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OpenCloudOS-Kernel/arch/x86/xen/enlighten_pv.c

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// SPDX-License-Identifier: GPL-2.0
/*
* Core of Xen paravirt_ops implementation.
*
* This file contains the xen_paravirt_ops structure itself, and the
* implementations for:
* - privileged instructions
* - interrupt flags
* - segment operations
* - booting and setup
*
* Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
*/
#include <linux/cpu.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/preempt.h>
#include <linux/hardirq.h>
#include <linux/percpu.h>
#include <linux/delay.h>
#include <linux/start_kernel.h>
#include <linux/sched.h>
#include <linux/kprobes.h>
#include <linux/memblock.h>
#include <linux/export.h>
#include <linux/mm.h>
#include <linux/page-flags.h>
#include <linux/highmem.h>
#include <linux/console.h>
#include <linux/pci.h>
#include <linux/gfp.h>
#include <linux/edd.h>
#include <linux/frame.h>
#include <xen/xen.h>
#include <xen/events.h>
#include <xen/interface/xen.h>
#include <xen/interface/version.h>
#include <xen/interface/physdev.h>
#include <xen/interface/vcpu.h>
#include <xen/interface/memory.h>
#include <xen/interface/nmi.h>
#include <xen/interface/xen-mca.h>
#include <xen/features.h>
#include <xen/page.h>
#include <xen/hvc-console.h>
#include <xen/acpi.h>
#include <asm/paravirt.h>
#include <asm/apic.h>
#include <asm/page.h>
#include <asm/xen/pci.h>
#include <asm/xen/hypercall.h>
#include <asm/xen/hypervisor.h>
#include <asm/xen/cpuid.h>
#include <asm/fixmap.h>
#include <asm/processor.h>
#include <asm/proto.h>
#include <asm/msr-index.h>
#include <asm/traps.h>
#include <asm/setup.h>
#include <asm/desc.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/tlbflush.h>
#include <asm/reboot.h>
#include <asm/stackprotector.h>
#include <asm/hypervisor.h>
#include <asm/mach_traps.h>
#include <asm/mwait.h>
#include <asm/pci_x86.h>
#include <asm/cpu.h>
#ifdef CONFIG_ACPI
#include <linux/acpi.h>
#include <asm/acpi.h>
#include <acpi/pdc_intel.h>
#include <acpi/processor.h>
#include <xen/interface/platform.h>
#endif
#include "xen-ops.h"
#include "mmu.h"
#include "smp.h"
#include "multicalls.h"
#include "pmu.h"
#include "../kernel/cpu/cpu.h" /* get_cpu_cap() */
void *xen_initial_gdt;
static int xen_cpu_up_prepare_pv(unsigned int cpu);
static int xen_cpu_dead_pv(unsigned int cpu);
struct tls_descs {
struct desc_struct desc[3];
};
/*
* Updating the 3 TLS descriptors in the GDT on every task switch is
* surprisingly expensive so we avoid updating them if they haven't
* changed. Since Xen writes different descriptors than the one
* passed in the update_descriptor hypercall we keep shadow copies to
* compare against.
*/
static DEFINE_PER_CPU(struct tls_descs, shadow_tls_desc);
static void __init xen_banner(void)
{
unsigned version = HYPERVISOR_xen_version(XENVER_version, NULL);
struct xen_extraversion extra;
HYPERVISOR_xen_version(XENVER_extraversion, &extra);
pr_info("Booting paravirtualized kernel on %s\n", pv_info.name);
printk(KERN_INFO "Xen version: %d.%d%s%s\n",
version >> 16, version & 0xffff, extra.extraversion,
xen_feature(XENFEAT_mmu_pt_update_preserve_ad) ? " (preserve-AD)" : "");
#ifdef CONFIG_X86_32
pr_warn("WARNING! WARNING! WARNING! WARNING! WARNING! WARNING! WARNING!\n"
"Support for running as 32-bit PV-guest under Xen will soon be removed\n"
"from the Linux kernel!\n"
"Please use either a 64-bit kernel or switch to HVM or PVH mode!\n"
"WARNING! WARNING! WARNING! WARNING! WARNING! WARNING! WARNING!\n");
#endif
}
static void __init xen_pv_init_platform(void)
{
populate_extra_pte(fix_to_virt(FIX_PARAVIRT_BOOTMAP));
set_fixmap(FIX_PARAVIRT_BOOTMAP, xen_start_info->shared_info);
HYPERVISOR_shared_info = (void *)fix_to_virt(FIX_PARAVIRT_BOOTMAP);
/* xen clock uses per-cpu vcpu_info, need to init it for boot cpu */
xen_vcpu_info_reset(0);
/* pvclock is in shared info area */
xen_init_time_ops();
}
static void __init xen_pv_guest_late_init(void)
{
#ifndef CONFIG_SMP
/* Setup shared vcpu info for non-smp configurations */
xen_setup_vcpu_info_placement();
#endif
}
/* Check if running on Xen version (major, minor) or later */
bool
xen_running_on_version_or_later(unsigned int major, unsigned int minor)
{
unsigned int version;
if (!xen_domain())
return false;
version = HYPERVISOR_xen_version(XENVER_version, NULL);
if ((((version >> 16) == major) && ((version & 0xffff) >= minor)) ||
((version >> 16) > major))
return true;
return false;
}
static __read_mostly unsigned int cpuid_leaf5_ecx_val;
static __read_mostly unsigned int cpuid_leaf5_edx_val;
static void xen_cpuid(unsigned int *ax, unsigned int *bx,
unsigned int *cx, unsigned int *dx)
{
unsigned maskebx = ~0;
/*
* Mask out inconvenient features, to try and disable as many
* unsupported kernel subsystems as possible.
