linux-kernel - [tip: x86/core] x86/smpboot: Fix INIT delay assignment for extended Intel Families

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Message-ID: <174238221892.14745.2711535962153025870.tip-bot2@tip-bot2>
Date: Wed, 19 Mar 2025 11:03:38 -0000
From: "tip-bot2 for Sohil Mehta" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Sohil Mehta <sohil.mehta@...el.com>, Ingo Molnar <mingo@...nel.org>,
 x86@...nel.org, linux-kernel@...r.kernel.org
Subject: [tip: x86/core] x86/smpboot: Fix INIT delay assignment for extended
 Intel Families

The following commit has been merged into the x86/core branch of tip:

Commit-ID:     7a2ad752746bfb13e89a83984ecc52a48bae4969
Gitweb:        https://git.kernel.org/tip/7a2ad752746bfb13e89a83984ecc52a48bae4969
Author:        Sohil Mehta <sohil.mehta@...el.com>
AuthorDate:    Wed, 19 Feb 2025 18:41:28 
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Wed, 19 Mar 2025 11:19:50 +01:00

x86/smpboot: Fix INIT delay assignment for extended Intel Families

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
---
 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 5e586f5..d6cf1e2 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -656,9 +656,9 @@ static void __init smp_set_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;
 	}