summaryrefslogtreecommitdiffstats
path: root/arch/x86/kernel/cpu/common.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/kernel/cpu/common.c')
-rw-r--r--arch/x86/kernel/cpu/common.c2419
1 files changed, 2419 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
new file mode 100644
index 0000000000..4e5ffc8b0e
--- /dev/null
+++ b/arch/x86/kernel/cpu/common.c
@@ -0,0 +1,2419 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* cpu_feature_enabled() cannot be used this early */
+#define USE_EARLY_PGTABLE_L5
+
+#include <linux/memblock.h>
+#include <linux/linkage.h>
+#include <linux/bitops.h>
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/percpu.h>
+#include <linux/string.h>
+#include <linux/ctype.h>
+#include <linux/delay.h>
+#include <linux/sched/mm.h>
+#include <linux/sched/clock.h>
+#include <linux/sched/task.h>
+#include <linux/sched/smt.h>
+#include <linux/init.h>
+#include <linux/kprobes.h>
+#include <linux/kgdb.h>
+#include <linux/mem_encrypt.h>
+#include <linux/smp.h>
+#include <linux/cpu.h>
+#include <linux/io.h>
+#include <linux/syscore_ops.h>
+#include <linux/pgtable.h>
+#include <linux/stackprotector.h>
+#include <linux/utsname.h>
+
+#include <asm/alternative.h>
+#include <asm/cmdline.h>
+#include <asm/perf_event.h>
+#include <asm/mmu_context.h>
+#include <asm/doublefault.h>
+#include <asm/archrandom.h>
+#include <asm/hypervisor.h>
+#include <asm/processor.h>
+#include <asm/tlbflush.h>
+#include <asm/debugreg.h>
+#include <asm/sections.h>
+#include <asm/vsyscall.h>
+#include <linux/topology.h>
+#include <linux/cpumask.h>
+#include <linux/atomic.h>
+#include <asm/proto.h>
+#include <asm/setup.h>
+#include <asm/apic.h>
+#include <asm/desc.h>
+#include <asm/fpu/api.h>
+#include <asm/mtrr.h>
+#include <asm/hwcap2.h>
+#include <linux/numa.h>
+#include <asm/numa.h>
+#include <asm/asm.h>
+#include <asm/bugs.h>
+#include <asm/cpu.h>
+#include <asm/mce.h>
+#include <asm/msr.h>
+#include <asm/cacheinfo.h>
+#include <asm/memtype.h>
+#include <asm/microcode.h>
+#include <asm/intel-family.h>
+#include <asm/cpu_device_id.h>
+#include <asm/uv/uv.h>
+#include <asm/set_memory.h>
+#include <asm/traps.h>
+#include <asm/sev.h>
+
+#include "cpu.h"
+
+u32 elf_hwcap2 __read_mostly;
+
+/* Number of siblings per CPU package */
+int smp_num_siblings = 1;
+EXPORT_SYMBOL(smp_num_siblings);
+
+/* Last level cache ID of each logical CPU */
+DEFINE_PER_CPU_READ_MOSTLY(u16, cpu_llc_id) = BAD_APICID;
+
+u16 get_llc_id(unsigned int cpu)
+{
+ return per_cpu(cpu_llc_id, cpu);
+}
+EXPORT_SYMBOL_GPL(get_llc_id);
+
+/* L2 cache ID of each logical CPU */
+DEFINE_PER_CPU_READ_MOSTLY(u16, cpu_l2c_id) = BAD_APICID;
+
+static struct ppin_info {
+ int feature;
+ int msr_ppin_ctl;
+ int msr_ppin;
+} ppin_info[] = {
+ [X86_VENDOR_INTEL] = {
+ .feature = X86_FEATURE_INTEL_PPIN,
+ .msr_ppin_ctl = MSR_PPIN_CTL,
+ .msr_ppin = MSR_PPIN
+ },
+ [X86_VENDOR_AMD] = {
+ .feature = X86_FEATURE_AMD_PPIN,
+ .msr_ppin_ctl = MSR_AMD_PPIN_CTL,
+ .msr_ppin = MSR_AMD_PPIN
+ },
+};
+
+static const struct x86_cpu_id ppin_cpuids[] = {
+ X86_MATCH_FEATURE(X86_FEATURE_AMD_PPIN, &ppin_info[X86_VENDOR_AMD]),
+ X86_MATCH_FEATURE(X86_FEATURE_INTEL_PPIN, &ppin_info[X86_VENDOR_INTEL]),
+
+ /* Legacy models without CPUID enumeration */
+ X86_MATCH_INTEL_FAM6_MODEL(IVYBRIDGE_X, &ppin_info[X86_VENDOR_INTEL]),
+ X86_MATCH_INTEL_FAM6_MODEL(HASWELL_X, &ppin_info[X86_VENDOR_INTEL]),
+ X86_MATCH_INTEL_FAM6_MODEL(BROADWELL_D, &ppin_info[X86_VENDOR_INTEL]),
+ X86_MATCH_INTEL_FAM6_MODEL(BROADWELL_X, &ppin_info[X86_VENDOR_INTEL]),
+ X86_MATCH_INTEL_FAM6_MODEL(SKYLAKE_X, &ppin_info[X86_VENDOR_INTEL]),
+ X86_MATCH_INTEL_FAM6_MODEL(ICELAKE_X, &ppin_info[X86_VENDOR_INTEL]),
+ X86_MATCH_INTEL_FAM6_MODEL(ICELAKE_D, &ppin_info[X86_VENDOR_INTEL]),
+ X86_MATCH_INTEL_FAM6_MODEL(SAPPHIRERAPIDS_X, &ppin_info[X86_VENDOR_INTEL]),
+ X86_MATCH_INTEL_FAM6_MODEL(EMERALDRAPIDS_X, &ppin_info[X86_VENDOR_INTEL]),
+ X86_MATCH_INTEL_FAM6_MODEL(XEON_PHI_KNL, &ppin_info[X86_VENDOR_INTEL]),
+ X86_MATCH_INTEL_FAM6_MODEL(XEON_PHI_KNM, &ppin_info[X86_VENDOR_INTEL]),
+
+ {}
+};
+
+static void ppin_init(struct cpuinfo_x86 *c)
+{
+ const struct x86_cpu_id *id;
+ unsigned long long val;
+ struct ppin_info *info;
+
+ id = x86_match_cpu(ppin_cpuids);
+ if (!id)
+ return;
+
+ /*
+ * Testing the presence of the MSR is not enough. Need to check
+ * that the PPIN_CTL allows reading of the PPIN.
+ */
+ info = (struct ppin_info *)id->driver_data;
+
+ if (rdmsrl_safe(info->msr_ppin_ctl, &val))
+ goto clear_ppin;
+
+ if ((val & 3UL) == 1UL) {
+ /* PPIN locked in disabled mode */
+ goto clear_ppin;
+ }
+
+ /* If PPIN is disabled, try to enable */
+ if (!(val & 2UL)) {
+ wrmsrl_safe(info->msr_ppin_ctl, val | 2UL);
+ rdmsrl_safe(info->msr_ppin_ctl, &val);
+ }
+
+ /* Is the enable bit set? */
+ if (val & 2UL) {
+ c->ppin = __rdmsr(info->msr_ppin);
+ set_cpu_cap(c, info->feature);
+ return;
+ }
+
+clear_ppin:
+ clear_cpu_cap(c, info->feature);
+}
+
+static void default_init(struct cpuinfo_x86 *c)
+{
+#ifdef CONFIG_X86_64
+ cpu_detect_cache_sizes(c);
+#else
+ /* Not much we can do here... */
+ /* Check if at least it has cpuid */
+ if (c->cpuid_level == -1) {
+ /* No cpuid. It must be an ancient CPU */
+ if (c->x86 == 4)
+ strcpy(c->x86_model_id, "486");
+ else if (c->x86 == 3)
+ strcpy(c->x86_model_id, "386");
+ }
+#endif
+}
+
+static const struct cpu_dev default_cpu = {
+ .c_init = default_init,
+ .c_vendor = "Unknown",
+ .c_x86_vendor = X86_VENDOR_UNKNOWN,
+};
+
+static const struct cpu_dev *this_cpu = &default_cpu;
+
+DEFINE_PER_CPU_PAGE_ALIGNED(struct gdt_page, gdt_page) = { .gdt = {
+#ifdef CONFIG_X86_64
+ /*
+ * We need valid kernel segments for data and code in long mode too
+ * IRET will check the segment types kkeil 2000/10/28
+ * Also sysret mandates a special GDT layout
+ *
+ * TLS descriptors are currently at a different place compared to i386.
+ * Hopefully nobody expects them at a fixed place (Wine?)
+ */
+ [GDT_ENTRY_KERNEL32_CS] = GDT_ENTRY_INIT(0xc09b, 0, 0xfffff),
+ [GDT_ENTRY_KERNEL_CS] = GDT_ENTRY_INIT(0xa09b, 0, 0xfffff),
+ [GDT_ENTRY_KERNEL_DS] = GDT_ENTRY_INIT(0xc093, 0, 0xfffff),
+ [GDT_ENTRY_DEFAULT_USER32_CS] = GDT_ENTRY_INIT(0xc0fb, 0, 0xfffff),
+ [GDT_ENTRY_DEFAULT_USER_DS] = GDT_ENTRY_INIT(0xc0f3, 0, 0xfffff),
+ [GDT_ENTRY_DEFAULT_USER_CS] = GDT_ENTRY_INIT(0xa0fb, 0, 0xfffff),
+#else
+ [GDT_ENTRY_KERNEL_CS] = GDT_ENTRY_INIT(0xc09a, 0, 0xfffff),
+ [GDT_ENTRY_KERNEL_DS] = GDT_ENTRY_INIT(0xc092, 0, 0xfffff),
+ [GDT_ENTRY_DEFAULT_USER_CS] = GDT_ENTRY_INIT(0xc0fa, 0, 0xfffff),
+ [GDT_ENTRY_DEFAULT_USER_DS] = GDT_ENTRY_INIT(0xc0f2, 0, 0xfffff),
+ /*
+ * Segments used for calling PnP BIOS have byte granularity.
+ * They code segments and data segments have fixed 64k limits,
+ * the transfer segment sizes are set at run time.
+ */
+ /* 32-bit code */
+ [GDT_ENTRY_PNPBIOS_CS32] = GDT_ENTRY_INIT(0x409a, 0, 0xffff),
+ /* 16-bit code */
+ [GDT_ENTRY_PNPBIOS_CS16] = GDT_ENTRY_INIT(0x009a, 0, 0xffff),
+ /* 16-bit data */
+ [GDT_ENTRY_PNPBIOS_DS] = GDT_ENTRY_INIT(0x0092, 0, 0xffff),
+ /* 16-bit data */
+ [GDT_ENTRY_PNPBIOS_TS1] = GDT_ENTRY_INIT(0x0092, 0, 0),
+ /* 16-bit data */
+ [GDT_ENTRY_PNPBIOS_TS2] = GDT_ENTRY_INIT(0x0092, 0, 0),
+ /*
+ * The APM segments have byte granularity and their bases
+ * are set at run time. All have 64k limits.
+ */
+ /* 32-bit code */
+ [GDT_ENTRY_APMBIOS_BASE] = GDT_ENTRY_INIT(0x409a, 0, 0xffff),
+ /* 16-bit code */
+ [GDT_ENTRY_APMBIOS_BASE+1] = GDT_ENTRY_INIT(0x009a, 0, 0xffff),
+ /* data */
+ [GDT_ENTRY_APMBIOS_BASE+2] = GDT_ENTRY_INIT(0x4092, 0, 0xffff),
+
+ [GDT_ENTRY_ESPFIX_SS] = GDT_ENTRY_INIT(0xc092, 0, 0xfffff),
+ [GDT_ENTRY_PERCPU] = GDT_ENTRY_INIT(0xc092, 0, 0xfffff),
+#endif
+} };
+EXPORT_PER_CPU_SYMBOL_GPL(gdt_page);
+
+#ifdef CONFIG_X86_64
+static int __init x86_nopcid_setup(char *s)
+{
+ /* nopcid doesn't accept parameters */
+ if (s)
+ return -EINVAL;
+
+ /* do not emit a message if the feature is not present */
+ if (!boot_cpu_has(X86_FEATURE_PCID))
+ return 0;
+
+ setup_clear_cpu_cap(X86_FEATURE_PCID);
+ pr_info("nopcid: PCID feature disabled\n");
+ return 0;
+}
+early_param("nopcid", x86_nopcid_setup);
+#endif
+
+static int __init x86_noinvpcid_setup(char *s)
+{
+ /* noinvpcid doesn't accept parameters */
+ if (s)
+ return -EINVAL;
+
+ /* do not emit a message if the feature is not present */
+ if (!boot_cpu_has(X86_FEATURE_INVPCID))
+ return 0;
+
+ setup_clear_cpu_cap(X86_FEATURE_INVPCID);
+ pr_info("noinvpcid: INVPCID feature disabled\n");
+ return 0;
+}
+early_param("noinvpcid", x86_noinvpcid_setup);
+
+#ifdef CONFIG_X86_32
+static int cachesize_override = -1;
+static int disable_x86_serial_nr = 1;
+
+static int __init cachesize_setup(char *str)
+{
+ get_option(&str, &cachesize_override);
+ return 1;
+}
+__setup("cachesize=", cachesize_setup);
+
+/* Standard macro to see if a specific flag is changeable */
+static inline int flag_is_changeable_p(u32 flag)
+{
+ u32 f1, f2;
+
+ /*
+ * Cyrix and IDT cpus allow disabling of CPUID
+ * so the code below may return different results
+ * when it is executed before and after enabling
+ * the CPUID. Add "volatile" to not allow gcc to
+ * optimize the subsequent calls to this function.