*/
switch (*ax) {
case CPUID_MWAIT_LEAF:
/* Synthesize the values.. */
*ax = 0;
*bx = 0;
*cx = cpuid_leaf5_ecx_val;
*dx = cpuid_leaf5_edx_val;
return;
case 0xb:
/* Suppress extended topology stuff */
maskebx = 0;
break;
}
asm(XEN_EMULATE_PREFIX "cpuid"
: "=a" (*ax),
"=b" (*bx),
"=c" (*cx),
"=d" (*dx)
: "0" (*ax), "2" (*cx));
*bx &= maskebx;
}
STACK_FRAME_NON_STANDARD(xen_cpuid); /* XEN_EMULATE_PREFIX */
static bool __init xen_check_mwait(void)
{
#ifdef CONFIG_ACPI
struct xen_platform_op op = {
.cmd = XENPF_set_processor_pminfo,
.u.set_pminfo.id = -1,
.u.set_pminfo.type = XEN_PM_PDC,
};
uint32_t buf[3];
unsigned int ax, bx, cx, dx;
unsigned int mwait_mask;
/* We need to determine whether it is OK to expose the MWAIT
* capability to the kernel to harvest deeper than C3 states from ACPI
* _CST using the processor_harvest_xen.c module. For this to work, we
* need to gather the MWAIT_LEAF values (which the cstate.c code
* checks against). The hypervisor won't expose the MWAIT flag because
* it would break backwards compatibility; so we will find out directly
* from the hardware and hypercall.
*/
if (!xen_initial_domain())
return false;
/*
* When running under platform earlier than Xen4.2, do not expose
* mwait, to avoid the risk of loading native acpi pad driver
*/
if (!xen_running_on_version_or_later(4, 2))
return false;
ax = 1;
cx = 0;
native_cpuid(&ax, &bx, &cx, &dx);
mwait_mask = (1 << (X86_FEATURE_EST % 32)) |
(1 << (X86_FEATURE_MWAIT % 32));
if ((cx & mwait_mask) != mwait_mask)
return false;
/* We need to emulate the MWAIT_LEAF and for that we need both
* ecx and edx. The hypercall provides only partial information.
*/
ax = CPUID_MWAIT_LEAF;
bx = 0;
cx = 0;
dx = 0;
native_cpuid(&ax, &bx, &cx, &dx);
/* Ask the Hypervisor whether to clear ACPI_PDC_C_C2C3_FFH. If so,
* don't expose MWAIT_LEAF and let ACPI pick the IOPORT version of C3.
*/
buf[0] = ACPI_PDC_REVISION_ID;
buf[1] = 1;
buf[2] = (ACPI_PDC_C_CAPABILITY_SMP | ACPI_PDC_EST_CAPABILITY_SWSMP);
set_xen_guest_handle(op.u.set_pminfo.pdc, buf);
if ((HYPERVISOR_platform_op(&op) == 0) &&
(buf[2] & (ACPI_PDC_C_C1_FFH | ACPI_PDC_C_C2C3_FFH))) {
cpuid_leaf5_ecx_val = cx;
cpuid_leaf5_edx_val = dx;
}
return true;
#else
return false;
#endif
}
static bool __init xen_check_xsave(void)
{
unsigned int cx, xsave_mask;
cx = cpuid_ecx(1);
xsave_mask = (1 << (X86_FEATURE_XSAVE % 32)) |
(1 << (X86_FEATURE_OSXSAVE % 32));
/* Xen will set CR4.OSXSAVE if supported and not disabled by force */
return (cx & xsave_mask) == xsave_mask;
}
static void __init xen_init_capabilities(void)
{
setup_force_cpu_cap(X86_FEATURE_XENPV);
setup_clear_cpu_cap(X86_FEATURE_DCA);
setup_clear_cpu_cap(X86_FEATURE_APERFMPERF);
setup_clear_cpu_cap(X86_FEATURE_MTRR);
setup_clear_cpu_cap(X86_FEATURE_ACC);
setup_clear_cpu_cap(X86_FEATURE_X2APIC);
setup_clear_cpu_cap(X86_FEATURE_SME);
/*
* Xen PV would need some work to support PCID: CR3 handling as well
* as xen_flush_tlb_others() would need updating.
*/
setup_clear_cpu_cap(X86_FEATURE_PCID);
if (!xen_initial_domain())
setup_clear_cpu_cap(X86_FEATURE_ACPI);
if (xen_check_mwait())
setup_force_cpu_cap(X86_FEATURE_MWAIT);
else
setup_clear_cpu_cap(X86_FEATURE_MWAIT);
if (!xen_check_xsave()) {
setup_clear_cpu_cap(X86_FEATURE_XSAVE);
setup_clear_cpu_cap(X86_FEATURE_OSXSAVE);
}
}
static void xen_set_debugreg(int reg, unsigned long val)
{
HYPERVISOR_set_debugreg(reg, val);
}
static unsigned long xen_get_debugreg(int reg)
{
return HYPERVISOR_get_debugreg(reg);
}
static void xen_end_context_switch(struct task_struct *next)
{
xen_mc_flush();
paravirt_end_context_switch(next);
}
static unsigned long xen_store_tr(void)
{
return 0;
}
/*
* Set the page permissions for a particular virtual address. If the
* address is a vmalloc mapping (or other non-linear mapping), then
* find the linear mapping of the page and also set its protections to
* match.
