pci.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * s390 kvm PCI passthrough support
  4 *
  5 * Copyright IBM Corp. 2022
  6 *
  7 *    Author(s): Matthew Rosato <mjrosato@linux.ibm.com>
  8 */
  9
 10#include <linux/kvm_host.h>
 11#include <linux/pci.h>
 12#include <asm/pci.h>
 13#include <asm/pci_insn.h>
 14#include <asm/pci_io.h>
 15#include <asm/sclp.h>
 16#include "pci.h"
 17#include "kvm-s390.h"
 18
 19struct zpci_aift *aift;
 20
 21static inline int __set_irq_noiib(u16 ctl, u8 isc)
 22{
 23	union zpci_sic_iib iib = {{0}};
 24
 25	return zpci_set_irq_ctrl(ctl, isc, &iib);
 26}
 27
 28void kvm_s390_pci_aen_exit(void)
 29{
 30	unsigned long flags;
 31	struct kvm_zdev **gait_kzdev;
 32
 33	lockdep_assert_held(&aift->aift_lock);
 34
 35	/*
 36	 * Contents of the aipb remain registered for the life of the host
 37	 * kernel, the information preserved in zpci_aipb and zpci_aif_sbv
 38	 * in case we insert the KVM module again later.  Clear the AIFT
 39	 * information and free anything not registered with underlying
 40	 * firmware.
 41	 */
 42	spin_lock_irqsave(&aift->gait_lock, flags);
 43	gait_kzdev = aift->kzdev;
 44	aift->gait = NULL;
 45	aift->sbv = NULL;
 46	aift->kzdev = NULL;
 47	spin_unlock_irqrestore(&aift->gait_lock, flags);
 48
 49	kfree(gait_kzdev);
 50}
 51
 52static int zpci_setup_aipb(u8 nisc)
 53{
 54	struct page *page;
 55	int size, rc;
 56
 57	zpci_aipb = kzalloc(sizeof(union zpci_sic_iib), GFP_KERNEL);
 58	if (!zpci_aipb)
 59		return -ENOMEM;
 60
 61	aift->sbv = airq_iv_create(ZPCI_NR_DEVICES, AIRQ_IV_ALLOC, NULL);
 62	if (!aift->sbv) {
 63		rc = -ENOMEM;
 64		goto free_aipb;
 65	}
 66	zpci_aif_sbv = aift->sbv;
 67	size = get_order(PAGE_ALIGN(ZPCI_NR_DEVICES *
 68						sizeof(struct zpci_gaite)));
 69	page = alloc_pages(GFP_KERNEL | __GFP_ZERO, size);
 70	if (!page) {
 71		rc = -ENOMEM;
 72		goto free_sbv;
 73	}
 74	aift->gait = (struct zpci_gaite *)page_to_virt(page);
 75
 76	zpci_aipb->aipb.faisb = virt_to_phys(aift->sbv->vector);
 77	zpci_aipb->aipb.gait = virt_to_phys(aift->gait);
 78	zpci_aipb->aipb.afi = nisc;
 79	zpci_aipb->aipb.faal = ZPCI_NR_DEVICES;
 80
 81	/* Setup Adapter Event Notification Interpretation */
 82	if (zpci_set_irq_ctrl(SIC_SET_AENI_CONTROLS, 0, zpci_aipb)) {
 83		rc = -EIO;
 84		goto free_gait;
 85	}
 86
 87	return 0;
 88
 89free_gait:
 90	free_pages((unsigned long)aift->gait, size);
 91free_sbv:
 92	airq_iv_release(aift->sbv);
 93	zpci_aif_sbv = NULL;
 94free_aipb:
 95	kfree(zpci_aipb);
 96	zpci_aipb = NULL;
 97
 98	return rc;
 99}
100
101static int zpci_reset_aipb(u8 nisc)
102{
103	/*
104	 * AEN registration can only happen once per system boot.  If
105	 * an aipb already exists then AEN was already registered and
106	 * we can reuse the aipb contents.  This can only happen if
107	 * the KVM module was removed and re-inserted.  However, we must
108	 * ensure that the same forwarding ISC is used as this is assigned
109	 * during KVM module load.