+ */
+ asm volatile ("pushfl \n\t"
+ "pushfl \n\t"
+ "popl %0 \n\t"
+ "movl %0, %1 \n\t"
+ "xorl %2, %0 \n\t"
+ "pushl %0 \n\t"
+ "popfl \n\t"
+ "pushfl \n\t"
+ "popl %0 \n\t"
+ "popfl \n\t"
+
+ : "=&r" (f1), "=&r" (f2)
+ : "ir" (flag));
+
+ return ((f1^f2) & flag) != 0;
+}
+
+/* Probe for the CPUID instruction */
+int have_cpuid_p(void)
+{
+ return flag_is_changeable_p(X86_EFLAGS_ID);
+}
+
+static void squash_the_stupid_serial_number(struct cpuinfo_x86 *c)
+{
+ unsigned long lo, hi;
+
+ if (!cpu_has(c, X86_FEATURE_PN) || !disable_x86_serial_nr)
+ return;
+
+ /* Disable processor serial number: */
+
+ rdmsr(MSR_IA32_BBL_CR_CTL, lo, hi);
+ lo |= 0x200000;
+ wrmsr(MSR_IA32_BBL_CR_CTL, lo, hi);
+
+ pr_notice("CPU serial number disabled.\n");
+ clear_cpu_cap(c, X86_FEATURE_PN);
+
+ /* Disabling the serial number may affect the cpuid level */
+ c->cpuid_level = cpuid_eax(0);
+}
+
+static int __init x86_serial_nr_setup(char *s)
+{
+ disable_x86_serial_nr = 0;
+ return 1;
+}
+__setup("serialnumber", x86_serial_nr_setup);
+#else
+static inline int flag_is_changeable_p(u32 flag)
+{
+ return 1;
+}
+static inline void squash_the_stupid_serial_number(struct cpuinfo_x86 *c)
+{
+}
+#endif
+
+static __always_inline void setup_smep(struct cpuinfo_x86 *c)
+{
+ if (cpu_has(c, X86_FEATURE_SMEP))
+ cr4_set_bits(X86_CR4_SMEP);
+}
+
+static __always_inline void setup_smap(struct cpuinfo_x86 *c)
+{
+ unsigned long eflags = native_save_fl();
+
+ /* This should have been cleared long ago */
+ BUG_ON(eflags & X86_EFLAGS_AC);
+
+ if (cpu_has(c, X86_FEATURE_SMAP))
+ cr4_set_bits(X86_CR4_SMAP);
+}
+
+static __always_inline void setup_umip(struct cpuinfo_x86 *c)
+{
+ /* Check the boot processor, plus build option for UMIP. */
+ if (!cpu_feature_enabled(X86_FEATURE_UMIP))
+ goto out;
+
+ /* Check the current processor's cpuid bits. */
+ if (!cpu_has(c, X86_FEATURE_UMIP))
+ goto out;
+
+ cr4_set_bits(X86_CR4_UMIP);
+
+ pr_info_once("x86/cpu: User Mode Instruction Prevention (UMIP) activated\n");
+
+ return;
+
+out:
+ /*
+ * Make sure UMIP is disabled in case it was enabled in a
+ * previous boot (e.g., via kexec).
+ */
+ cr4_clear_bits(X86_CR4_UMIP);
+}
+
+/* These bits should not change their value after CPU init is finished. */
+static const unsigned long cr4_pinned_mask =
+ X86_CR4_SMEP | X86_CR4_SMAP | X86_CR4_UMIP |
+ X86_CR4_FSGSBASE | X86_CR4_CET;
+static DEFINE_STATIC_KEY_FALSE_RO(cr_pinning);
+static unsigned long cr4_pinned_bits __ro_after_init;
+
+void native_write_cr0(unsigned long val)
+{
+ unsigned long bits_missing = 0;
+
+set_register:
+ asm volatile("mov %0,%%cr0": "+r" (val) : : "memory");
+
+ if (static_branch_likely(&cr_pinning)) {
+ if (unlikely((val & X86_CR0_WP) != X86_CR0_WP)) {
+ bits_missing = X86_CR0_WP;
+ val |= bits_missing;
+ goto set_register;
+ }
+ /* Warn after we've set the missing bits. */
+ WARN_ONCE(bits_missing, "CR0 WP bit went missing!?\n");
+ }
+}
+EXPORT_SYMBOL(native_write_cr0);
+
+void __no_profile native_write_cr4(unsigned long val)
+{
+ unsigned long bits_changed = 0;
+
+set_register:
+ asm volatile("mov %0,%%cr4": "+r" (val) : : "memory");
+
+ if (static_branch_likely(&cr_pinning)) {
+ if (unlikely((val & cr4_pinned_mask) != cr4_pinned_bits)) {
+ bits_changed = (val & cr4_pinned_mask) ^ cr4_pinned_bits;
+ val = (val & ~cr4_pinned_mask) | cr4_pinned_bits;
+ goto set_register;
+ }
+ /* Warn after we've corrected the changed bits. */
+ WARN_ONCE(bits_changed, "pinned CR4 bits changed: 0x%lx!?\n",
+ bits_changed);
+ }
+}
+#if IS_MODULE(CONFIG_LKDTM)
+EXPORT_SYMBOL_GPL(native_write_cr4);
+#endif
+
+void cr4_update_irqsoff(unsigned long set, unsigned long clear)
+{
+ unsigned long newval, cr4 = this_cpu_read(cpu_tlbstate.cr4);
+
+ lockdep_assert_irqs_disabled();
+
+ newval = (cr4 & ~clear) | set;
+ if (newval != cr4) {
+ this_cpu_write(cpu_tlbstate.cr4, newval);
+ __write_cr4(newval);
+ }
+}
+EXPORT_SYMBOL(cr4_update_irqsoff);
+
+/* Read the CR4 shadow. */
+unsigned long cr4_read_shadow(void)
+{
+ return this_cpu_read(cpu_tlbstate.cr4);
+}
+EXPORT_SYMBOL_GPL(cr4_read_shadow);
+
+void cr4_init(void)
+{
+ unsigned long cr4 = __read_cr4();
+
+ if (boot_cpu_has(X86_FEATURE_PCID))
+ cr4 |= X86_CR4_PCIDE;
+ if (static_branch_likely(&cr_pinning))
+ cr4 = (cr4 & ~cr4_pinned_mask) | cr4_pinned_bits;
+
+ __write_cr4(cr4);
+
+ /* Initialize cr4 shadow for this CPU. */
+ this_cpu_write(cpu_tlbstate.cr4, cr4);
+}
+
+/*
+ * Once CPU feature detection is finished (and boot params have been
+ * parsed), record any of the sensitive CR bits that are set, and
+ * enable CR pinning.
+ */
+static void __init setup_cr_pinning(void)
+{
+ cr4_pinned_bits = this_cpu_read(cpu_tlbstate.cr4) & cr4_pinned_mask;
+ static_key_enable(&cr_pinning.key);
+}
+
+static __init int x86_nofsgsbase_setup(char *arg)
+{
+ /* Require an exact match without trailing characters. */
+ if (strlen(arg))
+ return 0;
+
+ /* Do not emit a message if the feature is not present. */
+ if (!boot_cpu_has(X86_FEATURE_FSGSBASE))
+ return 1;
+
+ setup_clear_cpu_cap(X86_FEATURE_FSGSBASE);
+ pr_info("FSGSBASE disabled via kernel command line\n");
+ return 1;
+}
+__setup("nofsgsbase", x86_nofsgsbase_setup);
+
+/*
+ * Protection Keys are not available in 32-bit mode.
+ */
+static bool pku_disabled;
+
+static __always_inline void setup_pku(struct cpuinfo_x86 *c)
+{
+ if (c == &boot_cpu_data) {
+ if (pku_disabled || !cpu_feature_enabled(X86_FEATURE_PKU))
+ return;
+ /*
+ * Setting CR4.PKE will cause the X86_FEATURE_OSPKE cpuid
+ * bit to be set. Enforce it.
+ */
+ setup_force_cpu_cap(X86_FEATURE_OSPKE);
+
+ } else if (!cpu_feature_enabled(X86_FEATURE_OSPKE)) {
+ return;
+ }
+
+ cr4_set_bits(X86_CR4_PKE);
+ /* Load the default PKRU value */
+ pkru_write_default();
+}
+
+#ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS
+static __init int setup_disable_pku(char *arg)
+{
+ /*
+ * Do not clear the X86_FEATURE_PKU bit. All of the
+ * runtime checks are against OSPKE so clearing the
+ * bit does nothing.
+ *
+ * This way, we will see "pku" in cpuinfo, but not
+ * "ospke", which is exactly what we want. It shows
+ * that the CPU has PKU, but the OS has not enabled it.
+ * This happens to be exactly how a system would look
+ * if we disabled the config option.
+ */
+ pr_info("x86: 'nopku' specified, disabling Memory Protection Keys\n");
+ pku_disabled = true;
+ return 1;
+}
+__setup("nopku", setup_disable_pku);
+#endif
+
+#ifdef CONFIG_X86_KERNEL_IBT
+
+__noendbr u64 ibt_save(bool disable)
+{
+ u64 msr = 0;
+
+ if (cpu_feature_enabled(X86_FEATURE_IBT)) {
+ rdmsrl(MSR_IA32_S_CET, msr);
+ if (disable)
+ wrmsrl(MSR_IA32_S_CET, msr & ~CET_ENDBR_EN);
+ }
+
+ return msr;
+}
+
+__noendbr void ibt_restore(u64 save)
+{
+ u64 msr;
+
+ if (cpu_feature_enabled(X86_FEATURE_IBT)) {
+ rdmsrl(MSR_IA32_S_CET, msr);
+ msr &= ~CET_ENDBR_EN;
+ msr |= (save & CET_ENDBR_EN);
+ wrmsrl(MSR_IA32_S_CET, msr);
+ }
+}
+
+#endif
+
+static __always_inline void setup_cet(struct cpuinfo_x86 *c)
+{
+ bool user_shstk, kernel_ibt;
+
+ if (!IS_ENABLED(CONFIG_X86_CET))
+ return;
+
+ kernel_ibt = HAS_KERNEL_IBT && cpu_feature_enabled(X86_FEATURE_IBT);
+ user_shstk = cpu_feature_enabled(X86_FEATURE_SHSTK) &&
+ IS_ENABLED(CONFIG_X86_USER_SHADOW_STACK);
+
+ if (!kernel_ibt && !user_shstk)
+ return;
+
+ if (user_shstk)
+ set_cpu_cap(c, X86_FEATURE_USER_SHSTK);
+
+ if (kernel_ibt)
+ wrmsrl(MSR_IA32_S_CET, CET_ENDBR_EN);
+ else
+ wrmsrl(MSR_IA32_S_CET, 0);
+
+ cr4_set_bits(X86_CR4_CET);
+
+ if (kernel_ibt && ibt_selftest()) {
+ pr_err("IBT selftest: Failed!\n");
+ wrmsrl(MSR_IA32_S_CET, 0);
+ setup_clear_cpu_cap(X86_FEATURE_IBT);
+ }
+}
+
+__noendbr void cet_disable(void)
+{
+ if (!(cpu_feature_enabled(X86_FEATURE_IBT) ||
+ cpu_feature_enabled(X86_FEATURE_SHSTK)))
+ return;
+
+ wrmsrl(MSR_IA32_S_CET, 0);
+ wrmsrl(MSR_IA32_U_CET, 0);
+}
+
+/*
+ * Some CPU features depend on higher CPUID levels, which may not always
+ * be available due to CPUID level capping or broken virtualization
+ * software. Add those features to this table to auto-disable them.
