ptdump.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Debug helper used to dump the stage-2 pagetables of the system and their
  4 * associated permissions.
  5 *
  6 * Copyright (C) Google, 2024
  7 * Author: Sebastian Ene <sebastianene@google.com>
  8 */
  9#include <linux/debugfs.h>
 10#include <linux/kvm_host.h>
 11#include <linux/seq_file.h>
 12
 13#include <asm/kvm_mmu.h>
 14#include <asm/kvm_pgtable.h>
 15#include <asm/ptdump.h>
 16
 17#define MARKERS_LEN		2
 18#define KVM_PGTABLE_MAX_LEVELS	(KVM_PGTABLE_LAST_LEVEL + 1)
 19
 20struct kvm_ptdump_guest_state {
 21	struct kvm		*kvm;
 22	struct ptdump_pg_state	parser_state;
 23	struct addr_marker	ipa_marker[MARKERS_LEN];
 24	struct ptdump_pg_level	level[KVM_PGTABLE_MAX_LEVELS];
 25	struct ptdump_range	range[MARKERS_LEN];
 26};
 27
 28static const struct ptdump_prot_bits stage2_pte_bits[] = {
 29	{
 30		.mask	= PTE_VALID,
 31		.val	= PTE_VALID,
 32		.set	= " ",
 33		.clear	= "F",
 34	},
 35	{
 36		.mask	= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R,
 37		.val	= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R,
 38		.set	= "R",
 39		.clear	= " ",
 40	},
 41	{
 42		.mask	= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W,
 43		.val	= KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W,
 44		.set	= "W",
 45		.clear	= " ",
 46	},
 47	{
 48		.mask	= KVM_PTE_LEAF_ATTR_HI_S2_XN,
 49		.val	= 0b00UL << __bf_shf(KVM_PTE_LEAF_ATTR_HI_S2_XN),
 50		.set	= "px ux ",
 51	},
 52	{
 53		.mask	= KVM_PTE_LEAF_ATTR_HI_S2_XN,
 54		.val	= 0b01UL << __bf_shf(KVM_PTE_LEAF_ATTR_HI_S2_XN),
 55		.set	= "PXNux ",
 56	},
 57	{
 58		.mask	= KVM_PTE_LEAF_ATTR_HI_S2_XN,
 59		.val	= 0b10UL << __bf_shf(KVM_PTE_LEAF_ATTR_HI_S2_XN),
 60		.set	= "PXNUXN",
 61	},
 62	{
 63		.mask	= KVM_PTE_LEAF_ATTR_HI_S2_XN,
 64		.val	= 0b11UL << __bf_shf(KVM_PTE_LEAF_ATTR_HI_S2_XN),
 65		.set	= "px UXN",
 66	},
 67	{
 68		.mask	= KVM_PTE_LEAF_ATTR_LO_S2_AF,
 69		.val	= KVM_PTE_LEAF_ATTR_LO_S2_AF,
 70		.set	= "AF",
 71		.clear	= "  ",
 72	},
 73	{
 74		.mask	= PMD_TYPE_MASK,
 75		.val	= PMD_TYPE_SECT,
 76		.set	= "BLK",
 77		.clear	= "   ",
 78	},
 79};
 80
 81static int kvm_ptdump_visitor(const struct kvm_pgtable_visit_ctx *ctx,
 82			      enum kvm_pgtable_walk_flags visit)
 83{
 84	struct ptdump_pg_state *st = ctx->arg;
 85	struct ptdump_state *pt_st = &st->ptdump;
 86
 87	note_page(pt_st, ctx->addr, ctx->level, ctx->old);
 88
 89	return 0;
 90}
 91
 92static int kvm_ptdump_build_levels(struct ptdump_pg_level *level, u32 start_lvl)
 93{
 94	u32 i;
 95	u64 mask;
 96
 97	if (WARN_ON_ONCE(start_lvl >= KVM_PGTABLE_LAST_LEVEL))
 98		return -EINVAL;
 99
100	mask = 0;
101	for (i = 0; i < ARRAY_SIZE(stage2_pte_bits); i++)
102		mask |= stage2_pte_bits[i].mask;
103
104	for (i = start_lvl; i < KVM_PGTABLE_MAX_LEVELS; i++) {
105		snprintf(level[i].name, sizeof(level[i].name), "%u", i);
106
107		level[i].num	= ARRAY_SIZE(stage2_pte_bits);
108		level[i].bits	= stage2_pte_bits;
109		level[i].mask	= mask;
110	}
111
112	return 0;
113}
114
115static struct kvm_ptdump_guest_state *kvm_ptdump_parser_create(struct kvm *kvm)
116{
117	struct kvm_ptdump_guest_state *st;
118	struct kvm_s2_mmu *mmu = &kvm->arch.mmu;
119	struct kvm_pgtable *pgtable = mmu->pgt;
120	int ret;
121
122	st = kzalloc(sizeof(struct kvm_ptdump_guest_state), GFP_KERNEL_ACCOUNT);
123	if (!st)
124		return ERR_PTR(-ENOMEM);
125
126	ret = kvm_ptdump_build_levels(&st->level[0], pgtable->start_level);
127	if (ret) {
128		kfree(st);
129		return ERR_PTR(ret);
130	}
131
132	st->ipa_marker[0].name		= "Guest IPA";
133	st->ipa_marker[1].start_address = BIT(pgtable->ia_bits);
134	st->range[0].end		= BIT(pgtable->ia_bits);
135
136	st->kvm				= kvm;
137	st->parser_state = (struct ptdump_pg_state) {
138		.marker		= &st->ipa_marker[0],
139		.level		= -1,
140		.pg_level	= &st->level[0],
141		.ptdump.range	= &st->range[0],
