1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Paravirtualization interfaces
3 Copyright (C) 2006 Rusty Russell IBM Corporation
6 2007 - x86_64 support added by Glauber de Oliveira Costa, Red Hat Inc
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>
19 #include <asm/paravirt.h>
20 #include <asm/debugreg.h>
22 #include <asm/setup.h>
24 #include <asm/pgalloc.h>
26 #include <asm/delay.h>
27 #include <asm/fixmap.h>
29 #include <asm/tlbflush.h>
30 #include <asm/timer.h>
31 #include <asm/special_insns.h>
33 #include <asm/io_bitmap.h>
34 #include <asm/text-patching.h>
37 * nop stub, which must not clobber anything *including the stack* to
38 * avoid confusing the entry prologues.
40 extern void _paravirt_nop(void);
41 asm (".pushsection .entry.text, \"ax\"\n"
42 ".global _paravirt_nop\n"
45 ".size _paravirt_nop, . - _paravirt_nop\n\t"
46 ".type _paravirt_nop, @function\n\t"
49 void __init default_banner(void)
51 printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
55 /* Undefined instruction for dealing with missing ops pointers. */
56 static const unsigned char ud2a[] = { 0x0f, 0x0b };
61 } __attribute__((packed));
63 static unsigned paravirt_patch_call(void *insn_buff, const void *target,
64 unsigned long addr, unsigned len)
66 __text_gen_insn(insn_buff, CALL_INSN_OPCODE,
67 (void *)addr, target, CALL_INSN_SIZE);
68 return CALL_INSN_SIZE;
71 #ifdef CONFIG_PARAVIRT_XXL
72 /* identity function, which can be inlined */
73 u64 notrace _paravirt_ident_64(u64 x)
78 static unsigned paravirt_patch_jmp(void *insn_buff, const void *target,
79 unsigned long addr, unsigned len)
81 struct branch *b = insn_buff;
82 unsigned long delta = (unsigned long)target - (addr+5);
85 #ifdef CONFIG_RETPOLINE
86 WARN_ONCE(1, "Failing to patch indirect JMP in %ps\n", (void *)addr);
88 return len; /* call too long for patch site */
91 b->opcode = 0xe9; /* jmp */
98 DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key);
100 void __init native_pv_lock_init(void)
102 if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
103 static_branch_disable(&virt_spin_lock_key);
106 unsigned paravirt_patch_default(u8 type, void *insn_buff,
107 unsigned long addr, unsigned len)
110 * Neat trick to map patch type back to the call within the
111 * corresponding structure.
113 void *opfunc = *((void **)&pv_ops + type);
117 /* If there's no function, patch it with a ud2a (BUG) */
118 ret = paravirt_patch_insns(insn_buff, len, ud2a, ud2a+sizeof(ud2a));
119 else if (opfunc == _paravirt_nop)
122 #ifdef CONFIG_PARAVIRT_XXL
123 /* identity functions just return their single argument */
124 else if (opfunc == _paravirt_ident_64)
125 ret = paravirt_patch_ident_64(insn_buff, len);
127 else if (type == PARAVIRT_PATCH(cpu.iret) ||
128 type == PARAVIRT_PATCH(cpu.usergs_sysret64))
129 /* If operation requires a jmp, then jmp */
130 ret = paravirt_patch_jmp(insn_buff, opfunc, addr, len);
133 /* Otherwise call the function. */
134 ret = paravirt_patch_call(insn_buff, opfunc, addr, len);
139 unsigned paravirt_patch_insns(void *insn_buff, unsigned len,
140 const char *start, const char *end)
142 unsigned insn_len = end - start;
144 /* Alternative instruction is too large for the patch site and we cannot continue: */
145 BUG_ON(insn_len > len || start == NULL);
147 memcpy(insn_buff, start, insn_len);
152 struct static_key paravirt_steal_enabled;
153 struct static_key paravirt_steal_rq_enabled;
155 static u64 native_steal_clock(int cpu)
160 /* These are in entry.S */
161 extern void native_iret(void);
162 extern void native_usergs_sysret64(void);
164 static struct resource reserve_ioports = {
166 .end = IO_SPACE_LIMIT,
167 .name = "paravirt-ioport",
168 .flags = IORESOURCE_IO | IORESOURCE_BUSY,
172 * Reserve the whole legacy IO space to prevent any legacy drivers
173 * from wasting time probing for their hardware. This is a fairly
174 * brute-force approach to disabling all non-virtual drivers.
