summaryrefslogtreecommitdiff
path: root/arch/x86/kernel/paravirt.c
blob: c60222ab8ab9b8ae2dded7687609b3165020c544 (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
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
// SPDX-License-Identifier: GPL-2.0-or-later
/*  Paravirtualization interfaces
    Copyright (C) 2006 Rusty Russell IBM Corporation


    2007 - x86_64 support added by Glauber de Oliveira Costa, Red Hat Inc
*/

#include <linux/errno.h>
#include <linux/init.h>
#include <linux/export.h>
#include <linux/efi.h>
#include <linux/bcd.h>
#include <linux/highmem.h>
#include <linux/kprobes.h>
#include <linux/pgtable.h>

#include <asm/bug.h>
#include <asm/paravirt.h>
#include <asm/debugreg.h>
#include <asm/desc.h>
#include <asm/setup.h>
#include <asm/time.h>
#include <asm/pgalloc.h>
#include <asm/irq.h>
#include <asm/delay.h>
#include <asm/fixmap.h>
#include <asm/apic.h>
#include <asm/tlbflush.h>
#include <asm/timer.h>
#include <asm/special_insns.h>
#include <asm/tlb.h>
#include <asm/io_bitmap.h>

/*
 * nop stub, which must not clobber anything *including the stack* to
 * avoid confusing the entry prologues.
 */
extern void _paravirt_nop(void);
asm (".pushsection .entry.text, \"ax\"\n"
     ".global _paravirt_nop\n"
     "_paravirt_nop:\n\t"
     "ret\n\t"
     ".size _paravirt_nop, . - _paravirt_nop\n\t"
     ".type _paravirt_nop, @function\n\t"
     ".popsection");

void __init default_banner(void)
{
	printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
	       pv_info.name);
}

/* Undefined instruction for dealing with missing ops pointers. */
static const unsigned char ud2a[] = { 0x0f, 0x0b };

struct branch {
	unsigned char opcode;
	u32 delta;
} __attribute__((packed));

static unsigned paravirt_patch_call(void *insn_buff, const void *target,
				    unsigned long addr, unsigned len)
{
	const int call_len = 5;
	struct branch *b = insn_buff;
	unsigned long delta = (unsigned long)target - (addr+call_len);

	if (len < call_len) {
		pr_warn("paravirt: Failed to patch indirect CALL at %ps\n", (void *)addr);
		/* Kernel might not be viable if patching fails, bail out: */
		BUG_ON(1);
	}

	b->opcode = 0xe8; /* call */
	b->delta = delta;
	BUILD_BUG_ON(sizeof(*b) != call_len);

	return call_len;
}

#ifdef CONFIG_PARAVIRT_XXL
/* identity function, which can be inlined */
u64 notrace _paravirt_ident_64(u64 x)
{
	return x;
}

static unsigned paravirt_patch_jmp(void *insn_buff, const void *target,
				   unsigned long addr, unsigned len)
{
	struct branch *b = insn_buff;
	unsigned long delta = (unsigned long)target - (addr+5);

	if (len < 5) {
#ifdef CONFIG_RETPOLINE
		WARN_ONCE(1, "Failing to patch indirect JMP in %ps\n", (void *)addr);
#endif
		return len;	/* call too long for patch site */
	}

	b->opcode = 0xe9;	/* jmp */
	b->delta = delta;

	return 5;
}
#endif

DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key);

void __init native_pv_lock_init(void)
{
	if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
		static_branch_disable(&virt_spin_lock_key);
}

unsigned paravirt_patch_default(u8 type, void *insn_buff,
				unsigned long addr, unsigned len)
{
	/*
	 * Neat trick to map patch type back to the call within the
	 * corresponding structure.
	 */
	void *opfunc = *((void **)&pv_ops + type);
	unsigned ret;

	if (opfunc == NULL)
		/* If there's no function, patch it with a ud2a (BUG) */
		ret = paravirt_patch_insns(insn_buff, len, ud2a, ud2a+sizeof(ud2a));
	else if (opfunc == _paravirt_nop)
		ret = 0;

#ifdef CONFIG_PARAVIRT_XXL
	/* identity functions just return their single argument */
	else if (opfunc == _paravirt_ident_64)
		ret = paravirt_patch_ident_64(insn_buff, len);

	else if (type == PARAVIRT_PATCH(cpu.iret))
		/* If operation requires a jmp, then jmp */
		ret = paravirt_patch_jmp(insn_buff, opfunc, addr, len);
#endif
	else
		/* Otherwise call the function. */
		ret = paravirt_patch_call(insn_buff, opfunc, addr, len);

	return ret;
}

unsigned paravirt_patch_insns(void *insn_buff, unsigned len,
			      const char *start, const char *end)
{
	unsigned insn_len = end - start;

