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linux/arch/x86/kernel/cpu/intel.c
Pallipadi, Venkatesh 6c56ccecf0 x86: Reenable TSC sync check at boot, even with NONSTOP_TSC 
Commit 83ce4009 did the following change
If the TSC is constant and non-stop, also set it reliable.

But, there seems to be few systems that will end up with TSC warp across
sockets, depending on how the cpus come out of reset. Skipping TSC sync
test on such systems may result in time inconsistency later.

So, reenable TSC sync test even on constant and non-stop TSC systems.
Set, sched_clock_stable to 1 by default and reset it in
mark_tsc_unstable, if TSC sync fails.

This change still gives perf benefit mentioned in 83ce4009 for systems
where TSC is reliable.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <20091217202702.GA18015@linux-os.sc.intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
2009-12-17 14:44:35 -08:00

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#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/bitops.h>
#include <linux/smp.h>
#include <linux/sched.h>
#include <linux/thread_info.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <asm/processor.h>
#include <asm/pgtable.h>
#include <asm/msr.h>
#include <asm/ds.h>
#include <asm/bugs.h>
#include <asm/cpu.h>
#ifdef CONFIG_X86_64
#include <linux/topology.h>
#include <asm/numa_64.h>
#endif
#include "cpu.h"
#ifdef CONFIG_X86_LOCAL_APIC
#include <asm/mpspec.h>
#include <asm/apic.h>
#endif
static void __cpuinit early_init_intel(struct cpuinfo_x86 *c)
{
/* Unmask CPUID levels if masked: */
if (c->x86 > 6 || (c->x86 == 6 && c->x86_model >= 0xd)) {
u64 misc_enable;
rdmsrl(MSR_IA32_MISC_ENABLE, misc_enable);
if (misc_enable & MSR_IA32_MISC_ENABLE_LIMIT_CPUID) {
misc_enable &= ~MSR_IA32_MISC_ENABLE_LIMIT_CPUID;
wrmsrl(MSR_IA32_MISC_ENABLE, misc_enable);
c->cpuid_level = cpuid_eax(0);
}
}
if ((c->x86 == 0xf && c->x86_model >= 0x03) ||
(c->x86 == 0x6 && c->x86_model >= 0x0e))
set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
#ifdef CONFIG_X86_64
set_cpu_cap(c, X86_FEATURE_SYSENTER32);
#else
/* Netburst reports 64 bytes clflush size, but does IO in 128 bytes */
if (c->x86 == 15 && c->x86_cache_alignment == 64)
c->x86_cache_alignment = 128;
#endif
/* CPUID workaround for 0F33/0F34 CPU */
if (c->x86 == 0xF && c->x86_model == 0x3
&& (c->x86_mask == 0x3 || c->x86_mask == 0x4))
c->x86_phys_bits = 36;
/*
* c->x86_power is 8000_0007 edx. Bit 8 is TSC runs at constant rate
* with P/T states and does not stop in deep C-states.
*
* It is also reliable across cores and sockets. (but not across
* cabinets - we turn it off in that case explicitly.)
*/
if (c->x86_power & (1 << 8)) {
set_cpu_cap(c, X86_FEATURE_CONSTANT_TSC);
set_cpu_cap(c, X86_FEATURE_NONSTOP_TSC);
sched_clock_stable = 1;
}
/*
* There is a known erratum on Pentium III and Core Solo
* and Core Duo CPUs.
* " Page with PAT set to WC while associated MTRR is UC
* may consolidate to UC "
* Because of this erratum, it is better to stick with
* setting WC in MTRR rather than using PAT on these CPUs.
*
* Enable PAT WC only on P4, Core 2 or later CPUs.
*/
if (c->x86 == 6 && c->x86_model < 15)
clear_cpu_cap(c, X86_FEATURE_PAT);
#ifdef CONFIG_KMEMCHECK
/*
* P4s have a "fast strings" feature which causes single-
* stepping REP instructions to only generate a #DB on
* cache-line boundaries.
*
* Ingo Molnar reported a Pentium D (model 6) and a Xeon
* (model 2) with the same problem.