110	 */
111	if (zpci_aipb->aipb.afi != nisc)
112		return -EINVAL;
113
114	aift->sbv = zpci_aif_sbv;
115	aift->gait = phys_to_virt(zpci_aipb->aipb.gait);
116
117	return 0;
118}
119
120int kvm_s390_pci_aen_init(u8 nisc)
121{
122	int rc = 0;
123
124	/* If already enabled for AEN, bail out now */
125	if (aift->gait || aift->sbv)
126		return -EPERM;
127
128	mutex_lock(&aift->aift_lock);
129	aift->kzdev = kcalloc(ZPCI_NR_DEVICES, sizeof(struct kvm_zdev *),
130			      GFP_KERNEL);
131	if (!aift->kzdev) {
132		rc = -ENOMEM;
133		goto unlock;
134	}
135
136	if (!zpci_aipb)
137		rc = zpci_setup_aipb(nisc);
138	else
139		rc = zpci_reset_aipb(nisc);
140	if (rc)
141		goto free_zdev;
142
143	/* Enable floating IRQs */
144	if (__set_irq_noiib(SIC_IRQ_MODE_SINGLE, nisc)) {
145		rc = -EIO;
146		kvm_s390_pci_aen_exit();
147	}
148
149	goto unlock;
150
151free_zdev:
152	kfree(aift->kzdev);
153unlock:
154	mutex_unlock(&aift->aift_lock);
155	return rc;
156}
157
158/* Modify PCI: Register floating adapter interruption forwarding */
159static int kvm_zpci_set_airq(struct zpci_dev *zdev)
160{
161	u64 req = ZPCI_CREATE_REQ(zdev->fh, 0, ZPCI_MOD_FC_REG_INT);
162	struct zpci_fib fib = {};
163	u8 status;
164
165	fib.fmt0.isc = zdev->kzdev->fib.fmt0.isc;
166	fib.fmt0.sum = 1;       /* enable summary notifications */
167	fib.fmt0.noi = airq_iv_end(zdev->aibv);
168	fib.fmt0.aibv = virt_to_phys(zdev->aibv->vector);
169	fib.fmt0.aibvo = 0;
170	fib.fmt0.aisb = virt_to_phys(aift->sbv->vector + (zdev->aisb / 64) * 8);
171	fib.fmt0.aisbo = zdev->aisb & 63;
172	fib.gd = zdev->gisa;
173
174	return zpci_mod_fc(req, &fib, &status) ? -EIO : 0;
175}
176
177/* Modify PCI: Unregister floating adapter interruption forwarding */
178static int kvm_zpci_clear_airq(struct zpci_dev *zdev)
179{
180	u64 req = ZPCI_CREATE_REQ(zdev->fh, 0, ZPCI_MOD_FC_DEREG_INT);
181	struct zpci_fib fib = {};
182	u8 cc, status;
183
184	fib.gd = zdev->gisa;
185
186	cc = zpci_mod_fc(req, &fib, &status);
187	if (cc == 3 || (cc == 1 && status == 24))
188		/* Function already gone or IRQs already deregistered. */
189		cc = 0;
190
191	return cc ? -EIO : 0;
192}
193
194static inline void unaccount_mem(unsigned long nr_pages)
195{
196	struct user_struct *user = get_uid(current_user());
197
198	if (user)
199		atomic_long_sub(nr_pages, &user->locked_vm);
200	if (current->mm)
201		atomic64_sub(nr_pages, &current->mm->pinned_vm);
202}
203
204static inline int account_mem(unsigned long nr_pages)
205{
206	struct user_struct *user = get_uid(current_user());
207	unsigned long page_limit, cur_pages, new_pages;
208
209	page_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
210
211	cur_pages = atomic_long_read(&user->locked_vm);
212	do {
213		new_pages = cur_pages + nr_pages;
214		if (new_pages > page_limit)
215			return -ENOMEM;
216	} while (!atomic_long_try_cmpxchg(&user->locked_vm, &cur_pages, new_pages));
217
218	atomic64_add(nr_pages, &current->mm->pinned_vm);
219
220	return 0;
221}
222
223static int kvm_s390_pci_aif_enable(struct zpci_dev *zdev, struct zpci_fib *fib,
224				   bool assist)
225{
226	struct page *pages[1], *aibv_page, *aisb_page = NULL;
227	unsigned int msi_vecs, idx;
228	struct zpci_gaite *gaite;
229	unsigned long hva, bit;
230	struct kvm *kvm;
231	phys_addr_t gaddr;
232	int rc = 0, gisc, npages, pcount = 0;
233
234	/*
235	 * Interrupt forwarding is only applicable if the device is already
236	 * enabled for interpretation
237	 */
238	if (zdev->gisa == 0)
