45 #include "opt_reset.h"
46 
47 #include <sys/param.h>
48 #include <sys/systm.h>
49 #include <sys/malloc.h>
50 #include <sys/proc.h>
51 #include <sys/buf.h>
52 #include <sys/interrupt.h>
53 #include <sys/vnode.h>
54 #include <sys/vmmeter.h>
55 #include <sys/kernel.h>
56 #include <sys/sysctl.h>
57 #include <sys/unistd.h>
58 #include <sys/lwp.h>
59 
60 #include <machine/clock.h>
61 #include <machine/cpu.h>
62 #include <machine/md_var.h>
63 #include <machine/smp.h>
64 #include <machine/pcb.h>
65 #include <machine/pcb_ext.h>
66 #include <machine/segments.h>
67 #include <machine/globaldata.h>	/* npxthread */
68 #include <machine/specialreg.h>
69 
70 #include <vm/vm.h>
71 #include <vm/vm_param.h>
72 #include <sys/lock.h>
73 #include <vm/vm_kern.h>
74 #include <vm/vm_page.h>
75 #include <vm/vm_map.h>
76 #include <vm/vm_extern.h>
77 
78 #include <sys/thread2.h>
79 
80 #include <bus/isa/isa.h>
81 
82 static void	cpu_reset_real (void);
83 
84 static int spectre_mitigation = -1;
85 static int spectre_support = 0;
86 static int spectre_mode = 0;
87 SYSCTL_INT(_machdep, OID_AUTO, spectre_mode, CTLFLAG_RD,
88 	&spectre_mode, 0, "current Spectre enablements");
89 
90 static int mds_mitigation = -1;
91 static int mds_support = 0;
92 static int mds_mode = 0;
93 SYSCTL_INT(_machdep, OID_AUTO, mds_mode, CTLFLAG_RD,
94 	&mds_mode, 0, "current MDS enablements");
95 
96 /*
97  * Finish a fork operation, with lwp lp2 nearly set up.
98  * Copy and update the pcb, set up the stack so that the child
99  * ready to run and return to user mode.
100  */
101 void
102 cpu_fork(struct lwp *lp1, struct lwp *lp2, int flags)
103 {
104 	struct pcb *pcb2;
105 	struct pmap *pmap2;
106 
107 	if ((flags & RFPROC) == 0) {
108 		if ((flags & RFMEM) == 0) {
109 			/*
110 			 * Unshare user LDT.  > 1 test is MPSAFE.  While
111 			 * it can potentially race a 2->1 transition, the
112 			 * worst that happens is that we do an unnecessary
113 			 * ldt replacement.
114 			 */
115 			struct pcb *pcb1 = lp1->lwp_thread->td_pcb;
116 			struct pcb_ldt *pcb_ldt = pcb1->pcb_ldt;
117 
118 			if (pcb_ldt && pcb_ldt->ldt_refcnt > 1) {
119 				pcb_ldt = user_ldt_alloc(pcb1,pcb_ldt->ldt_len);
120 				user_ldt_free(pcb1);
121 				pcb1->pcb_ldt = pcb_ldt;
122 				set_user_ldt(pcb1);
123 			}
124 		}
125 		return;
126 	}
127 
128 	/* Ensure that lp1's pcb is up to date. */
129 	if (mdcpu->gd_npxthread == lp1->lwp_thread)
130 		npxsave(lp1->lwp_thread->td_savefpu);
131 
132 	/*
133 	 * Copy lp1's PCB.  This really only applies to the
134 	 * debug registers and FP state, but its faster to just copy the
135 	 * whole thing.  Because we only save the PCB at switchout time,
136 	 * the register state may not be current.
137 	 */
138 	pcb2 = lp2->lwp_thread->td_pcb;
139 	*pcb2 = *lp1->lwp_thread->td_pcb;
140 
141 	/*
142 	 * Create a new fresh stack for the new process.
143 	 * Copy the trap frame for the return to user mode as if from a
144 	 * syscall.  This copies the user mode register values.
145 	 *
146 	 * pcb_rsp must allocate an additional call-return pointer below
147 	 * the trap frame which will be restored by cpu_heavy_restore from
148 	 * PCB_RIP, and the thread's td_sp pointer must allocate an
149 	 * additonal two quadwords below the pcb_rsp call-return pointer to
150 	 * hold the LWKT restore function pointer and rflags.
151 	 *
152 	 * The LWKT restore function pointer must be set to cpu_heavy_restore,
153 	 * which is our standard heavy-weight process switch-in function.
154 	 * YYY eventually we should shortcut fork_return and fork_trampoline
155 	 * to use the LWKT restore function directly so we can get rid of
156 	 * all the extra crap we are setting up.
157 	 */
158 	lp2->lwp_md.md_regs = (struct trapframe *)pcb2 - 1;
159 	bcopy(lp1->lwp_md.md_regs, lp2->lwp_md.md_regs, sizeof(*lp2->lwp_md.md_regs));
160 
161 	/*
162 	 * Set registers for trampoline to user mode.  Leave space for the
163 	 * return address on stack.  These are the kernel mode register values.
164 	 *
165 	 * Set the new pmap CR3.  If the new process uses isolated VM spaces,
166 	 * also set the isolated CR3.
167 	 */
168 	pmap2 = vmspace_pmap(lp2->lwp_proc->p_vmspace);
169 	pcb2->pcb_cr3 = vtophys(pmap2->pm_pml4);
170 	if ((pcb2->pcb_flags & PCB_ISOMMU) && pmap2->pm_pmlpv_iso) {
171 		pcb2->pcb_cr3_iso = vtophys(pmap2->pm_pml4_iso);
172 	} else {
173 		pcb2->pcb_flags &= ~PCB_ISOMMU;
174 		pcb2->pcb_cr3_iso = 0;
175 	}
176 
177 #if 0
178 	/*
179 	 * Per-process spectre mitigation (future)
180 	 */
181 	pcb2->pcb_flags &= ~(PCB_IBRS1 | PCB_IBRS2);
182 	switch (spectre_mitigation) {
183 	case 1:
184 		pcb2->pcb_flags |= PCB_IBRS1;
185 		break;
186 	case 2:
187 		pcb2->pcb_flags |= PCB_IBRS2;
188 		break;
189 	default:
190 		break;
191 	}
192 #endif
193 
194 	pcb2->pcb_rbx = (unsigned long)fork_return;	/* fork_trampoline argument */
195 	pcb2->pcb_rbp = 0;
196 	pcb2->pcb_rsp = (unsigned long)lp2->lwp_md.md_regs - sizeof(void *);
197 	pcb2->pcb_r12 = (unsigned long)lp2;		/* fork_trampoline argument */
198 	pcb2->pcb_r13 = 0;
199 	pcb2->pcb_r14 = 0;
200 	pcb2->pcb_r15 = 0;
201 	pcb2->pcb_rip = (unsigned long)fork_trampoline;
202 	lp2->lwp_thread->td_sp = (char *)(pcb2->pcb_rsp - sizeof(void *));
203 	*(u_int64_t *)lp2->lwp_thread->td_sp = PSL_USER;
204 	lp2->lwp_thread->td_sp -= sizeof(void *);
205 	*(void **)lp2->lwp_thread->td_sp = (void *)cpu_heavy_restore;
206 
207 	/*
208 	 * pcb2->pcb_ldt:	duplicated below, if necessary.