+ */
+struct cpuid_dependent_feature {
+ u32 feature;
+ u32 level;
+};
+
+static const struct cpuid_dependent_feature
+cpuid_dependent_features[] = {
+ { X86_FEATURE_MWAIT, 0x00000005 },
+ { X86_FEATURE_DCA, 0x00000009 },
+ { X86_FEATURE_XSAVE, 0x0000000d },
+ { 0, 0 }
+};
+
+static void filter_cpuid_features(struct cpuinfo_x86 *c, bool warn)
+{
+ const struct cpuid_dependent_feature *df;
+
+ for (df = cpuid_dependent_features; df->feature; df++) {
+
+ if (!cpu_has(c, df->feature))
+ continue;
+ /*
+ * Note: cpuid_level is set to -1 if unavailable, but
+ * extended_extended_level is set to 0 if unavailable
+ * and the legitimate extended levels are all negative
+ * when signed; hence the weird messing around with
+ * signs here...
+ */
+ if (!((s32)df->level < 0 ?
+ (u32)df->level > (u32)c->extended_cpuid_level :
+ (s32)df->level > (s32)c->cpuid_level))
+ continue;
+
+ clear_cpu_cap(c, df->feature);
+ if (!warn)
+ continue;
+
+ pr_warn("CPU: CPU feature " X86_CAP_FMT " disabled, no CPUID level 0x%x\n",
+ x86_cap_flag(df->feature), df->level);
+ }
+}
+
+/*
+ * Naming convention should be: <Name> [(<Codename>)]
+ * This table only is used unless init_<vendor>() below doesn't set it;
+ * in particular, if CPUID levels 0x80000002..4 are supported, this
+ * isn't used
+ */
+
+/* Look up CPU names by table lookup. */
+static const char *table_lookup_model(struct cpuinfo_x86 *c)
+{
+#ifdef CONFIG_X86_32
+ const struct legacy_cpu_model_info *info;
+
+ if (c->x86_model >= 16)
+ return NULL; /* Range check */
+
+ if (!this_cpu)
+ return NULL;
+
+ info = this_cpu->legacy_models;
+
+ while (info->family) {
+ if (info->family == c->x86)
+ return info->model_names[c->x86_model];
+ info++;
+ }
+#endif
+ return NULL; /* Not found */
+}
+
+/* Aligned to unsigned long to avoid split lock in atomic bitmap ops */
+__u32 cpu_caps_cleared[NCAPINTS + NBUGINTS] __aligned(sizeof(unsigned long));
+__u32 cpu_caps_set[NCAPINTS + NBUGINTS] __aligned(sizeof(unsigned long));
+
+#ifdef CONFIG_X86_32
+/* The 32-bit entry code needs to find cpu_entry_area. */
+DEFINE_PER_CPU(struct cpu_entry_area *, cpu_entry_area);
+#endif
+
+/* Load the original GDT from the per-cpu structure */
+void load_direct_gdt(int cpu)
+{
+ struct desc_ptr gdt_descr;
+
+ gdt_descr.address = (long)get_cpu_gdt_rw(cpu);
+ gdt_descr.size = GDT_SIZE - 1;
+ load_gdt(&gdt_descr);
+}
+EXPORT_SYMBOL_GPL(load_direct_gdt);
+
+/* Load a fixmap remapping of the per-cpu GDT */
+void load_fixmap_gdt(int cpu)
+{
+ struct desc_ptr gdt_descr;
+
+ gdt_descr.address = (long)get_cpu_gdt_ro(cpu);
+ gdt_descr.size = GDT_SIZE - 1;
+ load_gdt(&gdt_descr);
+}
+EXPORT_SYMBOL_GPL(load_fixmap_gdt);
+
+/**
+ * switch_gdt_and_percpu_base - Switch to direct GDT and runtime per CPU base
+ * @cpu: The CPU number for which this is invoked
+ *
+ * Invoked during early boot to switch from early GDT and early per CPU to
+ * the direct GDT and the runtime per CPU area. On 32-bit the percpu base
+ * switch is implicit by loading the direct GDT. On 64bit this requires
+ * to update GSBASE.
+ */
+void __init switch_gdt_and_percpu_base(int cpu)
+{
+ load_direct_gdt(cpu);
+
+#ifdef CONFIG_X86_64
+ /*
+ * No need to load %gs. It is already correct.
+ *
+ * Writing %gs on 64bit would zero GSBASE which would make any per
+ * CPU operation up to the point of the wrmsrl() fault.
+ *
+ * Set GSBASE to the new offset. Until the wrmsrl() happens the
+ * early mapping is still valid. That means the GSBASE update will
+ * lose any prior per CPU data which was not copied over in
+ * setup_per_cpu_areas().
+ *
+ * This works even with stackprotector enabled because the
+ * per CPU stack canary is 0 in both per CPU areas.
+ */
+ wrmsrl(MSR_GS_BASE, cpu_kernelmode_gs_base(cpu));
+#else
+ /*
+ * %fs is already set to __KERNEL_PERCPU, but after switching GDT
+ * it is required to load FS again so that the 'hidden' part is
+ * updated from the new GDT. Up to this point the early per CPU
+ * translation is active. Any content of the early per CPU data
+ * which was not copied over in setup_per_cpu_areas() is lost.
+ */
+ loadsegment(fs, __KERNEL_PERCPU);
+#endif
+}
+
+static const struct cpu_dev *cpu_devs[X86_VENDOR_NUM] = {};
+
+static void get_model_name(struct cpuinfo_x86 *c)
+{
+ unsigned int *v;
+ char *p, *q, *s;
+
+ if (c->extended_cpuid_level < 0x80000004)
+ return;
+
+ v = (unsigned int *)c->x86_model_id;
+ cpuid(0x80000002, &v[0], &v[1], &v[2], &v[3]);
+ cpuid(0x80000003, &v[4], &v[5], &v[6], &v[7]);
+ cpuid(0x80000004, &v[8], &v[9], &v[10], &v[11]);
+ c->x86_model_id[48] = 0;
+
+ /* Trim whitespace */
+ p = q = s = &c->x86_model_id[0];
+
+ while (*p == ' ')
+ p++;
+
+ while (*p) {
+ /* Note the last non-whitespace index */
+ if (!isspace(*p))
+ s = q;
+
+ *q++ = *p++;
+ }
+
+ *(s + 1) = '\0';
+}
+
+void detect_num_cpu_cores(struct cpuinfo_x86 *c)
+{
+ unsigned int eax, ebx, ecx, edx;
+
+ c->x86_max_cores = 1;
+ if (!IS_ENABLED(CONFIG_SMP) || c->cpuid_level < 4)
+ return;
+
+ cpuid_count(4, 0, &eax, &ebx, &ecx, &edx);
+ if (eax & 0x1f)
+ c->x86_max_cores = (eax >> 26) + 1;
+}
+
+void cpu_detect_cache_sizes(struct cpuinfo_x86 *c)
+{
+ unsigned int n, dummy, ebx, ecx, edx, l2size;
+
+ n = c->extended_cpuid_level;
+
+ if (n >= 0x80000005) {
+ cpuid(0x80000005, &dummy, &ebx, &ecx, &edx);
+ c->x86_cache_size = (ecx>>24) + (edx>>24);
+#ifdef CONFIG_X86_64
+ /* On K8 L1 TLB is inclusive, so don't count it */
+ c->x86_tlbsize = 0;
+#endif
+ }
+
+ if (n < 0x80000006) /* Some chips just has a large L1. */
+ return;
+
+ cpuid(0x80000006, &dummy, &ebx, &ecx, &edx);
+ l2size = ecx >> 16;
+
+#ifdef CONFIG_X86_64
+ c->x86_tlbsize += ((ebx >> 16) & 0xfff) + (ebx & 0xfff);
+#else
+ /* do processor-specific cache resizing */
+ if (this_cpu->legacy_cache_size)
+ l2size = this_cpu->legacy_cache_size(c, l2size);
+
+ /* Allow user to override all this if necessary. */
+ if (cachesize_override != -1)
+ l2size = cachesize_override;
+
+ if (l2size == 0)
+ return; /* Again, no L2 cache is possible */
+#endif
+
+ c->x86_cache_size = l2size;
+}
+
+u16 __read_mostly tlb_lli_4k[NR_INFO];
+u16 __read_mostly tlb_lli_2m[NR_INFO];
+u16 __read_mostly tlb_lli_4m[NR_INFO];
+u16 __read_mostly tlb_lld_4k[NR_INFO];
+u16 __read_mostly tlb_lld_2m[NR_INFO];
+u16 __read_mostly tlb_lld_4m[NR_INFO];
+u16 __read_mostly tlb_lld_1g[NR_INFO];
+
+static void cpu_detect_tlb(struct cpuinfo_x86 *c)
+{
+ if (this_cpu->c_detect_tlb)
+ this_cpu->c_detect_tlb(c);
+
+ pr_info("Last level iTLB entries: 4KB %d, 2MB %d, 4MB %d\n",
+ tlb_lli_4k[ENTRIES], tlb_lli_2m[ENTRIES],
+ tlb_lli_4m[ENTRIES]);
+
+ pr_info("Last level dTLB entries: 4KB %d, 2MB %d, 4MB %d, 1GB %d\n",
+ tlb_lld_4k[ENTRIES], tlb_lld_2m[ENTRIES],
+ tlb_lld_4m[ENTRIES], tlb_lld_1g[ENTRIES]);
+}
+
+int detect_ht_early(struct cpuinfo_x86 *c)
+{
+#ifdef CONFIG_SMP
+ u32 eax, ebx, ecx, edx;
+
+ if (!cpu_has(c, X86_FEATURE_HT))
+ return -1;
+
+ if (cpu_has(c, X86_FEATURE_CMP_LEGACY))
+ return -1;
+
+ if (cpu_has(c, X86_FEATURE_XTOPOLOGY))
+ return -1;
+
+ cpuid(1, &eax, &ebx, &ecx, &edx);
+
+ smp_num_siblings = (ebx & 0xff0000) >> 16;
+ if (smp_num_siblings == 1)
+ pr_info_once("CPU0: Hyper-Threading is disabled\n");
+#endif
+ return 0;
+}
+
+void detect_ht(struct cpuinfo_x86 *c)
+{
+#ifdef CONFIG_SMP
+ int index_msb, core_bits;
+
+ if (detect_ht_early(c) < 0)
+ return;
+
+ index_msb = get_count_order(smp_num_siblings);
+ c->phys_proc_id = apic->phys_pkg_id(c->initial_apicid, index_msb);
+
+ smp_num_siblings = smp_num_siblings / c->x86_max_cores;
+
+ index_msb = get_count_order(smp_num_siblings);
+
+ core_bits = get_count_order(c->x86_max_cores);
+
+ c->cpu_core_id = apic->phys_pkg_id(c->initial_apicid, index_msb) &
+ ((1 << core_bits) - 1);
+#endif
+}
+
+static void get_cpu_vendor(struct cpuinfo_x86 *c)
+{
+ char *v = c->x86_vendor_id;
+ int i;
+
+ for (i = 0; i < X86_VENDOR_NUM; i++) {
+ if (!cpu_devs[i])
+ break;
+
+ if (!strcmp(v, cpu_devs[i]->c_ident[0]) ||
+ (cpu_devs[i]->c_ident[1] &&
+ !strcmp(v, cpu_devs[i]->c_ident[1]))) {
+
+ this_cpu = cpu_devs[i];
+ c->x86_vendor = this_cpu->c_x86_vendor;
+ return;
+ }
+ }
+
+ pr_err_once("CPU: vendor_id '%s' unknown, using generic init.\n" \
+ "CPU: Your system may be unstable.\n", v);
+
+ c->x86_vendor = X86_VENDOR_UNKNOWN;
+ this_cpu = &default_cpu;
+}
+
+void cpu_detect(struct cpuinfo_x86 *c)
+{
+ /* Get vendor name */
+ cpuid(0x00000000, (unsigned int *)&c->cpuid_level,
+ (unsigned int *)&c->x86_vendor_id[0],
+ (unsigned int *)&c->x86_vendor_id[8],
+ (unsigned int *)&c->x86_vendor_id[4]);
+
+ c->x86 = 4;
+ /* Intel-defined flags: level 0x00000001 */
+ if (c->cpuid_level >= 0x00000001) {
+ u32 junk, tfms, cap0, misc;
+
+ cpuid(0x00000001, &tfms, &misc, &junk, &cap0);
+ c->x86 = x86_family(tfms);
+ c->x86_model = x86_model(tfms);
+ c->x86_stepping = x86_stepping(tfms);
+
+ if (cap0 & (1<<19)) {
+ c->x86_clflush_size = ((misc >> 8) & 0xff) * 8;
+ c->x86_cache_alignment = c->x86_clflush_size;
+ }
+ }
+}
+
+static void apply_forced_caps(struct cpuinfo_x86 *c)
+{
+ int i;
+
+ for (i = 0; i < NCAPINTS + NBUGINTS; i++) {
+ c->x86_capability[i] &= ~cpu_caps_cleared[i];
+ c->x86_capability[i] |= cpu_caps_set[i];
+ }
+}
+
+static void init_speculation_control(struct cpuinfo_x86 *c)
+{
+ /*
+ * The Intel SPEC_CTRL CPUID bit implies IBRS and IBPB support,
+ * and they also have a different bit for STIBP support. Also,
+ * a hypervisor might have set the individual AMD bits even on
+ * Intel CPUs, for finer-grained selection of what's available.
