git: 84369dd52369 - main - x86: Probe the TSC frequency earlier
Date: Tue, 01 Mar 2022 14:39:55 UTC
The branch main has been updated by markj:
URL: https://cgit.FreeBSD.org/src/commit/?id=84369dd52369cbae28970dca20a53d3de1719907
commit 84369dd52369cbae28970dca20a53d3de1719907
Author: Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2022-03-01 14:39:35 +0000
Commit: Mark Johnston <markj@FreeBSD.org>
CommitDate: 2022-03-01 14:39:35 +0000
x86: Probe the TSC frequency earlier
This lets us use the TSC to implement early DELAY, limiting the use of
the sometimes-unreliable 8254 PIT.
PR: 262155
Reviewed by: emaste
Tested by: emaste, mike tancsa <mike@sentex.net>, Stefan Hegnauer <stefan.hegnauer@gmx.ch>
MFC after: 1 month
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D34367
---
sys/amd64/amd64/machdep.c | 14 +++++-
sys/i386/i386/machdep.c | 11 ++++-
sys/x86/include/clock.h | 3 +-
sys/x86/isa/clock.c | 4 +-
sys/x86/x86/tsc.c | 123 +++++++++++++++++++++++++---------------------
5 files changed, 94 insertions(+), 61 deletions(-)
diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c
index c629db566528..6eda6c9c8352 100644
--- a/sys/amd64/amd64/machdep.c
+++ b/sys/amd64/amd64/machdep.c
@@ -169,6 +169,9 @@ extern u_int64_t hammer_time(u_int64_t, u_int64_t);
static void cpu_startup(void *);
SYSINIT(cpu, SI_SUB_CPU, SI_ORDER_FIRST, cpu_startup, NULL);
+/* Probe 8254 PIT and TSC. */
+static void native_clock_source_init(void);
+
/* Preload data parse function */
static caddr_t native_parse_preload_data(u_int64_t);
@@ -177,8 +180,8 @@ static void native_parse_memmap(caddr_t, vm_paddr_t *, int *);
/* Default init_ops implementation. */
struct init_ops init_ops = {
- .parse_preload_data = native_parse_preload_data,
- .early_clock_source_init = i8254_init,
+ .parse_preload_data = native_parse_preload_data,
+ .early_clock_source_init = native_clock_source_init,
.early_delay = i8254_delay,
.parse_memmap = native_parse_memmap,
};
@@ -1160,6 +1163,13 @@ native_parse_preload_data(u_int64_t modulep)
return (kmdp);
}
+static void
+native_clock_source_init(void)
+{
+ i8254_init();
+ tsc_init();
+}
+
static void
amd64_kdb_init(void)
{
diff --git a/sys/i386/i386/machdep.c b/sys/i386/i386/machdep.c
index ee6752861c9e..6913c0691fd4 100644
--- a/sys/i386/i386/machdep.c
+++ b/sys/i386/i386/machdep.c
@@ -188,6 +188,8 @@ struct kva_md_info kmi;
static struct trapframe proc0_tf;
struct pcpu __pcpu[MAXCPU];
+static void i386_clock_source_init(void);
+
struct mtx icu_lock;
struct mem_range_softc mem_range_softc;
@@ -198,10 +200,17 @@ extern struct sysentvec elf32_freebsd_sysvec;
/* Default init_ops implementation. */
struct init_ops init_ops = {
- .early_clock_source_init = i8254_init,
+ .early_clock_source_init = i386_clock_source_init,
.early_delay = i8254_delay,
};
+static void
+i386_clock_source_init(void)
+{
+ i8254_init();
+ tsc_init();
+}
+
static void
cpu_startup(dummy)
void *dummy;
diff --git a/sys/x86/include/clock.h b/sys/x86/include/clock.h
index 83c8351ed31c..9aeccadf89aa 100644
--- a/sys/x86/include/clock.h
+++ b/sys/x86/include/clock.h
@@ -28,6 +28,7 @@ void i8254_init(void);
void i8254_delay(int);
void clock_init(void);
void lapic_calibrate(void);
+void tsc_init(void);
void tsc_calibrate(void);
/*
@@ -35,7 +36,7 @@ void tsc_calibrate(void);
*/
void startrtclock(void);
-void init_TSC(void);
+void start_TSC(void);
void resume_TSC(void);
#define HAS_TIMER_SPKR 1
diff --git a/sys/x86/isa/clock.c b/sys/x86/isa/clock.c
index 1178d35979c1..f21f847709cd 100644
--- a/sys/x86/isa/clock.c
+++ b/sys/x86/isa/clock.c
@@ -398,10 +398,10 @@ i8254_init(void)
}
void
-startrtclock()
+startrtclock(void)
{
- init_TSC();
+ start_TSC();
}
void
diff --git a/sys/x86/x86/tsc.c b/sys/x86/x86/tsc.c
index 317be8979feb..82ee358b6895 100644
--- a/sys/x86/x86/tsc.c
+++ b/sys/x86/x86/tsc.c
@@ -265,17 +265,42 @@ tsc_freq_8254(uint64_t *res)
static void
probe_tsc_freq(void)
{
- if (cpu_power_ecx & CPUID_PERF_STAT) {
- /*
- * XXX Some emulators expose host CPUID without actual support
- * for these MSRs. We must test whether they really work.