209 	 * pcb2->pcb_savefpu:	cloned above.
210 	 * pcb2->pcb_flags:	cloned above
211 	 * pcb2->pcb_onfault:	cloned above (always NULL here).
212 	 * pcb2->pcb_onfault_sp:cloned above (dont care)
213 	 */
214 
215 	/*
216 	 * XXX don't copy the i/o pages.  this should probably be fixed.
217 	 */
218 	pcb2->pcb_ext = NULL;
219 
220         /* Copy the LDT, if necessary. */
221         if (pcb2->pcb_ldt != NULL) {
222 		if (flags & RFMEM) {
223 			atomic_add_int(&pcb2->pcb_ldt->ldt_refcnt, 1);
224 		} else {
225 			pcb2->pcb_ldt = user_ldt_alloc(pcb2,
226 						       pcb2->pcb_ldt->ldt_len);
227 		}
228         }
229 	bcopy(&lp1->lwp_thread->td_tls, &lp2->lwp_thread->td_tls,
230 	      sizeof(lp2->lwp_thread->td_tls));
231 	/*
232 	 * Now, cpu_switch() can schedule the new lwp.
233 	 * pcb_rsp is loaded pointing to the cpu_switch() stack frame
234 	 * containing the return address when exiting cpu_switch.
235 	 * This will normally be to fork_trampoline(), which will have
236 	 * %rbx loaded with the new lwp's pointer.  fork_trampoline()
237 	 * will set up a stack to call fork_return(lp, frame); to complete
238 	 * the return to user-mode.
239 	 */
240 }
241 
242 /*
243  * Prepare new lwp to return to the address specified in params.
244  */
245 int
246 cpu_prepare_lwp(struct lwp *lp, struct lwp_params *params)
247 {
248 	struct trapframe *regs = lp->lwp_md.md_regs;
249 	void *bad_return = NULL;
250 	int error;
251 
252 	regs->tf_rip = (long)params->lwp_func;
253 	regs->tf_rsp = (long)params->lwp_stack;
254 	/* Set up argument for function call */
255 	regs->tf_rdi = (long)params->lwp_arg;
256 
257 	/*
258 	 * Set up fake return address.  As the lwp function may never return,
259 	 * we simply copy out a NULL pointer and force the lwp to receive
260 	 * a SIGSEGV if it returns anyways.
261 	 */
262 	regs->tf_rsp -= sizeof(void *);
263 	error = copyout(&bad_return, (void *)regs->tf_rsp, sizeof(bad_return));
264 	if (error)
265 		return (error);
266 
267 	cpu_set_fork_handler(lp,
268 	    (void (*)(void *, struct trapframe *))generic_lwp_return, lp);
269 	return (0);
270 }
271 
272 /*
273  * Intercept the return address from a freshly forked process that has NOT
274  * been scheduled yet.
275  *
276  * This is needed to make kernel threads stay in kernel mode.
277  */
278 void
279 cpu_set_fork_handler(struct lwp *lp, void (*func)(void *, struct trapframe *),
280 		     void *arg)
281 {
282 	/*
283 	 * Note that the trap frame follows the args, so the function
284 	 * is really called like this:  func(arg, frame);
285 	 */
286 	lp->lwp_thread->td_pcb->pcb_rbx = (long)func;	/* function */
287 	lp->lwp_thread->td_pcb->pcb_r12 = (long)arg;	/* first arg */
288 }
289 
290 void
291 cpu_set_thread_handler(thread_t td, void (*rfunc)(void), void *func, void *arg)
292 {
293 	td->td_pcb->pcb_rbx = (long)func;
294 	td->td_pcb->pcb_r12 = (long)arg;
295 	td->td_switch = cpu_lwkt_switch;
296 	td->td_sp -= sizeof(void *);
297 	*(void **)td->td_sp = rfunc;	/* exit function on return */
298 	td->td_sp -= sizeof(void *);
299 	*(void **)td->td_sp = cpu_kthread_restore;
300 }
301 
302 void
303 cpu_lwp_exit(void)
304 {
305 	struct thread *td = curthread;
306 	struct pcb *pcb;
307 
308 	pcb = td->td_pcb;
309 
310 	/* Some x86 functionality was dropped */
311 	KKASSERT(pcb->pcb_ext == NULL);
312 
313 	/*
314 	 * disable all hardware breakpoints
315 	 */
316         if (pcb->pcb_flags & PCB_DBREGS) {
317                 reset_dbregs();
318                 pcb->pcb_flags &= ~PCB_DBREGS;
319         }
320 	td->td_gd->gd_cnt.v_swtch++;
321 
322 	crit_enter_quick(td);
323 	if (td->td_flags & TDF_TSLEEPQ)
324 		tsleep_remove(td);
325 	lwkt_deschedule_self(td);
326 	lwkt_remove_tdallq(td);
327 	cpu_thread_exit();
328 }
329 
330 /*
331  * Terminate the current thread.  The caller must have already acquired
332  * the thread's rwlock and placed it on a reap list or otherwise notified
333  * a reaper of its existance.  We set a special assembly switch function which
334  * releases td_rwlock after it has cleaned up the MMU state and switched
335  * out the stack.
336  *
337  * Must be caller from a critical section and with the thread descheduled.
338  */
339 void
340 cpu_thread_exit(void)
341 {
342 	npxexit();
343 	curthread->td_switch = cpu_exit_switch;
344 	curthread->td_flags |= TDF_EXITING;
345 	lwkt_switch();
346 	panic("cpu_thread_exit: lwkt_switch() unexpectedly returned");
347 }
348 
349 void
350 cpu_reset(void)
351 {
352 	cpu_reset_real();
353 }
354 
355 static void
356 cpu_reset_real(void)
357 {
358 	/*
359 	 * Attempt to do a CPU reset via the keyboard controller,
360 	 * do not turn off the GateA20, as any machine that fails
361 	 * to do the reset here would then end up in no man's land.
