FAILED: patch "[PATCH] intel_idle: Handle older CPUs, which stop the TSC in deeper C" failed to apply to 6.6-stable tree

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x c157d351460bcf202970e97e611cb6b54a3dd4a4
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2025030415-uncombed-drinking-e339@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From c157d351460bcf202970e97e611cb6b54a3dd4a4 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <[email protected]>
Date: Tue, 25 Feb 2025 23:37:08 +0100
Subject: [PATCH] intel_idle: Handle older CPUs, which stop the TSC in deeper C
states, correctly

The Intel idle driver is preferred over the ACPI processor idle driver, but fails to implement the work around for Core2 generation CPUs, where the TSC stops in C2 and deeper C-states. This causes stalls and boot delays, when the clocksource watchdog does not catch the unstable TSC before the CPU goes deep idle for the first time.

The ACPI driver marks the TSC unstable when it detects that the CPU supports C2 or deeper and the CPU does not have a non-stop TSC.

Add the equivivalent work around to the Intel idle driver to cure that.

index 118fe1d37c22..0fdb1d1316c4 100644
@@ -56,6 +56,7 @@
 #include <asm/intel-family.h>
 #include <asm/mwait.h>
 #include <asm/spec-ctrl.h>
+#include <asm/tsc.h>
 #include <asm/fpu/api.h>
 
 #define INTEL_IDLE_VERSION "0.5.1"

@@ -1799,6 +1800,9 @@ static void __init intel_idle_init_cstates_acpi(struct cpuidle_driver *drv)
 		if (intel_idle_state_needs_timer_stop(state))
 			state->flags |= CPUIDLE_FLAG_TIMER_STOP;
 
+		if (cx->type > ACPI_STATE_C1 && !boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
+			mark_tsc_unstable("TSC halts in idle");
+
 		state->enter = intel_idle;
 		state->enter_s2idle = intel_idle_s2idle;
 	}

commit c157d351460bcf202970e97e611cb6b54a3dd4a4 upstream.

The Intel idle driver is preferred over the ACPI processor idle driver, but fails to implement the work around for Core2 generation CPUs, where the TSC stops in C2 and deeper C-states. This causes stalls and boot delays, when the clocksource watchdog does not catch the unstable TSC before the CPU goes deep idle for the first time.

The ACPI driver marks the TSC unstable when it detects that the CPU supports C2 or deeper and the CPU does not have a non-stop TSC.

Add the equivivalent work around to the Intel idle driver to cure that.

---
Backport to 6.6.y and 6.1.y

---
 drivers/idle/intel_idle.c |    4 ++++
 1 file changed, 4 insertions(+)

@@ -56,6 +56,7 @@
 #include <asm/nospec-branch.h>
 #include <asm/mwait.h>
 #include <asm/msr.h>
+#include <asm/tsc.h>
 #include <asm/fpu/api.h>
 
 #define INTEL_IDLE_VERSION "0.5.1"

@@ -1573,6 +1574,9 @@ static void __init intel_idle_init_cstat
 		if (intel_idle_state_needs_timer_stop(state))
 			state->flags |= CPUIDLE_FLAG_TIMER_STOP;
 
+		if (cx->type > ACPI_STATE_C1 && !boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
+			mark_tsc_unstable("TSC halts in idle");
+
 		state->enter = intel_idle;
 		state->enter_s2idle = intel_idle_s2idle;
 	}