summaryrefslogtreecommitdiffstats
path: root/arch/arm64/kvm/hyp/nvhe/mm.c
blob: 318298eb3d6b20eeda1854b10adf06ce676ee790 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2020 Google LLC
 * Author: Quentin Perret <qperret@google.com>
 */

#include <linux/kvm_host.h>
#include <asm/kvm_hyp.h>
#include <asm/kvm_mmu.h>
#include <asm/kvm_pgtable.h>
#include <asm/kvm_pkvm.h>
#include <asm/spectre.h>

#include <nvhe/early_alloc.h>
#include <nvhe/gfp.h>
#include <nvhe/memory.h>
#include <nvhe/mem_protect.h>
#include <nvhe/mm.h>
#include <nvhe/spinlock.h>

struct kvm_pgtable pkvm_pgtable;
hyp_spinlock_t pkvm_pgd_lock;

struct memblock_region hyp_memory[HYP_MEMBLOCK_REGIONS];
unsigned int hyp_memblock_nr;

static u64 __io_map_base;

struct hyp_fixmap_slot {
	u64 addr;
	kvm_pte_t *ptep;
};
static DEFINE_PER_CPU(struct hyp_fixmap_slot, fixmap_slots);

static int __pkvm_create_mappings(unsigned long start, unsigned long size,
				  unsigned long phys, enum kvm_pgtable_prot prot)
{
	int err;

	hyp_spin_lock(&pkvm_pgd_lock);
	err = kvm_pgtable_hyp_map(&pkvm_pgtable, start, size, phys, prot);
	hyp_spin_unlock(&pkvm_pgd_lock);

	return err;
}

/**
 * pkvm_alloc_private_va_range - Allocates a private VA range.
 * @size:	The size of the VA range to reserve.
 * @haddr:	The hypervisor virtual start address of the allocation.
 *
 * The private virtual address (VA) range is allocated above __io_map_base
 * and aligned based on the order of @size.
 *
 * Return: 0 on success or negative error code on failure.
 */
int pkvm_alloc_private_va_range(size_t size, unsigned long *haddr)
{
	unsigned long base, addr;
	int ret = 0;

	hyp_spin_lock(&pkvm_pgd_lock);

	/* Align the allocation based on the order of its size */
	addr = ALIGN(__io_map_base, PAGE_SIZE << get_order(size));

	/* The allocated size is always a multiple of PAGE_SIZE */
	base = addr + PAGE_ALIGN(size);

	/* Are we overflowing on the vmemmap ? */
	if (!addr || base > __hyp_vmemmap)
		ret = -ENOMEM;
	else {
		__io_map_base = base;
		*haddr = addr;
	}

	hyp_spin_unlock(&pkvm_pgd_lock);

	return ret;
}

int __pkvm_create_private_mapping(phys_addr_t phys, size_t size,
				  enum kvm_pgtable_prot prot,
				  unsigned long *haddr)
{
	unsigned long addr;
	int err;

	size = PAGE_ALIGN(size + offset_in_page(phys));
	err = pkvm_alloc_private_va_range(size, &addr);
	if (err)
		return err;

	err = __pkvm_create_mappings(addr, size, phys, prot);
	if (err)
		return err;

	*haddr = addr + offset_in_page(phys);
	return err;
}

int pkvm_create_mappings_locked(void *from, void *to, enum kvm_pgtable_prot prot)
{
	unsigned long start = (unsigned long)from;
	unsigned long end = (unsigned long)to;
	unsigned long virt_addr;
	phys_addr_t phys;

	hyp_assert_lock_held(&pkvm_pgd_lock);

	start = start & PAGE_MASK;
	end = PAGE_ALIGN(end);

	for (virt_addr = start; virt_addr < end; virt_addr += PAGE_SIZE) {
		int err;

		phys = hyp_virt_to_phys((void *)virt_addr);
		err = kvm_pgtable_hyp_map(&pkvm_pgtable, virt_addr, PAGE_SIZE,
					  phys, prot);
		if (err)
			return err;
	}

	return 0;
}

int pkvm_create_mappings(void *from, void *to, enum kvm_pgtable_prot prot)
{
	int ret;