362 	 */
363 
364 #if !defined(BROKEN_KEYBOARD_RESET)
365 	outb(IO_KBD + 4, 0xFE);
366 	DELAY(500000);	/* wait 0.5 sec to see if that did it */
367 	kprintf("Keyboard reset did not work, attempting CPU shutdown\n");
368 	DELAY(1000000);	/* wait 1 sec for kprintf to complete */
369 #endif
370 #if 0 /* JG */
371 	/* force a shutdown by unmapping entire address space ! */
372 	bzero((caddr_t) PTD, PAGE_SIZE);
373 #endif
374 
375 	/* "good night, sweet prince .... <THUNK!>" */
376 	cpu_invltlb();
377 	/* NOTREACHED */
378 	while(1);
379 }
380 
381 static void
382 swi_vm(void *arg, void *frame)
383 {
384 	if (busdma_swi_pending != 0)
385 		busdma_swi();
386 }
387 
388 static void
389 swi_vm_setup(void *arg)
390 {
391 	register_swi_mp(SWI_VM, swi_vm, NULL, "swi_vm", NULL, 0);
392 }
393 
394 SYSINIT(swi_vm_setup, SI_BOOT2_MACHDEP, SI_ORDER_ANY, swi_vm_setup, NULL);
395 
396 /*
397  * NOTE: This routine is also called after a successful microcode
398  *	 reload on cpu 0.
399  */
400 void mitigation_vm_setup(void *arg);
401 
402 /*
403  * Check for IBPB and IBRS support
404  *
405  * This bits also specify desired modes in the spectre_mitigation sysctl.
406  */
407 #define IBRS_SUPPORTED		0x0001
408 #define STIBP_SUPPORTED		0x0002
409 #define IBPB_SUPPORTED		0x0004
410 #define IBRS_AUTO_SUPPORTED	0x0008
411 #define STIBP_AUTO_SUPPORTED	0x0010
412 #define IBRS_PREFERRED_REQUEST	0x0020
413 
414 static
415 int
416 spectre_check_support(void)
417 {
418 	uint32_t p[4];
419 	int rv = 0;
420 
421 	/*
422 	 * Spectre mitigation hw bits
423 	 *
424 	 * IBRS		Indirect Branch Restricted Speculation   (isolation)
425 	 * STIBP	Single Thread Indirect Branch Prediction (isolation)
426 	 * IBPB		Branch Prediction Barrier                (barrier)
427 	 *
428 	 * IBRS and STIBP must be toggled (enabled on entry to kernel,
429 	 * disabled on exit, as well as disabled during any MWAIT/HLT).
430 	 * When *_AUTO bits are available, IBRS and STIBP may be left
431 	 * turned on and do not have to be toggled on kernel entry/exit.
432 	 * Be sure to clear before going idle (else hyperthread performance
433 	 * will drop).
434 	 *
435 	 * All this shit has enormous overhead.  IBPB in particular, and
436 	 * non-auto modes are disabled by default.
437 	 */
438 	if (cpu_vendor_id == CPU_VENDOR_INTEL) {
439 		p[0] = 0;
440 		p[1] = 0;
441 		p[2] = 0;
442 		p[3] = 0;
443 		cpuid_count(7, 0, p);
444 		if (p[3] & CPUID_STDEXT3_IBPB)
445 			rv |= IBRS_SUPPORTED | IBPB_SUPPORTED;
446 		if (p[3] & CPUID_STDEXT3_STIBP)
447 			rv |= STIBP_SUPPORTED;
448 
449 		/*
450 		 * 0x80000008 p[1] bit 12 indicates IBPB support
451 		 *
452 		 * This bit might be set even though STDEXT3_IBPB is not set.
453 		 */
454 		p[0] = 0;
455 		p[1] = 0;
456 		p[2] = 0;
457 		p[3] = 0;
458 		do_cpuid(0x80000008U, p);
459 		if (p[1] & CPUID_CAPEX_IBPB)
460 			rv |= IBPB_SUPPORTED;
461 	} else if (cpu_vendor_id == CPU_VENDOR_AMD) {
462 		/*
463 		 * 0x80000008
464 		 *	p[1] bit 12 indicates IBPB support
465 		 *	p[1] bit 14 indicates IBRS support
466 		 *	p[1] bit 15 indicates STIBP support
467 		 *
468 		 *	p[1] bit 16 indicates IBRS auto support
469 		 *	p[1] bit 17 indicates STIBP auto support
470 		 *	p[1] bit 18 indicates processor prefers using
471 		 *		IBRS instead of retpoline.
472 		 */
473 		p[0] = 0;
474 		p[1] = 0;
475 		p[2] = 0;
476 		p[3] = 0;
477 		do_cpuid(0x80000008U, p);
478 		if (p[1] & CPUID_CAPEX_IBPB)
479 			rv |= IBPB_SUPPORTED;
480 		if (p[1] & CPUID_CAPEX_IBRS)
481 			rv |= IBRS_SUPPORTED;
482 		if (p[1] & CPUID_CAPEX_STIBP)
483 			rv |= STIBP_SUPPORTED;
484 
485 		if (p[1] & CPUID_CAPEX_IBRS_ALWAYSON)
486 			rv |= IBRS_AUTO_SUPPORTED;
487 		if (p[1] & CPUID_CAPEX_STIBP_ALWAYSON)
488 			rv |= STIBP_AUTO_SUPPORTED;
489 		if (p[1] & CPUID_CAPEX_PREFER_IBRS)
490 			rv |= IBRS_PREFERRED_REQUEST;
491 	}
492 
493 	return rv;
494 }
495 
496 /*
497  * Iterate CPUs and adjust MSR for global operations, since
498  * the KMMU* code won't do it if spectre_mitigation is 0 or 2.
499  */
500 #define CHECK(flag)	(spectre_mitigation & spectre_support & (flag))
501 
502 static
503 void
504 spectre_sysctl_changed(void)
505 {
506 	globaldata_t save_gd;
507 	struct trampframe *tr;
508 	int spec_ctrl;
509 	int spec_mask;
510 	int mode;
511 	int n;
512 
513 	spec_mask = SPEC_CTRL_IBRS | SPEC_CTRL_STIBP |
514 		    SPEC_CTRL_DUMMY_ENABLE | SPEC_CTRL_DUMMY_IBPB;
515 
516 	/*
517 	 * Fixup state
518 	 */
519 	mode = 0;
520 	save_gd = mycpu;
521 	for (n = 0; n < ncpus; ++n) {
522 		lwkt_setcpu_self(globaldata_find(n));
523 		cpu_ccfence();
524 		tr = &pscpu->trampoline;
525 
526 		/*
527 		 * Make sure we are cleaned out.
