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authorLinus Torvalds <torvalds@linux-foundation.org>2017-11-14 06:07:38 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2017-11-14 06:07:38 +0300
commit99306dfc067e6098365d395168b6fd5db3095292 (patch)
treef3da80eba0c633da69bcad47df565f06ff075947 /arch/x86/kernel/tsc_sync.c
parent3643b7e05b16a9fc4077ec56b655a1f8547d259c (diff)
parent120fc3fbb7787fb70240190cc9c113d1f6523c42 (diff)
downloadlinux-99306dfc067e6098365d395168b6fd5db3095292.tar.xz
Merge branch 'x86-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 timer updates from Thomas Gleixner: "These updates are related to TSC handling: - Support platforms which have synchronized TSCs but the boot CPU has a non zero TSC_ADJUST value, which is considered a firmware bug on normal systems. This applies to HPE/SGI UV platforms where the platform firmware uses TSC_ADJUST to ensure TSC synchronization across a huge number of sockets, but due to power on timings the boot CPU cannot be guaranteed to have a zero TSC_ADJUST register value. - Fix the ordering of udelay calibration and kvmclock_init() - Cleanup the udelay and calibration code" * 'x86-timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/tsc: Mark cyc2ns_init() and detect_art() __init x86/platform/UV: Mark tsc_check_sync as an init function x86/tsc: Make CONFIG_X86_TSC=n build work again x86/platform/UV: Add check of TSC state set by UV BIOS x86/tsc: Provide a means to disable TSC ART x86/tsc: Drastically reduce the number of firmware bug warnings x86/tsc: Skip TSC test and error messages if already unstable x86/tsc: Add option that TSC on Socket 0 being non-zero is valid x86/timers: Move simple_udelay_calibration() past kvmclock_init() x86/timers: Make recalibrate_cpu_khz() void x86/timers: Move the simple udelay calibration to tsc.h
Diffstat (limited to 'arch/x86/kernel/tsc_sync.c')
-rw-r--r--arch/x86/kernel/tsc_sync.c56
1 files changed, 46 insertions, 10 deletions
diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c
index e76a9881306b..ec534f978867 100644
--- a/arch/x86/kernel/tsc_sync.c
+++ b/arch/x86/kernel/tsc_sync.c
@@ -31,6 +31,20 @@ struct tsc_adjust {
static DEFINE_PER_CPU(struct tsc_adjust, tsc_adjust);
+/*
+ * TSC's on different sockets may be reset asynchronously.
+ * This may cause the TSC ADJUST value on socket 0 to be NOT 0.
+ */
+bool __read_mostly tsc_async_resets;
+
+void mark_tsc_async_resets(char *reason)
+{
+ if (tsc_async_resets)
+ return;
+ tsc_async_resets = true;
+ pr_info("tsc: Marking TSC async resets true due to %s\n", reason);
+}
+
void tsc_verify_tsc_adjust(bool resume)
{
struct tsc_adjust *adj = this_cpu_ptr(&tsc_adjust);
@@ -39,6 +53,10 @@ void tsc_verify_tsc_adjust(bool resume)
if (!boot_cpu_has(X86_FEATURE_TSC_ADJUST))
return;
+ /* Skip unnecessary error messages if TSC already unstable */
+ if (check_tsc_unstable())
+ return;
+
/* Rate limit the MSR check */
if (!resume && time_before(jiffies, adj->nextcheck))
return;
@@ -72,12 +90,22 @@ static void tsc_sanitize_first_cpu(struct tsc_adjust *cur, s64 bootval,
* non zero. We don't do that on non boot cpus because physical
* hotplug should have set the ADJUST register to a value > 0 so
* the TSC is in sync with the already running cpus.
+ *
+ * Also don't force the ADJUST value to zero if that is a valid value
+ * for socket 0 as determined by the system arch. This is required
+ * when multiple sockets are reset asynchronously with each other
+ * and socket 0 may not have an TSC ADJUST value of 0.
*/
if (bootcpu && bootval != 0) {
- pr_warn(FW_BUG "TSC ADJUST: CPU%u: %lld force to 0\n", cpu,
- bootval);
- wrmsrl(MSR_IA32_TSC_ADJUST, 0);
- bootval = 0;
+ if (likely(!tsc_async_resets)) {
+ pr_warn(FW_BUG "TSC ADJUST: CPU%u: %lld force to 0\n",
+ cpu, bootval);
+ wrmsrl(MSR_IA32_TSC_ADJUST, 0);
+ bootval = 0;
+ } else {
+ pr_info("TSC ADJUST: CPU%u: %lld NOT forced to 0\n",
+ cpu, bootval);
+ }
}
cur->adjusted = bootval;
}
@@ -91,6 +119,10 @@ bool __init tsc_store_and_check_tsc_adjust(bool bootcpu)
if (!boot_cpu_has(X86_FEATURE_TSC_ADJUST))
return false;
+ /* Skip unnecessary error messages if TSC already unstable */
+ if (check_tsc_unstable())
+ return false;
+
rdmsrl(MSR_IA32_TSC_ADJUST, bootval);
cur->bootval = bootval;
cur->nextcheck = jiffies + HZ;
@@ -119,6 +151,13 @@ bool tsc_store_and_check_tsc_adjust(bool bootcpu)
cur->warned = false;
/*
+ * If a non-zero TSC value for socket 0 may be valid then the default
+ * adjusted value cannot assumed to be zero either.
+ */
+ if (tsc_async_resets)
+ cur->adjusted = bootval;
+
+ /*
* Check whether this CPU is the first in a package to come up. In
* this case do not check the boot value against another package
* because the new package might have been physically hotplugged,
@@ -139,10 +178,9 @@ bool tsc_store_and_check_tsc_adjust(bool bootcpu)
* Compare the boot value and complain if it differs in the
* package.
*/
- if (bootval != ref->bootval) {
- pr_warn(FW_BUG "TSC ADJUST differs: Reference CPU%u: %lld CPU%u: %lld\n",
- refcpu, ref->bootval, cpu, bootval);
- }
+ if (bootval != ref->bootval)
+ printk_once(FW_BUG "TSC ADJUST differs within socket(s), fixing all errors\n");
+
/*
* The TSC_ADJUST values in a package must be the same. If the boot
* value on this newly upcoming CPU differs from the adjustment
@@ -150,8 +188,6 @@ bool tsc_store_and_check_tsc_adjust(bool bootcpu)
* adjusted value.
*/
if (bootval != ref->adjusted) {
- pr_warn("TSC ADJUST synchronize: Reference CPU%u: %lld CPU%u: %lld\n",
- refcpu, ref->adjusted, cpu, bootval);
cur->adjusted = ref->adjusted;
wrmsrl(MSR_IA32_TSC_ADJUST, ref->adjusted);
}