*/
static void set_aliased_prot(void *v, pgprot_t prot)
{
int level;
pte_t *ptep;
pte_t pte;
unsigned long pfn;
struct page *page;
unsigned char dummy;
ptep = lookup_address((unsigned long)v, &level);
BUG_ON(ptep == NULL);
pfn = pte_pfn(*ptep);
page = pfn_to_page(pfn);
pte = pfn_pte(pfn, prot);
/*
* Careful: update_va_mapping() will fail if the virtual address
* we're poking isn't populated in the page tables. We don't
* need to worry about the direct map (that's always in the page
* tables), but we need to be careful about vmap space. In
* particular, the top level page table can lazily propagate
* entries between processes, so if we've switched mms since we
* vmapped the target in the first place, we might not have the
* top-level page table entry populated.
*
* We disable preemption because we want the same mm active when
* we probe the target and when we issue the hypercall. We'll
* have the same nominal mm, but if we're a kernel thread, lazy
* mm dropping could change our pgd.
*
* Out of an abundance of caution, this uses __get_user() to fault
* in the target address just in case there's some obscure case
* in which the target address isn't readable.
*/
preempt_disable();
probe_kernel_read(&dummy, v, 1);
if (HYPERVISOR_update_va_mapping((unsigned long)v, pte, 0))
BUG();
if (!PageHighMem(page)) {
void *av = __va(PFN_PHYS(pfn));
if (av != v)
if (HYPERVISOR_update_va_mapping((unsigned long)av, pte, 0))
BUG();
} else
kmap_flush_unused();
preempt_enable();
}
static void xen_alloc_ldt(struct desc_struct *ldt, unsigned entries)
{
const unsigned entries_per_page = PAGE_SIZE / LDT_ENTRY_SIZE;
int i;
/*
* We need to mark the all aliases of the LDT pages RO. We
* don't need to call vm_flush_aliases(), though, since that's
* only responsible for flushing aliases out the TLBs, not the
* page tables, and Xen will flush the TLB for us if needed.
*
* To avoid confusing future readers: none of this is necessary
* to load the LDT. The hypervisor only checks this when the
* LDT is faulted in due to subsequent descriptor access.
*/
for (i = 0; i < entries; i += entries_per_page)
set_aliased_prot(ldt + i, PAGE_KERNEL_RO);
}
static void xen_free_ldt(struct desc_struct *ldt, unsigned entries)
{
const unsigned entries_per_page = PAGE_SIZE / LDT_ENTRY_SIZE;
int i;
for (i = 0; i < entries; i += entries_per_page)
set_aliased_prot(ldt + i, PAGE_KERNEL);
}
static void xen_set_ldt(const void *addr, unsigned entries)
{
struct mmuext_op *op;
struct multicall_space mcs = xen_mc_entry(sizeof(*op));
trace_xen_cpu_set_ldt(addr, entries);
op = mcs.args;
op->cmd = MMUEXT_SET_LDT;
op->arg1.linear_addr = (unsigned long)addr;
op->arg2.nr_ents = entries;
MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);
xen_mc_issue(PARAVIRT_LAZY_CPU);
}
static void xen_load_gdt(const struct desc_ptr *dtr)
{
unsigned long va = dtr->address;
unsigned int size = dtr->size + 1;
unsigned long pfn, mfn;
int level;
pte_t *ptep;
void *virt;
/* @size should be at most GDT_SIZE which is smaller than PAGE_SIZE. */
BUG_ON(size > PAGE_SIZE);
BUG_ON(va & ~PAGE_MASK);
/*
* The GDT is per-cpu and is in the percpu data area.
* That can be virtually mapped, so we need to do a
* page-walk to get the underlying MFN for the
* hypercall. The page can also be in the kernel's
* linear range, so we need to RO that mapping too.
*/
ptep = lookup_address(va, &level);
BUG_ON(ptep == NULL);
pfn = pte_pfn(*ptep);
mfn = pfn_to_mfn(pfn);
virt = __va(PFN_PHYS(pfn));
make_lowmem_page_readonly((void *)va);
make_lowmem_page_readonly(virt);
if (HYPERVISOR_set_gdt(&mfn, size / sizeof(struct desc_struct)))
BUG();
}
/*
* load_gdt for early boot, when the gdt is only mapped once
*/
static void __init xen_load_gdt_boot(const struct desc_ptr *dtr)
{
unsigned long va = dtr->address;
unsigned int size = dtr->size + 1;
unsigned long pfn, mfn;
pte_t pte;
/* @size should be at most GDT_SIZE which is smaller than PAGE_SIZE. */
BUG_ON(size > PAGE_SIZE);
BUG_ON(va & ~PAGE_MASK);
pfn = virt_to_pfn(va);
mfn = pfn_to_mfn(pfn);
pte = pfn_pte(pfn, PAGE_KERNEL_RO);
if (HYPERVISOR_update_va_mapping((unsigned long)va, pte, 0))
BUG();
if (HYPERVISOR_set_gdt(&mfn, size / sizeof(struct desc_struct)))
BUG();
}
static inline bool desc_equal(const struct desc_struct *d1,
const struct desc_struct *d2)
{
return !memcmp(d1, d2, sizeof(*d1));
}
static void load_TLS_descriptor(struct thread_struct *t,
unsigned int cpu, unsigned int i)
{
struct desc_struct *shadow = &per_cpu(shadow_tls_desc, cpu).desc[i];
struct desc_struct *gdt;
xmaddr_t maddr;
struct multicall_space mc;
if (desc_equal(shadow, &t->tls_array[i]))
return;
*shadow = t->tls_array[i];
gdt = get_cpu_gdt_rw(cpu);
maddr = arbitrary_virt_to_machine(&gdt[GDT_ENTRY_TLS_MIN+i]);
mc = __xen_mc_entry(0);
MULTI_update_descriptor(mc.mc, maddr.maddr, t->tls_array[i]);
}
static void xen_load_tls(struct thread_struct *t, unsigned int cpu)
{
/*
* XXX sleazy hack: If we're being called in a lazy-cpu zone
* and lazy gs handling is enabled, it means we're in a
* context switch, and %gs has just been saved. This means we
* can zero it out to prevent faults on exit from the
* hypervisor if the next process has no %gs. Either way, it
* has been saved, and the new value will get loaded properly.