528 		 *
529 		 * XXX cleanup, reusing globals inside the loop (they get
530 		 * set to the same thing each loop)
531 		 *
532 		 * [0] kernel entry (idle exit)
533 		 * [1] kernel exit  (idle entry)
534 		 */
535 		tr->tr_pcb_spec_ctrl[0] &= ~spec_mask;
536 		tr->tr_pcb_spec_ctrl[1] &= ~spec_mask;
537 
538 		/*
539 		 * Don't try to parse if not available
540 		 */
541 		if (spectre_mitigation < 0)
542 			continue;
543 
544 		/*
545 		 * IBRS mode.  Auto overrides toggling.
546 		 *
547 		 * Only set the ENABLE flag if we have to toggle something
548 		 * on entry and exit.
549 		 */
550 		spec_ctrl = 0;
551 		if (CHECK(IBRS_AUTO_SUPPORTED)) {
552 			spec_ctrl |= SPEC_CTRL_IBRS;
553 			mode |= IBRS_AUTO_SUPPORTED;
554 		} else if (CHECK(IBRS_SUPPORTED)) {
555 			spec_ctrl |= SPEC_CTRL_IBRS | SPEC_CTRL_DUMMY_ENABLE;
556 			mode |= IBRS_SUPPORTED;
557 		}
558 		if (CHECK(STIBP_AUTO_SUPPORTED)) {
559 			spec_ctrl |= SPEC_CTRL_STIBP;
560 			mode |= STIBP_AUTO_SUPPORTED;
561 		} else if (CHECK(STIBP_SUPPORTED)) {
562 			spec_ctrl |= SPEC_CTRL_STIBP | SPEC_CTRL_DUMMY_ENABLE;
563 			mode |= STIBP_SUPPORTED;
564 		}
565 
566 		/*
567 		 * IBPB requested and supported.
568 		 */
569 		if (CHECK(IBPB_SUPPORTED)) {
570 			spec_ctrl |= SPEC_CTRL_DUMMY_IBPB;
571 			mode |= IBPB_SUPPORTED;
572 		}
573 
574 		/*
575 		 * Update the MSR if the cpu supports the modes to ensure
576 		 * proper disablement if the user disabled the mode.
577 		 */
578 		if (spectre_support & (IBRS_SUPPORTED | IBRS_AUTO_SUPPORTED |
579 				    STIBP_SUPPORTED | STIBP_AUTO_SUPPORTED)) {
580 			wrmsr(MSR_SPEC_CTRL,
581 			      spec_ctrl & (SPEC_CTRL_IBRS|SPEC_CTRL_STIBP));
582 		}
583 
584 		/*
585 		 * Update spec_ctrl fields in the trampoline.
586 		 *
587 		 * [0] on-kernel-entry (on-idle-exit)
588 		 * [1] on-kernel-exit  (on-idle-entry)
589 		 *
590 		 * When auto mode is supported we leave the bit set, otherwise
591 		 * we clear the bits.
592 		 */
593 		tr->tr_pcb_spec_ctrl[0] |= spec_ctrl;
594 		if (CHECK(IBRS_AUTO_SUPPORTED) == 0)
595 			spec_ctrl &= ~SPEC_CTRL_IBRS;
596 		if (CHECK(STIBP_AUTO_SUPPORTED) == 0)
597 			spec_ctrl &= ~SPEC_CTRL_STIBP;
598 		tr->tr_pcb_spec_ctrl[1] |= spec_ctrl;
599 
600 		/*
601 		 * Make sure we set this on the first loop.  It will be
602 		 * the same value on remaining loops.
603 		 */
604 		spectre_mode = mode;
605 	}
606 	lwkt_setcpu_self(save_gd);
607 	cpu_ccfence();
608 
609 	/*
610 	 * Console message on mitigation mode change
611 	 */
612 	kprintf("Spectre: support=(");
613 	if (spectre_support == 0) {
614 		kprintf(" none");
615 	} else {
616 		if (spectre_support & IBRS_SUPPORTED)
617 			kprintf(" IBRS");
618 		if (spectre_support & STIBP_SUPPORTED)
619 			kprintf(" STIBP");
620 		if (spectre_support & IBPB_SUPPORTED)
621 			kprintf(" IBPB");
622 		if (spectre_support & IBRS_AUTO_SUPPORTED)
623 			kprintf(" IBRS_AUTO");
624 		if (spectre_support & STIBP_AUTO_SUPPORTED)
625 			kprintf(" STIBP_AUTO");
626 		if (spectre_support & IBRS_PREFERRED_REQUEST)
627 			kprintf(" IBRS_REQUESTED");
628 	}
629 	kprintf(" ) req=%04x operating=(", (uint16_t)spectre_mitigation);
630 	if (spectre_mode == 0) {
631 		kprintf(" none");
632 	} else {
633 		if (spectre_mode & IBRS_SUPPORTED)
634 			kprintf(" IBRS");
635 		if (spectre_mode & STIBP_SUPPORTED)
636 			kprintf(" STIBP");
637 		if (spectre_mode & IBPB_SUPPORTED)
638 			kprintf(" IBPB");
639 		if (spectre_mode & IBRS_AUTO_SUPPORTED)
640 			kprintf(" IBRS_AUTO");
641 		if (spectre_mode & STIBP_AUTO_SUPPORTED)
642 			kprintf(" STIBP_AUTO");
643 		if (spectre_mode & IBRS_PREFERRED_REQUEST)
644 			kprintf(" IBRS_REQUESTED");
645 	}
646 	kprintf(" )\n");
647 }
648 
649 #undef CHECK
650 
651 /*
652  * User changes sysctl value
653  */
654 static int
655 sysctl_spectre_mitigation(SYSCTL_HANDLER_ARGS)
656 {
657 	char buf[128];
658 	char *ptr;
659 	char *iter;
660 	size_t len;
661 	int spectre;
662 	int error = 0;
663 	int loop = 0;
664 
665 	/*
666 	 * Return current operating mode or support.