+ */
+ if (cpu_has(c, X86_FEATURE_SPEC_CTRL)) {
+ set_cpu_cap(c, X86_FEATURE_IBRS);
+ set_cpu_cap(c, X86_FEATURE_IBPB);
+ set_cpu_cap(c, X86_FEATURE_MSR_SPEC_CTRL);
+ }
+
+ if (cpu_has(c, X86_FEATURE_INTEL_STIBP))
+ set_cpu_cap(c, X86_FEATURE_STIBP);
+
+ if (cpu_has(c, X86_FEATURE_SPEC_CTRL_SSBD) ||
+ cpu_has(c, X86_FEATURE_VIRT_SSBD))
+ set_cpu_cap(c, X86_FEATURE_SSBD);
+
+ if (cpu_has(c, X86_FEATURE_AMD_IBRS)) {
+ set_cpu_cap(c, X86_FEATURE_IBRS);
+ set_cpu_cap(c, X86_FEATURE_MSR_SPEC_CTRL);
+ }
+
+ if (cpu_has(c, X86_FEATURE_AMD_IBPB))
+ set_cpu_cap(c, X86_FEATURE_IBPB);
+
+ if (cpu_has(c, X86_FEATURE_AMD_STIBP)) {
+ set_cpu_cap(c, X86_FEATURE_STIBP);
+ set_cpu_cap(c, X86_FEATURE_MSR_SPEC_CTRL);
+ }
+
+ if (cpu_has(c, X86_FEATURE_AMD_SSBD)) {
+ set_cpu_cap(c, X86_FEATURE_SSBD);
+ set_cpu_cap(c, X86_FEATURE_MSR_SPEC_CTRL);
+ clear_cpu_cap(c, X86_FEATURE_VIRT_SSBD);
+ }
+}
+
+void get_cpu_cap(struct cpuinfo_x86 *c)
+{
+ u32 eax, ebx, ecx, edx;
+
+ /* Intel-defined flags: level 0x00000001 */
+ if (c->cpuid_level >= 0x00000001) {
+ cpuid(0x00000001, &eax, &ebx, &ecx, &edx);
+
+ c->x86_capability[CPUID_1_ECX] = ecx;
+ c->x86_capability[CPUID_1_EDX] = edx;
+ }
+
+ /* Thermal and Power Management Leaf: level 0x00000006 (eax) */
+ if (c->cpuid_level >= 0x00000006)
+ c->x86_capability[CPUID_6_EAX] = cpuid_eax(0x00000006);
+
+ /* Additional Intel-defined flags: level 0x00000007 */
+ if (c->cpuid_level >= 0x00000007) {
+ cpuid_count(0x00000007, 0, &eax, &ebx, &ecx, &edx);
+ c->x86_capability[CPUID_7_0_EBX] = ebx;
+ c->x86_capability[CPUID_7_ECX] = ecx;
+ c->x86_capability[CPUID_7_EDX] = edx;
+
+ /* Check valid sub-leaf index before accessing it */
+ if (eax >= 1) {
+ cpuid_count(0x00000007, 1, &eax, &ebx, &ecx, &edx);
+ c->x86_capability[CPUID_7_1_EAX] = eax;
+ }
+ }
+
+ /* Extended state features: level 0x0000000d */
+ if (c->cpuid_level >= 0x0000000d) {
+ cpuid_count(0x0000000d, 1, &eax, &ebx, &ecx, &edx);
+
+ c->x86_capability[CPUID_D_1_EAX] = eax;
+ }
+
+ /* AMD-defined flags: level 0x80000001 */
+ eax = cpuid_eax(0x80000000);
+ c->extended_cpuid_level = eax;
+
+ if ((eax & 0xffff0000) == 0x80000000) {
+ if (eax >= 0x80000001) {
+ cpuid(0x80000001, &eax, &ebx, &ecx, &edx);
+
+ c->x86_capability[CPUID_8000_0001_ECX] = ecx;
+ c->x86_capability[CPUID_8000_0001_EDX] = edx;
+ }
+ }
+
+ if (c->extended_cpuid_level >= 0x80000007) {
+ cpuid(0x80000007, &eax, &ebx, &ecx, &edx);
+
+ c->x86_capability[CPUID_8000_0007_EBX] = ebx;
+ c->x86_power = edx;
+ }
+
+ if (c->extended_cpuid_level >= 0x80000008) {
+ cpuid(0x80000008, &eax, &ebx, &ecx, &edx);
+ c->x86_capability[CPUID_8000_0008_EBX] = ebx;
+ }
+
+ if (c->extended_cpuid_level >= 0x8000000a)
+ c->x86_capability[CPUID_8000_000A_EDX] = cpuid_edx(0x8000000a);
+
+ if (c->extended_cpuid_level >= 0x8000001f)
+ c->x86_capability[CPUID_8000_001F_EAX] = cpuid_eax(0x8000001f);
+
+ if (c->extended_cpuid_level >= 0x80000021)
+ c->x86_capability[CPUID_8000_0021_EAX] = cpuid_eax(0x80000021);
+
+ init_scattered_cpuid_features(c);
+ init_speculation_control(c);
+
+ /*
+ * Clear/Set all flags overridden by options, after probe.
+ * This needs to happen each time we re-probe, which may happen
+ * several times during CPU initialization.
+ */
+ apply_forced_caps(c);
+}
+
+void get_cpu_address_sizes(struct cpuinfo_x86 *c)
+{
+ u32 eax, ebx, ecx, edx;
+
+ if (c->extended_cpuid_level >= 0x80000008) {
+ cpuid(0x80000008, &eax, &ebx, &ecx, &edx);
+
+ c->x86_virt_bits = (eax >> 8) & 0xff;
+ c->x86_phys_bits = eax & 0xff;
+ }
+#ifdef CONFIG_X86_32
+ else if (cpu_has(c, X86_FEATURE_PAE) || cpu_has(c, X86_FEATURE_PSE36))
+ c->x86_phys_bits = 36;
+#endif
+ c->x86_cache_bits = c->x86_phys_bits;
+}
+
+static void identify_cpu_without_cpuid(struct cpuinfo_x86 *c)
+{
+#ifdef CONFIG_X86_32
+ int i;
+
+ /*
+ * First of all, decide if this is a 486 or higher
+ * It's a 486 if we can modify the AC flag
+ */
+ if (flag_is_changeable_p(X86_EFLAGS_AC))
+ c->x86 = 4;
+ else
+ c->x86 = 3;
+
+ for (i = 0; i < X86_VENDOR_NUM; i++)
+ if (cpu_devs[i] && cpu_devs[i]->c_identify) {
+ c->x86_vendor_id[0] = 0;
+ cpu_devs[i]->c_identify(c);
+ if (c->x86_vendor_id[0]) {
+ get_cpu_vendor(c);
+ break;
+ }
+ }
+#endif
+}
+
+#define NO_SPECULATION BIT(0)
+#define NO_MELTDOWN BIT(1)
+#define NO_SSB BIT(2)
+#define NO_L1TF BIT(3)
+#define NO_MDS BIT(4)
+#define MSBDS_ONLY BIT(5)
+#define NO_SWAPGS BIT(6)
+#define NO_ITLB_MULTIHIT BIT(7)
+#define NO_SPECTRE_V2 BIT(8)
+#define NO_MMIO BIT(9)
+#define NO_EIBRS_PBRSB BIT(10)
+
+#define VULNWL(vendor, family, model, whitelist) \
+ X86_MATCH_VENDOR_FAM_MODEL(vendor, family, model, whitelist)
+
+#define VULNWL_INTEL(model, whitelist) \
+ VULNWL(INTEL, 6, INTEL_FAM6_##model, whitelist)
+
+#define VULNWL_AMD(family, whitelist) \
+ VULNWL(AMD, family, X86_MODEL_ANY, whitelist)
+
+#define VULNWL_HYGON(family, whitelist) \
+ VULNWL(HYGON, family, X86_MODEL_ANY, whitelist)
+
+static const __initconst struct x86_cpu_id cpu_vuln_whitelist[] = {
+ VULNWL(ANY, 4, X86_MODEL_ANY, NO_SPECULATION),
+ VULNWL(CENTAUR, 5, X86_MODEL_ANY, NO_SPECULATION),
+ VULNWL(INTEL, 5, X86_MODEL_ANY, NO_SPECULATION),
+ VULNWL(NSC, 5, X86_MODEL_ANY, NO_SPECULATION),
+ VULNWL(VORTEX, 5, X86_MODEL_ANY, NO_SPECULATION),
+ VULNWL(VORTEX, 6, X86_MODEL_ANY, NO_SPECULATION),
+
+ /* Intel Family 6 */
+ VULNWL_INTEL(TIGERLAKE, NO_MMIO),
+ VULNWL_INTEL(TIGERLAKE_L, NO_MMIO),
+ VULNWL_INTEL(ALDERLAKE, NO_MMIO),
+ VULNWL_INTEL(ALDERLAKE_L, NO_MMIO),
+
+ VULNWL_INTEL(ATOM_SALTWELL, NO_SPECULATION | NO_ITLB_MULTIHIT),
+ VULNWL_INTEL(ATOM_SALTWELL_TABLET, NO_SPECULATION | NO_ITLB_MULTIHIT),
+ VULNWL_INTEL(ATOM_SALTWELL_MID, NO_SPECULATION | NO_ITLB_MULTIHIT),
+ VULNWL_INTEL(ATOM_BONNELL, NO_SPECULATION | NO_ITLB_MULTIHIT),
+ VULNWL_INTEL(ATOM_BONNELL_MID, NO_SPECULATION | NO_ITLB_MULTIHIT),
+
+ VULNWL_INTEL(ATOM_SILVERMONT, NO_SSB | NO_L1TF | MSBDS_ONLY | NO_SWAPGS | NO_ITLB_MULTIHIT),
+ VULNWL_INTEL(ATOM_SILVERMONT_D, NO_SSB | NO_L1TF | MSBDS_ONLY | NO_SWAPGS | NO_ITLB_MULTIHIT),
+ VULNWL_INTEL(ATOM_SILVERMONT_MID, NO_SSB | NO_L1TF | MSBDS_ONLY | NO_SWAPGS | NO_ITLB_MULTIHIT),
+ VULNWL_INTEL(ATOM_AIRMONT, NO_SSB | NO_L1TF | MSBDS_ONLY | NO_SWAPGS | NO_ITLB_MULTIHIT),
+ VULNWL_INTEL(XEON_PHI_KNL, NO_SSB | NO_L1TF | MSBDS_ONLY | NO_SWAPGS | NO_ITLB_MULTIHIT),
+ VULNWL_INTEL(XEON_PHI_KNM, NO_SSB | NO_L1TF | MSBDS_ONLY | NO_SWAPGS | NO_ITLB_MULTIHIT),
+
+ VULNWL_INTEL(CORE_YONAH, NO_SSB),
+
+ VULNWL_INTEL(ATOM_AIRMONT_MID, NO_L1TF | MSBDS_ONLY | NO_SWAPGS | NO_ITLB_MULTIHIT),
+ VULNWL_INTEL(ATOM_AIRMONT_NP, NO_L1TF | NO_SWAPGS | NO_ITLB_MULTIHIT),
+
+ VULNWL_INTEL(ATOM_GOLDMONT, NO_MDS | NO_L1TF | NO_SWAPGS | NO_ITLB_MULTIHIT | NO_MMIO),
+ VULNWL_INTEL(ATOM_GOLDMONT_D, NO_MDS | NO_L1TF | NO_SWAPGS | NO_ITLB_MULTIHIT | NO_MMIO),
+ VULNWL_INTEL(ATOM_GOLDMONT_PLUS, NO_MDS | NO_L1TF | NO_SWAPGS | NO_ITLB_MULTIHIT | NO_MMIO | NO_EIBRS_PBRSB),
+
+ /*
+ * Technically, swapgs isn't serializing on AMD (despite it previously
+ * being documented as such in the APM). But according to AMD, %gs is
+ * updated non-speculatively, and the issuing of %gs-relative memory
+ * operands will be blocked until the %gs update completes, which is
+ * good enough for our purposes.