*/
if (c->x86 == 15) {
u64 misc_enable;
rdmsrl(MSR_IA32_MISC_ENABLE, misc_enable);
if (misc_enable & MSR_IA32_MISC_ENABLE_FAST_STRING) {
printk(KERN_INFO "kmemcheck: Disabling fast string operations\n");
misc_enable &= ~MSR_IA32_MISC_ENABLE_FAST_STRING;
wrmsrl(MSR_IA32_MISC_ENABLE, misc_enable);
}
}
#endif
}
#ifdef CONFIG_X86_32
/*
* Early probe support logic for ppro memory erratum #50
*
* This is called before we do cpu ident work
*/
int __cpuinit ppro_with_ram_bug(void)
{
/* Uses data from early_cpu_detect now */
if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
boot_cpu_data.x86 == 6 &&
boot_cpu_data.x86_model == 1 &&
boot_cpu_data.x86_mask < 8) {
printk(KERN_INFO "Pentium Pro with Errata#50 detected. Taking evasive action.\n");
return 1;
}
return 0;
}
#ifdef CONFIG_X86_F00F_BUG
static void __cpuinit trap_init_f00f_bug(void)
{
__set_fixmap(FIX_F00F_IDT, __pa(&idt_table), PAGE_KERNEL_RO);
/*
* Update the IDT descriptor and reload the IDT so that
* it uses the read-only mapped virtual address.
*/
idt_descr.address = fix_to_virt(FIX_F00F_IDT);
load_idt(&idt_descr);
}
#endif
static void __cpuinit intel_smp_check(struct cpuinfo_x86 *c)
{
#ifdef CONFIG_SMP
/* calling is from identify_secondary_cpu() ? */
if (c->cpu_index == boot_cpu_id)
return;
/*
* Mask B, Pentium, but not Pentium MMX
*/
if (c->x86 == 5 &&
c->x86_mask >= 1 && c->x86_mask <= 4 &&
c->x86_model <= 3) {
/*
* Remember we have B step Pentia with bugs
*/
WARN_ONCE(1, "WARNING: SMP operation may be unreliable"
"with B stepping processors.\n");
}
#endif
}
static void __cpuinit intel_workarounds(struct cpuinfo_x86 *c)
{
unsigned long lo, hi;
#ifdef CONFIG_X86_F00F_BUG
/*
* All current models of Pentium and Pentium with MMX technology CPUs
* have the F0 0F bug, which lets nonprivileged users lock up the
* system.
* Note that the workaround only should be initialized once...
*/
c->f00f_bug = 0;
if (!paravirt_enabled() && c->x86 == 5) {
static int f00f_workaround_enabled;
c->f00f_bug = 1;
if (!f00f_workaround_enabled) {
trap_init_f00f_bug();
printk(KERN_NOTICE "Intel Pentium with F0 0F bug - workaround enabled.\n");
f00f_workaround_enabled = 1;
}
}
#endif
/*
* SEP CPUID bug: Pentium Pro reports SEP but doesn't have it until
* model 3 mask 3
*/
if ((c->x86<<8 | c->x86_model<<4 | c->x86_mask) < 0x633)
clear_cpu_cap(c, X86_FEATURE_SEP);
/*
* P4 Xeon errata 037 workaround.
* Hardware prefetcher may cause stale data to be loaded into the cache.
*/
if ((c->x86 == 15) && (c->x86_model == 1) && (c->x86_mask == 1)) {
rdmsr(MSR_IA32_MISC_ENABLE, lo, hi);
if ((lo & MSR_IA32_MISC_ENABLE_PREFETCH_DISABLE) == 0) {
printk (KERN_INFO "CPU: C0 stepping P4 Xeon detected.\n");
printk (KERN_INFO "CPU: Disabling hardware prefetching (Errata 037)\n");
lo |= MSR_IA32_MISC_ENABLE_PREFETCH_DISABLE;
wrmsr(MSR_IA32_MISC_ENABLE, lo, hi);
}
}
/*
* See if we have a good local APIC by checking for buggy Pentia,
* i.e. all B steppings and the C2 stepping of P54C when using their
* integrated APIC (see 11AP erratum in "Pentium Processor
* Specification Update").
