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>
18 #include <asm/paravirt.h>
19 #include <asm/debugreg.h>
21 #include <asm/setup.h>
22 #include <asm/pgtable.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>
35 * nop stub, which must not clobber anything *including the stack* to
36 * avoid confusing the entry prologues.
38 extern void _paravirt_nop(void);
39 asm (".pushsection .entry.text, \"ax\"\n"
40 ".global _paravirt_nop\n"
43 ".size _paravirt_nop, . - _paravirt_nop\n\t"
44 ".type _paravirt_nop, @function\n\t"
47 void __init default_banner(void)
49 printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
53 /* Undefined instruction for dealing with missing ops pointers. */
54 static const unsigned char ud2a[] = { 0x0f, 0x0b };
59 } __attribute__((packed));
61 static unsigned paravirt_patch_call(void *insn_buff, const void *target,
62 unsigned long addr, unsigned len)
64 const int call_len = 5;
65 struct branch *b = insn_buff;
66 unsigned long delta = (unsigned long)target - (addr+call_len);
69 pr_warn("paravirt: Failed to patch indirect CALL at %ps\n", (void *)addr);
70 /* Kernel might not be viable if patching fails, bail out: */
74 b->opcode = 0xe8; /* call */
76 BUILD_BUG_ON(sizeof(*b) != call_len);
81 #ifdef CONFIG_PARAVIRT_XXL
82 /* identity function, which can be inlined */
83 u64 notrace _paravirt_ident_64(u64 x)
88 static unsigned paravirt_patch_jmp(void *insn_buff, const void *target,
89 unsigned long addr, unsigned len)
91 struct branch *b = insn_buff;
92 unsigned long delta = (unsigned long)target - (addr+5);
95 #ifdef CONFIG_RETPOLINE
96 WARN_ONCE(1, "Failing to patch indirect JMP in %ps\n", (void *)addr);
98 return len; /* call too long for patch site */
101 b->opcode = 0xe9; /* jmp */
108 DEFINE_STATIC_KEY_TRUE(virt_spin_lock_key);
110 void __init native_pv_lock_init(void)
112 if (!boot_cpu_has(X86_FEATURE_HYPERVISOR))
113 static_branch_disable(&virt_spin_lock_key);
116 unsigned paravirt_patch_default(u8 type, void *insn_buff,
117 unsigned long addr, unsigned len)
120 * Neat trick to map patch type back to the call within the
121 * corresponding structure.
123 void *opfunc = *((void **)&pv_ops + type);
127 /* If there's no function, patch it with a ud2a (BUG) */
128 ret = paravirt_patch_insns(insn_buff, len, ud2a, ud2a+sizeof(ud2a));
129 else if (opfunc == _paravirt_nop)
132 #ifdef CONFIG_PARAVIRT_XXL
133 /* identity functions just return their single argument */
134 else if (opfunc == _paravirt_ident_64)
135 ret = paravirt_patch_ident_64(insn_buff, len);
137 else if (type == PARAVIRT_PATCH(cpu.iret) ||
138 type == PARAVIRT_PATCH(cpu.usergs_sysret64))
139 /* If operation requires a jmp, then jmp */
140 ret = paravirt_patch_jmp(insn_buff, opfunc, addr, len);
143 /* Otherwise call the function. */
144 ret = paravirt_patch_call(insn_buff, opfunc, addr, len);
149 unsigned paravirt_patch_insns(void *insn_buff, unsigned len,
150 const char *start, const char *end)
152 unsigned insn_len = end - start;
154 /* Alternative instruction is too large for the patch site and we cannot continue: */
155 BUG_ON(insn_len > len || start == NULL);
157 memcpy(insn_buff, start, insn_len);
162 static void native_flush_tlb(void)
164 __native_flush_tlb();
168 * Global pages have to be flushed a bit differently. Not a real
169 * performance problem because this does not happen often.
171 static void native_flush_tlb_global(void)
173 __native_flush_tlb_global();
176 static void native_flush_tlb_one_user(unsigned long addr)
178 __native_flush_tlb_one_user(addr);
181 struct static_key paravirt_steal_enabled;
182 struct static_key paravirt_steal_rq_enabled;
184 static u64 native_steal_clock(int cpu)
189 /* These are in entry.S */
190 extern void native_iret(void);
191 extern void native_usergs_sysret64(void);
193 static struct resource reserve_ioports = {
195 .end = IO_SPACE_LIMIT,
196 .name = "paravirt-ioport",
197 .flags = IORESOURCE_IO | IORESOURCE_BUSY,
201 * Reserve the whole legacy IO space to prevent any legacy drivers
202 * from wasting time probing for their hardware. This is a fairly
203 * brute-force approach to disabling all non-virtual drivers.
