1// SPDX-License-Identifier: GPL-2.0-or-later
2/*  Paravirtualization interfaces
3    Copyright (C) 2006 Rusty Russell IBM Corporation
4
5
6    2007 - x86_64 support added by Glauber de Oliveira Costa, Red Hat Inc
7*/
8
9#include <linux/errno.h>
10#include <linux/init.h>
11#include <linux/export.h>
12#include <linux/efi.h>
13#include <linux/bcd.h>
14#include <linux/highmem.h>
15#include <linux/kprobes.h>
16#include <linux/pgtable.h>
17
18#include <asm/bug.h>
19#include <asm/paravirt.h>
20#include <asm/debugreg.h>
21#include <asm/desc.h>
22#include <asm/setup.h>
23#include <asm/time.h>
24#include <asm/pgalloc.h>
25#include <asm/irq.h>
26#include <asm/delay.h>
27#include <asm/fixmap.h>
28#include <asm/apic.h>
29#include <asm/tlbflush.h>
30#include <asm/timer.h>
31#include <asm/special_insns.h>
32#include <asm/tlb.h>
33#include <asm/io_bitmap.h>
34
35/*
36 * nop stub, which must not clobber anything *including the stack* to
37 * avoid confusing the entry prologues.
38 */
39extern void _paravirt_nop(void);
40asm (".pushsection .entry.text, \"ax\"\n"
41     ".global _paravirt_nop\n"
42     "_paravirt_nop:\n\t"
43     ASM_RET
44     ".size _paravirt_nop, . - _paravirt_nop\n\t"
45     ".type _paravirt_nop, @function\n\t"
46     ".popsection");
47
48void __init default_banner(void)
49{
50	printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
51	       pv_info.name);
52}
53
54/* Undefined instruction for dealing with missing ops pointers. */
55static const unsigned char ud2a[] = { 0x0f, 0x0b };
56
57struct branch {
58	unsigned char opcode;
59	u32 delta;
60} __attribute__((packed));
61
62static unsigned paravirt_patch_call(void *insn_buff, const void *target,
63				    unsigned long addr, unsigned len)
64{
65	const int call_len = 5;
66	struct branch *b = insn_buff;
67	unsigned long delta = (unsigned long)target - (addr+call_len);
68
69	if (len < call_len) {
70		pr_warn("paravirt: Failed to patch indirect CALL at %ps\n", (void *)addr);
71		/* Kernel might not be viable if patching fails, bail out: */
72		BUG_ON(1);
73	}
74
75	b->opcode = 0xe8; /* call */
76	b->delta = delta;
77	BUILD_BUG_ON(sizeof(*b) != call_len);
78
79	return call_len;
80}
81
82#ifdef CONFIG_PARAVIRT_XXL
83/* identity function, which can be inlined */
84u64 notrace _paravirt_ident_64(u64 x)
85{
86	return x;
87}
88
89static unsigned paravirt_patch_jmp(void *insn_buff, const void *target,
90				   unsigned long addr, unsigned len)
91{
92	struct branch *b = insn_buff;
93	unsigned long delta = (unsigned long)target - (addr+5);
94
95	if (len < 5) {
96#ifdef CONFIG_RETPOLINE
97		WARN_ONCE(1, "Failing to patch indirect JMP in %ps\n", (void *)addr);
98#endif
99		return len;	/* call too long for patch site */
100	}
101
102	b->opcode = 0xe9;	/* jmp */
103	b->delta = delta;
104
105	return 5;
106}
107#endif
108
109DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key);
110
111void __init native_pv_lock_init(void)
112{
113	if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
114		static_branch_disable(&virt_spin_lock_key);
115}
116
117unsigned paravirt_patch_default(u8 type, void *insn_buff,
118				unsigned long addr, unsigned len)
119{
120	/*
121	 * Neat trick to map patch type back to the call within the
122	 * corresponding structure.