	/* Alternative instruction is too large for the patch site and we cannot continue: */
	BUG_ON(insn_len > len || start == NULL);

	memcpy(insn_buff, start, insn_len);

	return insn_len;
}

struct static_key paravirt_steal_enabled;
struct static_key paravirt_steal_rq_enabled;

static u64 native_steal_clock(int cpu)
{
	return 0;
}

/* These are in entry.S */
extern void native_iret(void);

static struct resource reserve_ioports = {
	.start = 0,
	.end = IO_SPACE_LIMIT,
	.name = "paravirt-ioport",
	.flags = IORESOURCE_IO | IORESOURCE_BUSY,
};

/*
 * Reserve the whole legacy IO space to prevent any legacy drivers
 * from wasting time probing for their hardware.  This is a fairly
 * brute-force approach to disabling all non-virtual drivers.
 *
 * Note that this must be called very early to have any effect.
 */
int paravirt_disable_iospace(void)
{
	return request_resource(&ioport_resource, &reserve_ioports);
}

static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;

static inline void enter_lazy(enum paravirt_lazy_mode mode)
{
	BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);

	this_cpu_write(paravirt_lazy_mode, mode);
}

static void leave_lazy(enum paravirt_lazy_mode mode)
{
	BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);

	this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
}

void paravirt_enter_lazy_mmu(void)
{
	enter_lazy(PARAVIRT_LAZY_MMU);
}

void paravirt_leave_lazy_mmu(void)
{
	leave_lazy(PARAVIRT_LAZY_MMU);
}

void paravirt_flush_lazy_mmu(void)
{
	preempt_disable();

	if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
		arch_leave_lazy_mmu_mode();
		arch_enter_lazy_mmu_mode();
	}

	preempt_enable();
}

#ifdef CONFIG_PARAVIRT_XXL
void paravirt_start_context_switch(struct task_struct *prev)
{
	BUG_ON(preemptible());

	if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
		arch_leave_lazy_mmu_mode();
		set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
	}
	enter_lazy(PARAVIRT_LAZY_CPU);
}

void paravirt_end_context_switch(struct task_struct *next)
{
	BUG_ON(preemptible());

	leave_lazy(PARAVIRT_LAZY_CPU);

	if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
		arch_enter_lazy_mmu_mode();
}
#endif

enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
{
	if (in_interrupt())
		return PARAVIRT_LAZY_NONE;

	return this_cpu_read(paravirt_lazy_mode);
}

struct pv_info pv_info = {
	.name = "bare hardware",
#ifdef CONFIG_PARAVIRT_XXL
	.extra_user_64bit_cs = __USER_CS,
#endif
};

/* 64-bit pagetable entries */
#define PTE_IDENT	__PV_IS_CALLEE_SAVE(_paravirt_ident_64)

struct paravirt_patch_template pv_ops = {
	/* Init ops. */
	.init.patch		= native_patch,

	/* Time ops. */
	.time.sched_clock	= native_sched_clock,
	.time.steal_clock	= native_steal_clock,

	/* Cpu ops. */
	.cpu.io_delay		= native_io_delay,

#ifdef CONFIG_PARAVIRT_XXL
	.cpu.cpuid		= native_cpuid,
	.cpu.get_debugreg	= native_get_debugreg,
	.cpu.set_debugreg	= native_set_debugreg,
	.cpu.read_cr0		= native_read_cr0,
	.cpu.write_cr0		= native_write_cr0,
	.cpu.write_cr4		= native_write_cr4,
	.cpu.wbinvd		= native_wbinvd,
	.cpu.read_msr		= native_read_msr,
	.cpu.write_msr		= native_write_msr,
	.cpu.read_msr_safe	= native_read_msr_safe,
	.cpu.write_msr_safe	= native_write_msr_safe,
	.cpu.read_pmc		= native_read_pmc,
	.cpu.load_tr_desc	= native_load_tr_desc,
	.cpu.set_ldt		= native_set_ldt,
	.cpu.load_gdt		= native_load_gdt,
	.cpu.load_idt		= native_load_idt,
	.cpu.store_tr		= native_store_tr,
	.cpu.load_tls		= native_load_tls,
	.cpu.load_gs_index	= native_load_gs_index,
	.cpu.write_ldt_entry	= native_write_ldt_entry,
	.cpu.write_gdt_entry	= native_write_gdt_entry,
	.cpu.write_idt_entry	= native_write_idt_entry,

	.cpu.alloc_ldt		= paravirt_nop,
	.cpu.free_ldt		= paravirt_nop,

	.cpu.load_sp0		= native_load_sp0,

	.cpu.iret		= native_iret,

#ifdef CONFIG_X86_IOPL_IOPERM
	.cpu.invalidate_io_bitmap	= native_tss_invalidate_io_bitmap,
	.cpu.update_io_bitmap		= native_tss_update_io_bitmap,
#endif

