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 #include <linux/static_call.h>
18 
19 #include <asm/bug.h>
20 #include <asm/paravirt.h>
21 #include <asm/debugreg.h>
22 #include <asm/desc.h>
23 #include <asm/setup.h>
24 #include <asm/time.h>
25 #include <asm/pgalloc.h>
26 #include <asm/irq.h>
27 #include <asm/delay.h>
28 #include <asm/fixmap.h>
29 #include <asm/apic.h>
30 #include <asm/tlbflush.h>
31 #include <asm/timer.h>
32 #include <asm/special_insns.h>
33 #include <asm/tlb.h>
34 #include <asm/io_bitmap.h>
35 
36 /*
37  * nop stub, which must not clobber anything *including the stack* to
38  * avoid confusing the entry prologues.
39  */
40 extern void _paravirt_nop(void);
41 asm (".pushsection .entry.text, \"ax\"\n"
42      ".global _paravirt_nop\n"
43      "_paravirt_nop:\n\t"
44      ASM_ENDBR
45      ASM_RET
46      ".size _paravirt_nop, . - _paravirt_nop\n\t"
47      ".type _paravirt_nop, @function\n\t"
48      ".popsection");
49 
50 /* stub always returning 0. */
51 asm (".pushsection .entry.text, \"ax\"\n"
52      ".global paravirt_ret0\n"
53      "paravirt_ret0:\n\t"
54      ASM_ENDBR
55      "xor %" _ASM_AX ", %" _ASM_AX ";\n\t"
56      ASM_RET
57      ".size paravirt_ret0, . - paravirt_ret0\n\t"
58      ".type paravirt_ret0, @function\n\t"
59      ".popsection");
60 
61 
default_banner(void)62 void __init default_banner(void)
63 {
64 	printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
65 	       pv_info.name);
66 }
67 
68 /* Undefined instruction for dealing with missing ops pointers. */
paravirt_BUG(void)69 noinstr void paravirt_BUG(void)
70 {
71 	BUG();
72 }
73 
paravirt_patch_call(void * insn_buff,const void * target,unsigned long addr,unsigned len)74 static unsigned paravirt_patch_call(void *insn_buff, const void *target,
75 				    unsigned long addr, unsigned len)
76 {
77 	__text_gen_insn(insn_buff, CALL_INSN_OPCODE,
78 			(void *)addr, target, CALL_INSN_SIZE);
79 	return CALL_INSN_SIZE;
80 }
81 
82 #ifdef CONFIG_PARAVIRT_XXL
83 /* identity function, which can be inlined */
_paravirt_ident_64(u64 x)84 u64 notrace _paravirt_ident_64(u64 x)
85 {
86 	return x;
87 }
88 #endif
89 
90 DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key);
91 
native_pv_lock_init(void)92 void __init native_pv_lock_init(void)
93 {
94 	if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
95 		static_branch_disable(&virt_spin_lock_key);
96 }
97 
paravirt_patch(u8 type,void * insn_buff,unsigned long addr,unsigned int len)98 unsigned int paravirt_patch(u8 type, void *insn_buff, unsigned long addr,
99 			    unsigned int len)
100 {
101 	/*
102 	 * Neat trick to map patch type back to the call within the
103 	 * corresponding structure.
