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2024-02-20 ea08eeccae9297f7aabd2ef7f0c2517ac4549acc 
 kernel/arch/powerpc/kvm/book3s_64_vio.c
....@@ -1,16 +1,5 @@
1
+// SPDX-License-Identifier: GPL-2.0-only
12 /*
2
- * This program is free software; you can redistribute it and/or modify
3
- * it under the terms of the GNU General Public License, version 2, as
4
- * published by the Free Software Foundation.
5
- *
6
- * This program is distributed in the hope that it will be useful,
7
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
8
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
9
- * GNU General Public License for more details.
10
- *
11
- * You should have received a copy of the GNU General Public License
12
- * along with this program; if not, write to the Free Software
13
- * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
143  *
154  * Copyright 2010 Paul Mackerras, IBM Corp. <paulus@au1.ibm.com>
165  * Copyright 2011 David Gibson, IBM Corporation <dwg@au1.ibm.com>
....@@ -30,6 +19,7 @@
3019 #include <linux/anon_inodes.h>
3120 #include <linux/iommu.h>
3221 #include <linux/file.h>
22
+#include <linux/mm.h>
3323 
3424 #include <asm/kvm_ppc.h>
3525 #include <asm/kvm_book3s.h>
....@@ -37,7 +27,6 @@
3727 #include <asm/hvcall.h>
3828 #include <asm/synch.h>
3929 #include <asm/ppc-opcode.h>
40
-#include <asm/kvm_host.h>
4130 #include <asm/udbg.h>
4231 #include <asm/iommu.h>
4332 #include <asm/tce.h>
....@@ -54,43 +43,6 @@
5443 			(tce_pages * sizeof(struct page *));
5544 
5645 	return tce_pages + ALIGN(stt_bytes, PAGE_SIZE) / PAGE_SIZE;
57
-}
58
-
59
-static long kvmppc_account_memlimit(unsigned long stt_pages, bool inc)
60
-{
61
-	long ret = 0;
62
-
63
-	if (!current || !current->mm)
64
-		return ret; /* process exited */
65
-
66
-	down_write(&current->mm->mmap_sem);
67
-
68
-	if (inc) {
69
-		unsigned long locked, lock_limit;
70
-
71
-		locked = current->mm->locked_vm + stt_pages;
72
-		lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
73
-		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
74
-			ret = -ENOMEM;
75
-		else
76
-			current->mm->locked_vm += stt_pages;
77
-	} else {
78
-		if (WARN_ON_ONCE(stt_pages > current->mm->locked_vm))
79
-			stt_pages = current->mm->locked_vm;
80
-
81
-		current->mm->locked_vm -= stt_pages;
82
-	}
83
-
84
-	pr_debug("[%d] RLIMIT_MEMLOCK KVM %c%ld %ld/%ld%s\n", current->pid,
85
-			inc ? '+' : '-',
86
-			stt_pages << PAGE_SHIFT,
87
-			current->mm->locked_vm << PAGE_SHIFT,
88
-			rlimit(RLIMIT_MEMLOCK),
89
-			ret ? " - exceeded" : "");
90
-
91
-	up_write(&current->mm->mmap_sem);
92
-
93
-	return ret;
9446 }
9547 
9648 static void kvm_spapr_tce_iommu_table_free(struct rcu_head *head)
....@@ -121,6 +73,7 @@
12173 	struct kvmppc_spapr_tce_iommu_table *stit, *tmp;
12274 	struct iommu_table_group *table_group = NULL;
12375 
76
+	rcu_read_lock();
12477 	list_for_each_entry_rcu(stt, &kvm->arch.spapr_tce_tables, list) {
12578 
12679 		table_group = iommu_group_get_iommudata(grp);
....@@ -135,7 +88,9 @@
13588 				kref_put(&stit->kref, kvm_spapr_tce_liobn_put);
13689 			}
13790 		}
91
+		cond_resched_rcu();
13892 	}
93
+	rcu_read_unlock();
13994 }
14095 
14196 extern long kvm_spapr_tce_attach_iommu_group(struct kvm *kvm, int tablefd,
....@@ -153,12 +108,14 @@
153108 	if (!f.file)
154109 		return -EBADF;
155110 
111
+	rcu_read_lock();
156112 	list_for_each_entry_rcu(stt, &kvm->arch.spapr_tce_tables, list) {
157113 		if (stt == f.file->private_data) {
158114 			found = true;
159115 			break;
160116 		}
161117 	}
118
+	rcu_read_unlock();
162119 
163120 	fdput(f);
164121 
....@@ -191,6 +148,7 @@
191148 	if (!tbl)
192149 		return -EINVAL;
193150 
151
+	rcu_read_lock();
194152 	list_for_each_entry_rcu(stit, &stt->iommu_tables, next) {
195153 		if (tbl != stit->tbl)
196154 			continue;
....@@ -198,14 +156,17 @@
198156 		if (!kref_get_unless_zero(&stit->kref)) {
199157 			/* stit is being destroyed */
200158 			iommu_tce_table_put(tbl);
159
+			rcu_read_unlock();
201160 			return -ENOTTY;
202161 		}
203162 		/*
204163 		 * The table is already known to this KVM, we just increased
205164 		 * its KVM reference counter and can return.
