1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2020 Google LLC
4 * Author: Quentin Perret <qperret@google.com>
5 */
6
7 #include <linux/kvm_host.h>
8 #include <asm/kvm_hyp.h>
9 #include <asm/kvm_mmu.h>
10 #include <asm/kvm_pgtable.h>
11 #include <asm/kvm_pkvm.h>
12 #include <asm/spectre.h>
13
14 #include <nvhe/early_alloc.h>
15 #include <nvhe/gfp.h>
16 #include <nvhe/memory.h>
17 #include <nvhe/mem_protect.h>
18 #include <nvhe/mm.h>
19 #include <nvhe/spinlock.h>
20
21 struct kvm_pgtable pkvm_pgtable;
22 hyp_spinlock_t pkvm_pgd_lock;
23
24 struct memblock_region hyp_memory[HYP_MEMBLOCK_REGIONS];
25 unsigned int hyp_memblock_nr;
26
27 static u64 __io_map_base;
28
29 struct hyp_fixmap_slot {
30 u64 addr;
31 kvm_pte_t *ptep;
32 };
33 static DEFINE_PER_CPU(struct hyp_fixmap_slot, fixmap_slots);
34
35 static int __pkvm_create_mappings(unsigned long start, unsigned long size,
36 unsigned long phys, enum kvm_pgtable_prot prot)
37 {
38 int err;
39
40 hyp_spin_lock(&pkvm_pgd_lock);
41 err = kvm_pgtable_hyp_map(&pkvm_pgtable, start, size, phys, prot);
42 hyp_spin_unlock(&pkvm_pgd_lock);
43
44 return err;
45 }
46
47 static int __pkvm_alloc_private_va_range(unsigned long start, size_t size)
48 {
49 unsigned long cur;
50
51 hyp_assert_lock_held(&pkvm_pgd_lock);
52
53 if (!start || start < __io_map_base)
54 return -EINVAL;
55
56 /* The allocated size is always a multiple of PAGE_SIZE */
57 cur = start + PAGE_ALIGN(size);
58
59 /* Are we overflowing on the vmemmap ? */
60 if (cur > __hyp_vmemmap)
61 return -ENOMEM;
62
63 __io_map_base = cur;
64
65 return 0;
66 }
67
68 /**
69 * pkvm_alloc_private_va_range - Allocates a private VA range.
70 * @size: The size of the VA range to reserve.
71 * @haddr: The hypervisor virtual start address of the allocation.
72 *
73 * The private virtual address (VA) range is allocated above __io_map_base
74 * and aligned based on the order of @size.
75 *
76 * Return: 0 on success or negative error code on failure.
77 */
78 int pkvm_alloc_private_va_range(size_t size, unsigned long *haddr)
79 {
80 unsigned long addr;
81 int ret;
82
83 hyp_spin_lock(&pkvm_pgd_lock);
84 addr = __io_map_base;
85 ret = __pkvm_alloc_private_va_range(addr, size);
86 hyp_spin_unlock(&pkvm_pgd_lock);
87
88 *haddr = addr;
89
90 return ret;
91 }
92
93 int __pkvm_create_private_mapping(phys_addr_t phys, size_t size,
94 enum kvm_pgtable_prot prot,
95 unsigned long *haddr)
96 {
97 unsigned long addr;
98 int err;
99
100 size = PAGE_ALIGN(size + offset_in_page(phys));
101 err = pkvm_alloc_private_va_range(size, &addr);
102 if (err)
103 return err;
104
105 err = __pkvm_create_mappings(addr, size, phys, prot);
106 if (err)
107 return err;
108
109 *haddr = addr + offset_in_page(phys);
110 return err;
111 }
112
113 int pkvm_create_mappings_locked(void *from, void *to, enum kvm_pgtable_prot prot)
114 {
115 unsigned long start = (unsigned long)from;
116 unsigned long end = (unsigned long)to;
117 unsigned long virt_addr;
118 phys_addr_t phys;
119
120 hyp_assert_lock_held(&pkvm_pgd_lock);
121
122 start = start & PAGE_MASK;
123 end = PAGE_ALIGN(end);
124
125 for (virt_addr = start; virt_addr < end; virt_addr += PAGE_SIZE) {
126 int err;
127
128 phys = hyp_virt_to_phys((void *)virt_addr);
129 err = kvm_pgtable_hyp_map(&pkvm_pgtable, virt_addr, PAGE_SIZE,
130 phys, prot);
131 if (err)
132 return err;
133 }
134
135 return 0;
136 }
137
138 int pkvm_create_mappings(void *from, void *to, enum kvm_pgtable_prot prot)
139 {
140 int ret;
141
142 hyp_spin_lock(&pkvm_pgd_lock);
143 ret = pkvm_create_mappings_locked(from, to, prot);
144 hyp_spin_unlock(&pkvm_pgd_lock);
145
146 return ret;
147 }
148
149 int hyp_back_vmemmap(phys_addr_t back)
150 {
151 unsigned long i, start, size, end = 0;
152 int ret;
153
154 for (i = 0; i < hyp_memblock_nr; i++) {
155 start = hyp_memory[i].base;
156 start = ALIGN_DOWN((u64)hyp_phys_to_page(start), PAGE_SIZE);
157 /*
158 * The beginning of the hyp_vmemmap region for the current
159 * memblock may already be backed by the page backing the end
160 * the previous region, so avoid mapping it twice.