667 	 */
668 	if (oidp->oid_kind & CTLFLAG_WR)
669 		spectre = spectre_mode;
670 	else
671 		spectre = spectre_support;
672 
673 	spectre &= (IBRS_SUPPORTED | IBRS_AUTO_SUPPORTED |
674 		    STIBP_SUPPORTED | STIBP_AUTO_SUPPORTED |
675 		    IBPB_SUPPORTED);
676 	while (spectre) {
677 		if (error)
678 			break;
679 		if (loop++) {
680 			error = SYSCTL_OUT(req, " ", 1);
681 			if (error)
682 				break;
683 		}
684 		if (spectre & IBRS_SUPPORTED) {
685 			spectre &= ~IBRS_SUPPORTED;
686 			error = SYSCTL_OUT(req, "IBRS", 4);
687 		} else
688 		if (spectre & IBRS_AUTO_SUPPORTED) {
689 			spectre &= ~IBRS_AUTO_SUPPORTED;
690 			error = SYSCTL_OUT(req, "IBRS_AUTO", 9);
691 		} else
692 		if (spectre & STIBP_SUPPORTED) {
693 			spectre &= ~STIBP_SUPPORTED;
694 			error = SYSCTL_OUT(req, "STIBP", 5);
695 		} else
696 		if (spectre & STIBP_AUTO_SUPPORTED) {
697 			spectre &= ~STIBP_AUTO_SUPPORTED;
698 			error = SYSCTL_OUT(req, "STIBP_AUTO", 10);
699 		} else
700 		if (spectre & IBPB_SUPPORTED) {
701 			spectre &= ~IBPB_SUPPORTED;
702 			error = SYSCTL_OUT(req, "IBPB", 4);
703 		}
704 	}
705 	if (loop == 0) {
706 		error = SYSCTL_OUT(req, "NONE", 4);
707 	}
708 
709 	if (error || req->newptr == NULL)
710 		return error;
711 	if ((oidp->oid_kind & CTLFLAG_WR) == 0)
712 		return error;
713 
714 	/*
715 	 * Change current operating mode
716 	 */
717 	len = req->newlen - req->newidx;
718 	if (len >= sizeof(buf)) {
719 		error = EINVAL;
720 		len = 0;
721 	} else {
722 		error = SYSCTL_IN(req, buf, len);
723 	}
724 	buf[len] = 0;
725 	iter = &buf[0];
726 	spectre = 0;
727 
728 	while (error == 0 && iter) {
729 		ptr = strsep(&iter, " ,\t\r\n");
730 		if (*ptr == 0)
731 			continue;
732 		if (strcasecmp(ptr, "NONE") == 0)
733 			spectre |= 0;
734 		else if (strcasecmp(ptr, "IBRS") == 0)
735 			spectre |= IBRS_SUPPORTED;
736 		else if (strcasecmp(ptr, "IBRS_AUTO") == 0)
737 			spectre |= IBRS_AUTO_SUPPORTED;
738 		else if (strcasecmp(ptr, "STIBP") == 0)
739 			spectre |= STIBP_SUPPORTED;
740 		else if (strcasecmp(ptr, "STIBP_AUTO") == 0)
741 			spectre |= STIBP_AUTO_SUPPORTED;
742 		else if (strcasecmp(ptr, "IBPB") == 0)
743 			spectre |= IBPB_SUPPORTED;
744 		else
745 			error = ENOENT;
746 	}
747 	if (error == 0) {
748 		spectre_mitigation = spectre;
749 		spectre_sysctl_changed();
750 	}
751 	return error;
752 }
753 
754 SYSCTL_PROC(_machdep, OID_AUTO, spectre_mitigation,
755 	CTLTYPE_STRING | CTLFLAG_RW,
756 	0, 0, sysctl_spectre_mitigation, "A", "Spectre exploit mitigation");
757 SYSCTL_PROC(_machdep, OID_AUTO, spectre_support,
758 	CTLTYPE_STRING | CTLFLAG_RD,
759 	0, 0, sysctl_spectre_mitigation, "A", "Spectre supported features");
760 
761 /*
762  * NOTE: Called at SI_BOOT2_MACHDEP and also when the microcode is
763  *	 updated.  Microcode updates must be applied to all cpus
764  *	 for support to be recognized.
765  */
766 static void
767 spectre_vm_setup(void *arg)
768 {
769 	int inconsistent = 0;
770 	int supmask;
771 
772 	/*
773 	 * Fetch tunable in auto mode
774 	 */
775 	if (spectre_mitigation < 0) {
776 		TUNABLE_INT_FETCH("machdep.spectre_mitigation",
777 				  &spectre_mitigation);
778 	}
779 
780 	if ((supmask = spectre_check_support()) != 0) {
781 		/*
782 		 * Must be supported on all cpus before we
783 		 * can enable it.  Returns silently if it
784 		 * isn't.
785 		 *
786 		 * NOTE! arg != NULL indicates we were called
787 		 *	 from cpuctl after a successful microcode
788 		 *	 update.
789 		 */
790 		if (arg != NULL) {
791 			globaldata_t save_gd;
792 			int n;
793 
794 			save_gd = mycpu;
795 			for (n = 0; n < ncpus; ++n) {
796 				lwkt_setcpu_self(globaldata_find(n));
797 				cpu_ccfence();
798 				if (spectre_check_support() !=
799 				    supmask) {
800 					inconsistent = 1;
801 					break;
802 				}
803 			}
804 			lwkt_setcpu_self(save_gd);
805 			cpu_ccfence();
806 		}
807 	}
808 
809 	/*
810 	 * Be silent while microcode is being loaded on various CPUs,
811 	 * until all done.
812 	 */
813 	if (inconsistent) {
814 		spectre_mitigation = -1;
815 		spectre_support = 0;
816 		return;
817 	}
818 
819 	/*
820 	 * IBRS support
821 	 */
822 	spectre_support = supmask;
823 
824 	/*
825 	 * Enable spectre_mitigation, set defaults if -1, adjust
826 	 * tuned value according to support if not.
827 	 *
828 	 * NOTE!  We do not enable IBPB for user->kernel transitions
829 	 *	  by default, so this code is commented out for now.
830 	 */
831 	if (spectre_support) {
832 		if (spectre_mitigation < 0) {
833 			spectre_mitigation = 0;
834 
835 			/*
836 			 * IBRS toggling not currently recommended as a
837 			 * default.
838 			 */
839 			if (spectre_support & IBRS_AUTO_SUPPORTED)
840 				spectre_mitigation |= IBRS_AUTO_SUPPORTED;
841 			else if (spectre_support & IBRS_SUPPORTED)
842 				spectre_mitigation |= 0;
843 
844 			/*
845 			 * STIBP toggling not currently recommended as a
846 			 * default.
847 			 */
848 			if (spectre_support & STIBP_AUTO_SUPPORTED)
849 				spectre_mitigation |= STIBP_AUTO_SUPPORTED;
850 			else if (spectre_support & STIBP_SUPPORTED)
851 				spectre_mitigation |= 0;
852 
853 			/*
854 			 * IBPB adds enormous (~2uS) overhead to system
855 			 * calls etc, we do not enable it by default.
856 			 */
857 			if (spectre_support & IBPB_SUPPORTED)
858 				spectre_mitigation |= 0;
859 		}
860 	} else {
861 		spectre_mitigation = -1;
862 	}
863 
864 	/*
865 	 * Disallow sysctl changes when there is no support (otherwise
866 	 * the wrmsr will cause a protection fault).