206165 		 */
166
+		rcu_read_unlock();
207167 		return 0;
208168 	}
169
+	rcu_read_unlock();
209170 
210171 	stit = kzalloc(sizeof(*stit), GFP_KERNEL);
211172 	if (!stit) {
....@@ -228,9 +189,31 @@
228189 	unsigned long i, npages = kvmppc_tce_pages(stt->size);
229190 
230191 	for (i = 0; i < npages; i++)
231
-		__free_page(stt->pages[i]);
192
+		if (stt->pages[i])
193
+			__free_page(stt->pages[i]);
232194 
233195 	kfree(stt);
196
+}
197
+
198
+static struct page *kvm_spapr_get_tce_page(struct kvmppc_spapr_tce_table *stt,
199
+		unsigned long sttpage)
200
+{
201
+	struct page *page = stt->pages[sttpage];
202
+
203
+	if (page)
204
+		return page;
205
+
206
+	mutex_lock(&stt->alloc_lock);
207
+	page = stt->pages[sttpage];
208
+	if (!page) {
209
+		page = alloc_page(GFP_KERNEL | __GFP_ZERO);
210
+		WARN_ON_ONCE(!page);
211
+		if (page)
212
+			stt->pages[sttpage] = page;
213
+	}
214
+	mutex_unlock(&stt->alloc_lock);
215
+
216
+	return page;
234217 }
235218 
236219 static vm_fault_t kvm_spapr_tce_fault(struct vm_fault *vmf)
....@@ -241,7 +224,10 @@
241224 	if (vmf->pgoff >= kvmppc_tce_pages(stt->size))
242225 		return VM_FAULT_SIGBUS;
243226 
244
-	page = stt->pages[vmf->pgoff];
227
+	page = kvm_spapr_get_tce_page(stt, vmf->pgoff);
228
+	if (!page)
229
+		return VM_FAULT_OOM;
230
+
245231 	get_page(page);
246232 	vmf->page = page;
247233 	return 0;
....@@ -275,10 +261,11 @@
275261 		}
276262 	}
277263 
264
+	account_locked_vm(kvm->mm,
265
+		kvmppc_stt_pages(kvmppc_tce_pages(stt->size)), false);
266
+
278267 	kvm_put_kvm(stt->kvm);
279268 
280
-	kvmppc_account_memlimit(
281
-		kvmppc_stt_pages(kvmppc_tce_pages(stt->size)), false);
282269 	call_rcu(&stt->rcu, release_spapr_tce_table);
283270 
284271 	return 0;
....@@ -294,16 +281,16 @@
294281 {
295282 	struct kvmppc_spapr_tce_table *stt = NULL;
296283 	struct kvmppc_spapr_tce_table *siter;
284
+	struct mm_struct *mm = kvm->mm;
297285 	unsigned long npages, size = args->size;
298
-	int ret = -ENOMEM;
299
-	int i;
286
+	int ret;
300287 
301288 	if (!args->size || args->page_shift < 12 || args->page_shift > 34 ||
302289 		(args->offset + args->size > (ULLONG_MAX >> args->page_shift)))
303290 		return -EINVAL;
304291 
305292 	npages = kvmppc_tce_pages(size);
306
-	ret = kvmppc_account_memlimit(kvmppc_stt_pages(npages), true);
293
+	ret = account_locked_vm(mm, kvmppc_stt_pages(npages), true);
307294 	if (ret)
308295 		return ret;
309296 
....@@ -318,13 +305,8 @@
318305 	stt->offset = args->offset;
319306 	stt->size = size;
320307 	stt->kvm = kvm;
308
+	mutex_init(&stt->alloc_lock);
321309 	INIT_LIST_HEAD_RCU(&stt->iommu_tables);
322
-
323
-	for (i = 0; i < npages; i++) {
324
-		stt->pages[i] = alloc_page(GFP_KERNEL | __GFP_ZERO);
325
-		if (!stt->pages[i])
326
-			goto fail;
327
-	}
328310 