142		.start_address	= 0,
143	};
144
145	return st;
146}
147
148static int kvm_ptdump_guest_show(struct seq_file *m, void *unused)
149{
150	int ret;
151	struct kvm_ptdump_guest_state *st = m->private;
152	struct kvm *kvm = st->kvm;
153	struct kvm_s2_mmu *mmu = &kvm->arch.mmu;
154	struct ptdump_pg_state *parser_state = &st->parser_state;
155	struct kvm_pgtable_walker walker = (struct kvm_pgtable_walker) {
156		.cb	= kvm_ptdump_visitor,
157		.arg	= parser_state,
158		.flags	= KVM_PGTABLE_WALK_LEAF,
159	};
160
161	parser_state->seq = m;
162
163	write_lock(&kvm->mmu_lock);
164	ret = kvm_pgtable_walk(mmu->pgt, 0, BIT(mmu->pgt->ia_bits), &walker);
165	write_unlock(&kvm->mmu_lock);
166
167	return ret;
168}
169
170static int kvm_ptdump_guest_open(struct inode *m, struct file *file)
171{
172	struct kvm *kvm = m->i_private;
173	struct kvm_ptdump_guest_state *st;
174	int ret;
175
176	if (!kvm_get_kvm_safe(kvm))
177		return -ENOENT;
178
179	st = kvm_ptdump_parser_create(kvm);
180	if (IS_ERR(st)) {
181		ret = PTR_ERR(st);
182		goto err_with_kvm_ref;
183	}
184
185	ret = single_open(file, kvm_ptdump_guest_show, st);
186	if (!ret)
187		return 0;
188
189	kfree(st);
190err_with_kvm_ref:
191	kvm_put_kvm(kvm);
192	return ret;
193}
194
195static int kvm_ptdump_guest_close(struct inode *m, struct file *file)
196{
197	struct kvm *kvm = m->i_private;
198	void *st = ((struct seq_file *)file->private_data)->private;
199
200	kfree(st);
201	kvm_put_kvm(kvm);
202
203	return single_release(m, file);
204}
205
206static const struct file_operations kvm_ptdump_guest_fops = {
207	.open		= kvm_ptdump_guest_open,
208	.read		= seq_read,
209	.llseek		= seq_lseek,
210	.release	= kvm_ptdump_guest_close,
211};
212
213static int kvm_pgtable_range_show(struct seq_file *m, void *unused)
214{
215	struct kvm_pgtable *pgtable = m->private;
216
217	seq_printf(m, "%2u\n", pgtable->ia_bits);
218	return 0;
219}
220
221static int kvm_pgtable_levels_show(struct seq_file *m, void *unused)
222{
223	struct kvm_pgtable *pgtable = m->private;
224
225	seq_printf(m, "%1d\n", KVM_PGTABLE_MAX_LEVELS - pgtable->start_level);
226	return 0;
227}
228
229static int kvm_pgtable_debugfs_open(struct inode *m, struct file *file,
230				    int (*show)(struct seq_file *, void *))
231{
232	struct kvm *kvm = m->i_private;
233	struct kvm_pgtable *pgtable;
234	int ret;
235
236	if (!kvm_get_kvm_safe(kvm))
237		return -ENOENT;
238
239	pgtable = kvm->arch.mmu.pgt;
240
241	ret = single_open(file, show, pgtable);
242	if (ret < 0)
243		kvm_put_kvm(kvm);
244	return ret;
245}
246
247static int kvm_pgtable_range_open(struct inode *m, struct file *file)
248{
249	return kvm_pgtable_debugfs_open(m, file, kvm_pgtable_range_show);
250}
251
252static int kvm_pgtable_levels_open(struct inode *m, struct file *file)
253{
254	return kvm_pgtable_debugfs_open(m, file, kvm_pgtable_levels_show);
255}
256
257static int kvm_pgtable_debugfs_close(struct inode *m, struct file *file)
258{
259	struct kvm *kvm = m->i_private;
260
261	kvm_put_kvm(kvm);
262	return single_release(m, file);
263}
264
265static const struct file_operations kvm_pgtable_range_fops = {
266	.open		= kvm_pgtable_range_open,
267	.read		= seq_read,
268	.llseek		= seq_lseek,
269	.release	= kvm_pgtable_debugfs_close,
270};
271
272static const struct file_operations kvm_pgtable_levels_fops = {
273	.open		= kvm_pgtable_levels_open,
274	.read		= seq_read,
275	.llseek		= seq_lseek,
276	.release	= kvm_pgtable_debugfs_close,
277};
278
279void kvm_s2_ptdump_create_debugfs(struct kvm *kvm)
280{
281	debugfs_create_file("stage2_page_tables", 0400, kvm->debugfs_dentry,
282			    kvm, &kvm_ptdump_guest_fops);
283	debugfs_create_file("ipa_range", 0400, kvm->debugfs_dentry, kvm,
284			    &kvm_pgtable_range_fops);
285	debugfs_create_file("stage2_levels", 0400, kvm->debugfs_dentry,
286			    kvm, &kvm_pgtable_levels_fops);
287}