*/
if (cpu_has_apic && (c->x86<<8 | c->x86_model<<4) == 0x520 &&
(c->x86_mask < 0x6 || c->x86_mask == 0xb))
set_cpu_cap(c, X86_FEATURE_11AP);
#ifdef CONFIG_X86_INTEL_USERCOPY
/*
* Set up the preferred alignment for movsl bulk memory moves
*/
switch (c->x86) {
case 4: /* 486: untested */
break;
case 5: /* Old Pentia: untested */
break;
case 6: /* PII/PIII only like movsl with 8-byte alignment */
movsl_mask.mask = 7;
break;
case 15: /* P4 is OK down to 8-byte alignment */
movsl_mask.mask = 7;
break;
}
#endif
#ifdef CONFIG_X86_NUMAQ
numaq_tsc_disable();
#endif
intel_smp_check(c);
}
#else
static void __cpuinit intel_workarounds(struct cpuinfo_x86 *c)
{
}
#endif
static void __cpuinit srat_detect_node(struct cpuinfo_x86 *c)
{
#if defined(CONFIG_NUMA) && defined(CONFIG_X86_64)
unsigned node;
int cpu = smp_processor_id();
int apicid = cpu_has_apic ? hard_smp_processor_id() : c->apicid;
/* Don't do the funky fallback heuristics the AMD version employs
for now. */
node = apicid_to_node[apicid];
if (node == NUMA_NO_NODE)
node = first_node(node_online_map);
else if (!node_online(node)) {
/* reuse the value from init_cpu_to_node() */
node = cpu_to_node(cpu);
}
numa_set_node(cpu, node);
#endif
}
/*
* find out the number of processor cores on the die
*/
static int __cpuinit intel_num_cpu_cores(struct cpuinfo_x86 *c)
{
unsigned int eax, ebx, ecx, edx;
if (c->cpuid_level < 4)
return 1;
/* Intel has a non-standard dependency on %ecx for this CPUID level. */
cpuid_count(4, 0, &eax, &ebx, &ecx, &edx);
if (eax & 0x1f)
return (eax >> 26) + 1;
else
return 1;
}
static void __cpuinit detect_vmx_virtcap(struct cpuinfo_x86 *c)
{
/* Intel VMX MSR indicated features */
#define X86_VMX_FEATURE_PROC_CTLS_TPR_SHADOW 0x00200000
#define X86_VMX_FEATURE_PROC_CTLS_VNMI 0x00400000
#define X86_VMX_FEATURE_PROC_CTLS_2ND_CTLS 0x80000000
#define X86_VMX_FEATURE_PROC_CTLS2_VIRT_APIC 0x00000001
#define X86_VMX_FEATURE_PROC_CTLS2_EPT 0x00000002
#define X86_VMX_FEATURE_PROC_CTLS2_VPID 0x00000020
u32 vmx_msr_low, vmx_msr_high, msr_ctl, msr_ctl2;
clear_cpu_cap(c, X86_FEATURE_TPR_SHADOW);
clear_cpu_cap(c, X86_FEATURE_VNMI);
clear_cpu_cap(c, X86_FEATURE_FLEXPRIORITY);
clear_cpu_cap(c, X86_FEATURE_EPT);
clear_cpu_cap(c, X86_FEATURE_VPID);
rdmsr(MSR_IA32_VMX_PROCBASED_CTLS, vmx_msr_low, vmx_msr_high);
msr_ctl = vmx_msr_high | vmx_msr_low;
if (msr_ctl & X86_VMX_FEATURE_PROC_CTLS_TPR_SHADOW)
set_cpu_cap(c, X86_FEATURE_TPR_SHADOW);
if (msr_ctl & X86_VMX_FEATURE_PROC_CTLS_VNMI)
set_cpu_cap(c, X86_FEATURE_VNMI);
if (msr_ctl & X86_VMX_FEATURE_PROC_CTLS_2ND_CTLS) {
rdmsr(MSR_IA32_VMX_PROCBASED_CTLS2,
vmx_msr_low, vmx_msr_high);
msr_ctl2 = vmx_msr_high | vmx_msr_low;
if ((msr_ctl2 & X86_VMX_FEATURE_PROC_CTLS2_VIRT_APIC) &&
(msr_ctl & X86_VMX_FEATURE_PROC_CTLS_TPR_SHADOW))
set_cpu_cap(c, X86_FEATURE_FLEXPRIORITY);
if (msr_ctl2 & X86_VMX_FEATURE_PROC_CTLS2_EPT)
set_cpu_cap(c, X86_FEATURE_EPT);
if (msr_ctl2 & X86_VMX_FEATURE_PROC_CTLS2_VPID)
set_cpu_cap(c, X86_FEATURE_VPID);
}
}
static void __cpuinit init_intel(struct cpuinfo_x86 *c)
{
unsigned int l2 = 0;
early_init_intel(c);
intel_workarounds(c);
/*
* Detect the extended topology information if available. This
* will reinitialise the initial_apicid which will be used
* in init_intel_cacheinfo()
*/
detect_extended_topology(c);
l2 = init_intel_cacheinfo(c);
if (c->cpuid_level > 9) {
unsigned eax = cpuid_eax(10);
/* Check for version and the number of counters */
if ((eax & 0xff) && (((eax>>8) & 0xff) > 1))
set_cpu_cap(c, X86_FEATURE_ARCH_PERFMON);
}
if (c->cpuid_level > 6) {
unsigned ecx = cpuid_ecx(6);
if (ecx & 0x01)
set_cpu_cap(c, X86_FEATURE_APERFMPERF);
}
if (cpu_has_xmm2)
set_cpu_cap(c, X86_FEATURE_LFENCE_RDTSC);
if (cpu_has_ds) {
unsigned int l1;
rdmsr(MSR_IA32_MISC_ENABLE, l1, l2);
if (!(l1 & (1<<11)))
set_cpu_cap(c, X86_FEATURE_BTS);
if (!(l1 & (1<<12)))
set_cpu_cap(c, X86_FEATURE_PEBS);
ds_init_intel(c);
}
if (c->x86 == 6 && c->x86_model == 29 && cpu_has_clflush)
set_cpu_cap(c, X86_FEATURE_CLFLUSH_MONITOR);
#ifdef CONFIG_X86_64
if (c->x86 == 15)
c->x86_cache_alignment = c->x86_clflush_size * 2;
if (c->x86 == 6)
set_cpu_cap(c, X86_FEATURE_REP_GOOD);
#else
/*
* Names for the Pentium II/Celeron processors
* detectable only by also checking the cache size.
