linux-kernel - [PATCH AUTOSEL 6.12 067/486] x86/smpboot: Fix INIT delay assignment for extended Intel Families

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Message-Id: <20250505223922.2682012-67-sashal@kernel.org>
Date: Mon,  5 May 2025 18:32:23 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Sohil Mehta <sohil.mehta@...el.com>,
	Ingo Molnar <mingo@...nel.org>,
	Sasha Levin <sashal@...nel.org>,
	tglx@...utronix.de,
	mingo@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com,
	x86@...nel.org,
	gautham.shenoy@....com,
	peterz@...radead.org,
	brgerst@...il.com,
	patryk.wlazlyn@...ux.intel.com,
	kprateek.nayak@....com
Subject: [PATCH AUTOSEL 6.12 067/486] x86/smpboot: Fix INIT delay assignment for extended Intel Families

From: Sohil Mehta <sohil.mehta@...el.com>

[ Upstream commit 7a2ad752746bfb13e89a83984ecc52a48bae4969 ]

Some old crusty CPUs need an extra delay that slows down booting. See
the comment above 'init_udelay' for details. Newer CPUs don't need the
delay.

Right now, for Intel, Family 6 and only Family 6 skips the delay. That
leaves out both the Family 15 (Pentium 4s) and brand new Family 18/19
models.

The omission of Family 15 (Pentium 4s) seems like an oversight and 18/19
do not need the delay.

Skip the delay on all Intel processors Family 6 and beyond.

Signed-off-by: Sohil Mehta <sohil.mehta@...el.com>
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Link: https://lore.kernel.org/r/20250219184133.816753-11-sohil.mehta@intel.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/x86/kernel/smpboot.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index f1fac08fdef28..2c451de702c87 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -681,9 +681,9 @@ static void __init smp_quirk_init_udelay(void)
 		return;
 
 	/* if modern processor, use no delay */
-	if (((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) && (boot_cpu_data.x86 == 6)) ||
-	    ((boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) && (boot_cpu_data.x86 >= 0x18)) ||
-	    ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) && (boot_cpu_data.x86 >= 0xF))) {
+	if ((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL && boot_cpu_data.x86_vfm >= INTEL_PENTIUM_PRO) ||
+	    (boot_cpu_data.x86_vendor == X86_VENDOR_HYGON && boot_cpu_data.x86 >= 0x18) ||
+	    (boot_cpu_data.x86_vendor == X86_VENDOR_AMD   && boot_cpu_data.x86 >= 0xF)) {
 		init_udelay = 0;
 		return;
 	}
-- 
2.39.5