* This will go away as soon as Xen has been modified to not
* save/restore %gs for normal hypercalls.
*
* On x86_64, this hack is not used for %gs, because gs points
* to KERNEL_GS_BASE (and uses it for PDA references), so we
* must not zero %gs on x86_64
*
* For x86_64, we need to zero %fs, otherwise we may get an
* exception between the new %fs descriptor being loaded and
* %fs being effectively cleared at __switch_to().
*/
if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_CPU) {
#ifdef CONFIG_X86_32
lazy_load_gs(0);
#else
loadsegment(fs, 0);
#endif
}
xen_mc_batch();
load_TLS_descriptor(t, cpu, 0);
load_TLS_descriptor(t, cpu, 1);
load_TLS_descriptor(t, cpu, 2);
xen_mc_issue(PARAVIRT_LAZY_CPU);
}
#ifdef CONFIG_X86_64
static void xen_load_gs_index(unsigned int idx)
{
if (HYPERVISOR_set_segment_base(SEGBASE_GS_USER_SEL, idx))
BUG();
}
#endif
static void xen_write_ldt_entry(struct desc_struct *dt, int entrynum,
const void *ptr)
{
xmaddr_t mach_lp = arbitrary_virt_to_machine(&dt[entrynum]);
u64 entry = *(u64 *)ptr;
trace_xen_cpu_write_ldt_entry(dt, entrynum, entry);
preempt_disable();
xen_mc_flush();
if (HYPERVISOR_update_descriptor(mach_lp.maddr, entry))
BUG();
preempt_enable();
}
#ifdef CONFIG_X86_64
struct trap_array_entry {
void (*orig)(void);
void (*xen)(void);
bool ist_okay;
};
static struct trap_array_entry trap_array[] = {
{ debug, xen_xendebug, true },
{ double_fault, xen_double_fault, true },
#ifdef CONFIG_X86_MCE
{ machine_check, xen_machine_check, true },
#endif
{ nmi, xen_xennmi, true },
{ int3, xen_int3, false },
{ overflow, xen_overflow, false },
#ifdef CONFIG_IA32_EMULATION
{ entry_INT80_compat, xen_entry_INT80_compat, false },
#endif
{ page_fault, xen_page_fault, false },
{ divide_error, xen_divide_error, false },
{ bounds, xen_bounds, false },
{ invalid_op, xen_invalid_op, false },
{ device_not_available, xen_device_not_available, false },
{ coprocessor_segment_overrun, xen_coprocessor_segment_overrun, false },
{ invalid_TSS, xen_invalid_TSS, false },
{ segment_not_present, xen_segment_not_present, false },
{ stack_segment, xen_stack_segment, false },
{ general_protection, xen_general_protection, false },
{ spurious_interrupt_bug, xen_spurious_interrupt_bug, false },
{ coprocessor_error, xen_coprocessor_error, false },
{ alignment_check, xen_alignment_check, false },
{ simd_coprocessor_error, xen_simd_coprocessor_error, false },
};
static bool __ref get_trap_addr(void **addr, unsigned int ist)
{
unsigned int nr;
bool ist_okay = false;
/*
* Replace trap handler addresses by Xen specific ones.
* Check for known traps using IST and whitelist them.
* The debugger ones are the only ones we care about.
* Xen will handle faults like double_fault, * so we should never see
* them. Warn if there's an unexpected IST-using fault handler.
*/
for (nr = 0; nr < ARRAY_SIZE(trap_array); nr++) {
struct trap_array_entry *entry = trap_array + nr;
if (*addr == entry->orig) {
*addr = entry->xen;
ist_okay = entry->ist_okay;
break;
}
}
if (nr == ARRAY_SIZE(trap_array) &&
*addr >= (void *)early_idt_handler_array[0] &&
*addr < (void *)early_idt_handler_array[NUM_EXCEPTION_VECTORS]) {
nr = (*addr - (void *)early_idt_handler_array[0]) /
EARLY_IDT_HANDLER_SIZE;
*addr = (void *)xen_early_idt_handler_array[nr];
}
if (WARN_ON(ist != 0 && !ist_okay))
return false;
return true;
}
#endif
static int cvt_gate_to_trap(int vector, const gate_desc *val,
struct trap_info *info)
{
unsigned long addr;
if (val->bits.type != GATE_TRAP && val->bits.type != GATE_INTERRUPT)
return 0;
info->vector = vector;
addr = gate_offset(val);
#ifdef CONFIG_X86_64
if (!get_trap_addr((void **)&addr, val->bits.ist))
return 0;
#endif /* CONFIG_X86_64 */
info->address = addr;
info->cs = gate_segment(val);
info->flags = val->bits.dpl;
/* interrupt gates clear IF */
if (val->bits.type == GATE_INTERRUPT)
info->flags |= 1 << 2;
return 1;
}
/* Locations of each CPU's IDT */
static DEFINE_PER_CPU(struct desc_ptr, idt_desc);
/* Set an IDT entry. If the entry is part of the current IDT, then
also update Xen. */
static void xen_write_idt_entry(gate_desc *dt, int entrynum, const gate_desc *g)
{
unsigned long p = (unsigned long)&dt[entrynum];
unsigned long start, end;
trace_xen_cpu_write_idt_entry(dt, entrynum, g);
preempt_disable();
start = __this_cpu_read(idt_desc.address);
end = start + __this_cpu_read(idt_desc.size) + 1;
xen_mc_flush();
native_write_idt_entry(dt, entrynum, g);
if (p >= start && (p + 8) <= end) {
struct trap_info info[2];
info[1].address = 0;
if (cvt_gate_to_trap(entrynum, g, &info[0]))