123	 */
124	void *opfunc = *((void **)&pv_ops + type);
125	unsigned ret;
126
127	if (opfunc == NULL)
128		/* If there's no function, patch it with a ud2a (BUG) */
129		ret = paravirt_patch_insns(insn_buff, len, ud2a, ud2a+sizeof(ud2a));
130	else if (opfunc == _paravirt_nop)
131		ret = 0;
132
133#ifdef CONFIG_PARAVIRT_XXL
134	/* identity functions just return their single argument */
135	else if (opfunc == _paravirt_ident_64)
136		ret = paravirt_patch_ident_64(insn_buff, len);
137
138	else if (type == PARAVIRT_PATCH(cpu.iret) ||
139		 type == PARAVIRT_PATCH(cpu.usergs_sysret64))
140		/* If operation requires a jmp, then jmp */
141		ret = paravirt_patch_jmp(insn_buff, opfunc, addr, len);
142#endif
143	else
144		/* Otherwise call the function. */
145		ret = paravirt_patch_call(insn_buff, opfunc, addr, len);
146
147	return ret;
148}
149
150unsigned paravirt_patch_insns(void *insn_buff, unsigned len,
151			      const char *start, const char *end)
152{
153	unsigned insn_len = end - start;
154
155	/* Alternative instruction is too large for the patch site and we cannot continue: */
156	BUG_ON(insn_len > len || start == NULL);
157
158	memcpy(insn_buff, start, insn_len);
159
160	return insn_len;
161}
162
163struct static_key paravirt_steal_enabled;
164struct static_key paravirt_steal_rq_enabled;
165
166static u64 native_steal_clock(int cpu)
167{
168	return 0;
169}
170
171/* These are in entry.S */
172extern void native_iret(void);
173extern void native_usergs_sysret64(void);
174
175static struct resource reserve_ioports = {
176	.start = 0,
177	.end = IO_SPACE_LIMIT,
178	.name = "paravirt-ioport",
179	.flags = IORESOURCE_IO | IORESOURCE_BUSY,
180};
181
182/*
183 * Reserve the whole legacy IO space to prevent any legacy drivers
184 * from wasting time probing for their hardware.  This is a fairly
185 * brute-force approach to disabling all non-virtual drivers.
186 *
187 * Note that this must be called very early to have any effect.
188 */
189int paravirt_disable_iospace(void)
190{
191	return request_resource(&ioport_resource, &reserve_ioports);
192}
193
194static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
195
196static inline void enter_lazy(enum paravirt_lazy_mode mode)
197{
198	BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
199
200	this_cpu_write(paravirt_lazy_mode, mode);
201}
202
203static void leave_lazy(enum paravirt_lazy_mode mode)
204{
205	BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);
206
207	this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
208}
209
210void paravirt_enter_lazy_mmu(void)
211{
212	enter_lazy(PARAVIRT_LAZY_MMU);
213}
214
215void paravirt_leave_lazy_mmu(void)
216{
217	leave_lazy(PARAVIRT_LAZY_MMU);
218}
219
220void paravirt_flush_lazy_mmu(void)
221{
222	preempt_disable();
223
224	if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
225		arch_leave_lazy_mmu_mode();
226		arch_enter_lazy_mmu_mode();
227	}