+ */
+
+ VULNWL_INTEL(ATOM_TREMONT, NO_EIBRS_PBRSB),
+ VULNWL_INTEL(ATOM_TREMONT_L, NO_EIBRS_PBRSB),
+ VULNWL_INTEL(ATOM_TREMONT_D, NO_ITLB_MULTIHIT | NO_EIBRS_PBRSB),
+
+ /* AMD Family 0xf - 0x12 */
+ VULNWL_AMD(0x0f, NO_MELTDOWN | NO_SSB | NO_L1TF | NO_MDS | NO_SWAPGS | NO_ITLB_MULTIHIT | NO_MMIO),
+ VULNWL_AMD(0x10, NO_MELTDOWN | NO_SSB | NO_L1TF | NO_MDS | NO_SWAPGS | NO_ITLB_MULTIHIT | NO_MMIO),
+ VULNWL_AMD(0x11, NO_MELTDOWN | NO_SSB | NO_L1TF | NO_MDS | NO_SWAPGS | NO_ITLB_MULTIHIT | NO_MMIO),
+ VULNWL_AMD(0x12, NO_MELTDOWN | NO_SSB | NO_L1TF | NO_MDS | NO_SWAPGS | NO_ITLB_MULTIHIT | NO_MMIO),
+
+ /* FAMILY_ANY must be last, otherwise 0x0f - 0x12 matches won't work */
+ VULNWL_AMD(X86_FAMILY_ANY, NO_MELTDOWN | NO_L1TF | NO_MDS | NO_SWAPGS | NO_ITLB_MULTIHIT | NO_MMIO | NO_EIBRS_PBRSB),
+ VULNWL_HYGON(X86_FAMILY_ANY, NO_MELTDOWN | NO_L1TF | NO_MDS | NO_SWAPGS | NO_ITLB_MULTIHIT | NO_MMIO | NO_EIBRS_PBRSB),
+
+ /* Zhaoxin Family 7 */
+ VULNWL(CENTAUR, 7, X86_MODEL_ANY, NO_SPECTRE_V2 | NO_SWAPGS | NO_MMIO),
+ VULNWL(ZHAOXIN, 7, X86_MODEL_ANY, NO_SPECTRE_V2 | NO_SWAPGS | NO_MMIO),
+ {}
+};
+
+#define VULNBL(vendor, family, model, blacklist) \
+ X86_MATCH_VENDOR_FAM_MODEL(vendor, family, model, blacklist)
+
+#define VULNBL_INTEL_STEPPINGS(model, steppings, issues) \
+ X86_MATCH_VENDOR_FAM_MODEL_STEPPINGS_FEATURE(INTEL, 6, \
+ INTEL_FAM6_##model, steppings, \
+ X86_FEATURE_ANY, issues)
+
+#define VULNBL_AMD(family, blacklist) \
+ VULNBL(AMD, family, X86_MODEL_ANY, blacklist)
+
+#define VULNBL_HYGON(family, blacklist) \
+ VULNBL(HYGON, family, X86_MODEL_ANY, blacklist)
+
+#define SRBDS BIT(0)
+/* CPU is affected by X86_BUG_MMIO_STALE_DATA */
+#define MMIO BIT(1)
+/* CPU is affected by Shared Buffers Data Sampling (SBDS), a variant of X86_BUG_MMIO_STALE_DATA */
+#define MMIO_SBDS BIT(2)
+/* CPU is affected by RETbleed, speculating where you would not expect it */
+#define RETBLEED BIT(3)
+/* CPU is affected by SMT (cross-thread) return predictions */
+#define SMT_RSB BIT(4)
+/* CPU is affected by SRSO */
+#define SRSO BIT(5)
+/* CPU is affected by GDS */
+#define GDS BIT(6)
+
+static const struct x86_cpu_id cpu_vuln_blacklist[] __initconst = {
+ VULNBL_INTEL_STEPPINGS(IVYBRIDGE, X86_STEPPING_ANY, SRBDS),
+ VULNBL_INTEL_STEPPINGS(HASWELL, X86_STEPPING_ANY, SRBDS),
+ VULNBL_INTEL_STEPPINGS(HASWELL_L, X86_STEPPING_ANY, SRBDS),
+ VULNBL_INTEL_STEPPINGS(HASWELL_G, X86_STEPPING_ANY, SRBDS),
+ VULNBL_INTEL_STEPPINGS(HASWELL_X, X86_STEPPING_ANY, MMIO),
+ VULNBL_INTEL_STEPPINGS(BROADWELL_D, X86_STEPPING_ANY, MMIO),
+ VULNBL_INTEL_STEPPINGS(BROADWELL_G, X86_STEPPING_ANY, SRBDS),
+ VULNBL_INTEL_STEPPINGS(BROADWELL_X, X86_STEPPING_ANY, MMIO),
+ VULNBL_INTEL_STEPPINGS(BROADWELL, X86_STEPPING_ANY, SRBDS),
+ VULNBL_INTEL_STEPPINGS(SKYLAKE_X, X86_STEPPING_ANY, MMIO | RETBLEED | GDS),
+ VULNBL_INTEL_STEPPINGS(SKYLAKE_L, X86_STEPPING_ANY, MMIO | RETBLEED | GDS | SRBDS),
+ VULNBL_INTEL_STEPPINGS(SKYLAKE, X86_STEPPING_ANY, MMIO | RETBLEED | GDS | SRBDS),
+ VULNBL_INTEL_STEPPINGS(KABYLAKE_L, X86_STEPPING_ANY, MMIO | RETBLEED | GDS | SRBDS),
+ VULNBL_INTEL_STEPPINGS(KABYLAKE, X86_STEPPING_ANY, MMIO | RETBLEED | GDS | SRBDS),
+ VULNBL_INTEL_STEPPINGS(CANNONLAKE_L, X86_STEPPING_ANY, RETBLEED),
+ VULNBL_INTEL_STEPPINGS(ICELAKE_L, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RETBLEED | GDS),
+ VULNBL_INTEL_STEPPINGS(ICELAKE_D, X86_STEPPING_ANY, MMIO | GDS),
+ VULNBL_INTEL_STEPPINGS(ICELAKE_X, X86_STEPPING_ANY, MMIO | GDS),
+ VULNBL_INTEL_STEPPINGS(COMETLAKE, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RETBLEED | GDS),
+ VULNBL_INTEL_STEPPINGS(COMETLAKE_L, X86_STEPPINGS(0x0, 0x0), MMIO | RETBLEED),
+ VULNBL_INTEL_STEPPINGS(COMETLAKE_L, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RETBLEED | GDS),
+ VULNBL_INTEL_STEPPINGS(TIGERLAKE_L, X86_STEPPING_ANY, GDS),
+ VULNBL_INTEL_STEPPINGS(TIGERLAKE, X86_STEPPING_ANY, GDS),
+ VULNBL_INTEL_STEPPINGS(LAKEFIELD, X86_STEPPING_ANY, MMIO | MMIO_SBDS | RETBLEED),
+ VULNBL_INTEL_STEPPINGS(ROCKETLAKE, X86_STEPPING_ANY, MMIO | RETBLEED | GDS),
+ VULNBL_INTEL_STEPPINGS(ATOM_TREMONT, X86_STEPPING_ANY, MMIO | MMIO_SBDS),
+ VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_D, X86_STEPPING_ANY, MMIO),
+ VULNBL_INTEL_STEPPINGS(ATOM_TREMONT_L, X86_STEPPING_ANY, MMIO | MMIO_SBDS),
+
+ VULNBL_AMD(0x15, RETBLEED),
+ VULNBL_AMD(0x16, RETBLEED),
+ VULNBL_AMD(0x17, RETBLEED | SMT_RSB | SRSO),
+ VULNBL_HYGON(0x18, RETBLEED | SMT_RSB | SRSO),
+ VULNBL_AMD(0x19, SRSO),
+ {}
+};
+
+static bool __init cpu_matches(const struct x86_cpu_id *table, unsigned long which)
+{
+ const struct x86_cpu_id *m = x86_match_cpu(table);
+
+ return m && !!(m->driver_data & which);
+}
+
+u64 x86_read_arch_cap_msr(void)
+{
+ u64 ia32_cap = 0;
+
+ if (boot_cpu_has(X86_FEATURE_ARCH_CAPABILITIES))
+ rdmsrl(MSR_IA32_ARCH_CAPABILITIES, ia32_cap);
+
+ return ia32_cap;
+}
+
+static bool arch_cap_mmio_immune(u64 ia32_cap)
+{
+ return (ia32_cap & ARCH_CAP_FBSDP_NO &&
+ ia32_cap & ARCH_CAP_PSDP_NO &&
+ ia32_cap & ARCH_CAP_SBDR_SSDP_NO);
+}
+
+static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
+{
+ u64 ia32_cap = x86_read_arch_cap_msr();
+
+ /* Set ITLB_MULTIHIT bug if cpu is not in the whitelist and not mitigated */
+ if (!cpu_matches(cpu_vuln_whitelist, NO_ITLB_MULTIHIT) &&
+ !(ia32_cap & ARCH_CAP_PSCHANGE_MC_NO))
+ setup_force_cpu_bug(X86_BUG_ITLB_MULTIHIT);
+
+ if (cpu_matches(cpu_vuln_whitelist, NO_SPECULATION))
+ return;
+
+ setup_force_cpu_bug(X86_BUG_SPECTRE_V1);
+
+ if (!cpu_matches(cpu_vuln_whitelist, NO_SPECTRE_V2))
+ setup_force_cpu_bug(X86_BUG_SPECTRE_V2);
+
+ if (!cpu_matches(cpu_vuln_whitelist, NO_SSB) &&
+ !(ia32_cap & ARCH_CAP_SSB_NO) &&
+ !cpu_has(c, X86_FEATURE_AMD_SSB_NO))
+ setup_force_cpu_bug(X86_BUG_SPEC_STORE_BYPASS);
+
+ /*
+ * AMD's AutoIBRS is equivalent to Intel's eIBRS - use the Intel feature
+ * flag and protect from vendor-specific bugs via the whitelist.
+ */
+ if ((ia32_cap & ARCH_CAP_IBRS_ALL) || cpu_has(c, X86_FEATURE_AUTOIBRS)) {
+ setup_force_cpu_cap(X86_FEATURE_IBRS_ENHANCED);
+ if (!cpu_matches(cpu_vuln_whitelist, NO_EIBRS_PBRSB) &&
+ !(ia32_cap & ARCH_CAP_PBRSB_NO))
+ setup_force_cpu_bug(X86_BUG_EIBRS_PBRSB);
+ }
+
+ if (!cpu_matches(cpu_vuln_whitelist, NO_MDS) &&
+ !(ia32_cap & ARCH_CAP_MDS_NO)) {
+ setup_force_cpu_bug(X86_BUG_MDS);
+ if (cpu_matches(cpu_vuln_whitelist, MSBDS_ONLY))
+ setup_force_cpu_bug(X86_BUG_MSBDS_ONLY);
+ }
+
+ if (!cpu_matches(cpu_vuln_whitelist, NO_SWAPGS))
+ setup_force_cpu_bug(X86_BUG_SWAPGS);
+
+ /*
+ * When the CPU is not mitigated for TAA (TAA_NO=0) set TAA bug when:
+ * - TSX is supported or
+ * - TSX_CTRL is present
+ *
+ * TSX_CTRL check is needed for cases when TSX could be disabled before
+ * the kernel boot e.g. kexec.
+ * TSX_CTRL check alone is not sufficient for cases when the microcode
+ * update is not present or running as guest that don't get TSX_CTRL.
+ */
+ if (!(ia32_cap & ARCH_CAP_TAA_NO) &&
+ (cpu_has(c, X86_FEATURE_RTM) ||
+ (ia32_cap & ARCH_CAP_TSX_CTRL_MSR)))
+ setup_force_cpu_bug(X86_BUG_TAA);
+
+ /*
+ * SRBDS affects CPUs which support RDRAND or RDSEED and are listed
+ * in the vulnerability blacklist.