if (HYPERVISOR_set_trap_table(info))
BUG();
}
preempt_enable();
}
static unsigned xen_convert_trap_info(const struct desc_ptr *desc,
struct trap_info *traps, bool full)
{
unsigned in, out, count;
count = (desc->size+1) / sizeof(gate_desc);
BUG_ON(count > 256);
for (in = out = 0; in < count; in++) {
gate_desc *entry = (gate_desc *)(desc->address) + in;
if (cvt_gate_to_trap(in, entry, &traps[out]) || full)
out++;
}
return out;
}
void xen_copy_trap_info(struct trap_info *traps)
{
const struct desc_ptr *desc = this_cpu_ptr(&idt_desc);
xen_convert_trap_info(desc, traps, true);
}
/* Load a new IDT into Xen. In principle this can be per-CPU, so we
hold a spinlock to protect the static traps[] array (static because
it avoids allocation, and saves stack space). */
static void xen_load_idt(const struct desc_ptr *desc)
{
static DEFINE_SPINLOCK(lock);
static struct trap_info traps[257];
unsigned out;
trace_xen_cpu_load_idt(desc);
spin_lock(&lock);
memcpy(this_cpu_ptr(&idt_desc), desc, sizeof(idt_desc));
out = xen_convert_trap_info(desc, traps, false);
memset(&traps[out], 0, sizeof(traps[0]));
xen_mc_flush();
if (HYPERVISOR_set_trap_table(traps))
BUG();
spin_unlock(&lock);
}
/* Write a GDT descriptor entry. Ignore LDT descriptors, since
they're handled differently. */
static void xen_write_gdt_entry(struct desc_struct *dt, int entry,
const void *desc, int type)
{
trace_xen_cpu_write_gdt_entry(dt, entry, desc, type);
preempt_disable();
switch (type) {
case DESC_LDT:
case DESC_TSS:
/* ignore */
break;
default: {
xmaddr_t maddr = arbitrary_virt_to_machine(&dt[entry]);
xen_mc_flush();
if (HYPERVISOR_update_descriptor(maddr.maddr, *(u64 *)desc))
BUG();
}
}
preempt_enable();
}
/*
* Version of write_gdt_entry for use at early boot-time needed to
* update an entry as simply as possible.
*/
static void __init xen_write_gdt_entry_boot(struct desc_struct *dt, int entry,
const void *desc, int type)
{
trace_xen_cpu_write_gdt_entry(dt, entry, desc, type);
switch (type) {
case DESC_LDT:
case DESC_TSS:
/* ignore */
break;
default: {
xmaddr_t maddr = virt_to_machine(&dt[entry]);
if (HYPERVISOR_update_descriptor(maddr.maddr, *(u64 *)desc))
dt[entry] = *(struct desc_struct *)desc;
}
}
}
static void xen_load_sp0(unsigned long sp0)
{
struct multicall_space mcs;
mcs = xen_mc_entry(0);
MULTI_stack_switch(mcs.mc, __KERNEL_DS, sp0);
xen_mc_issue(PARAVIRT_LAZY_CPU);
this_cpu_write(cpu_tss_rw.x86_tss.sp0, sp0);
}
void xen_set_iopl_mask(unsigned mask)
{
struct physdev_set_iopl set_iopl;
/* Force the change at ring 0. */
set_iopl.iopl = (mask == 0) ? 1 : (mask >> 12) & 3;
HYPERVISOR_physdev_op(PHYSDEVOP_set_iopl, &set_iopl);
}
static void xen_io_delay(void)
{
}
static DEFINE_PER_CPU(unsigned long, xen_cr0_value);
static unsigned long xen_read_cr0(void)
{
unsigned long cr0 = this_cpu_read(xen_cr0_value);
if (unlikely(cr0 == 0)) {
cr0 = native_read_cr0();
this_cpu_write(xen_cr0_value, cr0);
}
return cr0;
}
static void xen_write_cr0(unsigned long cr0)
{
struct multicall_space mcs;
this_cpu_write(xen_cr0_value, cr0);
/* Only pay attention to cr0.TS; everything else is
ignored. */
mcs = xen_mc_entry(0);
MULTI_fpu_taskswitch(mcs.mc, (cr0 & X86_CR0_TS) != 0);
xen_mc_issue(PARAVIRT_LAZY_CPU);
}
static void xen_write_cr4(unsigned long cr4)
{
cr4 &= ~(X86_CR4_PGE | X86_CR4_PSE | X86_CR4_PCE);
native_write_cr4(cr4);
}
static u64 xen_read_msr_safe(unsigned int msr, int *err)
{
u64 val;
if (pmu_msr_read(msr, &val, err))
return val;
val = native_read_msr_safe(msr, err);
switch (msr) {
case MSR_IA32_APICBASE:
val &= ~X2APIC_ENABLE;
break;
}
return val;
}
static int xen_write_msr_safe(unsigned int msr, unsigned low, unsigned high)
{
int ret;
#ifdef CONFIG_X86_64
unsigned int which;
u64 base;
#endif
ret = 0;
switch (msr) {
#ifdef CONFIG_X86_64
case MSR_FS_BASE: which = SEGBASE_FS; goto set;
case MSR_KERNEL_GS_BASE: which = SEGBASE_GS_USER; goto set;
case MSR_GS_BASE: which = SEGBASE_GS_KERNEL; goto set;
set:
base = ((u64)high << 32) | low;
if (HYPERVISOR_set_segment_base(which, base) != 0)
ret = -EIO;
break;
#endif
case MSR_STAR:
case MSR_CSTAR:
case MSR_LSTAR:
case MSR_SYSCALL_MASK:
case MSR_IA32_SYSENTER_CS:
case MSR_IA32_SYSENTER_ESP:
case MSR_IA32_SYSENTER_EIP:
/* Fast syscall setup is all done in hypercalls, so
these are all ignored. Stub them out here to stop
Xen console noise. */
break;
default:
if (!pmu_msr_write(msr, low, high, &ret))
ret = native_write_msr_safe(msr, low, high);
}
return ret;
}
static u64 xen_read_msr(unsigned int msr)
{
/*
* This will silently swallow a #GP from RDMSR. It may be worth
* changing that.