	hyp_spin_lock(&pkvm_pgd_lock);
	ret = pkvm_create_mappings_locked(from, to, prot);
	hyp_spin_unlock(&pkvm_pgd_lock);

	return ret;
}

int hyp_back_vmemmap(phys_addr_t back)
{
	unsigned long i, start, size, end = 0;
	int ret;

	for (i = 0; i < hyp_memblock_nr; i++) {
		start = hyp_memory[i].base;
		start = ALIGN_DOWN((u64)hyp_phys_to_page(start), PAGE_SIZE);
		/*
		 * The begining of the hyp_vmemmap region for the current
		 * memblock may already be backed by the page backing the end
		 * the previous region, so avoid mapping it twice.
		 */
		start = max(start, end);

		end = hyp_memory[i].base + hyp_memory[i].size;
		end = PAGE_ALIGN((u64)hyp_phys_to_page(end));
		if (start >= end)
			continue;

		size = end - start;
		ret = __pkvm_create_mappings(start, size, back, PAGE_HYP);
		if (ret)
			return ret;

		memset(hyp_phys_to_virt(back), 0, size);
		back += size;
	}

	return 0;
}

static void *__hyp_bp_vect_base;
int pkvm_cpu_set_vector(enum arm64_hyp_spectre_vector slot)
{
	void *vector;

	switch (slot) {
	case HYP_VECTOR_DIRECT: {
		vector = __kvm_hyp_vector;
		break;
	}
	case HYP_VECTOR_SPECTRE_DIRECT: {
		vector = __bp_harden_hyp_vecs;
		break;
	}
	case HYP_VECTOR_INDIRECT:
	case HYP_VECTOR_SPECTRE_INDIRECT: {
		vector = (void *)__hyp_bp_vect_base;
		break;
	}
	default:
		return -EINVAL;
	}

	vector = __kvm_vector_slot2addr(vector, slot);
	*this_cpu_ptr(&kvm_hyp_vector) = (unsigned long)vector;

	return 0;
}

int hyp_map_vectors(void)
{
	phys_addr_t phys;
	unsigned long bp_base;
	int ret;

	if (!kvm_system_needs_idmapped_vectors()) {
		__hyp_bp_vect_base = __bp_harden_hyp_vecs;
		return 0;
	}

	phys = __hyp_pa(__bp_harden_hyp_vecs);
	ret = __pkvm_create_private_mapping(phys, __BP_HARDEN_HYP_VECS_SZ,
					    PAGE_HYP_EXEC, &bp_base);
	if (ret)
		return ret;

	__hyp_bp_vect_base = (void *)bp_base;

	return 0;
}

void *hyp_fixmap_map(phys_addr_t phys)
{
	struct hyp_fixmap_slot *slot = this_cpu_ptr(&fixmap_slots);
	kvm_pte_t pte, *ptep = slot->ptep;

	pte = *ptep;
	pte &= ~kvm_phys_to_pte(KVM_PHYS_INVALID);
	pte |= kvm_phys_to_pte(phys) | KVM_PTE_VALID;
	WRITE_ONCE(*ptep, pte);
	dsb(ishst);

	return (void *)slot->addr;
}

static void fixmap_clear_slot(struct hyp_fixmap_slot *slot)
{
	kvm_pte_t *ptep = slot->ptep;
	u64 addr = slot->addr;

	WRITE_ONCE(*ptep, *ptep & ~KVM_PTE_VALID);

	/*
	 * Irritatingly, the architecture requires that we use inner-shareable
	 * broadcast TLB invalidation here in case another CPU speculates
	 * through our fixmap and decides to create an "amalagamation of the
	 * values held in the TLB" due to the apparent lack of a
	 * break-before-make sequence.
	 *
	 * https://lore.kernel.org/kvm/20221017115209.2099-1-will@kernel.org/T/#mf10dfbaf1eaef9274c581b81c53758918c1d0f03
	 */
	dsb(ishst);
	__tlbi_level(vale2is, __TLBI_VADDR(addr, 0), (KVM_PGTABLE_MAX_LEVELS - 1));
	dsb(ish);
	isb();
}