104 	 */
105 	void *opfunc = *((void **)&pv_ops + type);
106 	unsigned ret;
107 
108 	if (opfunc == NULL)
109 		/* If there's no function, patch it with paravirt_BUG() */
110 		ret = paravirt_patch_call(insn_buff, paravirt_BUG, addr, len);
111 	else if (opfunc == _paravirt_nop)
112 		ret = 0;
113 	else
114 		/* Otherwise call the function. */
115 		ret = paravirt_patch_call(insn_buff, opfunc, addr, len);
116 
117 	return ret;
118 }
119 
120 struct static_key paravirt_steal_enabled;
121 struct static_key paravirt_steal_rq_enabled;
122 
native_steal_clock(int cpu)123 static u64 native_steal_clock(int cpu)
124 {
125 	return 0;
126 }
127 
128 DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock);
129 DEFINE_STATIC_CALL(pv_sched_clock, native_sched_clock);
130 
paravirt_set_sched_clock(u64 (* func)(void))131 void paravirt_set_sched_clock(u64 (*func)(void))
132 {
133 	static_call_update(pv_sched_clock, func);
134 }
135 
136 /* These are in entry.S */
137 static struct resource reserve_ioports = {
138 	.start = 0,
139 	.end = IO_SPACE_LIMIT,
140 	.name = "paravirt-ioport",
141 	.flags = IORESOURCE_IO | IORESOURCE_BUSY,
142 };
143 
144 /*
145  * Reserve the whole legacy IO space to prevent any legacy drivers
146  * from wasting time probing for their hardware.  This is a fairly
147  * brute-force approach to disabling all non-virtual drivers.
148  *
149  * Note that this must be called very early to have any effect.
150  */
paravirt_disable_iospace(void)151 int paravirt_disable_iospace(void)
152 {
153 	return request_resource(&ioport_resource, &reserve_ioports);
154 }
155 
156 static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
157 
enter_lazy(enum paravirt_lazy_mode mode)158 static inline void enter_lazy(enum paravirt_lazy_mode mode)
159 {
160 	BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
161 
162 	this_cpu_write(paravirt_lazy_mode, mode);
163 }
164 
leave_lazy(enum paravirt_lazy_mode mode)165 static void leave_lazy(enum paravirt_lazy_mode mode)
166 {
167 	BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);
168 
169 	this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
170 }
171 
paravirt_enter_lazy_mmu(void)172 void paravirt_enter_lazy_mmu(void)
173 {
174 	enter_lazy(PARAVIRT_LAZY_MMU);
175 }
176 
paravirt_leave_lazy_mmu(void)177 void paravirt_leave_lazy_mmu(void)
178 {
179 	leave_lazy(PARAVIRT_LAZY_MMU);
180 }
181 
paravirt_flush_lazy_mmu(void)182 void paravirt_flush_lazy_mmu(void)
183 {
184 	preempt_disable();
185 
186 	if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
187 		arch_leave_lazy_mmu_mode();
188 		arch_enter_lazy_mmu_mode();
189 	}
190 
191 	preempt_enable();
192 }
193 
194 #ifdef CONFIG_PARAVIRT_XXL
paravirt_start_context_switch(struct task_struct * prev)195 void paravirt_start_context_switch(struct task_struct *prev)
196 {
197 	BUG_ON(preemptible());
198 
199 	if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
200 		arch_leave_lazy_mmu_mode();
201 		set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
202 	}
203 	enter_lazy(PARAVIRT_LAZY_CPU);
204 }
205 