867 	 */
868 	if (spectre_mitigation < 0)
869 		sysctl___machdep_spectre_mitigation.oid_kind &= ~CTLFLAG_WR;
870 	else
871 		sysctl___machdep_spectre_mitigation.oid_kind |= CTLFLAG_WR;
872 
873 	spectre_sysctl_changed();
874 }
875 
876 #define MDS_AVX512_4VNNIW_SUPPORTED	0x0001
877 #define MDS_AVX512_4FMAPS_SUPPORTED	0x0002
878 #define MDS_MD_CLEAR_SUPPORTED		0x0004
879 #define MDS_TSX_FORCE_ABORT_SUPPORTED	0x0008
880 #define MDS_NOT_REQUIRED		0x8000
881 
882 static
883 int
884 mds_check_support(void)
885 {
886 	uint64_t msr;
887 	uint32_t p[4];
888 	int rv = 0;
889 
890 	/*
891 	 * MDS mitigation hw bits
892 	 *
893 	 * MD_CLEAR	Use microcode-supported verf insn.  This is the
894 	 *		only mode we really support.
895 	 */
896 	if (cpu_vendor_id == CPU_VENDOR_INTEL) {
897 		p[0] = 0;
898 		p[1] = 0;
899 		p[2] = 0;
900 		p[3] = 0;
901 		cpuid_count(7, 0, p);
902 
903 		/*
904 		 * Some hypervisors fail to implement
905 		 * MSR_IA32_ARCH_CAPABILITIES.
906 		 */
907 		if (p[3] & CPUID_STDEXT3_ARCH_CAP) {
908 			msr = 0;
909 			if (rdmsr_safe(MSR_IA32_ARCH_CAPABILITIES, &msr)) {
910 				kprintf("Warning: MSR_IA32_ARCH_CAPABILITIES "
911 					"cannot be accessed\n");
912 			}
913 			if (msr & IA32_ARCH_CAP_MDS_NO)
914 				rv = MDS_NOT_REQUIRED;
915 		}
916 		if (p[3] & CPUID_STDEXT3_AVX5124VNNIW)
917 			rv |= MDS_AVX512_4VNNIW_SUPPORTED;
918 		if (p[3] & CPUID_STDEXT3_AVX5124FMAPS)
919 			rv |= MDS_AVX512_4FMAPS_SUPPORTED;
920 		if (p[3] & CPUID_STDEXT3_MD_CLEAR)
921 			rv |= MDS_MD_CLEAR_SUPPORTED;
922 		if (p[3] & CPUID_STDEXT3_TSXFA)
923 			rv |= MDS_TSX_FORCE_ABORT_SUPPORTED;
924 	} else {
925 		rv = MDS_NOT_REQUIRED;
926 	}
927 
928 	return rv;
929 }
930 
931 /*
932  * Iterate CPUs and adjust MSR for global operations, since
933  * the KMMU* code won't do it if spectre_mitigation is 0 or 2.
934  */
935 #define CHECK(flag)	(mds_mitigation & mds_support & (flag))
936 
937 static
938 void
939 mds_sysctl_changed(void)
940 {
941 	globaldata_t save_gd;
942 	struct trampframe *tr;
943 	int spec_ctrl;
944 	int spec_mask;
945 	int mode;
946 	int n;
947 
948 	spec_mask = SPEC_CTRL_MDS_ENABLE;
949 
950 	/*
951 	 * Fixup state
952 	 */
953 	mode = 0;
954 	save_gd = mycpu;
955 	for (n = 0; n < ncpus; ++n) {
956 		lwkt_setcpu_self(globaldata_find(n));
957 		cpu_ccfence();
958 		tr = &pscpu->trampoline;
959 
960 		/*
961 		 * Make sure we are cleaned out.
962 		 *
963 		 * XXX cleanup, reusing globals inside the loop (they get
964 		 * set to the same thing each loop)
965 		 *
966 		 * [0] kernel entry (idle exit)
967 		 * [1] kernel exit  (idle entry)
968 		 */
969 		tr->tr_pcb_spec_ctrl[0] &= ~spec_mask;
970 		tr->tr_pcb_spec_ctrl[1] &= ~spec_mask;
971 
972 		/*
973 		 * Don't try to parse if not available
974 		 */
975 		if (mds_mitigation < 0)
976 			continue;
977 
978 		spec_ctrl = 0;
979 		if (CHECK(MDS_MD_CLEAR_SUPPORTED)) {
980 			spec_ctrl |= SPEC_CTRL_MDS_ENABLE;
981 			mode |= MDS_MD_CLEAR_SUPPORTED;
982 		}
983 
984 		/*
985 		 * Update spec_ctrl fields in the trampoline.
986 		 *
987 		 * [0] on-kernel-entry (on-idle-exit)
988 		 * [1] on-kernel-exit  (on-idle-entry)
989 		 *
990 		 * The MDS stuff is only needed on kernel-exit or idle-entry
991 		 */
992 		/* tr->tr_pcb_spec_ctrl[0] |= spec_ctrl; */
993 		tr->tr_pcb_spec_ctrl[1] |= spec_ctrl;
994 
995 		/*
996 		 * Make sure we set this on the first loop.  It will be
997 		 * the same value on remaining loops.
998 		 */
999 		mds_mode = mode;
1000 	}
1001 	lwkt_setcpu_self(save_gd);
1002 	cpu_ccfence();
1003 
1004 	/*
1005 	 * Console message on mitigation mode change
1006 	 */
1007 	kprintf("MDS: support=(");
1008 	if (mds_support == 0) {
1009 		kprintf(" none");
1010 	} else {
1011 		if (mds_support & MDS_AVX512_4VNNIW_SUPPORTED)
1012 			kprintf(" AVX512_4VNNIW");
1013 		if (mds_support & MDS_AVX512_4FMAPS_SUPPORTED)
1014 			kprintf(" AVX512_4FMAPS");
1015 		if (mds_support & MDS_MD_CLEAR_SUPPORTED)
1016 			kprintf(" MD_CLEAR");
1017 		if (mds_support & MDS_TSX_FORCE_ABORT_SUPPORTED)
1018 			kprintf(" TSX_FORCE_ABORT");
1019 		if (mds_support & MDS_NOT_REQUIRED)
1020 			kprintf(" MDS_NOT_REQUIRED");
1021 	}
1022 	kprintf(" ) req=%04x operating=(", (uint16_t)mds_mitigation);
1023 	if (mds_mode == 0) {
1024 		kprintf(" none");
1025 	} else {
1026 		if (mds_mode & MDS_AVX512_4VNNIW_SUPPORTED)
1027 			kprintf(" AVX512_4VNNIW");
1028 		if (mds_mode & MDS_AVX512_4FMAPS_SUPPORTED)
1029 			kprintf(" AVX512_4FMAPS");
1030 		if (mds_mode & MDS_MD_CLEAR_SUPPORTED)
1031 			kprintf(" MD_CLEAR");
1032 		if (mds_mode & MDS_TSX_FORCE_ABORT_SUPPORTED)
1033 			kprintf(" TSX_FORCE_ABORT");
1034 		if (mds_mode & MDS_NOT_REQUIRED)
1035 			kprintf(" MDS_NOT_REQUIRED");
1036 	}
1037 	kprintf(" )\n");
1038 }
1039 
1040 #undef CHECK
1041 
1042 /*
1043  * User changes sysctl value
1044  */
1045 static int
1046 sysctl_mds_mitigation(SYSCTL_HANDLER_ARGS)
1047 {
1048 	char buf[128];
1049 	char *ptr;
1050 	char *iter;
1051 	size_t len;
1052 	int mds;
1053 	int error = 0;
1054 	int loop = 0;
1055 
1056 	/*
1057 	 * Return current operating mode or support.