*/
int err;
return xen_read_msr_safe(msr, &err);
}
static void xen_write_msr(unsigned int msr, unsigned low, unsigned high)
{
/*
* This will silently swallow a #GP from WRMSR. It may be worth
* changing that.
*/
xen_write_msr_safe(msr, low, high);
}
/* This is called once we have the cpu_possible_mask */
void __init xen_setup_vcpu_info_placement(void)
{
int cpu;
for_each_possible_cpu(cpu) {
/* Set up direct vCPU id mapping for PV guests. */
per_cpu(xen_vcpu_id, cpu) = cpu;
/*
* xen_vcpu_setup(cpu) can fail -- in which case it
* falls back to the shared_info version for cpus
* where xen_vcpu_nr(cpu) < MAX_VIRT_CPUS.
*
* xen_cpu_up_prepare_pv() handles the rest by failing
* them in hotplug.
*/
(void) xen_vcpu_setup(cpu);
}
/*
* xen_vcpu_setup managed to place the vcpu_info within the
* percpu area for all cpus, so make use of it.
*/
if (xen_have_vcpu_info_placement) {
pv_ops.irq.save_fl = __PV_IS_CALLEE_SAVE(xen_save_fl_direct);
pv_ops.irq.restore_fl =
__PV_IS_CALLEE_SAVE(xen_restore_fl_direct);
pv_ops.irq.irq_disable =
__PV_IS_CALLEE_SAVE(xen_irq_disable_direct);
pv_ops.irq.irq_enable =
__PV_IS_CALLEE_SAVE(xen_irq_enable_direct);
pv_ops.mmu.read_cr2 =
__PV_IS_CALLEE_SAVE(xen_read_cr2_direct);
}
}
static const struct pv_info xen_info __initconst = {
.shared_kernel_pmd = 0,
#ifdef CONFIG_X86_64
.extra_user_64bit_cs = FLAT_USER_CS64,
#endif
.name = "Xen",
};
static const struct pv_cpu_ops xen_cpu_ops __initconst = {
.cpuid = xen_cpuid,
.set_debugreg = xen_set_debugreg,
.get_debugreg = xen_get_debugreg,
.read_cr0 = xen_read_cr0,
.write_cr0 = xen_write_cr0,
.write_cr4 = xen_write_cr4,
.wbinvd = native_wbinvd,
.read_msr = xen_read_msr,
.write_msr = xen_write_msr,
.read_msr_safe = xen_read_msr_safe,
.write_msr_safe = xen_write_msr_safe,
.read_pmc = xen_read_pmc,
.iret = xen_iret,
#ifdef CONFIG_X86_64
.usergs_sysret64 = xen_sysret64,
#endif
.load_tr_desc = paravirt_nop,
.set_ldt = xen_set_ldt,
.load_gdt = xen_load_gdt,
.load_idt = xen_load_idt,
.load_tls = xen_load_tls,
#ifdef CONFIG_X86_64
.load_gs_index = xen_load_gs_index,
#endif
.alloc_ldt = xen_alloc_ldt,
.free_ldt = xen_free_ldt,
.store_tr = xen_store_tr,
.write_ldt_entry = xen_write_ldt_entry,
.write_gdt_entry = xen_write_gdt_entry,
.write_idt_entry = xen_write_idt_entry,
.load_sp0 = xen_load_sp0,
.set_iopl_mask = xen_set_iopl_mask,
.io_delay = xen_io_delay,
/* Xen takes care of %gs when switching to usermode for us */
.swapgs = paravirt_nop,
.start_context_switch = paravirt_start_context_switch,
.end_context_switch = xen_end_context_switch,
};
static void xen_restart(char *msg)
{
xen_reboot(SHUTDOWN_reboot);
}
static void xen_machine_halt(void)
{
xen_reboot(SHUTDOWN_poweroff);
}
static void xen_machine_power_off(void)
{
if (pm_power_off)
pm_power_off();
xen_reboot(SHUTDOWN_poweroff);
}
static void xen_crash_shutdown(struct pt_regs *regs)
{
xen_reboot(SHUTDOWN_crash);
}
static const struct machine_ops xen_machine_ops __initconst = {
.restart = xen_restart,
.halt = xen_machine_halt,
.power_off = xen_machine_power_off,
.shutdown = xen_machine_halt,
.crash_shutdown = xen_crash_shutdown,
.emergency_restart = xen_emergency_restart,
};
static unsigned char xen_get_nmi_reason(void)
{
unsigned char reason = 0;
/* Construct a value which looks like it came from port 0x61. */
if (test_bit(_XEN_NMIREASON_io_error,
&HYPERVISOR_shared_info->arch.nmi_reason))
reason |= NMI_REASON_IOCHK;
if (test_bit(_XEN_NMIREASON_pci_serr,
&HYPERVISOR_shared_info->arch.nmi_reason))
reason |= NMI_REASON_SERR;
return reason;
}
static void __init xen_boot_params_init_edd(void)
{
#if IS_ENABLED(CONFIG_EDD)
struct xen_platform_op op;
struct edd_info *edd_info;
u32 *mbr_signature;
unsigned nr;
int ret;
edd_info = boot_params.eddbuf;
mbr_signature = boot_params.edd_mbr_sig_buffer;
op.cmd = XENPF_firmware_info;
op.u.firmware_info.type = XEN_FW_DISK_INFO;
for (nr = 0; nr < EDDMAXNR; nr++) {
struct edd_info *info = edd_info + nr;
op.u.firmware_info.index = nr;
info->params.length = sizeof(info->params);
set_xen_guest_handle(op.u.firmware_info.u.disk_info.edd_params,
&info->params);
ret = HYPERVISOR_platform_op(&op);
if (ret)
break;
#define C(x) info->x = op.u.firmware_info.u.disk_info.x
C(device);
C(version);
C(interface_support);
C(legacy_max_cylinder);
C(legacy_max_head);
C(legacy_sectors_per_track);
#undef C
}
boot_params.eddbuf_entries = nr;
op.u.firmware_info.type = XEN_FW_DISK_MBR_SIGNATURE;
for (nr = 0; nr < EDD_MBR_SIG_MAX; nr++) {
op.u.firmware_info.index = nr;
ret = HYPERVISOR_platform_op(&op);
if (ret)
break;
mbr_signature[nr] = op.u.firmware_info.u.disk_mbr_signature.mbr_signature;
}
boot_params.edd_mbr_sig_buf_entries = nr;
#endif
}
/*
* Set up the GDT and segment registers for -fstack-protector. Until
* we do this, we have to be careful not to call any stack-protected
* function, which is most of the kernel.