paravirt_end_context_switch(struct task_struct * next)206 void paravirt_end_context_switch(struct task_struct *next)
207 {
208 	BUG_ON(preemptible());
209 
210 	leave_lazy(PARAVIRT_LAZY_CPU);
211 
212 	if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
213 		arch_enter_lazy_mmu_mode();
214 }
215 
pv_native_read_cr2(void)216 static noinstr unsigned long pv_native_read_cr2(void)
217 {
218 	return native_read_cr2();
219 }
220 
pv_native_write_cr2(unsigned long val)221 static noinstr void pv_native_write_cr2(unsigned long val)
222 {
223 	native_write_cr2(val);
224 }
225 
pv_native_get_debugreg(int regno)226 static noinstr unsigned long pv_native_get_debugreg(int regno)
227 {
228 	return native_get_debugreg(regno);
229 }
230 
pv_native_set_debugreg(int regno,unsigned long val)231 static noinstr void pv_native_set_debugreg(int regno, unsigned long val)
232 {
233 	native_set_debugreg(regno, val);
234 }
235 
pv_native_irq_enable(void)236 static noinstr void pv_native_irq_enable(void)
237 {
238 	native_irq_enable();
239 }
240 
pv_native_irq_disable(void)241 static noinstr void pv_native_irq_disable(void)
242 {
243 	native_irq_disable();
244 }
245 #endif
246 
paravirt_get_lazy_mode(void)247 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
248 {
249 	if (in_interrupt())
250 		return PARAVIRT_LAZY_NONE;
251 
252 	return this_cpu_read(paravirt_lazy_mode);
253 }
254 
255 struct pv_info pv_info = {
256 	.name = "bare hardware",
257 #ifdef CONFIG_PARAVIRT_XXL
258 	.extra_user_64bit_cs = __USER_CS,
259 #endif
260 };
261 
262 /* 64-bit pagetable entries */
263 #define PTE_IDENT	__PV_IS_CALLEE_SAVE(_paravirt_ident_64)
264 
265 struct paravirt_patch_template pv_ops = {
266 	/* Cpu ops. */
267 	.cpu.io_delay		= native_io_delay,
268 
269 #ifdef CONFIG_PARAVIRT_XXL
270 	.cpu.cpuid		= native_cpuid,
271 	.cpu.get_debugreg	= pv_native_get_debugreg,
272 	.cpu.set_debugreg	= pv_native_set_debugreg,
273 	.cpu.read_cr0		= native_read_cr0,
274 	.cpu.write_cr0		= native_write_cr0,
275 	.cpu.write_cr4		= native_write_cr4,
276 	.cpu.wbinvd		= native_wbinvd,
277 	.cpu.read_msr		= native_read_msr,
278 	.cpu.write_msr		= native_write_msr,
279 	.cpu.read_msr_safe	= native_read_msr_safe,
280 	.cpu.write_msr_safe	= native_write_msr_safe,
281 	.cpu.read_pmc		= native_read_pmc,
282 	.cpu.load_tr_desc	= native_load_tr_desc,
283 	.cpu.set_ldt		= native_set_ldt,
284 	.cpu.load_gdt		= native_load_gdt,
285 	.cpu.load_idt		= native_load_idt,
286 	.cpu.store_tr		= native_store_tr,
287 	.cpu.load_tls		= native_load_tls,
288 	.cpu.load_gs_index	= native_load_gs_index,
289 	.cpu.write_ldt_entry	= native_write_ldt_entry,
290 	.cpu.write_gdt_entry	= native_write_gdt_entry,
291 	.cpu.write_idt_entry	= native_write_idt_entry,
292 
293 	.cpu.alloc_ldt		= paravirt_nop,
294 	.cpu.free_ldt		= paravirt_nop,
295 
296 	.cpu.load_sp0		= native_load_sp0,
297 
298 #ifdef CONFIG_X86_IOPL_IOPERM
299 	.cpu.invalidate_io_bitmap	= native_tss_invalidate_io_bitmap,
300 	.cpu.update_io_bitmap		= native_tss_update_io_bitmap,
301 #endif
302 
303 	.cpu.start_context_switch	= paravirt_nop,