161 */
162 start = max(start, end);
163
164 end = hyp_memory[i].base + hyp_memory[i].size;
165 end = PAGE_ALIGN((u64)hyp_phys_to_page(end));
166 if (start >= end)
167 continue;
168
169 size = end - start;
170 ret = __pkvm_create_mappings(start, size, back, PAGE_HYP);
171 if (ret)
172 return ret;
173
174 memset(hyp_phys_to_virt(back), 0, size);
175 back += size;
176 }
177
178 return 0;
179 }
180
181 static void *__hyp_bp_vect_base;
182 int pkvm_cpu_set_vector(enum arm64_hyp_spectre_vector slot)
183 {
184 void *vector;
185
186 switch (slot) {
187 case HYP_VECTOR_DIRECT: {
188 vector = __kvm_hyp_vector;
189 break;
190 }
191 case HYP_VECTOR_SPECTRE_DIRECT: {
192 vector = __bp_harden_hyp_vecs;
193 break;
194 }
195 case HYP_VECTOR_INDIRECT:
196 case HYP_VECTOR_SPECTRE_INDIRECT: {
197 vector = (void *)__hyp_bp_vect_base;
198 break;
199 }
200 default:
201 return -EINVAL;
202 }
203
204 vector = __kvm_vector_slot2addr(vector, slot);
205 *this_cpu_ptr(&kvm_hyp_vector) = (unsigned long)vector;
206
207 return 0;
208 }
209
210 int hyp_map_vectors(void)
211 {
212 phys_addr_t phys;
213 unsigned long bp_base;
214 int ret;
215
216 if (!kvm_system_needs_idmapped_vectors()) {
217 __hyp_bp_vect_base = __bp_harden_hyp_vecs;
218 return 0;
219 }
220
221 phys = __hyp_pa(__bp_harden_hyp_vecs);
222 ret = __pkvm_create_private_mapping(phys, __BP_HARDEN_HYP_VECS_SZ,
223 PAGE_HYP_EXEC, &bp_base);
224 if (ret)
225 return ret;
226
227 __hyp_bp_vect_base = (void *)bp_base;
228
229 return 0;
230 }
231
232 void *hyp_fixmap_map(phys_addr_t phys)
233 {
234 struct hyp_fixmap_slot *slot = this_cpu_ptr(&fixmap_slots);
235 kvm_pte_t pte, *ptep = slot->ptep;
236
237 pte = *ptep;
238 pte &= ~kvm_phys_to_pte(KVM_PHYS_INVALID);
239 pte |= kvm_phys_to_pte(phys) | KVM_PTE_VALID;
240 WRITE_ONCE(*ptep, pte);
241 dsb(ishst);
242
243 return (void *)slot->addr;
244 }
245
246 static void fixmap_clear_slot(struct hyp_fixmap_slot *slot)
247 {
248 kvm_pte_t *ptep = slot->ptep;
249 u64 addr = slot->addr;
250
251 WRITE_ONCE(*ptep, *ptep & ~KVM_PTE_VALID);
252
253 /*
254 * Irritatingly, the architecture requires that we use inner-shareable
255 * broadcast TLB invalidation here in case another CPU speculates
256 * through our fixmap and decides to create an "amalagamation of the
257 * values held in the TLB" due to the apparent lack of a
258 * break-before-make sequence.
259 *
260 * https://lore.kernel.org/kvm/20221017115209.2099-1-will@kernel.org/T/#mf10dfbaf1eaef9274c581b81c53758918c1d0f03
261 */
262 dsb(ishst);
263 __tlbi_level(vale2is, __TLBI_VADDR(addr, 0), KVM_PGTABLE_LAST_LEVEL);
264 dsb(ish);
265 isb();
266 }
267
268 void hyp_fixmap_unmap(void)
269 {
270 fixmap_clear_slot(this_cpu_ptr(&fixmap_slots));
271 }
272
273 static int __create_fixmap_slot_cb(const struct kvm_pgtable_visit_ctx *ctx,
274 enum kvm_pgtable_walk_flags visit)
275 {
276 struct hyp_fixmap_slot *slot = per_cpu_ptr(&fixmap_slots, (u64)ctx->arg);
277
278 if (!kvm_pte_valid(ctx->old) || ctx->level != KVM_PGTABLE_LAST_LEVEL)
279 return -EINVAL;
280
281 slot->addr = ctx->addr;
282 slot->ptep = ctx->ptep;
283
284 /*
285 * Clear the PTE, but keep the page-table page refcount elevated to
286 * prevent it from ever being freed. This lets us manipulate the PTEs
287 * by hand safely without ever needing to allocate memory.