239		return -EINVAL;
240
241	kvm = zdev->kzdev->kvm;
242	msi_vecs = min_t(unsigned int, fib->fmt0.noi, zdev->max_msi);
243
244	/* Get the associated forwarding ISC - if invalid, return the error */
245	gisc = kvm_s390_gisc_register(kvm, fib->fmt0.isc);
246	if (gisc < 0)
247		return gisc;
248
249	/* Replace AIBV address */
250	idx = srcu_read_lock(&kvm->srcu);
251	hva = gfn_to_hva(kvm, gpa_to_gfn((gpa_t)fib->fmt0.aibv));
252	npages = pin_user_pages_fast(hva, 1, FOLL_WRITE | FOLL_LONGTERM, pages);
253	srcu_read_unlock(&kvm->srcu, idx);
254	if (npages < 1) {
255		rc = -EIO;
256		goto out;
257	}
258	aibv_page = pages[0];
259	pcount++;
260	gaddr = page_to_phys(aibv_page) + (fib->fmt0.aibv & ~PAGE_MASK);
261	fib->fmt0.aibv = gaddr;
262
263	/* Pin the guest AISB if one was specified */
264	if (fib->fmt0.sum == 1) {
265		idx = srcu_read_lock(&kvm->srcu);
266		hva = gfn_to_hva(kvm, gpa_to_gfn((gpa_t)fib->fmt0.aisb));
267		npages = pin_user_pages_fast(hva, 1, FOLL_WRITE | FOLL_LONGTERM,
268					     pages);
269		srcu_read_unlock(&kvm->srcu, idx);
270		if (npages < 1) {
271			rc = -EIO;
272			goto unpin1;
273		}
274		aisb_page = pages[0];
275		pcount++;
276	}
277
278	/* Account for pinned pages, roll back on failure */
279	if (account_mem(pcount))
280		goto unpin2;
281
282	/* AISB must be allocated before we can fill in GAITE */
283	mutex_lock(&aift->aift_lock);
284	bit = airq_iv_alloc_bit(aift->sbv);
285	if (bit == -1UL)
286		goto unlock;
287	zdev->aisb = bit; /* store the summary bit number */
288	zdev->aibv = airq_iv_create(msi_vecs, AIRQ_IV_DATA |
289				    AIRQ_IV_BITLOCK |
290				    AIRQ_IV_GUESTVEC,
291				    phys_to_virt(fib->fmt0.aibv));
292
293	spin_lock_irq(&aift->gait_lock);
294	gaite = (struct zpci_gaite *)aift->gait + (zdev->aisb *
295						   sizeof(struct zpci_gaite));
296
297	/* If assist not requested, host will get all alerts */
298	if (assist)
299		gaite->gisa = (u32)virt_to_phys(&kvm->arch.sie_page2->gisa);
300	else
301		gaite->gisa = 0;
302
303	gaite->gisc = fib->fmt0.isc;
304	gaite->count++;
305	gaite->aisbo = fib->fmt0.aisbo;
306	gaite->aisb = virt_to_phys(page_address(aisb_page) + (fib->fmt0.aisb &
307							      ~PAGE_MASK));
308	aift->kzdev[zdev->aisb] = zdev->kzdev;
309	spin_unlock_irq(&aift->gait_lock);
310
311	/* Update guest FIB for re-issue */
312	fib->fmt0.aisbo = zdev->aisb & 63;
313	fib->fmt0.aisb = virt_to_phys(aift->sbv->vector + (zdev->aisb / 64) * 8);
314	fib->fmt0.isc = gisc;
315
316	/* Save some guest fib values in the host for later use */
317	zdev->kzdev->fib.fmt0.isc = fib->fmt0.isc;
318	zdev->kzdev->fib.fmt0.aibv = fib->fmt0.aibv;
319	mutex_unlock(&aift->aift_lock);
320
321	/* Issue the clp to setup the irq now */
322	rc = kvm_zpci_set_airq(zdev);
323	return rc;
324
325unlock:
326	mutex_unlock(&aift->aift_lock);
327unpin2:
328	if (fib->fmt0.sum == 1)
329		unpin_user_page(aisb_page);
330unpin1:
331	unpin_user_page(aibv_page);
332out:
333	return rc;
334}
335
336static int kvm_s390_pci_aif_disable(struct zpci_dev *zdev, bool force)
337{
338	struct kvm_zdev *kzdev = zdev->kzdev;
339	struct zpci_gaite *gaite;
340	struct page *vpage = NULL, *spage = NULL;
341	int rc, pcount = 0;
342	u8 isc;
343
344	if (zdev->gisa == 0)
345		return -EINVAL;
346
347	mutex_lock(&aift->aift_lock);
348
349	/*
350	 * If the clear fails due to an error, leave now unless we know this
351	 * device is about to go away (force) -- In that case clear the GAITE
352	 * regardless.