176 * Note that this must be called very early to have any effect.
178 int paravirt_disable_iospace(void)
180 return request_resource(&ioport_resource, &reserve_ioports);
183 static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
185 static inline void enter_lazy(enum paravirt_lazy_mode mode)
187 BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
189 this_cpu_write(paravirt_lazy_mode, mode);
192 static void leave_lazy(enum paravirt_lazy_mode mode)
194 BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);
196 this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
199 void paravirt_enter_lazy_mmu(void)
201 enter_lazy(PARAVIRT_LAZY_MMU);
204 void paravirt_leave_lazy_mmu(void)
206 leave_lazy(PARAVIRT_LAZY_MMU);
209 void paravirt_flush_lazy_mmu(void)
213 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
214 arch_leave_lazy_mmu_mode();
215 arch_enter_lazy_mmu_mode();
221 #ifdef CONFIG_PARAVIRT_XXL
222 void paravirt_start_context_switch(struct task_struct *prev)
224 BUG_ON(preemptible());
226 if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
227 arch_leave_lazy_mmu_mode();
228 set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
230 enter_lazy(PARAVIRT_LAZY_CPU);
233 void paravirt_end_context_switch(struct task_struct *next)
235 BUG_ON(preemptible());
237 leave_lazy(PARAVIRT_LAZY_CPU);
239 if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
240 arch_enter_lazy_mmu_mode();
244 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
247 return PARAVIRT_LAZY_NONE;
249 return this_cpu_read(paravirt_lazy_mode);
252 struct pv_info pv_info = {
253 .name = "bare hardware",
254 #ifdef CONFIG_PARAVIRT_XXL
255 .extra_user_64bit_cs = __USER_CS,
259 /* 64-bit pagetable entries */
260 #define PTE_IDENT __PV_IS_CALLEE_SAVE(_paravirt_ident_64)
262 struct paravirt_patch_template pv_ops = {
264 .init.patch = native_patch,
267 .time.sched_clock = native_sched_clock,
268 .time.steal_clock = native_steal_clock,
271 .cpu.io_delay = native_io_delay,
273 #ifdef CONFIG_PARAVIRT_XXL
274 .cpu.cpuid = native_cpuid,
275 .cpu.get_debugreg = native_get_debugreg,
276 .cpu.set_debugreg = native_set_debugreg,
277 .cpu.read_cr0 = native_read_cr0,
278 .cpu.write_cr0 = native_write_cr0,
279 .cpu.write_cr4 = native_write_cr4,
280 .cpu.wbinvd = native_wbinvd,
281 .cpu.read_msr = native_read_msr,
282 .cpu.write_msr = native_write_msr,
283 .cpu.read_msr_safe = native_read_msr_safe,
284 .cpu.write_msr_safe = native_write_msr_safe,
285 .cpu.read_pmc = native_read_pmc,
286 .cpu.load_tr_desc = native_load_tr_desc,
287 .cpu.set_ldt = native_set_ldt,
288 .cpu.load_gdt = native_load_gdt,
289 .cpu.load_idt = native_load_idt,
290 .cpu.store_tr = native_store_tr,
291 .cpu.load_tls = native_load_tls,
292 .cpu.load_gs_index = native_load_gs_index,
293 .cpu.write_ldt_entry = native_write_ldt_entry,
294 .cpu.write_gdt_entry = native_write_gdt_entry,
295 .cpu.write_idt_entry = native_write_idt_entry,
297 .cpu.alloc_ldt = paravirt_nop,
298 .cpu.free_ldt = paravirt_nop,
300 .cpu.load_sp0 = native_load_sp0,
302 .cpu.usergs_sysret64 = native_usergs_sysret64,