288 */
289 fixmap_clear_slot(slot);
290
291 return 0;
292 }
293
294 static int create_fixmap_slot(u64 addr, u64 cpu)
295 {
296 struct kvm_pgtable_walker walker = {
297 .cb = __create_fixmap_slot_cb,
298 .flags = KVM_PGTABLE_WALK_LEAF,
299 .arg = (void *)cpu,
300 };
301
302 return kvm_pgtable_walk(&pkvm_pgtable, addr, PAGE_SIZE, &walker);
303 }
304
305 int hyp_create_pcpu_fixmap(void)
306 {
307 unsigned long addr, i;
308 int ret;
309
310 for (i = 0; i < hyp_nr_cpus; i++) {
311 ret = pkvm_alloc_private_va_range(PAGE_SIZE, &addr);
312 if (ret)
313 return ret;
314
315 ret = kvm_pgtable_hyp_map(&pkvm_pgtable, addr, PAGE_SIZE,
316 __hyp_pa(__hyp_bss_start), PAGE_HYP);
317 if (ret)
318 return ret;
319
320 ret = create_fixmap_slot(addr, i);
321 if (ret)
322 return ret;
323 }
324
325 return 0;
326 }
327
328 int hyp_create_idmap(u32 hyp_va_bits)
329 {
330 unsigned long start, end;
331
332 start = hyp_virt_to_phys((void *)__hyp_idmap_text_start);
333 start = ALIGN_DOWN(start, PAGE_SIZE);
334
335 end = hyp_virt_to_phys((void *)__hyp_idmap_text_end);
336 end = ALIGN(end, PAGE_SIZE);
337
338 /*
339 * One half of the VA space is reserved to linearly map portions of
340 * memory -- see va_layout.c for more details. The other half of the VA
341 * space contains the trampoline page, and needs some care. Split that
342 * second half in two and find the quarter of VA space not conflicting
343 * with the idmap to place the IOs and the vmemmap. IOs use the lower
344 * half of the quarter and the vmemmap the upper half.
345 */
346 __io_map_base = start & BIT(hyp_va_bits - 2);
347 __io_map_base ^= BIT(hyp_va_bits - 2);
348 __hyp_vmemmap = __io_map_base | BIT(hyp_va_bits - 3);
349
350 return __pkvm_create_mappings(start, end - start, start, PAGE_HYP_EXEC);
351 }
352
353 int pkvm_create_stack(phys_addr_t phys, unsigned long *haddr)
354 {
355 unsigned long addr, prev_base;
356 size_t size;
357 int ret;
358
359 hyp_spin_lock(&pkvm_pgd_lock);
360
361 prev_base = __io_map_base;
362 /*
363 * Efficient stack verification using the PAGE_SHIFT bit implies
364 * an alignment of our allocation on the order of the size.
365 */
366 size = PAGE_SIZE * 2;
367 addr = ALIGN(__io_map_base, size);
368
369 ret = __pkvm_alloc_private_va_range(addr, size);
370 if (!ret) {
371 /*
372 * Since the stack grows downwards, map the stack to the page
373 * at the higher address and leave the lower guard page
374 * unbacked.
375 *
376 * Any valid stack address now has the PAGE_SHIFT bit as 1
377 * and addresses corresponding to the guard page have the
378 * PAGE_SHIFT bit as 0 - this is used for overflow detection.
379 */
380 ret = kvm_pgtable_hyp_map(&pkvm_pgtable, addr + PAGE_SIZE,
381 PAGE_SIZE, phys, PAGE_HYP);
382 if (ret)
383 __io_map_base = prev_base;
384 }
385 hyp_spin_unlock(&pkvm_pgd_lock);
386
387 *haddr = addr + size;
388
389 return ret;
390 }
391
392 static void *admit_host_page(void *arg)
393 {
394 struct kvm_hyp_memcache *host_mc = arg;
395
396 if (!host_mc->nr_pages)
397 return NULL;
398
399 /*
400 * The host still owns the pages in its memcache, so we need to go
401 * through a full host-to-hyp donation cycle to change it. Fortunately,
402 * __pkvm_host_donate_hyp() takes care of races for us, so if it
403 * succeeds we're good to go.
404 */
405 if (__pkvm_host_donate_hyp(hyp_phys_to_pfn(host_mc->head), 1))
406 return NULL;
407
408 return pop_hyp_memcache(host_mc, hyp_phys_to_virt);
409 }
410
411 /* Refill our local memcache by popping pages from the one provided by the host. */
412 int refill_memcache(struct kvm_hyp_memcache *mc, unsigned long min_pages,
413 struct kvm_hyp_memcache *host_mc)
414 {
415 struct kvm_hyp_memcache tmp = *host_mc;
416 int ret;
417
418 ret = __topup_hyp_memcache(mc, min_pages, admit_host_page,
419 hyp_virt_to_phys, &tmp);
420 *host_mc = tmp;
421
422 return ret;
423 }
424
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