353	 */
354	rc = kvm_zpci_clear_airq(zdev);
355	if (rc && !force)
356		goto out;
357
358	if (zdev->kzdev->fib.fmt0.aibv == 0)
359		goto out;
360	spin_lock_irq(&aift->gait_lock);
361	gaite = (struct zpci_gaite *)aift->gait + (zdev->aisb *
362						   sizeof(struct zpci_gaite));
363	isc = gaite->gisc;
364	gaite->count--;
365	if (gaite->count == 0) {
366		/* Release guest AIBV and AISB */
367		vpage = phys_to_page(kzdev->fib.fmt0.aibv);
368		if (gaite->aisb != 0)
369			spage = phys_to_page(gaite->aisb);
370		/* Clear the GAIT entry */
371		gaite->aisb = 0;
372		gaite->gisc = 0;
373		gaite->aisbo = 0;
374		gaite->gisa = 0;
375		aift->kzdev[zdev->aisb] = NULL;
376		/* Clear zdev info */
377		airq_iv_free_bit(aift->sbv, zdev->aisb);
378		airq_iv_release(zdev->aibv);
379		zdev->aisb = 0;
380		zdev->aibv = NULL;
381	}
382	spin_unlock_irq(&aift->gait_lock);
383	kvm_s390_gisc_unregister(kzdev->kvm, isc);
384	kzdev->fib.fmt0.isc = 0;
385	kzdev->fib.fmt0.aibv = 0;
386
387	if (vpage) {
388		unpin_user_page(vpage);
389		pcount++;
390	}
391	if (spage) {
392		unpin_user_page(spage);
393		pcount++;
394	}
395	if (pcount > 0)
396		unaccount_mem(pcount);
397out:
398	mutex_unlock(&aift->aift_lock);
399
400	return rc;
401}
402
403static int kvm_s390_pci_dev_open(struct zpci_dev *zdev)
404{
405	struct kvm_zdev *kzdev;
406
407	kzdev = kzalloc(sizeof(struct kvm_zdev), GFP_KERNEL);
408	if (!kzdev)
409		return -ENOMEM;
410
411	kzdev->zdev = zdev;
412	zdev->kzdev = kzdev;
413
414	return 0;
415}
416
417static void kvm_s390_pci_dev_release(struct zpci_dev *zdev)
418{
419	struct kvm_zdev *kzdev;
420
421	kzdev = zdev->kzdev;
422	WARN_ON(kzdev->zdev != zdev);
423	zdev->kzdev = NULL;
424	kfree(kzdev);
425}
426
427
428/*
429 * Register device with the specified KVM. If interpretation facilities are
430 * available, enable them and let userspace indicate whether or not they will
431 * be used (specify SHM bit to disable).