1058 	 */
1059 	if (oidp->oid_kind & CTLFLAG_WR)
1060 		mds = mds_mode;
1061 	else
1062 		mds = mds_support;
1063 
1064 	mds &= MDS_AVX512_4VNNIW_SUPPORTED |
1065 	       MDS_AVX512_4FMAPS_SUPPORTED |
1066 	       MDS_MD_CLEAR_SUPPORTED |
1067 	       MDS_TSX_FORCE_ABORT_SUPPORTED |
1068 	       MDS_NOT_REQUIRED;
1069 
1070 	while (mds) {
1071 		if (error)
1072 			break;
1073 		if (loop++) {
1074 			error = SYSCTL_OUT(req, " ", 1);
1075 			if (error)
1076 				break;
1077 		}
1078 		if (mds & MDS_AVX512_4VNNIW_SUPPORTED) {
1079 			mds &= ~MDS_AVX512_4VNNIW_SUPPORTED;
1080 			error = SYSCTL_OUT(req, "AVX512_4VNNIW", 13);
1081 		} else
1082 		if (mds & MDS_AVX512_4FMAPS_SUPPORTED) {
1083 			mds &= ~MDS_AVX512_4FMAPS_SUPPORTED;
1084 			error = SYSCTL_OUT(req, "AVX512_4FMAPS", 13);
1085 		} else
1086 		if (mds & MDS_MD_CLEAR_SUPPORTED) {
1087 			mds &= ~MDS_MD_CLEAR_SUPPORTED;
1088 			error = SYSCTL_OUT(req, "MD_CLEAR", 8);
1089 		} else
1090 		if (mds & MDS_TSX_FORCE_ABORT_SUPPORTED) {
1091 			mds &= ~MDS_TSX_FORCE_ABORT_SUPPORTED;
1092 			error = SYSCTL_OUT(req, "TSX_FORCE_ABORT", 15);
1093 		} else
1094 		if (mds & MDS_NOT_REQUIRED) {
1095 			mds &= ~MDS_NOT_REQUIRED;
1096 			error = SYSCTL_OUT(req, "MDS_NOT_REQUIRED", 16);
1097 		}
1098 	}
1099 	if (loop == 0) {
1100 		error = SYSCTL_OUT(req, "NONE", 4);
1101 	}
1102 
1103 	if (error || req->newptr == NULL)
1104 		return error;
1105 	if ((oidp->oid_kind & CTLFLAG_WR) == 0)
1106 		return error;
1107 
1108 	/*
1109 	 * Change current operating mode
1110 	 */
1111 	len = req->newlen - req->newidx;
1112 	if (len >= sizeof(buf)) {
1113 		error = EINVAL;
1114 		len = 0;
1115 	} else {
1116 		error = SYSCTL_IN(req, buf, len);
1117 	}
1118 	buf[len] = 0;
1119 	iter = &buf[0];
1120 	mds = 0;
1121 
1122 	while (error == 0 && iter) {
1123 		ptr = strsep(&iter, " ,\t\r\n");
1124 		if (*ptr == 0)
1125 			continue;
1126 		if (strcasecmp(ptr, "NONE") == 0)
1127 			mds |= 0;
1128 		else if (strcasecmp(ptr, "AVX512_4VNNIW") == 0)
1129 			mds |= MDS_AVX512_4VNNIW_SUPPORTED;
1130 		else if (strcasecmp(ptr, "AVX512_4FMAPS") == 0)
1131 			mds |= MDS_AVX512_4FMAPS_SUPPORTED;
1132 		else if (strcasecmp(ptr, "MD_CLEAR") == 0)
1133 			mds |= MDS_MD_CLEAR_SUPPORTED;
1134 		else if (strcasecmp(ptr, "TSX_FORCE_ABORT") == 0)
1135 			mds |= MDS_TSX_FORCE_ABORT_SUPPORTED;
1136 		else if (strcasecmp(ptr, "MDS_NOT_REQUIRED") == 0)
1137 			mds |= MDS_NOT_REQUIRED;
1138 		else
1139 			error = ENOENT;
1140 	}
1141 	if (error == 0) {
1142 		mds_mitigation = mds;
1143 		mds_sysctl_changed();
1144 	}
1145 	return error;
1146 }
1147 
1148 SYSCTL_PROC(_machdep, OID_AUTO, mds_mitigation,
1149 	CTLTYPE_STRING | CTLFLAG_RW,
1150 	0, 0, sysctl_mds_mitigation, "A", "MDS exploit mitigation");
1151 SYSCTL_PROC(_machdep, OID_AUTO, mds_support,
1152 	CTLTYPE_STRING | CTLFLAG_RD,
1153 	0, 0, sysctl_mds_mitigation, "A", "MDS supported features");
1154 
1155 /*
1156  * NOTE: Called at SI_BOOT2_MACHDEP and also when the microcode is
1157  *	 updated.  Microcode updates must be applied to all cpus
1158  *	 for support to be recognized.
1159  */
1160 static void
1161 mds_vm_setup(void *arg)
1162 {
1163 	int inconsistent = 0;
1164 	int supmask;
1165 
1166 	/*
1167 	 * Fetch tunable in auto mode
1168 	 */
1169 	if (mds_mitigation < 0) {
1170 		TUNABLE_INT_FETCH("machdep.mds_mitigation", &mds_mitigation);
1171 	}
1172 
1173 	if ((supmask = mds_check_support()) != 0) {
1174 		/*
1175 		 * Must be supported on all cpus before we
1176 		 * can enable it.  Returns silently if it
1177 		 * isn't.
1178 		 *
1179 		 * NOTE! arg != NULL indicates we were called
1180 		 *	 from cpuctl after a successful microcode
1181 		 *	 update.
