linux-kernel - [PATCH v2 01/17] x86/smpboot: Remove confusing quirk usage in INIT delay

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Message-ID: <20250211194407.2577252-2-sohil.mehta@intel.com>
Date: Tue, 11 Feb 2025 19:43:51 +0000
From: Sohil Mehta <sohil.mehta@...el.com>
To: x86@...nel.org,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Tony Luck <tony.luck@...el.com>
Cc: Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Ian Rogers <irogers@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Kan Liang <kan.liang@...ux.intel.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Borislav Petkov <bp@...en8.de>,
	"H . Peter Anvin" <hpa@...or.com>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	Len Brown <lenb@...nel.org>,
	Andy Lutomirski <luto@...nel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Fenghua Yu <fenghua.yu@...el.com>,
	Jean Delvare <jdelvare@...e.com>,
	Guenter Roeck <linux@...ck-us.net>,
	Zhang Rui <rui.zhang@...el.com>,
	Andrew Cooper <andrew.cooper3@...rix.com>,
	David Laight <david.laight.linux@...il.com>,
	Sohil Mehta <sohil.mehta@...el.com>,
	linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-acpi@...r.kernel.org,
	linux-pm@...r.kernel.org,
	linux-hwmon@...r.kernel.org
Subject: [PATCH v2 01/17] x86/smpboot: Remove confusing quirk usage in INIT delay

The usage of the "quirk" wording while setting the INIT assert -
de-assert delay is misleading. The comments suggest that modern
processors need the quirk (to clear init_udelay) while legacy processors
don't need the quirk (to use the default init_udelay).

With a lot more modern processors, the wording should be inverted if at
all needed. Instead, simplify the comments and the code by getting rid of
"quirk" usage altogether.

No functional change.

Signed-off-by: Sohil Mehta <sohil.mehta@...el.com>

---

v2: New patch

---
 arch/x86/kernel/smpboot.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index c10850ae6f09..eb91ed0f2a06 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -654,10 +654,9 @@ static void impress_friends(void)
  * But that slows boot and resume on modern processors, which include
  * many cores and don't require that delay.
  *
- * Cmdline "init_cpu_udelay=" is available to over-ride this delay.
- * Modern processor families are quirked to remove the delay entirely.
+ * Cmdline "cpu_init_udelay=" is available to override this delay.
  */
-#define UDELAY_10MS_DEFAULT 10000
+#define UDELAY_10MS_LEGACY 10000
 
 static unsigned int init_udelay = UINT_MAX;
 
@@ -669,7 +668,7 @@ static int __init cpu_init_udelay(char *str)
 }
 early_param("cpu_init_udelay", cpu_init_udelay);
 
-static void __init smp_quirk_init_udelay(void)
+static void __init smp_set_init_udelay(void)
 {
 	/* if cmdline changed it from default, leave it alone */
 	if (init_udelay != UINT_MAX)
@@ -683,7 +682,7 @@ static void __init smp_quirk_init_udelay(void)
 		return;
 	}
 	/* else, use legacy delay */
-	init_udelay = UDELAY_10MS_DEFAULT;
+	init_udelay = UDELAY_10MS_LEGACY;
 }
 
 /*
@@ -1094,7 +1093,7 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
 
 	uv_system_init();
 
-	smp_quirk_init_udelay();
+	smp_set_init_udelay();
 
 	speculative_store_bypass_ht_init();
 
-- 
2.43.0