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// 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 <asm/bug.h>
#include <asm/paravirt.h>
#include <asm/debugreg.h>
#include <asm/desc.h>
#include <asm/setup.h>
#include <asm/pgtable.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>
/*
* 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) ||
type == PARAVIRT_PATCH(cpu.usergs_sysret64))
/* 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;
}
static void native_flush_tlb(void)
{
__native_flush_tlb();
}
/*
* Global pages have to be flushed a bit differently. Not a real
* performance problem because this does not happen often.
*/
static void native_flush_tlb_global(void)
{
__native_flush_tlb_global();
}
static void native_flush_tlb_one_user(unsigned long addr)
{
__native_flush_tlb_one_user(addr);
}
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);
extern void native_usergs_sysret64(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
.kernel_rpl = 0,
.shared_kernel_pmd = 1, /* Only used when CONFIG_X86_PAE is set */
#ifdef CONFIG_X86_64
.extra_user_64bit_cs = __USER_CS,
#endif
#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.wri
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