303 .cpu.iret = native_iret,
305 #ifdef CONFIG_X86_IOPL_IOPERM
306 .cpu.invalidate_io_bitmap = native_tss_invalidate_io_bitmap,
307 .cpu.update_io_bitmap = native_tss_update_io_bitmap,
310 .cpu.start_context_switch = paravirt_nop,
311 .cpu.end_context_switch = paravirt_nop,
314 .irq.save_fl = __PV_IS_CALLEE_SAVE(native_save_fl),
315 .irq.restore_fl = __PV_IS_CALLEE_SAVE(native_restore_fl),
316 .irq.irq_disable = __PV_IS_CALLEE_SAVE(native_irq_disable),
317 .irq.irq_enable = __PV_IS_CALLEE_SAVE(native_irq_enable),
318 .irq.safe_halt = native_safe_halt,
319 .irq.halt = native_halt,
320 #endif /* CONFIG_PARAVIRT_XXL */
323 .mmu.flush_tlb_user = native_flush_tlb_local,
324 .mmu.flush_tlb_kernel = native_flush_tlb_global,
325 .mmu.flush_tlb_one_user = native_flush_tlb_one_user,
326 .mmu.flush_tlb_others = native_flush_tlb_others,
327 .mmu.tlb_remove_table =
328 (void (*)(struct mmu_gather *, void *))tlb_remove_page,
330 .mmu.exit_mmap = paravirt_nop,
332 #ifdef CONFIG_PARAVIRT_XXL
333 .mmu.read_cr2 = __PV_IS_CALLEE_SAVE(native_read_cr2),
334 .mmu.write_cr2 = native_write_cr2,
335 .mmu.read_cr3 = __native_read_cr3,
336 .mmu.write_cr3 = native_write_cr3,
338 .mmu.pgd_alloc = __paravirt_pgd_alloc,
339 .mmu.pgd_free = paravirt_nop,
341 .mmu.alloc_pte = paravirt_nop,
342 .mmu.alloc_pmd = paravirt_nop,
343 .mmu.alloc_pud = paravirt_nop,
344 .mmu.alloc_p4d = paravirt_nop,
345 .mmu.release_pte = paravirt_nop,
346 .mmu.release_pmd = paravirt_nop,
347 .mmu.release_pud = paravirt_nop,
348 .mmu.release_p4d = paravirt_nop,
350 .mmu.set_pte = native_set_pte,
351 .mmu.set_pmd = native_set_pmd,
353 .mmu.ptep_modify_prot_start = __ptep_modify_prot_start,
354 .mmu.ptep_modify_prot_commit = __ptep_modify_prot_commit,
356 .mmu.set_pud = native_set_pud,
358 .mmu.pmd_val = PTE_IDENT,
359 .mmu.make_pmd = PTE_IDENT,
361 .mmu.pud_val = PTE_IDENT,
362 .mmu.make_pud = PTE_IDENT,
364 .mmu.set_p4d = native_set_p4d,
366 #if CONFIG_PGTABLE_LEVELS >= 5
367 .mmu.p4d_val = PTE_IDENT,
368 .mmu.make_p4d = PTE_IDENT,
370 .mmu.set_pgd = native_set_pgd,
371 #endif /* CONFIG_PGTABLE_LEVELS >= 5 */
373 .mmu.pte_val = PTE_IDENT,
374 .mmu.pgd_val = PTE_IDENT,
376 .mmu.make_pte = PTE_IDENT,
377 .mmu.make_pgd = PTE_IDENT,
379 .mmu.dup_mmap = paravirt_nop,
380 .mmu.activate_mm = paravirt_nop,
383 .enter = paravirt_nop,
384 .leave = paravirt_nop,
385 .flush = paravirt_nop,
388 .mmu.set_fixmap = native_set_fixmap,
389 #endif /* CONFIG_PARAVIRT_XXL */
391 #if defined(CONFIG_PARAVIRT_SPINLOCKS)
394 .lock.queued_spin_lock_slowpath = native_queued_spin_lock_slowpath,
395 .lock.queued_spin_unlock =
396 PV_CALLEE_SAVE(__native_queued_spin_unlock),
397 .lock.wait = paravirt_nop,
398 .lock.kick = paravirt_nop,
399 .lock.vcpu_is_preempted =
400 PV_CALLEE_SAVE(__native_vcpu_is_preempted),
405 #ifdef CONFIG_PARAVIRT_XXL
406 /* At this point, native_get/set_debugreg has real function entries */
407 NOKPROBE_SYMBOL(native_get_debugreg);
408 NOKPROBE_SYMBOL(native_set_debugreg);
409 NOKPROBE_SYMBOL(native_load_idt);
412 EXPORT_SYMBOL(pv_ops);
413 EXPORT_SYMBOL_GPL(pv_info);