	.cpu.start_context_switch	= paravirt_nop,
	.cpu.end_context_switch		= paravirt_nop,

	/* Irq ops. */
	.irq.save_fl		= __PV_IS_CALLEE_SAVE(native_save_fl),
	.irq.irq_disable	= __PV_IS_CALLEE_SAVE(native_irq_disable),
	.irq.irq_enable		= __PV_IS_CALLEE_SAVE(native_irq_enable),
	.irq.safe_halt		= native_safe_halt,
	.irq.halt		= native_halt,
#endif /* CONFIG_PARAVIRT_XXL */

	/* Mmu ops. */
	.mmu.flush_tlb_user	= native_flush_tlb_local,
	.mmu.flush_tlb_kernel	= native_flush_tlb_global,
	.mmu.flush_tlb_one_user	= native_flush_tlb_one_user,
	.mmu.flush_tlb_others	= native_flush_tlb_others,
	.mmu.tlb_remove_table	=
			(void (*)(struct mmu_gather *, void *))tlb_remove_page,

	.mmu.exit_mmap		= paravirt_nop,

#ifdef CONFIG_PARAVIRT_XXL
	.mmu.read_cr2		= __PV_IS_CALLEE_SAVE(native_read_cr2),
	.mmu.write_cr2		= native_write_cr2,
	.mmu.read_cr3		= __native_read_cr3,
	.mmu.write_cr3		= native_write_cr3,

	.mmu.pgd_alloc		= __paravirt_pgd_alloc,
	.mmu.pgd_free		= paravirt_nop,

	.mmu.alloc_pte		= paravirt_nop,
	.mmu.alloc_pmd		= paravirt_nop,
	.mmu.alloc_pud		= paravirt_nop,
	.mmu.alloc_p4d		= paravirt_nop,
	.mmu.release_pte	= paravirt_nop,
	.mmu.release_pmd	= paravirt_nop,
	.mmu.release_pud	= paravirt_nop,
	.mmu.release_p4d	= paravirt_nop,

	.mmu.set_pte		= native_set_pte,
	.mmu.set_pmd		= native_set_pmd,

	.mmu.ptep_modify_prot_start	= __ptep_modify_prot_start,
	.mmu.ptep_modify_prot_commit	= __ptep_modify_prot_commit,

	.mmu.set_pud		= native_set_pud,

	.mmu.pmd_val		= PTE_IDENT,
	.mmu.make_pmd		= PTE_IDENT,

	.mmu.pud_val		= PTE_IDENT,
	.mmu.make_pud		= PTE_IDENT,

	.mmu.set_p4d		= native_set_p4d,

#if CONFIG_PGTABLE_LEVELS >= 5
	.mmu.p4d_val		= PTE_IDENT,
	.mmu.make_p4d		= PTE_IDENT,

	.mmu.set_pgd		= native_set_pgd,
#endif /* CONFIG_PGTABLE_LEVELS >= 5 */

	.mmu.pte_val		= PTE_IDENT,
	.mmu.pgd_val		= PTE_IDENT,

	.mmu.make_pte		= PTE_IDENT,
	.mmu.make_pgd		= PTE_IDENT,

	.mmu.dup_mmap		= paravirt_nop,
	.mmu.activate_mm	= paravirt_nop,

	.mmu.lazy_mode = {
		.enter		= paravirt_nop,
		.leave		= paravirt_nop,
		.flush		= paravirt_nop,
	},

	.mmu.set_fixmap		= native_set_fixmap,
#endif /* CONFIG_PARAVIRT_XXL */

#if defined(CONFIG_PARAVIRT_SPINLOCKS)
	/* Lock ops. */
#ifdef CONFIG_SMP
	.lock.queued_spin_lock_slowpath	= native_queued_spin_lock_slowpath,
	.lock.queued_spin_unlock	=
				PV_CALLEE_SAVE(__native_queued_spin_unlock),
	.lock.wait			= paravirt_nop,
	.lock.kick			= paravirt_nop,
	.lock.vcpu_is_preempted		=
				PV_CALLEE_SAVE(__native_vcpu_is_preempted),
#endif /* SMP */
#endif
};

#ifdef CONFIG_PARAVIRT_XXL
/* At this point, native_get/set_debugreg has real function entries */
NOKPROBE_SYMBOL(native_get_debugreg);
NOKPROBE_SYMBOL(native_set_debugreg);
NOKPROBE_SYMBOL(native_load_idt);
#endif

EXPORT_SYMBOL(pv_ops);
EXPORT_SYMBOL_GPL(pv_info);