329311 	mutex_lock(&kvm->lock);
330312 
....@@ -337,37 +319,121 @@
337319 		}
338320 	}
339321 
322
+	kvm_get_kvm(kvm);
340323 	if (!ret)
341324 		ret = anon_inode_getfd("kvm-spapr-tce", &kvm_spapr_tce_fops,
342325 				       stt, O_RDWR | O_CLOEXEC);
343326 
344
-	if (ret >= 0) {
327
+	if (ret >= 0)
345328 		list_add_rcu(&stt->list, &kvm->arch.spapr_tce_tables);
346
-		kvm_get_kvm(kvm);
347
-	}
329
+	else
330
+		kvm_put_kvm_no_destroy(kvm);
348331 
349332 	mutex_unlock(&kvm->lock);
350333 
351334 	if (ret >= 0)
352335 		return ret;
353336 
354
- fail:
355
-	for (i = 0; i < npages; i++)
356
-		if (stt->pages[i])
357
-			__free_page(stt->pages[i]);
358
-
359337 	kfree(stt);
360338  fail_acct:
361
-	kvmppc_account_memlimit(kvmppc_stt_pages(npages), false);
339
+	account_locked_vm(mm, kvmppc_stt_pages(npages), false);
362340 	return ret;
363341 }
364342 
365
-static void kvmppc_clear_tce(struct iommu_table *tbl, unsigned long entry)
343
+static long kvmppc_tce_to_ua(struct kvm *kvm, unsigned long tce,
344
+		unsigned long *ua)
366345 {
367
-	unsigned long hpa = 0;
368
-	enum dma_data_direction dir = DMA_NONE;
346
+	unsigned long gfn = tce >> PAGE_SHIFT;
347
+	struct kvm_memory_slot *memslot;
369348 
370
-	iommu_tce_xchg(tbl, entry, &hpa, &dir);
349
+	memslot = search_memslots(kvm_memslots(kvm), gfn);
350
+	if (!memslot)
351
+		return -EINVAL;
352
+
353
+	*ua = __gfn_to_hva_memslot(memslot, gfn) |
354
+		(tce & ~(PAGE_MASK | TCE_PCI_READ | TCE_PCI_WRITE));
355
+
356
+	return 0;
357
+}
358
+
359
+static long kvmppc_tce_validate(struct kvmppc_spapr_tce_table *stt,
360
+		unsigned long tce)
361
+{
362
+	unsigned long gpa = tce & ~(TCE_PCI_READ | TCE_PCI_WRITE);
363
+	enum dma_data_direction dir = iommu_tce_direction(tce);
364
+	struct kvmppc_spapr_tce_iommu_table *stit;
365
+	unsigned long ua = 0;
366
+
367
+	/* Allow userspace to poison TCE table */
368
+	if (dir == DMA_NONE)
369
+		return H_SUCCESS;
370
+
371
+	if (iommu_tce_check_gpa(stt->page_shift, gpa))
372
+		return H_TOO_HARD;
373
+
374
+	if (kvmppc_tce_to_ua(stt->kvm, tce, &ua))
375
+		return H_TOO_HARD;
376
+
377
+	rcu_read_lock();
378
+	list_for_each_entry_rcu(stit, &stt->iommu_tables, next) {
379
+		unsigned long hpa = 0;
380
+		struct mm_iommu_table_group_mem_t *mem;
381
+		long shift = stit->tbl->it_page_shift;
382
+
383
+		mem = mm_iommu_lookup(stt->kvm->mm, ua, 1ULL << shift);
384
+		if (!mem || mm_iommu_ua_to_hpa(mem, ua, shift, &hpa)) {
385
+			rcu_read_unlock();
386
+			return H_TOO_HARD;
387
+		}
388
+	}
389
+	rcu_read_unlock();
390
+
391
+	return H_SUCCESS;
392
+}
393
+
394
+/*
395
+ * Handles TCE requests for emulated devices.
396
+ * Puts guest TCE values to the table and expects user space to convert them.
397
+ * Cannot fail so kvmppc_tce_validate must be called before it.