+ *
+ * Some of the implications and mitigation of Shared Buffers Data
+ * Sampling (SBDS) are similar to SRBDS. Give SBDS same treatment as
+ * SRBDS.
+ */
+ if ((cpu_has(c, X86_FEATURE_RDRAND) ||
+ cpu_has(c, X86_FEATURE_RDSEED)) &&
+ cpu_matches(cpu_vuln_blacklist, SRBDS | MMIO_SBDS))
+ setup_force_cpu_bug(X86_BUG_SRBDS);
+
+ /*
+ * Processor MMIO Stale Data bug enumeration
+ *
+ * Affected CPU list is generally enough to enumerate the vulnerability,
+ * but for virtualization case check for ARCH_CAP MSR bits also, VMM may
+ * not want the guest to enumerate the bug.
+ *
+ * Set X86_BUG_MMIO_UNKNOWN for CPUs that are neither in the blacklist,
+ * nor in the whitelist and also don't enumerate MSR ARCH_CAP MMIO bits.
+ */
+ if (!arch_cap_mmio_immune(ia32_cap)) {
+ if (cpu_matches(cpu_vuln_blacklist, MMIO))
+ setup_force_cpu_bug(X86_BUG_MMIO_STALE_DATA);
+ else if (!cpu_matches(cpu_vuln_whitelist, NO_MMIO))
+ setup_force_cpu_bug(X86_BUG_MMIO_UNKNOWN);
+ }
+
+ if (!cpu_has(c, X86_FEATURE_BTC_NO)) {
+ if (cpu_matches(cpu_vuln_blacklist, RETBLEED) || (ia32_cap & ARCH_CAP_RSBA))
+ setup_force_cpu_bug(X86_BUG_RETBLEED);
+ }
+
+ if (cpu_matches(cpu_vuln_blacklist, SMT_RSB))
+ setup_force_cpu_bug(X86_BUG_SMT_RSB);
+
+ if (!cpu_has(c, X86_FEATURE_SRSO_NO)) {
+ if (cpu_matches(cpu_vuln_blacklist, SRSO))
+ setup_force_cpu_bug(X86_BUG_SRSO);
+ }
+
+ /*
+ * Check if CPU is vulnerable to GDS. If running in a virtual machine on
+ * an affected processor, the VMM may have disabled the use of GATHER by
+ * disabling AVX2. The only way to do this in HW is to clear XCR0[2],
+ * which means that AVX will be disabled.
+ */
+ if (cpu_matches(cpu_vuln_blacklist, GDS) && !(ia32_cap & ARCH_CAP_GDS_NO) &&
+ boot_cpu_has(X86_FEATURE_AVX))
+ setup_force_cpu_bug(X86_BUG_GDS);
+
+ if (cpu_matches(cpu_vuln_whitelist, NO_MELTDOWN))
+ return;
+
+ /* Rogue Data Cache Load? No! */
+ if (ia32_cap & ARCH_CAP_RDCL_NO)
+ return;
+
+ setup_force_cpu_bug(X86_BUG_CPU_MELTDOWN);
+
+ if (cpu_matches(cpu_vuln_whitelist, NO_L1TF))
+ return;
+
+ setup_force_cpu_bug(X86_BUG_L1TF);
+}
+
+/*
+ * The NOPL instruction is supposed to exist on all CPUs of family >= 6;
+ * unfortunately, that's not true in practice because of early VIA
+ * chips and (more importantly) broken virtualizers that are not easy
+ * to detect. In the latter case it doesn't even *fail* reliably, so
+ * probing for it doesn't even work. Disable it completely on 32-bit
+ * unless we can find a reliable way to detect all the broken cases.
+ * Enable it explicitly on 64-bit for non-constant inputs of cpu_has().
+ */
+static void detect_nopl(void)
+{
+#ifdef CONFIG_X86_32
+ setup_clear_cpu_cap(X86_FEATURE_NOPL);
+#else
+ setup_force_cpu_cap(X86_FEATURE_NOPL);
+#endif
+}
+
+/*
+ * We parse cpu parameters early because fpu__init_system() is executed
+ * before parse_early_param().
+ */
+static void __init cpu_parse_early_param(void)
+{
+ char arg[128];
+ char *argptr = arg, *opt;
+ int arglen, taint = 0;
+
+#ifdef CONFIG_X86_32
+ if (cmdline_find_option_bool(boot_command_line, "no387"))
+#ifdef CONFIG_MATH_EMULATION
+ setup_clear_cpu_cap(X86_FEATURE_FPU);
+#else
+ pr_err("Option 'no387' required CONFIG_MATH_EMULATION enabled.\n");
+#endif
+
+ if (cmdline_find_option_bool(boot_command_line, "nofxsr"))
+ setup_clear_cpu_cap(X86_FEATURE_FXSR);
+#endif
+
+ if (cmdline_find_option_bool(boot_command_line, "noxsave"))
+ setup_clear_cpu_cap(X86_FEATURE_XSAVE);
+
+ if (cmdline_find_option_bool(boot_command_line, "noxsaveopt"))
+ setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
+
+ if (cmdline_find_option_bool(boot_command_line, "noxsaves"))
+ setup_clear_cpu_cap(X86_FEATURE_XSAVES);
+
+ if (cmdline_find_option_bool(boot_command_line, "nousershstk"))
+ setup_clear_cpu_cap(X86_FEATURE_USER_SHSTK);
+
+ arglen = cmdline_find_option(boot_command_line, "clearcpuid", arg, sizeof(arg));
+ if (arglen <= 0)
+ return;
+
+ pr_info("Clearing CPUID bits:");
+
+ while (argptr) {
+ bool found __maybe_unused = false;
+ unsigned int bit;
+
+ opt = strsep(&argptr, ",");
+
+ /*
+ * Handle naked numbers first for feature flags which don't
+ * have names.
+ */
+ if (!kstrtouint(opt, 10, &bit)) {
+ if (bit < NCAPINTS * 32) {
+
+ /* empty-string, i.e., ""-defined feature flags */
+ if (!x86_cap_flags[bit])
+ pr_cont(" " X86_CAP_FMT_NUM, x86_cap_flag_num(bit));
+ else
+ pr_cont(" " X86_CAP_FMT, x86_cap_flag(bit));
+
+ setup_clear_cpu_cap(bit);
+ taint++;
+ }
+ /*
+ * The assumption is that there are no feature names with only
+ * numbers in the name thus go to the next argument.
+ */
+ continue;
+ }
+
+ for (bit = 0; bit < 32 * NCAPINTS; bit++) {
+ if (!x86_cap_flag(bit))
+ continue;
+
+ if (strcmp(x86_cap_flag(bit), opt))
+ continue;
+
+ pr_cont(" %s", opt);
+ setup_clear_cpu_cap(bit);
+ taint++;
+ found = true;
+ break;
+ }
+
+ if (!found)
+ pr_cont(" (unknown: %s)", opt);
+ }
+ pr_cont("\n");
+
+ if (taint)
+ add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
+}
+
+/*
+ * Do minimum CPU detection early.
+ * Fields really needed: vendor, cpuid_level, family, model, mask,
+ * cache alignment.
+ * The others are not touched to avoid unwanted side effects.
+ *
+ * WARNING: this function is only called on the boot CPU. Don't add code
+ * here that is supposed to run on all CPUs.
+ */
+static void __init early_identify_cpu(struct cpuinfo_x86 *c)
+{
+#ifdef CONFIG_X86_64
+ c->x86_clflush_size = 64;
+ c->x86_phys_bits = 36;
+ c->x86_virt_bits = 48;
+#else
+ c->x86_clflush_size = 32;
+ c->x86_phys_bits = 32;
+ c->x86_virt_bits = 32;
+#endif
+ c->x86_cache_alignment = c->x86_clflush_size;
+
+ memset(&c->x86_capability, 0, sizeof(c->x86_capability));
+ c->extended_cpuid_level = 0;
+
+ if (!have_cpuid_p())
+ identify_cpu_without_cpuid(c);
+
+ /* cyrix could have cpuid enabled via c_identify()*/
+ if (have_cpuid_p()) {
+ cpu_detect(c);
+ get_cpu_vendor(c);
+ get_cpu_cap(c);
+ get_cpu_address_sizes(c);
+ setup_force_cpu_cap(X86_FEATURE_CPUID);
+ cpu_parse_early_param();
+
+ if (this_cpu->c_early_init)
+ this_cpu->c_early_init(c);
+
+ c->cpu_index = 0;
+ filter_cpuid_features(c, false);
+
+ if (this_cpu->c_bsp_init)
+ this_cpu->c_bsp_init(c);
+ } else {
+ setup_clear_cpu_cap(X86_FEATURE_CPUID);
+ }
+
+ setup_force_cpu_cap(X86_FEATURE_ALWAYS);
+
+ cpu_set_bug_bits(c);
+
+ sld_setup(c);
+
+#ifdef CONFIG_X86_32
+ /*
+ * Regardless of whether PCID is enumerated, the SDM says
+ * that it can't be enabled in 32-bit mode.
+ */
+ setup_clear_cpu_cap(X86_FEATURE_PCID);
+#endif
+
+ /*
+ * Later in the boot process pgtable_l5_enabled() relies on
+ * cpu_feature_enabled(X86_FEATURE_LA57). If 5-level paging is not
+ * enabled by this point we need to clear the feature bit to avoid
+ * false-positives at the later stage.
+ *
+ * pgtable_l5_enabled() can be false here for several reasons:
+ * - 5-level paging is disabled compile-time;
+ * - it's 32-bit kernel;
+ * - machine doesn't support 5-level paging;
+ * - user specified 'no5lvl' in kernel command line.
+ */
+ if (!pgtable_l5_enabled())
+ setup_clear_cpu_cap(X86_FEATURE_LA57);
+
+ detect_nopl();
+}
+
+void __init early_cpu_init(void)
+{
+ const struct cpu_dev *const *cdev;
+ int count = 0;
+
+#ifdef CONFIG_PROCESSOR_SELECT
+ pr_info("KERNEL supported cpus:\n");
+#endif
+
+ for (cdev = __x86_cpu_dev_start; cdev < __x86_cpu_dev_end; cdev++) {
+ const struct cpu_dev *cpudev = *cdev;
+
+ if (count >= X86_VENDOR_NUM)
+ break;
+ cpu_devs[count] = cpudev;
+ count++;
+
+#ifdef CONFIG_PROCESSOR_SELECT
+ {
+ unsigned int j;
+
+ for (j = 0; j < 2; j++) {
+ if (!cpudev->c_ident[j])
+ continue;
+ pr_info(" %s %s\n", cpudev->c_vendor,
+ cpudev->c_ident[j]);
+ }
+ }
+#endif
+ }
+ early_identify_cpu(&boot_cpu_data);
+}
+
+static bool detect_null_seg_behavior(void)
+{
+ /*
+ * Empirically, writing zero to a segment selector on AMD does
+ * not clear the base, whereas writing zero to a segment
+ * selector on Intel does clear the base. Intel's behavior
+ * allows slightly faster context switches in the common case
+ * where GS is unused by the prev and next threads.
+ *
+ * Since neither vendor documents this anywhere that I can see,
+ * detect it directly instead of hard-coding the choice by
+ * vendor.
+ *
+ * I've designated AMD's behavior as the "bug" because it's
+ * counterintuitive and less friendly.
+ */
+
+ unsigned long old_base, tmp;
+ rdmsrl(MSR_FS_BASE, old_base);
+ wrmsrl(MSR_FS_BASE, 1);
+ loadsegment(fs, 0);
+ rdmsrl(MSR_FS_BASE, tmp);
+ wrmsrl(MSR_FS_BASE, old_base);
+ return tmp == 0;
+}
+
+void check_null_seg_clears_base(struct cpuinfo_x86 *c)
+{
+ /* BUG_NULL_SEG is only relevant with 64bit userspace */
+ if (!IS_ENABLED(CONFIG_X86_64))
+ return;
+
+ if (cpu_has(c, X86_FEATURE_NULL_SEL_CLR_BASE))
+ return;
+
+ /*
+ * CPUID bit above wasn't set. If this kernel is still running
+ * as a HV guest, then the HV has decided not to advertize
+ * that CPUID bit for whatever reason. For example, one
+ * member of the migration pool might be vulnerable. Which
+ * means, the bug is present: set the BUG flag and return.
+ */
+ if (cpu_has(c, X86_FEATURE_HYPERVISOR)) {
+ set_cpu_bug(c, X86_BUG_NULL_SEG);
+ return;
+ }
+
+ /*
+ * Zen2 CPUs also have this behaviour, but no CPUID bit.