304 	.cpu.end_context_switch		= paravirt_nop,
305 
306 	/* Irq ops. */
307 	.irq.save_fl		= __PV_IS_CALLEE_SAVE(native_save_fl),
308 	.irq.irq_disable	= __PV_IS_CALLEE_SAVE(pv_native_irq_disable),
309 	.irq.irq_enable		= __PV_IS_CALLEE_SAVE(pv_native_irq_enable),
310 	.irq.safe_halt		= native_safe_halt,
311 	.irq.halt		= native_halt,
312 #endif /* CONFIG_PARAVIRT_XXL */
313 
314 	/* Mmu ops. */
315 	.mmu.flush_tlb_user	= native_flush_tlb_local,
316 	.mmu.flush_tlb_kernel	= native_flush_tlb_global,
317 	.mmu.flush_tlb_one_user	= native_flush_tlb_one_user,
318 	.mmu.flush_tlb_multi	= native_flush_tlb_multi,
319 	.mmu.tlb_remove_table	=
320 			(void (*)(struct mmu_gather *, void *))tlb_remove_page,
321 
322 	.mmu.exit_mmap		= paravirt_nop,
323 	.mmu.notify_page_enc_status_changed	= paravirt_nop,
324 
325 #ifdef CONFIG_PARAVIRT_XXL
326 	.mmu.read_cr2		= __PV_IS_CALLEE_SAVE(pv_native_read_cr2),
327 	.mmu.write_cr2		= pv_native_write_cr2,
328 	.mmu.read_cr3		= __native_read_cr3,
329 	.mmu.write_cr3		= native_write_cr3,
330 
331 	.mmu.pgd_alloc		= __paravirt_pgd_alloc,
332 	.mmu.pgd_free		= paravirt_nop,
333 
334 	.mmu.alloc_pte		= paravirt_nop,
335 	.mmu.alloc_pmd		= paravirt_nop,
336 	.mmu.alloc_pud		= paravirt_nop,
337 	.mmu.alloc_p4d		= paravirt_nop,
338 	.mmu.release_pte	= paravirt_nop,
339 	.mmu.release_pmd	= paravirt_nop,
340 	.mmu.release_pud	= paravirt_nop,
341 	.mmu.release_p4d	= paravirt_nop,
342 
343 	.mmu.set_pte		= native_set_pte,
344 	.mmu.set_pmd		= native_set_pmd,
345 
346 	.mmu.ptep_modify_prot_start	= __ptep_modify_prot_start,
347 	.mmu.ptep_modify_prot_commit	= __ptep_modify_prot_commit,
348 
349 	.mmu.set_pud		= native_set_pud,
350 
351 	.mmu.pmd_val		= PTE_IDENT,
352 	.mmu.make_pmd		= PTE_IDENT,
353 
354 	.mmu.pud_val		= PTE_IDENT,
355 	.mmu.make_pud		= PTE_IDENT,
356 
357 	.mmu.set_p4d		= native_set_p4d,
358 
359 #if CONFIG_PGTABLE_LEVELS >= 5
360 	.mmu.p4d_val		= PTE_IDENT,
361 	.mmu.make_p4d		= PTE_IDENT,
362 
363 	.mmu.set_pgd		= native_set_pgd,
364 #endif /* CONFIG_PGTABLE_LEVELS >= 5 */
365 
366 	.mmu.pte_val		= PTE_IDENT,
367 	.mmu.pgd_val		= PTE_IDENT,
368 
369 	.mmu.make_pte		= PTE_IDENT,
370 	.mmu.make_pgd		= PTE_IDENT,
371 
372 	.mmu.dup_mmap		= paravirt_nop,
373 	.mmu.activate_mm	= paravirt_nop,
374 
375 	.mmu.lazy_mode = {
376 		.enter		= paravirt_nop,
377 		.leave		= paravirt_nop,
378 		.flush		= paravirt_nop,
379 	},
380 
381 	.mmu.set_fixmap		= native_set_fixmap,
382 #endif /* CONFIG_PARAVIRT_XXL */
383 
384 #if defined(CONFIG_PARAVIRT_SPINLOCKS)
385 	/* Lock ops. */
386 #ifdef CONFIG_SMP
387 	.lock.queued_spin_lock_slowpath	= native_queued_spin_lock_slowpath,
388 	.lock.queued_spin_unlock	=
389 				PV_CALLEE_SAVE(__native_queued_spin_unlock),
390 	.lock.wait			= paravirt_nop,
391 	.lock.kick			= paravirt_nop,
392 	.lock.vcpu_is_preempted		=
393 				PV_CALLEE_SAVE(__native_vcpu_is_preempted),
394 #endif /* SMP */
395 #endif
396 };
397 
398 #ifdef CONFIG_PARAVIRT_XXL
399 NOKPROBE_SYMBOL(native_load_idt);
400 #endif
401 
402 EXPORT_SYMBOL(pv_ops);
403 EXPORT_SYMBOL_GPL(pv_info);
404