1182 		 */
1183 		if (arg != NULL) {
1184 			globaldata_t save_gd;
1185 			int n;
1186 
1187 			save_gd = mycpu;
1188 			for (n = 0; n < ncpus; ++n) {
1189 				lwkt_setcpu_self(globaldata_find(n));
1190 				cpu_ccfence();
1191 				if (mds_check_support() != supmask) {
1192 					inconsistent = 1;
1193 					break;
1194 				}
1195 			}
1196 			lwkt_setcpu_self(save_gd);
1197 			cpu_ccfence();
1198 		}
1199 	}
1200 
1201 	/*
1202 	 * Be silent while microcode is being loaded on various CPUs,
1203 	 * until all done.
1204 	 */
1205 	if (inconsistent) {
1206 		mds_mitigation = -1;
1207 		mds_support = 0;
1208 		return;
1209 	}
1210 
1211 	/*
1212 	 * IBRS support
1213 	 */
1214 	mds_support = supmask;
1215 
1216 	/*
1217 	 * Enable mds_mitigation, set defaults if -1, adjust
1218 	 * tuned value according to support if not.
1219 	 *
1220 	 * NOTE!  MDS is not enabled by default.
1221 	 */
1222 	if (mds_support) {
1223 		if (mds_mitigation < 0) {
1224 			mds_mitigation = 0;
1225 
1226 			if ((mds_support & MDS_NOT_REQUIRED) == 0 &&
1227 			    (mds_support & MDS_MD_CLEAR_SUPPORTED)) {
1228 				/* mds_mitigation |= MDS_MD_CLEAR_SUPPORTED; */
1229 			}
1230 		}
1231 	} else {
1232 		mds_mitigation = -1;
1233 	}
1234 
1235 	/*
1236 	 * Disallow sysctl changes when there is no support (otherwise
1237 	 * the wrmsr will cause a protection fault).
1238 	 */
1239 	if (mds_mitigation < 0)
1240 		sysctl___machdep_mds_mitigation.oid_kind &= ~CTLFLAG_WR;
1241 	else
1242 		sysctl___machdep_mds_mitigation.oid_kind |= CTLFLAG_WR;
1243 
1244 	mds_sysctl_changed();
1245 }
1246 
1247 /*
1248  * NOTE: Called at SI_BOOT2_MACHDEP and also when the microcode is
1249  *	 updated.  Microcode updates must be applied to all cpus
1250  *	 for support to be recognized.
1251  */
1252 void
1253 mitigation_vm_setup(void *arg)
1254 {
1255 	spectre_vm_setup(arg);
1256 	mds_vm_setup(arg);
1257 }
1258 
1259 SYSINIT(mitigation_vm_setup, SI_BOOT2_MACHDEP, SI_ORDER_ANY,
1260 	mitigation_vm_setup, NULL);
1261 
1262 /*
1263  * platform-specific vmspace initialization (nothing for x86_64)
1264  */
1265 void
1266 cpu_vmspace_alloc(struct vmspace *vm __unused)
1267 {
1268 }
1269 
1270 void
1271 cpu_vmspace_free(struct vmspace *vm __unused)
1272 {
1273 }
1274 
1275 int
1276 kvm_access_check(vm_offset_t saddr, vm_offset_t eaddr, int prot)
1277 {
1278 	vm_offset_t addr;
1279 
1280 	if (saddr < KvaStart)
1281 		return EFAULT;
1282 	if (eaddr >= KvaEnd)
1283 		return EFAULT;
1284 	for (addr = saddr; addr < eaddr; addr += PAGE_SIZE)  {
1285 		if (pmap_kextract(addr) == 0)
1286 			return EFAULT;
1287 	}
1288 	if (!kernacc((caddr_t)saddr, eaddr - saddr, prot))
1289 		return EFAULT;
1290 	return 0;
1291 }
1292 
1293 #if 0
1294 
1295 void _test_frame_enter(struct trapframe *frame);
1296 void _test_frame_exit(struct trapframe *frame);
1297 
1298 void
1299 _test_frame_enter(struct trapframe *frame)
1300 {
1301 	thread_t td = curthread;
1302 
1303 	if (ISPL(frame->tf_cs) == SEL_UPL) {
1304 		KKASSERT(td->td_lwp);
1305                 KASSERT(td->td_lwp->lwp_md.md_regs == frame,
1306                         ("_test_frame_exit: Frame mismatch %p %p",
1307 			td->td_lwp->lwp_md.md_regs, frame));
1308 	    td->td_lwp->lwp_saveusp = (void *)frame->tf_rsp;
1309 	    td->td_lwp->lwp_saveupc = (void *)frame->tf_rip;
1310 	}
1311 	if ((char *)frame < td->td_kstack ||
1312 	    (char *)frame > td->td_kstack + td->td_kstack_size) {
1313 		panic("_test_frame_exit: frame not on kstack %p kstack=%p",
1314 			frame, td->td_kstack);
1315 	}
1316 }
1317 
1318 void
1319 _test_frame_exit(struct trapframe *frame)
1320 {
1321 	thread_t td = curthread;
1322 
1323 	if (ISPL(frame->tf_cs) == SEL_UPL) {
1324 		KKASSERT(td->td_lwp);
1325                 KASSERT(td->td_lwp->lwp_md.md_regs == frame,
1326                         ("_test_frame_exit: Frame mismatch %p %p",
1327 			td->td_lwp->lwp_md.md_regs, frame));
1328 		if (td->td_lwp->lwp_saveusp != (void *)frame->tf_rsp) {
1329 			kprintf("_test_frame_exit: %s:%d usp mismatch %p/%p\n",
1330 				td->td_comm, td->td_proc->p_pid,
1331 				td->td_lwp->lwp_saveusp,
1332 				(void *)frame->tf_rsp);
1333 		}
1334 		if (td->td_lwp->lwp_saveupc != (void *)frame->tf_rip) {
1335 			kprintf("_test_frame_exit: %s:%d upc mismatch %p/%p\n",
1336 				td->td_comm, td->td_proc->p_pid,
1337 				td->td_lwp->lwp_saveupc,
1338 				(void *)frame->tf_rip);
1339 		}
1340 
1341 		/*
1342 		 * adulterate the fields to catch entries that
1343 		 * don't run through test_frame_enter
1344 		 */
1345 		td->td_lwp->lwp_saveusp =
1346 			(void *)~(intptr_t)td->td_lwp->lwp_saveusp;
1347 		td->td_lwp->lwp_saveupc =
1348 			(void *)~(intptr_t)td->td_lwp->lwp_saveupc;
1349 	}
1350 	if ((char *)frame < td->td_kstack ||
1351 	    (char *)frame > td->td_kstack + td->td_kstack_size) {
1352 		panic("_test_frame_exit: frame not on kstack %p kstack=%p",
1353 			frame, td->td_kstack);
1354 	}
1355 }
1356 
1357 #endif
1358