+ * 0x18 is the respective family for Hygon.
+ */
+ if ((c->x86 == 0x17 || c->x86 == 0x18) &&
+ detect_null_seg_behavior())
+ return;
+
+ /* All the remaining ones are affected */
+ set_cpu_bug(c, X86_BUG_NULL_SEG);
+}
+
+static void generic_identify(struct cpuinfo_x86 *c)
+{
+ c->extended_cpuid_level = 0;
+
+ if (!have_cpuid_p())
+ identify_cpu_without_cpuid(c);
+
+ /* cyrix could have cpuid enabled via c_identify()*/
+ if (!have_cpuid_p())
+ return;
+
+ cpu_detect(c);
+
+ get_cpu_vendor(c);
+
+ get_cpu_cap(c);
+
+ get_cpu_address_sizes(c);
+
+ if (c->cpuid_level >= 0x00000001) {
+ c->initial_apicid = (cpuid_ebx(1) >> 24) & 0xFF;
+#ifdef CONFIG_X86_32
+# ifdef CONFIG_SMP
+ c->apicid = apic->phys_pkg_id(c->initial_apicid, 0);
+# else
+ c->apicid = c->initial_apicid;
+# endif
+#endif
+ c->phys_proc_id = c->initial_apicid;
+ }
+
+ get_model_name(c); /* Default name */
+
+ /*
+ * ESPFIX is a strange bug. All real CPUs have it. Paravirt
+ * systems that run Linux at CPL > 0 may or may not have the
+ * issue, but, even if they have the issue, there's absolutely
+ * nothing we can do about it because we can't use the real IRET
+ * instruction.
+ *
+ * NB: For the time being, only 32-bit kernels support
+ * X86_BUG_ESPFIX as such. 64-bit kernels directly choose
+ * whether to apply espfix using paravirt hooks. If any
+ * non-paravirt system ever shows up that does *not* have the
+ * ESPFIX issue, we can change this.
+ */
+#ifdef CONFIG_X86_32
+ set_cpu_bug(c, X86_BUG_ESPFIX);
+#endif
+}
+
+/*
+ * Validate that ACPI/mptables have the same information about the
+ * effective APIC id and update the package map.
+ */
+static void validate_apic_and_package_id(struct cpuinfo_x86 *c)
+{
+#ifdef CONFIG_SMP
+ unsigned int apicid, cpu = smp_processor_id();
+
+ apicid = apic->cpu_present_to_apicid(cpu);
+
+ if (apicid != c->apicid) {
+ pr_err(FW_BUG "CPU%u: APIC id mismatch. Firmware: %x APIC: %x\n",
+ cpu, apicid, c->initial_apicid);
+ }
+ BUG_ON(topology_update_package_map(c->phys_proc_id, cpu));
+ BUG_ON(topology_update_die_map(c->cpu_die_id, cpu));
+#else
+ c->logical_proc_id = 0;
+#endif
+}
+
+/*
+ * This does the hard work of actually picking apart the CPU stuff...
+ */
+static void identify_cpu(struct cpuinfo_x86 *c)
+{
+ int i;
+
+ c->loops_per_jiffy = loops_per_jiffy;
+ c->x86_cache_size = 0;
+ c->x86_vendor = X86_VENDOR_UNKNOWN;
+ c->x86_model = c->x86_stepping = 0; /* So far unknown... */
+ c->x86_vendor_id[0] = '\0'; /* Unset */
+ c->x86_model_id[0] = '\0'; /* Unset */
+ c->x86_max_cores = 1;
+ c->x86_coreid_bits = 0;
+ c->cu_id = 0xff;
+#ifdef CONFIG_X86_64
+ c->x86_clflush_size = 64;
+ c->x86_phys_bits = 36;
+ c->x86_virt_bits = 48;
+#else
+ c->cpuid_level = -1; /* CPUID not detected */
+ c->x86_clflush_size = 32;
+ c->x86_phys_bits = 32;
+ c->x86_virt_bits = 32;
+#endif
+ c->x86_cache_alignment = c->x86_clflush_size;
+ memset(&c->x86_capability, 0, sizeof(c->x86_capability));
+#ifdef CONFIG_X86_VMX_FEATURE_NAMES
+ memset(&c->vmx_capability, 0, sizeof(c->vmx_capability));
+#endif
+
+ generic_identify(c);
+
+ if (this_cpu->c_identify)
+ this_cpu->c_identify(c);
+
+ /* Clear/Set all flags overridden by options, after probe */
+ apply_forced_caps(c);
+
+#ifdef CONFIG_X86_64
+ c->apicid = apic->phys_pkg_id(c->initial_apicid, 0);
+#endif
+
+ /*
+ * Vendor-specific initialization. In this section we
+ * canonicalize the feature flags, meaning if there are
+ * features a certain CPU supports which CPUID doesn't
+ * tell us, CPUID claiming incorrect flags, or other bugs,
+ * we handle them here.
+ *
+ * At the end of this section, c->x86_capability better
+ * indicate the features this CPU genuinely supports!
+ */
+ if (this_cpu->c_init)
+ this_cpu->c_init(c);
+
+ /* Disable the PN if appropriate */
+ squash_the_stupid_serial_number(c);
+
+ /* Set up SMEP/SMAP/UMIP */
+ setup_smep(c);
+ setup_smap(c);
+ setup_umip(c);
+
+ /* Enable FSGSBASE instructions if available. */
+ if (cpu_has(c, X86_FEATURE_FSGSBASE)) {
+ cr4_set_bits(X86_CR4_FSGSBASE);
+ elf_hwcap2 |= HWCAP2_FSGSBASE;
+ }
+
+ /*
+ * The vendor-specific functions might have changed features.
+ * Now we do "generic changes."
+ */
+
+ /* Filter out anything that depends on CPUID levels we don't have */
+ filter_cpuid_features(c, true);
+
+ /* If the model name is still unset, do table lookup. */
+ if (!c->x86_model_id[0]) {
+ const char *p;
+ p = table_lookup_model(c);
+ if (p)
+ strcpy(c->x86_model_id, p);
+ else
+ /* Last resort... */
+ sprintf(c->x86_model_id, "%02x/%02x",
+ c->x86, c->x86_model);
+ }
+
+#ifdef CONFIG_X86_64
+ detect_ht(c);
+#endif
+
+ x86_init_rdrand(c);
+ setup_pku(c);
+ setup_cet(c);
+
+ /*
+ * Clear/Set all flags overridden by options, need do it
+ * before following smp all cpus cap AND.
+ */
+ apply_forced_caps(c);
+
+ /*
+ * On SMP, boot_cpu_data holds the common feature set between
+ * all CPUs; so make sure that we indicate which features are
+ * common between the CPUs. The first time this routine gets
+ * executed, c == &boot_cpu_data.
+ */
+ if (c != &boot_cpu_data) {
+ /* AND the already accumulated flags with these */
+ for (i = 0; i < NCAPINTS; i++)
+ boot_cpu_data.x86_capability[i] &= c->x86_capability[i];
+
+ /* OR, i.e. replicate the bug flags */
+ for (i = NCAPINTS; i < NCAPINTS + NBUGINTS; i++)
+ c->x86_capability[i] |= boot_cpu_data.x86_capability[i];
+ }
+
+ ppin_init(c);
+
+ /* Init Machine Check Exception if available. */
+ mcheck_cpu_init(c);
+
+ select_idle_routine(c);
+
+#ifdef CONFIG_NUMA
+ numa_add_cpu(smp_processor_id());
+#endif
+}
+
+/*
+ * Set up the CPU state needed to execute SYSENTER/SYSEXIT instructions
+ * on 32-bit kernels:
+ */
+#ifdef CONFIG_X86_32
+void enable_sep_cpu(void)
+{
+ struct tss_struct *tss;
+ int cpu;
+
+ if (!boot_cpu_has(X86_FEATURE_SEP))
+ return;
+
+ cpu = get_cpu();
+ tss = &per_cpu(cpu_tss_rw, cpu);
+
+ /*
+ * We cache MSR_IA32_SYSENTER_CS's value in the TSS's ss1 field --
+ * see the big comment in struct x86_hw_tss's definition.
+ */
+
+ tss->x86_tss.ss1 = __KERNEL_CS;
+ wrmsr(MSR_IA32_SYSENTER_CS, tss->x86_tss.ss1, 0);
+ wrmsr(MSR_IA32_SYSENTER_ESP, (unsigned long)(cpu_entry_stack(cpu) + 1), 0);
+ wrmsr(MSR_IA32_SYSENTER_EIP, (unsigned long)entry_SYSENTER_32, 0);
+
+ put_cpu();
+}
+#endif
+
+static __init void identify_boot_cpu(void)
+{
+ identify_cpu(&boot_cpu_data);
+ if (HAS_KERNEL_IBT && cpu_feature_enabled(X86_FEATURE_IBT))
+ pr_info("CET detected: Indirect Branch Tracking enabled\n");
+#ifdef CONFIG_X86_32
+ enable_sep_cpu();
+#endif
+ cpu_detect_tlb(&boot_cpu_data);
+ setup_cr_pinning();
+
+ tsx_init();
+ lkgs_init();
+}
+
+void identify_secondary_cpu(struct cpuinfo_x86 *c)
+{
+ BUG_ON(c == &boot_cpu_data);
+ identify_cpu(c);
+#ifdef CONFIG_X86_32
+ enable_sep_cpu();
+#endif
+ validate_apic_and_package_id(c);
+ x86_spec_ctrl_setup_ap();
+ update_srbds_msr();
+ if (boot_cpu_has_bug(X86_BUG_GDS))
+ update_gds_msr();
+
+ tsx_ap_init();
+}
+
+void print_cpu_info(struct cpuinfo_x86 *c)
+{
+ const char *vendor = NULL;
+
+ if (c->x86_vendor < X86_VENDOR_NUM) {
+ vendor = this_cpu->c_vendor;
+ } else {
+ if (c->cpuid_level >= 0)
+ vendor = c->x86_vendor_id;
+ }
+
+ if (vendor && !strstr(c->x86_model_id, vendor))
+ pr_cont("%s ", vendor);
+
+ if (c->x86_model_id[0])
+ pr_cont("%s", c->x86_model_id);
+ else
+ pr_cont("%d86", c->x86);
+
+ pr_cont(" (family: 0x%x, model: 0x%x", c->x86, c->x86_model);
+
+ if (c->x86_stepping || c->cpuid_level >= 0)
+ pr_cont(", stepping: 0x%x)\n", c->x86_stepping);
+ else
+ pr_cont(")\n");
+}
+
+/*
+ * clearcpuid= was already parsed in cpu_parse_early_param(). This dummy
+ * function prevents it from becoming an environment variable for init.
+ */
+static __init int setup_clearcpuid(char *arg)
+{
+ return 1;
+}
+__setup("clearcpuid=", setup_clearcpuid);
+
+DEFINE_PER_CPU_ALIGNED(struct pcpu_hot, pcpu_hot) = {
+ .current_task = &init_task,
+ .preempt_count = INIT_PREEMPT_COUNT,
+ .top_of_stack = TOP_OF_INIT_STACK,
+};
+EXPORT_PER_CPU_SYMBOL(pcpu_hot);
+
+#ifdef CONFIG_X86_64
+DEFINE_PER_CPU_FIRST(struct fixed_percpu_data,
+ fixed_percpu_data) __aligned(PAGE_SIZE) __visible;
+EXPORT_PER_CPU_SYMBOL_GPL(fixed_percpu_data);
+
+static void wrmsrl_cstar(unsigned long val)
+{
+ /*
+ * Intel CPUs do not support 32-bit SYSCALL. Writing to MSR_CSTAR
+ * is so far ignored by the CPU, but raises a #VE trap in a TDX
+ * guest. Avoid the pointless write on all Intel CPUs.
+ */
+ if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
+ wrmsrl(MSR_CSTAR, val);
+}
+
+/* May not be marked __init: used by software suspend */
+void syscall_init(void)
+{
+ wrmsr(MSR_STAR, 0, (__USER32_CS << 16) | __KERNEL_CS);
+ wrmsrl(MSR_LSTAR, (unsigned long)entry_SYSCALL_64);
+
+#ifdef CONFIG_IA32_EMULATION
+ wrmsrl_cstar((unsigned long)entry_SYSCALL_compat);
+ /*
+ * This only works on Intel CPUs.
+ * On AMD CPUs these MSRs are 32-bit, CPU truncates MSR_IA32_SYSENTER_EIP.
+ * This does not cause SYSENTER to jump to the wrong location, because
+ * AMD doesn't allow SYSENTER in long mode (either 32- or 64-bit).