398
+ */
399
+static void kvmppc_tce_put(struct kvmppc_spapr_tce_table *stt,
400
+		unsigned long idx, unsigned long tce)
401
+{
402
+	struct page *page;
403
+	u64 *tbl;
404
+	unsigned long sttpage;
405
+
406
+	idx -= stt->offset;
407
+	sttpage = idx / TCES_PER_PAGE;
408
+	page = stt->pages[sttpage];
409
+
410
+	if (!page) {
411
+		/* We allow any TCE, not just with read|write permissions */
412
+		if (!tce)
413
+			return;
414
+
415
+		page = kvm_spapr_get_tce_page(stt, sttpage);
416
+		if (!page)
417
+			return;
418
+	}
419
+	tbl = page_to_virt(page);
420
+
421
+	tbl[idx % TCES_PER_PAGE] = tce;
422
+}
423
+
424
+static void kvmppc_clear_tce(struct mm_struct *mm, struct kvmppc_spapr_tce_table *stt,
425
+		struct iommu_table *tbl, unsigned long entry)
426
+{
427
+	unsigned long i;
428
+	unsigned long subpages = 1ULL << (stt->page_shift - tbl->it_page_shift);
429
+	unsigned long io_entry = entry << (stt->page_shift - tbl->it_page_shift);
430
+
431
+	for (i = 0; i < subpages; ++i) {
432
+		unsigned long hpa = 0;
433
+		enum dma_data_direction dir = DMA_NONE;
434
+
435
+		iommu_tce_xchg_no_kill(mm, tbl, io_entry + i, &hpa, &dir);
436
+	}
371437 }
372438 
373439 static long kvmppc_tce_iommu_mapped_dec(struct kvm *kvm,
....@@ -375,11 +441,10 @@
375441 {
376442 	struct mm_iommu_table_group_mem_t *mem = NULL;
377443 	const unsigned long pgsize = 1ULL << tbl->it_page_shift;
378
-	__be64 *pua = IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry);
444
+	__be64 *pua = IOMMU_TABLE_USERSPACE_ENTRY_RO(tbl, entry);
379445 
380446 	if (!pua)
381
-		/* it_userspace allocation might be delayed */
382
-		return H_TOO_HARD;
447
+		return H_SUCCESS;
383448 
384449 	mem = mm_iommu_lookup(kvm->mm, be64_to_cpu(*pua), pgsize);
385450 	if (!mem)
....@@ -399,7 +464,8 @@
399464 	unsigned long hpa = 0;
400465 	long ret;
401466 
402
-	if (WARN_ON_ONCE(iommu_tce_xchg(tbl, entry, &hpa, &dir)))
467
+	if (WARN_ON_ONCE(iommu_tce_xchg_no_kill(kvm->mm, tbl, entry, &hpa,
468
+					&dir)))
403469 		return H_TOO_HARD;
404470 
405471 	if (dir == DMA_NONE)
....@@ -407,7 +473,7 @@
407473 
408474 	ret = kvmppc_tce_iommu_mapped_dec(kvm, tbl, entry);
409475 	if (ret != H_SUCCESS)
410
-		iommu_tce_xchg(tbl, entry, &hpa, &dir);
476
+		iommu_tce_xchg_no_kill(kvm->mm, tbl, entry, &hpa, &dir);
411477 
412478 	return ret;
413479 }
....@@ -426,10 +492,12 @@
426492 			break;
427493 	}
428494 
495
+	iommu_tce_kill(tbl, io_entry, subpages);
496
+
429497 	return ret;
430498 }
431499 
432
-long kvmppc_tce_iommu_do_map(struct kvm *kvm, struct iommu_table *tbl,
500
+static long kvmppc_tce_iommu_do_map(struct kvm *kvm, struct iommu_table *tbl,
433501 		unsigned long entry, unsigned long ua,
434502 		enum dma_data_direction dir)
435503 {
....@@ -453,7 +521,7 @@
453521 	if (mm_iommu_mapped_inc(mem))
454522 		return H_TOO_HARD;
455523 
456
-	ret = iommu_tce_xchg(tbl, entry, &hpa, &dir);
524
+	ret = iommu_tce_xchg_no_kill(kvm->mm, tbl, entry, &hpa, &dir);
457525 	if (WARN_ON_ONCE(ret)) {
458526 		mm_iommu_mapped_dec(mem);
459527 		return H_TOO_HARD;
....@@ -485,6 +553,8 @@
485553 			break;
486554 	}
487555 
556
+	iommu_tce_kill(tbl, io_entry, subpages);
557
+
488558 	return ret;
489559 }
490560 
....@@ -508,16 +578,15 @@
508578 	if (ret != H_SUCCESS)