*/
static void __init xen_setup_gdt(int cpu)
{
pv_ops.cpu.write_gdt_entry = xen_write_gdt_entry_boot;
pv_ops.cpu.load_gdt = xen_load_gdt_boot;
setup_stack_canary_segment(cpu);
switch_to_new_gdt(cpu);
pv_ops.cpu.write_gdt_entry = xen_write_gdt_entry;
pv_ops.cpu.load_gdt = xen_load_gdt;
}
static void __init xen_dom0_set_legacy_features(void)
{
x86_platform.legacy.rtc = 1;
}
static void __init xen_domu_set_legacy_features(void)
{
x86_platform.legacy.rtc = 0;
}
/* First C function to be called on Xen boot */
asmlinkage __visible void __init xen_start_kernel(void)
{
struct physdev_set_iopl set_iopl;
unsigned long initrd_start = 0;
int rc;
if (!xen_start_info)
return;
xen_domain_type = XEN_PV_DOMAIN;
xen_start_flags = xen_start_info->flags;
xen_setup_features();
/* Install Xen paravirt ops */
pv_info = xen_info;
pv_ops.init.patch = paravirt_patch_default;
pv_ops.cpu = xen_cpu_ops;
xen_init_irq_ops();
/*
* Setup xen_vcpu early because it is needed for
* local_irq_disable(), irqs_disabled(), e.g. in printk().
*
* Don't do the full vcpu_info placement stuff until we have
* the cpu_possible_mask and a non-dummy shared_info.
*/
xen_vcpu_info_reset(0);
x86_platform.get_nmi_reason = xen_get_nmi_reason;
x86_init.resources.memory_setup = xen_memory_setup;
x86_init.irqs.intr_mode_select = x86_init_noop;
x86_init.irqs.intr_mode_init = x86_init_noop;
x86_init.oem.arch_setup = xen_arch_setup;
x86_init.oem.banner = xen_banner;
x86_init.hyper.init_platform = xen_pv_init_platform;
x86_init.hyper.guest_late_init = xen_pv_guest_late_init;
/*
* Set up some pagetable state before starting to set any ptes.
*/
xen_setup_machphys_mapping();
xen_init_mmu_ops();
/* Prevent unwanted bits from being set in PTEs. */
__supported_pte_mask &= ~_PAGE_GLOBAL;
__default_kernel_pte_mask &= ~_PAGE_GLOBAL;
/*
* Prevent page tables from being allocated in highmem, even
* if CONFIG_HIGHPTE is enabled.
*/
__userpte_alloc_gfp &= ~__GFP_HIGHMEM;
/* Get mfn list */
xen_build_dynamic_phys_to_machine();
/*
* Set up kernel GDT and segment registers, mainly so that
* -fstack-protector code can be executed.
*/
xen_setup_gdt(0);
/* Work out if we support NX */
get_cpu_cap(&boot_cpu_data);
x86_configure_nx();
/* Determine virtual and physical address sizes */
get_cpu_address_sizes(&boot_cpu_data);
/* Let's presume PV guests always boot on vCPU with id 0. */
per_cpu(xen_vcpu_id, 0) = 0;
idt_setup_early_handler();
xen_init_capabilities();
#ifdef CONFIG_X86_LOCAL_APIC
/*
* set up the basic apic ops.
*/
xen_init_apic();
#endif
if (xen_feature(XENFEAT_mmu_pt_update_preserve_ad)) {
pv_ops.mmu.ptep_modify_prot_start =
xen_ptep_modify_prot_start;
pv_ops.mmu.ptep_modify_prot_commit =
xen_ptep_modify_prot_commit;
}
machine_ops = xen_machine_ops;
/*
* The only reliable way to retain the initial address of the
* percpu gdt_page is to remember it here, so we can go and
* mark it RW later, when the initial percpu area is freed.
*/
xen_initial_gdt = &per_cpu(gdt_page, 0);
xen_smp_init();
#ifdef CONFIG_ACPI_NUMA
/*
* The pages we from Xen are not related to machine pages, so
* any NUMA information the kernel tries to get from ACPI will
* be meaningless. Prevent it from trying.