228
229	preempt_enable();
230}
231
232#ifdef CONFIG_PARAVIRT_XXL
233void paravirt_start_context_switch(struct task_struct *prev)
234{
235	BUG_ON(preemptible());
236
237	if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
238		arch_leave_lazy_mmu_mode();
239		set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
240	}
241	enter_lazy(PARAVIRT_LAZY_CPU);
242}
243
244void paravirt_end_context_switch(struct task_struct *next)
245{
246	BUG_ON(preemptible());
247
248	leave_lazy(PARAVIRT_LAZY_CPU);
249
250	if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
251		arch_enter_lazy_mmu_mode();
252}
253#endif
254
255enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
256{
257	if (in_interrupt())
258		return PARAVIRT_LAZY_NONE;
259
260	return this_cpu_read(paravirt_lazy_mode);
261}
262
263struct pv_info pv_info = {
264	.name = "bare hardware",
265#ifdef CONFIG_PARAVIRT_XXL
266	.extra_user_64bit_cs = __USER_CS,
267#endif
268};
269
270/* 64-bit pagetable entries */
271#define PTE_IDENT	__PV_IS_CALLEE_SAVE(_paravirt_ident_64)
272
273struct paravirt_patch_template pv_ops = {
274	/* Init ops. */
275	.init.patch		= native_patch,
276
277	/* Time ops. */
278	.time.sched_clock	= native_sched_clock,
279	.time.steal_clock	= native_steal_clock,
280
281	/* Cpu ops. */
282	.cpu.io_delay		= native_io_delay,
283
284#ifdef CONFIG_PARAVIRT_XXL
285	.cpu.cpuid		= native_cpuid,
286	.cpu.get_debugreg	= native_get_debugreg,
287	.cpu.set_debugreg	= native_set_debugreg,
288	.cpu.read_cr0		= native_read_cr0,
289	.cpu.write_cr0		= native_write_cr0,
290	.cpu.write_cr4		= native_write_cr4,
291	.cpu.wbinvd		= native_wbinvd,
292	.cpu.read_msr		= native_read_msr,
293	.cpu.write_msr		= native_write_msr,
294	.cpu.read_msr_safe	= native_read_msr_safe,
295	.cpu.write_msr_safe	= native_write_msr_safe,
296	.cpu.read_pmc		= native_read_pmc,
297	.cpu.load_tr_desc	= native_load_tr_desc,
298	.cpu.set_ldt		= native_set_ldt,
299	.cpu.load_gdt		= native_load_gdt,
300	.cpu.load_idt		= native_load_idt,
301	.cpu.store_tr		= native_store_tr,
302	.cpu.load_tls		= native_load_tls,
303	.cpu.load_gs_index	= native_load_gs_index,
304	.cpu.write_ldt_entry	= native_write_ldt_entry,
305	.cpu.write_gdt_entry	= native_write_gdt_entry,
306	.cpu.write_idt_entry	= native_write_idt_entry,
307
308	.cpu.alloc_ldt		= paravirt_nop,
309	.cpu.free_ldt		= paravirt_nop,
310
311	.cpu.load_sp0		= native_load_sp0,
312
313	.cpu.usergs_sysret64	= native_usergs_sysret64,
314	.cpu.iret		= native_iret,
315
316#ifdef CONFIG_X86_IOPL_IOPERM
317	.cpu.invalidate_io_bitmap	= native_tss_invalidate_io_bitmap,
318	.cpu.update_io_bitmap		= native_tss_update_io_bitmap,
319#endif
320
321	.cpu.start_context_switch	= paravirt_nop,
322	.cpu.end_context_switch		= paravirt_nop,
323
324	/* Irq ops. */
325	.irq.save_fl		= __PV_IS_CALLEE_SAVE(native_save_fl),
326	.irq.restore_fl		= __PV_IS_CALLEE_SAVE(native_restore_fl),