205 * Note that this must be called very early to have any effect.
207 int paravirt_disable_iospace(void)
209 return request_resource(&ioport_resource, &reserve_ioports);
212 static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;
214 static inline void enter_lazy(enum paravirt_lazy_mode mode)
216 BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);
218 this_cpu_write(paravirt_lazy_mode, mode);
221 static void leave_lazy(enum paravirt_lazy_mode mode)
223 BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);
225 this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
228 void paravirt_enter_lazy_mmu(void)
230 enter_lazy(PARAVIRT_LAZY_MMU);
233 void paravirt_leave_lazy_mmu(void)
235 leave_lazy(PARAVIRT_LAZY_MMU);
238 void paravirt_flush_lazy_mmu(void)
242 if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
243 arch_leave_lazy_mmu_mode();
244 arch_enter_lazy_mmu_mode();
250 #ifdef CONFIG_PARAVIRT_XXL
251 void paravirt_start_context_switch(struct task_struct *prev)
253 BUG_ON(preemptible());
255 if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
256 arch_leave_lazy_mmu_mode();
257 set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
259 enter_lazy(PARAVIRT_LAZY_CPU);
262 void paravirt_end_context_switch(struct task_struct *next)
264 BUG_ON(preemptible());
266 leave_lazy(PARAVIRT_LAZY_CPU);
268 if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
269 arch_enter_lazy_mmu_mode();
273 enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
276 return PARAVIRT_LAZY_NONE;
278 return this_cpu_read(paravirt_lazy_mode);
281 struct pv_info pv_info = {
282 .name = "bare hardware",
283 #ifdef CONFIG_PARAVIRT_XXL
285 .shared_kernel_pmd = 1, /* Only used when CONFIG_X86_PAE is set */
288 .extra_user_64bit_cs = __USER_CS,
293 /* 64-bit pagetable entries */
294 #define PTE_IDENT __PV_IS_CALLEE_SAVE(_paravirt_ident_64)
296 struct paravirt_patch_template pv_ops = {
298 .init.patch = native_patch,
301 .time.sched_clock = native_sched_clock,
302 .time.steal_clock = native_steal_clock,
305 .cpu.io_delay = native_io_delay,
307 #ifdef CONFIG_PARAVIRT_XXL
308 .cpu.cpuid = native_cpuid,
309 .cpu.get_debugreg = native_get_debugreg,
310 .cpu.set_debugreg = native_set_debugreg,
311 .cpu.read_cr0 = native_read_cr0,
312 .cpu.write_cr0 = native_write_cr0,
313 .cpu.write_cr4 = native_write_cr4,
315 .cpu.read_cr8 = native_read_cr8,
316 .cpu.write_cr8 = native_write_cr8,
318 .cpu.wbinvd = native_wbinvd,
319 .cpu.read_msr = native_read_msr,
320 .cpu.write_msr = native_write_msr,
321 .cpu.read_msr_safe = native_read_msr_safe,
322 .cpu.write_msr_safe = native_write_msr_safe,
323 .cpu.read_pmc = native_read_pmc,
324 .cpu.load_tr_desc = native_load_tr_desc,
325 .cpu.set_ldt = native_set_ldt,
326 .cpu.load_gdt = native_load_gdt,
327 .cpu.load_idt = native_load_idt,
328 .cpu.store_tr = native_store_tr,
329 .cpu.load_tls = native_load_tls,
331 .cpu.load_gs_index = native_load_gs_index,
333 .cpu.write_ldt_entry = native_write_ldt_entry,
334 .cpu.write_gdt_entry = native_write_gdt_entry,
335 .cpu.write_idt_entry = native_write_idt_entry,
337 .cpu.alloc_ldt = paravirt_nop,
338 .cpu.free_ldt = paravirt_nop,
340 .cpu.load_sp0 = native_load_sp0,
343 .cpu.usergs_sysret64 = native_usergs_sysret64,
345 .cpu.iret = native_iret,
346 .cpu.swapgs = native_swapgs,