void hyp_fixmap_unmap(void)
{
	fixmap_clear_slot(this_cpu_ptr(&fixmap_slots));
}

static int __create_fixmap_slot_cb(const struct kvm_pgtable_visit_ctx *ctx,
				   enum kvm_pgtable_walk_flags visit)
{
	struct hyp_fixmap_slot *slot = per_cpu_ptr(&fixmap_slots, (u64)ctx->arg);

	if (!kvm_pte_valid(ctx->old) || ctx->level != KVM_PGTABLE_MAX_LEVELS - 1)
		return -EINVAL;

	slot->addr = ctx->addr;
	slot->ptep = ctx->ptep;

	/*
	 * Clear the PTE, but keep the page-table page refcount elevated to
	 * prevent it from ever being freed. This lets us manipulate the PTEs
	 * by hand safely without ever needing to allocate memory.
	 */
	fixmap_clear_slot(slot);

	return 0;
}

static int create_fixmap_slot(u64 addr, u64 cpu)
{
	struct kvm_pgtable_walker walker = {
		.cb	= __create_fixmap_slot_cb,
		.flags	= KVM_PGTABLE_WALK_LEAF,
		.arg = (void *)cpu,
	};

	return kvm_pgtable_walk(&pkvm_pgtable, addr, PAGE_SIZE, &walker);
}

int hyp_create_pcpu_fixmap(void)
{
	unsigned long addr, i;
	int ret;

	for (i = 0; i < hyp_nr_cpus; i++) {
		ret = pkvm_alloc_private_va_range(PAGE_SIZE, &addr);
		if (ret)
			return ret;

		ret = kvm_pgtable_hyp_map(&pkvm_pgtable, addr, PAGE_SIZE,
					  __hyp_pa(__hyp_bss_start), PAGE_HYP);
		if (ret)
			return ret;

		ret = create_fixmap_slot(addr, i);
		if (ret)
			return ret;
	}

	return 0;
}

int hyp_create_idmap(u32 hyp_va_bits)
{
	unsigned long start, end;

	start = hyp_virt_to_phys((void *)__hyp_idmap_text_start);
	start = ALIGN_DOWN(start, PAGE_SIZE);

	end = hyp_virt_to_phys((void *)__hyp_idmap_text_end);
	end = ALIGN(end, PAGE_SIZE);

	/*
	 * One half of the VA space is reserved to linearly map portions of
	 * memory -- see va_layout.c for more details. The other half of the VA
	 * space contains the trampoline page, and needs some care. Split that
	 * second half in two and find the quarter of VA space not conflicting
	 * with the idmap to place the IOs and the vmemmap. IOs use the lower
	 * half of the quarter and the vmemmap the upper half.
	 */
	__io_map_base = start & BIT(hyp_va_bits - 2);
	__io_map_base ^= BIT(hyp_va_bits - 2);
	__hyp_vmemmap = __io_map_base | BIT(hyp_va_bits - 3);

	return __pkvm_create_mappings(start, end - start, start, PAGE_HYP_EXEC);
}

static void *admit_host_page(void *arg)
{
	struct kvm_hyp_memcache *host_mc = arg;

	if (!host_mc->nr_pages)
		return NULL;

	/*
	 * The host still owns the pages in its memcache, so we need to go
	 * through a full host-to-hyp donation cycle to change it. Fortunately,
	 * __pkvm_host_donate_hyp() takes care of races for us, so if it
	 * succeeds we're good to go.
	 */
	if (__pkvm_host_donate_hyp(hyp_phys_to_pfn(host_mc->head), 1))
		return NULL;

	return pop_hyp_memcache(host_mc, hyp_phys_to_virt);
}

/* Refill our local memcache by poping pages from the one provided by the host. */
int refill_memcache(struct kvm_hyp_memcache *mc, unsigned long min_pages,
		    struct kvm_hyp_memcache *host_mc)
{
	struct kvm_hyp_memcache tmp = *host_mc;
	int ret;

	ret =  __topup_hyp_memcache(mc, min_pages, admit_host_page,
				    hyp_virt_to_phys, &tmp);
	*host_mc = tmp;

	return ret;
}