327	.irq.irq_disable	= __PV_IS_CALLEE_SAVE(native_irq_disable),
328	.irq.irq_enable		= __PV_IS_CALLEE_SAVE(native_irq_enable),
329	.irq.safe_halt		= native_safe_halt,
330	.irq.halt		= native_halt,
331#endif /* CONFIG_PARAVIRT_XXL */
332
333	/* Mmu ops. */
334	.mmu.flush_tlb_user	= native_flush_tlb_local,
335	.mmu.flush_tlb_kernel	= native_flush_tlb_global,
336	.mmu.flush_tlb_one_user	= native_flush_tlb_one_user,
337	.mmu.flush_tlb_others	= native_flush_tlb_others,
338	.mmu.tlb_remove_table	=
339			(void (*)(struct mmu_gather *, void *))tlb_remove_page,
340
341	.mmu.exit_mmap		= paravirt_nop,
342
343#ifdef CONFIG_PARAVIRT_XXL
344	.mmu.read_cr2		= __PV_IS_CALLEE_SAVE(native_read_cr2),
345	.mmu.write_cr2		= native_write_cr2,
346	.mmu.read_cr3		= __native_read_cr3,
347	.mmu.write_cr3		= native_write_cr3,
348
349	.mmu.pgd_alloc		= __paravirt_pgd_alloc,
350	.mmu.pgd_free		= paravirt_nop,
351
352	.mmu.alloc_pte		= paravirt_nop,
353	.mmu.alloc_pmd		= paravirt_nop,
354	.mmu.alloc_pud		= paravirt_nop,
355	.mmu.alloc_p4d		= paravirt_nop,
356	.mmu.release_pte	= paravirt_nop,
357	.mmu.release_pmd	= paravirt_nop,
358	.mmu.release_pud	= paravirt_nop,
359	.mmu.release_p4d	= paravirt_nop,
360
361	.mmu.set_pte		= native_set_pte,
362	.mmu.set_pmd		= native_set_pmd,
363
364	.mmu.ptep_modify_prot_start	= __ptep_modify_prot_start,
365	.mmu.ptep_modify_prot_commit	= __ptep_modify_prot_commit,
366
367	.mmu.set_pud		= native_set_pud,
368
369	.mmu.pmd_val		= PTE_IDENT,
370	.mmu.make_pmd		= PTE_IDENT,
371
372	.mmu.pud_val		= PTE_IDENT,
373	.mmu.make_pud		= PTE_IDENT,
374
375	.mmu.set_p4d		= native_set_p4d,
376
377#if CONFIG_PGTABLE_LEVELS >= 5
378	.mmu.p4d_val		= PTE_IDENT,
379	.mmu.make_p4d		= PTE_IDENT,
380
381	.mmu.set_pgd		= native_set_pgd,
382#endif /* CONFIG_PGTABLE_LEVELS >= 5 */
383
384	.mmu.pte_val		= PTE_IDENT,
385	.mmu.pgd_val		= PTE_IDENT,
386
387	.mmu.make_pte		= PTE_IDENT,
388	.mmu.make_pgd		= PTE_IDENT,
389
390	.mmu.dup_mmap		= paravirt_nop,
391	.mmu.activate_mm	= paravirt_nop,
392
393	.mmu.lazy_mode = {
394		.enter		= paravirt_nop,
395		.leave		= paravirt_nop,
396		.flush		= paravirt_nop,
397	},
398
399	.mmu.set_fixmap		= native_set_fixmap,
400#endif /* CONFIG_PARAVIRT_XXL */
401
402#if defined(CONFIG_PARAVIRT_SPINLOCKS)
403	/* Lock ops. */
404#ifdef CONFIG_SMP
405	.lock.queued_spin_lock_slowpath	= native_queued_spin_lock_slowpath,
406	.lock.queued_spin_unlock	=
407				PV_CALLEE_SAVE(__native_queued_spin_unlock),
408	.lock.wait			= paravirt_nop,
409	.lock.kick			= paravirt_nop,
410	.lock.vcpu_is_preempted		=
411				PV_CALLEE_SAVE(__native_vcpu_is_preempted),
412#endif /* SMP */
413#endif
414};
415
416#ifdef CONFIG_PARAVIRT_XXL
417/* At this point, native_get/set_debugreg has real function entries */
418NOKPROBE_SYMBOL(native_get_debugreg);
419NOKPROBE_SYMBOL(native_set_debugreg);
420NOKPROBE_SYMBOL(native_load_idt);
421#endif
422
423EXPORT_SYMBOL(pv_ops);
424EXPORT_SYMBOL_GPL(pv_info);
425