*/
acpi_numa = -1;
#endif
WARN_ON(xen_cpuhp_setup(xen_cpu_up_prepare_pv, xen_cpu_dead_pv));
local_irq_disable();
early_boot_irqs_disabled = true;
xen_raw_console_write("mapping kernel into physical memory\n");
xen_setup_kernel_pagetable((pgd_t *)xen_start_info->pt_base,
xen_start_info->nr_pages);
xen_reserve_special_pages();
/* keep using Xen gdt for now; no urgent need to change it */
#ifdef CONFIG_X86_32
pv_info.kernel_rpl = 1;
if (xen_feature(XENFEAT_supervisor_mode_kernel))
pv_info.kernel_rpl = 0;
#else
pv_info.kernel_rpl = 0;
#endif
/* set the limit of our address space */
xen_reserve_top();
/*
* We used to do this in xen_arch_setup, but that is too late
* on AMD were early_cpu_init (run before ->arch_setup()) calls
* early_amd_init which pokes 0xcf8 port.
*/
set_iopl.iopl = 1;
rc = HYPERVISOR_physdev_op(PHYSDEVOP_set_iopl, &set_iopl);
if (rc != 0)
xen_raw_printk("physdev_op failed %d\n", rc);
#ifdef CONFIG_X86_32
/* set up basic CPUID stuff */
cpu_detect(&new_cpu_data);
set_cpu_cap(&new_cpu_data, X86_FEATURE_FPU);
new_cpu_data.x86_capability[CPUID_1_EDX] = cpuid_edx(1);
#endif
if (xen_start_info->mod_start) {
if (xen_start_info->flags & SIF_MOD_START_PFN)
initrd_start = PFN_PHYS(xen_start_info->mod_start);
else
initrd_start = __pa(xen_start_info->mod_start);
}
/* Poke various useful things into boot_params */
boot_params.hdr.type_of_loader = (9 << 4) | 0;
boot_params.hdr.ramdisk_image = initrd_start;
boot_params.hdr.ramdisk_size = xen_start_info->mod_len;
boot_params.hdr.cmd_line_ptr = __pa(xen_start_info->cmd_line);
boot_params.hdr.hardware_subarch = X86_SUBARCH_XEN;
if (!xen_initial_domain()) {
add_preferred_console("xenboot", 0, NULL);
if (pci_xen)
x86_init.pci.arch_init = pci_xen_init;
x86_platform.set_legacy_features =
xen_domu_set_legacy_features;
} else {
const struct dom0_vga_console_info *info =
(void *)((char *)xen_start_info +
xen_start_info->console.dom0.info_off);
struct xen_platform_op op = {
.cmd = XENPF_firmware_info,
.interface_version = XENPF_INTERFACE_VERSION,
.u.firmware_info.type = XEN_FW_KBD_SHIFT_FLAGS,
};
x86_platform.set_legacy_features =
xen_dom0_set_legacy_features;
xen_init_vga(info, xen_start_info->console.dom0.info_size);
xen_start_info->console.domU.mfn = 0;
xen_start_info->console.domU.evtchn = 0;
if (HYPERVISOR_platform_op(&op) == 0)
boot_params.kbd_status = op.u.firmware_info.u.kbd_shift_flags;
/* Make sure ACS will be enabled */
pci_request_acs();
xen_acpi_sleep_register();
/* Avoid searching for BIOS MP tables */
x86_init.mpparse.find_smp_config = x86_init_noop;
x86_init.mpparse.get_smp_config = x86_init_uint_noop;
xen_boot_params_init_edd();
#ifdef CONFIG_ACPI
/*
* Disable selecting "Firmware First mode" for correctable
* memory errors, as this is the duty of the hypervisor to
* decide.
*/
acpi_disable_cmcff = 1;
#endif
}
if (!boot_params.screen_info.orig_video_isVGA)
add_preferred_console("tty", 0, NULL);
add_preferred_console("hvc", 0, NULL);
if (boot_params.screen_info.orig_video_isVGA)
add_preferred_console("tty", 0, NULL);
#ifdef CONFIG_PCI
/* PCI BIOS service won't work from a PV guest. */
pci_probe &= ~PCI_PROBE_BIOS;
#endif
xen_raw_console_write("about to get started...\n");
/* We need this for printk timestamps */
xen_setup_runstate_info(0);
xen_efi_init(&boot_params);
/* Start the world */
#ifdef CONFIG_X86_32
i386_start_kernel();
#else
cr4_init_shadow(); /* 32b kernel does this in i386_start_kernel() */
x86_64_start_reservations((char *)__pa_symbol(&boot_params));
#endif
}
static int xen_cpu_up_prepare_pv(unsigned int cpu)
{
int rc;
if (per_cpu(xen_vcpu, cpu) == NULL)
return -ENODEV;
xen_setup_timer(cpu);
rc = xen_smp_intr_init(cpu);
if (rc) {
WARN(1, "xen_smp_intr_init() for CPU %d failed: %d\n",
cpu, rc);
return rc;
}
rc = xen_smp_intr_init_pv(cpu);
if (rc) {
WARN(1, "xen_smp_intr_init_pv() for CPU %d failed: %d\n",
cpu, rc);
return rc;
}
return 0;
}
static int xen_cpu_dead_pv(unsigned int cpu)
{
xen_smp_intr_free(cpu);
xen_smp_intr_free_pv(cpu);
xen_teardown_timer(cpu);
return 0;
}
static uint32_t __init xen_platform_pv(void)
{
if (xen_pv_domain())
return xen_cpuid_base();
return 0;
}
const __initconst struct hypervisor_x86 x86_hyper_xen_pv = {
.name = "Xen PV",
.detect = xen_platform_pv,
.type = X86_HYPER_XEN_PV,
.runtime.pin_vcpu = xen_pin_vcpu,
.ignore_nopv = true,
};
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