509579 		return ret;
510580 
581
+	idx = srcu_read_lock(&vcpu->kvm->srcu);
582
+
511583 	ret = kvmppc_tce_validate(stt, tce);
512584 	if (ret != H_SUCCESS)
513
-		return ret;
585
+		goto unlock_exit;
514586 
515587 	dir = iommu_tce_direction(tce);
516588 
517
-	idx = srcu_read_lock(&vcpu->kvm->srcu);
518
-
519
-	if ((dir != DMA_NONE) && kvmppc_gpa_to_ua(vcpu->kvm,
520
-			tce & ~(TCE_PCI_READ | TCE_PCI_WRITE), &ua, NULL)) {
589
+	if ((dir != DMA_NONE) && kvmppc_tce_to_ua(vcpu->kvm, tce, &ua)) {
521590 		ret = H_PARAMETER;
522591 		goto unlock_exit;
523592 	}
....@@ -532,14 +601,11 @@
532601 			ret = kvmppc_tce_iommu_map(vcpu->kvm, stt, stit->tbl,
533602 					entry, ua, dir);
534603 
535
-		if (ret == H_SUCCESS)
536
-			continue;
537604 
538
-		if (ret == H_TOO_HARD)
605
+		if (ret != H_SUCCESS) {
606
+			kvmppc_clear_tce(vcpu->kvm->mm, stt, stit->tbl, entry);
539607 			goto unlock_exit;
540
-
541
-		WARN_ON_ONCE(1);
542
-		kvmppc_clear_tce(stit->tbl, entry);
608
+		}
543609 	}
544610 
545611 	kvmppc_tce_put(stt, entry, tce);
....@@ -582,7 +648,7 @@
582648 		return ret;
583649 
584650 	idx = srcu_read_lock(&vcpu->kvm->srcu);
585
-	if (kvmppc_gpa_to_ua(vcpu->kvm, tce_list, &ua, NULL)) {
651
+	if (kvmppc_tce_to_ua(vcpu->kvm, tce_list, &ua)) {
586652 		ret = H_TOO_HARD;
587653 		goto unlock_exit;
588654 	}
....@@ -598,10 +664,26 @@
598664 		ret = kvmppc_tce_validate(stt, tce);
599665 		if (ret != H_SUCCESS)
600666 			goto unlock_exit;
667
+	}
601668 
602
-		if (kvmppc_gpa_to_ua(vcpu->kvm,
603
-				tce & ~(TCE_PCI_READ | TCE_PCI_WRITE),
604
-				&ua, NULL)) {
669
+	for (i = 0; i < npages; ++i) {
670
+		/*
671
+		 * This looks unsafe, because we validate, then regrab
672
+		 * the TCE from userspace which could have been changed by
673
+		 * another thread.
674
+		 *
675
+		 * But it actually is safe, because the relevant checks will be
676
+		 * re-executed in the following code.  If userspace tries to
677
+		 * change this dodgily it will result in a messier failure mode
678
+		 * but won't threaten the host.
679
+		 */
680
+		if (get_user(tce, tces + i)) {
681
+			ret = H_TOO_HARD;
682
+			goto unlock_exit;
683
+		}
684
+		tce = be64_to_cpu(tce);
685
+
686
+		if (kvmppc_tce_to_ua(vcpu->kvm, tce, &ua)) {
605687 			ret = H_PARAMETER;
606688 			goto unlock_exit;
607689 		}
....@@ -611,14 +693,11 @@
611693 					stit->tbl, entry + i, ua,
612694 					iommu_tce_direction(tce));
613695 
614
-			if (ret == H_SUCCESS)
615
-				continue;
616
-
617
-			if (ret == H_TOO_HARD)
696
+			if (ret != H_SUCCESS) {
697
+				kvmppc_clear_tce(vcpu->kvm->mm, stt, stit->tbl,
698
+						 entry + i);
618699 				goto unlock_exit;
619
-
620
-			WARN_ON_ONCE(1);
621
-			kvmppc_clear_tce(stit->tbl, entry);
700
+			}
622701 		}
623702 
624703 		kvmppc_tce_put(stt, entry + i, tce);
....@@ -665,13 +744,13 @@
665744 				return ret;
666745 
667746 			WARN_ON_ONCE(1);
668
-			kvmppc_clear_tce(stit->tbl, entry);
747
+			kvmppc_clear_tce(vcpu->kvm->mm, stt, stit->tbl, entry + i);
669748 		}
670749 	}
671750 
672751 	for (i = 0; i < npages; ++i, ioba += (1ULL << stt->page_shift))
673752 		kvmppc_tce_put(stt, ioba >> stt->page_shift, tce_value);
674753 
675
-	return H_SUCCESS;
754
+	return ret;
676755 }
677756 EXPORT_SYMBOL_GPL(kvmppc_h_stuff_tce);