- */
- wrmsr(MSR_MPERF, 0);
- wrmsr(MSR_APERF, 0);
- DELAY(10);
- if (rdmsr(MSR_MPERF) > 0 && rdmsr(MSR_APERF) > 0)
- tsc_perf_stat = 1;
+#ifdef __i386__
+ /* The TSC is known to be broken on certain CPUs. */
+ switch (cpu_vendor_id) {
+ case CPU_VENDOR_AMD:
+ switch (cpu_id & 0xFF0) {
+ case 0x500:
+ /* K5 Model 0 */
+ tsc_disabled = 1;
+ return;
+ }
+ break;
+ case CPU_VENDOR_CENTAUR:
+ switch (cpu_id & 0xff0) {
+ case 0x540:
+ /*
+ * http://www.centtech.com/c6_data_sheet.pdf
+ *
+ * I-12 RDTSC may return incoherent values in EDX:EAX
+ * I-13 RDTSC hangs when certain event counters are used
+ */
+ tsc_disabled = 1;
+ return;
+ }
+ break;
+ case CPU_VENDOR_NSC:
+ switch (cpu_id & 0xff0) {
+ case 0x540:
+ if ((cpu_id & CPUID_STEPPING) == 0) {
+ tsc_disabled = 1;
+ return;
+ }
+ break;
+ }
+ break;
}
+#endif
switch (cpu_vendor_id) {
case CPU_VENDOR_AMD:
@@ -315,15 +340,18 @@ probe_tsc_freq(void)
break;
}
- if (tsc_freq_cpuid_vm())
- return;
-
- if (vm_guest == VM_GUEST_VMWARE) {
+ if (tsc_freq_cpuid_vm()) {
+ if (bootverbose)
+ printf(
+ "Early TSC frequency %juHz derived from hypervisor CPUID\n",
+ (uintmax_t)tsc_freq);
+ } else if (vm_guest == VM_GUEST_VMWARE) {
tsc_freq_vmware();
- return;
- }
-
- if (tsc_freq_cpuid(&tsc_freq)) {
+ if (bootverbose)
+ printf(
+ "Early TSC frequency %juHz derived from VMWare hypercall\n",
+ (uintmax_t)tsc_freq);
+ } else if (tsc_freq_cpuid(&tsc_freq)) {
/*
* If possible, use the value obtained from CPUID as the initial
* frequency. This will be refined later during boot but is
@@ -361,50 +389,26 @@ probe_tsc_freq(void)
"Early TSC frequency %juHz calibrated from 8254 PIT\n",
(uintmax_t)tsc_freq);
}
+
+ if (cpu_power_ecx & CPUID_PERF_STAT) {
+ /*
+ * XXX Some emulators expose host CPUID without actual support
+ * for these MSRs. We must test whether they really work.
+ */
+ wrmsr(MSR_MPERF, 0);
+ wrmsr(MSR_APERF, 0);
+ DELAY(10);
+ if (rdmsr(MSR_MPERF) > 0 && rdmsr(MSR_APERF) > 0)
+ tsc_perf_stat = 1;
+ }
}
void
-init_TSC(void)
+start_TSC(void)
{
-
if ((cpu_feature & CPUID_TSC) == 0 || tsc_disabled)
return;
-#ifdef __i386__
- /* The TSC is known to be broken on certain CPUs. */
- switch (cpu_vendor_id) {
- case CPU_VENDOR_AMD:
- switch (cpu_id & 0xFF0) {
- case 0x500:
- /* K5 Model 0 */
- return;
- }
- break;
- case CPU_VENDOR_CENTAUR:
- switch (cpu_id & 0xff0) {
- case 0x540:
- /*
- * http://www.centtech.com/c6_data_sheet.pdf
- *
- * I-12 RDTSC may return incoherent values in EDX:EAX
- * I-13 RDTSC hangs when certain event counters are used
- */
- return;
- }
- break;
- case CPU_VENDOR_NSC:
- switch (cpu_id & 0xff0) {
- case 0x540:
- if ((cpu_id & CPUID_STEPPING) == 0)
- return;
- break;
- }
- break;
- }
-#endif
-
- probe_tsc_freq();
-
/*
* Inform CPU accounting about our boot-time clock rate. This will
* be updated if someone loads a cpufreq driver after boot that
@@ -708,6 +712,15 @@ tsc_update_freq(uint64_t new_freq)
new_freq >> (int)(intptr_t)tsc_timecounter.tc_priv);
}
+void
+tsc_init(void)
+{
+ if ((cpu_feature & CPUID_TSC) == 0 || tsc_disabled)
+ return;
+
+ probe_tsc_freq();
+}
+
/*
* Perform late calibration of the TSC frequency once ACPI-based timecounters
* are available. At this point timehands are not set up, so we read the