+ */
+ wrmsrl_safe(MSR_IA32_SYSENTER_CS, (u64)__KERNEL_CS);
+ wrmsrl_safe(MSR_IA32_SYSENTER_ESP,
+ (unsigned long)(cpu_entry_stack(smp_processor_id()) + 1));
+ wrmsrl_safe(MSR_IA32_SYSENTER_EIP, (u64)entry_SYSENTER_compat);
+#else
+ wrmsrl_cstar((unsigned long)ignore_sysret);
+ wrmsrl_safe(MSR_IA32_SYSENTER_CS, (u64)GDT_ENTRY_INVALID_SEG);
+ wrmsrl_safe(MSR_IA32_SYSENTER_ESP, 0ULL);
+ wrmsrl_safe(MSR_IA32_SYSENTER_EIP, 0ULL);
+#endif
+
+ /*
+ * Flags to clear on syscall; clear as much as possible
+ * to minimize user space-kernel interference.
+ */
+ wrmsrl(MSR_SYSCALL_MASK,
+ X86_EFLAGS_CF|X86_EFLAGS_PF|X86_EFLAGS_AF|
+ X86_EFLAGS_ZF|X86_EFLAGS_SF|X86_EFLAGS_TF|
+ X86_EFLAGS_IF|X86_EFLAGS_DF|X86_EFLAGS_OF|
+ X86_EFLAGS_IOPL|X86_EFLAGS_NT|X86_EFLAGS_RF|
+ X86_EFLAGS_AC|X86_EFLAGS_ID);
+}
+
+#else /* CONFIG_X86_64 */
+
+#ifdef CONFIG_STACKPROTECTOR
+DEFINE_PER_CPU(unsigned long, __stack_chk_guard);
+EXPORT_PER_CPU_SYMBOL(__stack_chk_guard);
+#endif
+
+#endif /* CONFIG_X86_64 */
+
+/*
+ * Clear all 6 debug registers:
+ */
+static void clear_all_debug_regs(void)
+{
+ int i;
+
+ for (i = 0; i < 8; i++) {
+ /* Ignore db4, db5 */
+ if ((i == 4) || (i == 5))
+ continue;
+
+ set_debugreg(0, i);
+ }
+}
+
+#ifdef CONFIG_KGDB
+/*
+ * Restore debug regs if using kgdbwait and you have a kernel debugger
+ * connection established.
+ */
+static void dbg_restore_debug_regs(void)
+{
+ if (unlikely(kgdb_connected && arch_kgdb_ops.correct_hw_break))
+ arch_kgdb_ops.correct_hw_break();
+}
+#else /* ! CONFIG_KGDB */
+#define dbg_restore_debug_regs()
+#endif /* ! CONFIG_KGDB */
+
+static inline void setup_getcpu(int cpu)
+{
+ unsigned long cpudata = vdso_encode_cpunode(cpu, early_cpu_to_node(cpu));
+ struct desc_struct d = { };
+
+ if (boot_cpu_has(X86_FEATURE_RDTSCP) || boot_cpu_has(X86_FEATURE_RDPID))
+ wrmsr(MSR_TSC_AUX, cpudata, 0);
+
+ /* Store CPU and node number in limit. */
+ d.limit0 = cpudata;
+ d.limit1 = cpudata >> 16;
+
+ d.type = 5; /* RO data, expand down, accessed */
+ d.dpl = 3; /* Visible to user code */
+ d.s = 1; /* Not a system segment */
+ d.p = 1; /* Present */
+ d.d = 1; /* 32-bit */
+
+ write_gdt_entry(get_cpu_gdt_rw(cpu), GDT_ENTRY_CPUNODE, &d, DESCTYPE_S);
+}
+
+#ifdef CONFIG_X86_64
+static inline void ucode_cpu_init(int cpu) { }
+
+static inline void tss_setup_ist(struct tss_struct *tss)
+{
+ /* Set up the per-CPU TSS IST stacks */
+ tss->x86_tss.ist[IST_INDEX_DF] = __this_cpu_ist_top_va(DF);
+ tss->x86_tss.ist[IST_INDEX_NMI] = __this_cpu_ist_top_va(NMI);
+ tss->x86_tss.ist[IST_INDEX_DB] = __this_cpu_ist_top_va(DB);
+ tss->x86_tss.ist[IST_INDEX_MCE] = __this_cpu_ist_top_va(MCE);
+ /* Only mapped when SEV-ES is active */
+ tss->x86_tss.ist[IST_INDEX_VC] = __this_cpu_ist_top_va(VC);
+}
+
+#else /* CONFIG_X86_64 */
+
+static inline void ucode_cpu_init(int cpu)
+{
+ show_ucode_info_early();
+}
+
+static inline void tss_setup_ist(struct tss_struct *tss) { }
+
+#endif /* !CONFIG_X86_64 */
+
+static inline void tss_setup_io_bitmap(struct tss_struct *tss)
+{
+ tss->x86_tss.io_bitmap_base = IO_BITMAP_OFFSET_INVALID;
+
+#ifdef CONFIG_X86_IOPL_IOPERM
+ tss->io_bitmap.prev_max = 0;
+ tss->io_bitmap.prev_sequence = 0;
+ memset(tss->io_bitmap.bitmap, 0xff, sizeof(tss->io_bitmap.bitmap));
+ /*
+ * Invalidate the extra array entry past the end of the all
+ * permission bitmap as required by the hardware.
+ */
+ tss->io_bitmap.mapall[IO_BITMAP_LONGS] = ~0UL;
+#endif
+}
+
+/*
+ * Setup everything needed to handle exceptions from the IDT, including the IST
+ * exceptions which use paranoid_entry().
+ */
+void cpu_init_exception_handling(void)
+{
+ struct tss_struct *tss = this_cpu_ptr(&cpu_tss_rw);
+ int cpu = raw_smp_processor_id();
+
+ /* paranoid_entry() gets the CPU number from the GDT */
+ setup_getcpu(cpu);
+
+ /* IST vectors need TSS to be set up. */
+ tss_setup_ist(tss);
+ tss_setup_io_bitmap(tss);
+ set_tss_desc(cpu, &get_cpu_entry_area(cpu)->tss.x86_tss);
+
+ load_TR_desc();
+
+ /* GHCB needs to be setup to handle #VC. */
+ setup_ghcb();
+
+ /* Finally load the IDT */
+ load_current_idt();
+}
+
+/*
+ * cpu_init() initializes state that is per-CPU. Some data is already
+ * initialized (naturally) in the bootstrap process, such as the GDT. We
+ * reload it nevertheless, this function acts as a 'CPU state barrier',
+ * nothing should get across.
+ */
+void cpu_init(void)
+{
+ struct task_struct *cur = current;
+ int cpu = raw_smp_processor_id();
+
+ ucode_cpu_init(cpu);
+
+#ifdef CONFIG_NUMA
+ if (this_cpu_read(numa_node) == 0 &&
+ early_cpu_to_node(cpu) != NUMA_NO_NODE)
+ set_numa_node(early_cpu_to_node(cpu));
+#endif
+ pr_debug("Initializing CPU#%d\n", cpu);
+
+ if (IS_ENABLED(CONFIG_X86_64) || cpu_feature_enabled(X86_FEATURE_VME) ||
+ boot_cpu_has(X86_FEATURE_TSC) || boot_cpu_has(X86_FEATURE_DE))
+ cr4_clear_bits(X86_CR4_VME|X86_CR4_PVI|X86_CR4_TSD|X86_CR4_DE);
+
+ if (IS_ENABLED(CONFIG_X86_64)) {
+ loadsegment(fs, 0);
+ memset(cur->thread.tls_array, 0, GDT_ENTRY_TLS_ENTRIES * 8);
+ syscall_init();
+
+ wrmsrl(MSR_FS_BASE, 0);
+ wrmsrl(MSR_KERNEL_GS_BASE, 0);
+ barrier();
+
+ x2apic_setup();
+ }
+
+ mmgrab(&init_mm);
+ cur->active_mm = &init_mm;
+ BUG_ON(cur->mm);
+ initialize_tlbstate_and_flush();
+ enter_lazy_tlb(&init_mm, cur);
+
+ /*
+ * sp0 points to the entry trampoline stack regardless of what task
+ * is running.
+ */
+ load_sp0((unsigned long)(cpu_entry_stack(cpu) + 1));
+
+ load_mm_ldt(&init_mm);
+
+ clear_all_debug_regs();
+ dbg_restore_debug_regs();
+
+ doublefault_init_cpu_tss();
+
+ if (is_uv_system())
+ uv_cpu_init();
+
+ load_fixmap_gdt(cpu);
+}
+
+#ifdef CONFIG_MICROCODE_LATE_LOADING
+/**
+ * store_cpu_caps() - Store a snapshot of CPU capabilities
+ * @curr_info: Pointer where to store it
+ *
+ * Returns: None
+ */
+void store_cpu_caps(struct cpuinfo_x86 *curr_info)
+{
+ /* Reload CPUID max function as it might've changed. */
+ curr_info->cpuid_level = cpuid_eax(0);
+
+ /* Copy all capability leafs and pick up the synthetic ones. */
+ memcpy(&curr_info->x86_capability, &boot_cpu_data.x86_capability,
+ sizeof(curr_info->x86_capability));
+
+ /* Get the hardware CPUID leafs */
+ get_cpu_cap(curr_info);
+}
+
+/**
+ * microcode_check() - Check if any CPU capabilities changed after an update.
+ * @prev_info: CPU capabilities stored before an update.
+ *
+ * The microcode loader calls this upon late microcode load to recheck features,
+ * only when microcode has been updated. Caller holds and CPU hotplug lock.
+ *
+ * Return: None
+ */
+void microcode_check(struct cpuinfo_x86 *prev_info)
+{
+ struct cpuinfo_x86 curr_info;
+
+ perf_check_microcode();
+
+ amd_check_microcode();
+
+ store_cpu_caps(&curr_info);
+
+ if (!memcmp(&prev_info->x86_capability, &curr_info.x86_capability,
+ sizeof(prev_info->x86_capability)))
+ return;
+
+ pr_warn("x86/CPU: CPU features have changed after loading microcode, but might not take effect.\n");
+ pr_warn("x86/CPU: Please consider either early loading through initrd/built-in or a potential BIOS update.\n");
+}
+#endif
+
+/*
+ * Invoked from core CPU hotplug code after hotplug operations
+ */
+void arch_smt_update(void)
+{
+ /* Handle the speculative execution misfeatures */
+ cpu_bugs_smt_update();
+ /* Check whether IPI broadcasting can be enabled */
+ apic_smt_update();
+}
+
+void __init arch_cpu_finalize_init(void)
+{
+ identify_boot_cpu();
+
+ /*
+ * identify_boot_cpu() initialized SMT support information, let the
+ * core code know.
+ */
+ cpu_smt_set_num_threads(smp_num_siblings, smp_num_siblings);
+
+ if (!IS_ENABLED(CONFIG_SMP)) {
+ pr_info("CPU: ");
+ print_cpu_info(&boot_cpu_data);
+ }
+
+ cpu_select_mitigations();
+
+ arch_smt_update();
+
+ if (IS_ENABLED(CONFIG_X86_32)) {
+ /*
+ * Check whether this is a real i386 which is not longer
+ * supported and fixup the utsname.
+ */
+ if (boot_cpu_data.x86 < 4)
+ panic("Kernel requires i486+ for 'invlpg' and other features");
+
+ init_utsname()->machine[1] =
+ '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
+ }
+
+ /*
+ * Must be before alternatives because it might set or clear
+ * feature bits.
+ */
+ fpu__init_system();
+ fpu__init_cpu();
+
+ alternative_instructions();
+
+ if (IS_ENABLED(CONFIG_X86_64)) {
+ /*
+ * Make sure the first 2MB area is not mapped by huge pages
+ * There are typically fixed size MTRRs in there and overlapping
+ * MTRRs into large pages causes slow downs.
+ *
+ * Right now we don't do that with gbpages because there seems
+ * very little benefit for that case.
+ */
+ if (!direct_gbpages)
+ set_memory_4k((unsigned long)__va(0), 1);
+ } else {
+ fpu__init_check_bugs();
+ }
+
+ /*
+ * This needs to be called before any devices perform DMA
+ * operations that might use the SWIOTLB bounce buffers. It will
+ * mark the bounce buffers as decrypted so that their usage will
+ * not cause "plain-text" data to be decrypted when accessed. It
+ * must be called after late_time_init() so that Hyper-V x86/x64
+ * hypercalls work when the SWIOTLB bounce buffers are decrypted.
+ */
+ mem_encrypt_init();
+}