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
21struct kvm_pgtable pkvm_pgtable;
22hyp_spinlock_t pkvm_pgd_lock;
23
24struct memblock_region hyp_memory[HYP_MEMBLOCK_REGIONS];
25unsigned int hyp_memblock_nr;
26
27static u64 __io_map_base;
28
29struct hyp_fixmap_slot {
30	u64 addr;
31	kvm_pte_t *ptep;
32};
33static DEFINE_PER_CPU(struct hyp_fixmap_slot, fixmap_slots);
34
35static 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
47static 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 */
78int 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
93int __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
113int 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
138int 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
149int 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
181static void *__hyp_bp_vect_base;
182int 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
210int 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
232void *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
246static 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
268void hyp_fixmap_unmap(void)
269{
270	fixmap_clear_slot(this_cpu_ptr(&fixmap_slots));
271}
272
273static 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
294static 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
305int 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
328int 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
353int 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
392static 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. */
412int 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