432 */
433static int kvm_s390_pci_register_kvm(void *opaque, struct kvm *kvm)
434{
435	struct zpci_dev *zdev = opaque;
436	int rc;
437
438	if (!zdev)
439		return -EINVAL;
440
441	mutex_lock(&zdev->kzdev_lock);
442
443	if (zdev->kzdev || zdev->gisa != 0 || !kvm) {
444		mutex_unlock(&zdev->kzdev_lock);
445		return -EINVAL;
446	}
447
448	kvm_get_kvm(kvm);
449
450	mutex_lock(&kvm->lock);
451
452	rc = kvm_s390_pci_dev_open(zdev);
453	if (rc)
454		goto err;
455
456	/*
457	 * If interpretation facilities aren't available, add the device to
458	 * the kzdev list but don't enable for interpretation.
459	 */
460	if (!kvm_s390_pci_interp_allowed())
461		goto out;
462
463	/*
464	 * If this is the first request to use an interpreted device, make the
465	 * necessary vcpu changes
466	 */
467	if (!kvm->arch.use_zpci_interp)
468		kvm_s390_vcpu_pci_enable_interp(kvm);
469
470	if (zdev_enabled(zdev)) {
471		rc = zpci_disable_device(zdev);
472		if (rc)
473			goto err;
474	}
475
476	/*
477	 * Store information about the identity of the kvm guest allowed to
478	 * access this device via interpretation to be used by host CLP
479	 */
480	zdev->gisa = (u32)virt_to_phys(&kvm->arch.sie_page2->gisa);
481
482	rc = zpci_reenable_device(zdev);
483	if (rc)
484		goto clear_gisa;
485
486out:
487	zdev->kzdev->kvm = kvm;
488
489	spin_lock(&kvm->arch.kzdev_list_lock);
490	list_add_tail(&zdev->kzdev->entry, &kvm->arch.kzdev_list);
491	spin_unlock(&kvm->arch.kzdev_list_lock);
492
493	mutex_unlock(&kvm->lock);
494	mutex_unlock(&zdev->kzdev_lock);
495	return 0;
496
497clear_gisa:
498	zdev->gisa = 0;
499err:
500	if (zdev->kzdev)
501		kvm_s390_pci_dev_release(zdev);
502	mutex_unlock(&kvm->lock);
503	mutex_unlock(&zdev->kzdev_lock);
504	kvm_put_kvm(kvm);
505	return rc;
506}
507
508static void kvm_s390_pci_unregister_kvm(void *opaque)
509{
510	struct zpci_dev *zdev = opaque;
511	struct kvm *kvm;
512
513	if (!zdev)
514		return;
515
516	mutex_lock(&zdev->kzdev_lock);
517
518	if (WARN_ON(!zdev->kzdev)) {
519		mutex_unlock(&zdev->kzdev_lock);
520		return;
521	}
522
523	kvm = zdev->kzdev->kvm;
524	mutex_lock(&kvm->lock);
525
526	/*
527	 * A 0 gisa means interpretation was never enabled, just remove the
528	 * device from the list.
529	 */
530	if (zdev->gisa == 0)
531		goto out;
532
533	/* Forwarding must be turned off before interpretation */
534	if (zdev->kzdev->fib.fmt0.aibv != 0)
535		kvm_s390_pci_aif_disable(zdev, true);
536
537	/* Remove the host CLP guest designation */
538	zdev->gisa = 0;
539
540	if (zdev_enabled(zdev)) {
541		if (zpci_disable_device(zdev))
542			goto out;
543	}
544
545	zpci_reenable_device(zdev);
546
547out:
548	spin_lock(&kvm->arch.kzdev_list_lock);
549	list_del(&zdev->kzdev->entry);
550	spin_unlock(&kvm->arch.kzdev_list_lock);
551	kvm_s390_pci_dev_release(zdev);
552
553	mutex_unlock(&kvm->lock);
554	mutex_unlock(&zdev->kzdev_lock);
555
556	kvm_put_kvm(kvm);
557}
558
559void kvm_s390_pci_init_list(struct kvm *kvm)
560{
561	spin_lock_init(&kvm->arch.kzdev_list_lock);
562	INIT_LIST_HEAD(&kvm->arch.kzdev_list);
563}
564
565void kvm_s390_pci_clear_list(struct kvm *kvm)
566{
567	/*
568	 * This list should already be empty, either via vfio device closures
569	 * or kvm fd cleanup.