348 .cpu.set_iopl_mask = native_set_iopl_mask,
350 .cpu.start_context_switch = paravirt_nop,
351 .cpu.end_context_switch = paravirt_nop,
354 .irq.save_fl = __PV_IS_CALLEE_SAVE(native_save_fl),
355 .irq.restore_fl = __PV_IS_CALLEE_SAVE(native_restore_fl),
356 .irq.irq_disable = __PV_IS_CALLEE_SAVE(native_irq_disable),
357 .irq.irq_enable = __PV_IS_CALLEE_SAVE(native_irq_enable),
358 .irq.safe_halt = native_safe_halt,
359 .irq.halt = native_halt,
360 #endif /* CONFIG_PARAVIRT_XXL */
363 .mmu.flush_tlb_user = native_flush_tlb,
364 .mmu.flush_tlb_kernel = native_flush_tlb_global,
365 .mmu.flush_tlb_one_user = native_flush_tlb_one_user,
366 .mmu.flush_tlb_others = native_flush_tlb_others,
367 .mmu.tlb_remove_table =
368 (void (*)(struct mmu_gather *, void *))tlb_remove_page,
370 .mmu.exit_mmap = paravirt_nop,
372 #ifdef CONFIG_PARAVIRT_XXL
373 .mmu.read_cr2 = __PV_IS_CALLEE_SAVE(native_read_cr2),
374 .mmu.write_cr2 = native_write_cr2,
375 .mmu.read_cr3 = __native_read_cr3,
376 .mmu.write_cr3 = native_write_cr3,
378 .mmu.pgd_alloc = __paravirt_pgd_alloc,
379 .mmu.pgd_free = paravirt_nop,
381 .mmu.alloc_pte = paravirt_nop,
382 .mmu.alloc_pmd = paravirt_nop,
383 .mmu.alloc_pud = paravirt_nop,
384 .mmu.alloc_p4d = paravirt_nop,
385 .mmu.release_pte = paravirt_nop,
386 .mmu.release_pmd = paravirt_nop,
387 .mmu.release_pud = paravirt_nop,
388 .mmu.release_p4d = paravirt_nop,
390 .mmu.set_pte = native_set_pte,
391 .mmu.set_pte_at = native_set_pte_at,
392 .mmu.set_pmd = native_set_pmd,
394 .mmu.ptep_modify_prot_start = __ptep_modify_prot_start,
395 .mmu.ptep_modify_prot_commit = __ptep_modify_prot_commit,
397 #if CONFIG_PGTABLE_LEVELS >= 3
398 #ifdef CONFIG_X86_PAE
399 .mmu.set_pte_atomic = native_set_pte_atomic,
400 .mmu.pte_clear = native_pte_clear,
401 .mmu.pmd_clear = native_pmd_clear,
403 .mmu.set_pud = native_set_pud,
405 .mmu.pmd_val = PTE_IDENT,
406 .mmu.make_pmd = PTE_IDENT,
408 #if CONFIG_PGTABLE_LEVELS >= 4
409 .mmu.pud_val = PTE_IDENT,
410 .mmu.make_pud = PTE_IDENT,
412 .mmu.set_p4d = native_set_p4d,
414 #if CONFIG_PGTABLE_LEVELS >= 5
415 .mmu.p4d_val = PTE_IDENT,
416 .mmu.make_p4d = PTE_IDENT,
418 .mmu.set_pgd = native_set_pgd,
419 #endif /* CONFIG_PGTABLE_LEVELS >= 5 */
420 #endif /* CONFIG_PGTABLE_LEVELS >= 4 */
421 #endif /* CONFIG_PGTABLE_LEVELS >= 3 */
423 .mmu.pte_val = PTE_IDENT,
424 .mmu.pgd_val = PTE_IDENT,
426 .mmu.make_pte = PTE_IDENT,
427 .mmu.make_pgd = PTE_IDENT,
429 .mmu.dup_mmap = paravirt_nop,
430 .mmu.activate_mm = paravirt_nop,
433 .enter = paravirt_nop,
434 .leave = paravirt_nop,
435 .flush = paravirt_nop,
438 .mmu.set_fixmap = native_set_fixmap,
439 #endif /* CONFIG_PARAVIRT_XXL */
441 #if defined(CONFIG_PARAVIRT_SPINLOCKS)
444 .lock.queued_spin_lock_slowpath = native_queued_spin_lock_slowpath,
445 .lock.queued_spin_unlock =
446 PV_CALLEE_SAVE(__native_queued_spin_unlock),
447 .lock.wait = paravirt_nop,
448 .lock.kick = paravirt_nop,
449 .lock.vcpu_is_preempted =
450 PV_CALLEE_SAVE(__native_vcpu_is_preempted),
455 #ifdef CONFIG_PARAVIRT_XXL
456 /* At this point, native_get/set_debugreg has real function entries */
457 NOKPROBE_SYMBOL(native_get_debugreg);
458 NOKPROBE_SYMBOL(native_set_debugreg);
459 NOKPROBE_SYMBOL(native_load_idt);
462 EXPORT_SYMBOL(pv_ops);
463 EXPORT_SYMBOL_GPL(pv_info);