* Dixon is NOT a Celeron.
*/
if (c->x86 == 6) {
char *p = NULL;
switch (c->x86_model) {
case 5:
if (c->x86_mask == 0) {
if (l2 == 0)
p = "Celeron (Covington)";
else if (l2 == 256)
p = "Mobile Pentium II (Dixon)";
}
break;
case 6:
if (l2 == 128)
p = "Celeron (Mendocino)";
else if (c->x86_mask == 0 || c->x86_mask == 5)
p = "Celeron-A";
break;
case 8:
if (l2 == 128)
p = "Celeron (Coppermine)";
break;
}
if (p)
strcpy(c->x86_model_id, p);
}
if (c->x86 == 15)
set_cpu_cap(c, X86_FEATURE_P4);
if (c->x86 == 6)
set_cpu_cap(c, X86_FEATURE_P3);
#endif
if (!cpu_has(c, X86_FEATURE_XTOPOLOGY)) {
/*
* let's use the legacy cpuid vector 0x1 and 0x4 for topology
* detection.
*/
c->x86_max_cores = intel_num_cpu_cores(c);
#ifdef CONFIG_X86_32
detect_ht(c);
#endif
}
/* Work around errata */
srat_detect_node(c);
if (cpu_has(c, X86_FEATURE_VMX))
detect_vmx_virtcap(c);
}
#ifdef CONFIG_X86_32
static unsigned int __cpuinit intel_size_cache(struct cpuinfo_x86 *c, unsigned int size)
{
/*
* Intel PIII Tualatin. This comes in two flavours.
* One has 256kb of cache, the other 512. We have no way
* to determine which, so we use a boottime override
* for the 512kb model, and assume 256 otherwise.
*/
if ((c->x86 == 6) && (c->x86_model == 11) && (size == 0))
size = 256;
return size;
}
#endif
static const struct cpu_dev __cpuinitconst intel_cpu_dev = {
.c_vendor = "Intel",
.c_ident = { "GenuineIntel" },
#ifdef CONFIG_X86_32
.c_models = {
{ .vendor = X86_VENDOR_INTEL, .family = 4, .model_names =
{
[0] = "486 DX-25/33",
[1] = "486 DX-50",
[2] = "486 SX",
[3] = "486 DX/2",
[4] = "486 SL",
[5] = "486 SX/2",
[7] = "486 DX/2-WB",
[8] = "486 DX/4",
[9] = "486 DX/4-WB"
}
},
{ .vendor = X86_VENDOR_INTEL, .family = 5, .model_names =
{
[0] = "Pentium 60/66 A-step",
[1] = "Pentium 60/66",
[2] = "Pentium 75 - 200",
[3] = "OverDrive PODP5V83",
[4] = "Pentium MMX",
[7] = "Mobile Pentium 75 - 200",
[8] = "Mobile Pentium MMX"
}
},
{ .vendor = X86_VENDOR_INTEL, .family = 6, .model_names =
{
[0] = "Pentium Pro A-step",
[1] = "Pentium Pro",
[3] = "Pentium II (Klamath)",
[4] = "Pentium II (Deschutes)",
[5] = "Pentium II (Deschutes)",
[6] = "Mobile Pentium II",
[7] = "Pentium III (Katmai)",
[8] = "Pentium III (Coppermine)",
[10] = "Pentium III (Cascades)",
[11] = "Pentium III (Tualatin)",
}
},
{ .vendor = X86_VENDOR_INTEL, .family = 15, .model_names =
{
[0] = "Pentium 4 (Unknown)",
[1] = "Pentium 4 (Willamette)",
[2] = "Pentium 4 (Northwood)",
[4] = "Pentium 4 (Foster)",
[5] = "Pentium 4 (Foster)",
}
},
},
.c_size_cache = intel_size_cache,
#endif
.c_early_init = early_init_intel,
.c_init = init_intel,
.c_x86_vendor = X86_VENDOR_INTEL,
};
cpu_dev_register(intel_cpu_dev);
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