570	 */
571	spin_lock(&kvm->arch.kzdev_list_lock);
572	WARN_ON_ONCE(!list_empty(&kvm->arch.kzdev_list));
573	spin_unlock(&kvm->arch.kzdev_list_lock);
574}
575
576static struct zpci_dev *get_zdev_from_kvm_by_fh(struct kvm *kvm, u32 fh)
577{
578	struct zpci_dev *zdev = NULL;
579	struct kvm_zdev *kzdev;
580
581	spin_lock(&kvm->arch.kzdev_list_lock);
582	list_for_each_entry(kzdev, &kvm->arch.kzdev_list, entry) {
583		if (kzdev->zdev->fh == fh) {
584			zdev = kzdev->zdev;
585			break;
586		}
587	}
588	spin_unlock(&kvm->arch.kzdev_list_lock);
589
590	return zdev;
591}
592
593static int kvm_s390_pci_zpci_reg_aen(struct zpci_dev *zdev,
594				     struct kvm_s390_zpci_op *args)
595{
596	struct zpci_fib fib = {};
597	bool hostflag;
598
599	fib.fmt0.aibv = args->u.reg_aen.ibv;
600	fib.fmt0.isc = args->u.reg_aen.isc;
601	fib.fmt0.noi = args->u.reg_aen.noi;
602	if (args->u.reg_aen.sb != 0) {
603		fib.fmt0.aisb = args->u.reg_aen.sb;
604		fib.fmt0.aisbo = args->u.reg_aen.sbo;
605		fib.fmt0.sum = 1;
606	} else {
607		fib.fmt0.aisb = 0;
608		fib.fmt0.aisbo = 0;
609		fib.fmt0.sum = 0;
610	}
611
612	hostflag = !(args->u.reg_aen.flags & KVM_S390_ZPCIOP_REGAEN_HOST);
613	return kvm_s390_pci_aif_enable(zdev, &fib, hostflag);
614}
615
616int kvm_s390_pci_zpci_op(struct kvm *kvm, struct kvm_s390_zpci_op *args)
617{
618	struct kvm_zdev *kzdev;
619	struct zpci_dev *zdev;
620	int r;
621
622	zdev = get_zdev_from_kvm_by_fh(kvm, args->fh);
623	if (!zdev)
624		return -ENODEV;
625
626	mutex_lock(&zdev->kzdev_lock);
627	mutex_lock(&kvm->lock);
628
629	kzdev = zdev->kzdev;
630	if (!kzdev) {
631		r = -ENODEV;
632		goto out;
633	}
634	if (kzdev->kvm != kvm) {
635		r = -EPERM;
636		goto out;
637	}
638
639	switch (args->op) {
640	case KVM_S390_ZPCIOP_REG_AEN:
641		/* Fail on unknown flags */
642		if (args->u.reg_aen.flags & ~KVM_S390_ZPCIOP_REGAEN_HOST) {
643			r = -EINVAL;
644			break;
645		}
646		r = kvm_s390_pci_zpci_reg_aen(zdev, args);
647		break;
648	case KVM_S390_ZPCIOP_DEREG_AEN:
649		r = kvm_s390_pci_aif_disable(zdev, false);
650		break;
651	default:
652		r = -EINVAL;
653	}
654
655out:
656	mutex_unlock(&kvm->lock);
657	mutex_unlock(&zdev->kzdev_lock);
658	return r;
659}
660
661int __init kvm_s390_pci_init(void)
662{
663	zpci_kvm_hook.kvm_register = kvm_s390_pci_register_kvm;
664	zpci_kvm_hook.kvm_unregister = kvm_s390_pci_unregister_kvm;
665
666	if (!kvm_s390_pci_interp_allowed())
667		return 0;
668
669	aift = kzalloc(sizeof(struct zpci_aift), GFP_KERNEL);
670	if (!aift)
671		return -ENOMEM;
672
673	spin_lock_init(&aift->gait_lock);
674	mutex_init(&aift->aift_lock);
675
676	return 0;
677}
678
679void kvm_s390_pci_exit(void)
680{
681	zpci_kvm_hook.kvm_register = NULL;
682	zpci_kvm_hook.kvm_unregister = NULL;
683
684	if (!kvm_s390_pci_interp_allowed())
685		return;
686
687	mutex_destroy(&aift->aift_lock);
688
689	kfree(aift);
690}