linux-kernel - [RFC PATCH 03/15] x86/cpu/intel: Fix init_intel() checks for extended family numbers

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Message-ID: <20241220213711.1892696-4-sohil.mehta@intel.com>
Date: Fri, 20 Dec 2024 21:36:58 +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>,
	Sohil Mehta <sohil.mehta@...el.com>,
	Zhang Rui <rui.zhang@...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: [RFC PATCH 03/15] x86/cpu/intel: Fix init_intel() checks for extended family numbers

X86_FEATURE_REP_GOOD is only set for family 6 processors.  Extend the
check to family numbers beyond 15.

It is uncertain whether the Pentium 4s (family 15) should set the
feature flag as well. Commit 185f3b9da24c ("x86: make intel.c have
64-bit support code") that originally set X86_FEATURE_REP_GOOD also set
the x86_cache_alignment preference for family 15 processors. The
omission of the family 15 seems intentional.

Also, the 32-bit user copy alignment preference is only set for family 6
and 15 processors. Extend the preference to family numbers beyond 15.

Signed-off-by: Sohil Mehta <sohil.mehta@...el.com>
---
 arch/x86/kernel/cpu/intel.c | 19 ++++++-------------
 1 file changed, 6 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 8ded9f859a3a..f44b2e618fb3 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -449,23 +449,16 @@ static void intel_workarounds(struct cpuinfo_x86 *c)
 	    (c->x86_stepping < 0x6 || c->x86_stepping == 0xb))
 		set_cpu_bug(c, X86_BUG_11AP);
 
-
 #ifdef CONFIG_X86_INTEL_USERCOPY
 	/*
 	 * Set up the preferred alignment for movsl bulk memory moves
+	 * Family 4 - 486: untested
+	 * Family 5 - Pentium: untested
+	 * Family 6 - PII/PIII only like movsl with 8-byte alignment
+	 * Family 15 - P4 is OK down to 8-byte alignment
 	 */
-	switch (c->x86) {
-	case 4:		/* 486: untested */
-		break;
-	case 5:		/* Old Pentia: untested */
-		break;
-	case 6:		/* PII/PIII only like movsl with 8-byte alignment */
-		movsl_mask.mask = 7;
-		break;
-	case 15:	/* P4 is OK down to 8-byte alignment */
+	if (c->x86_vfm >= INTEL_PENTIUM_PRO)
 		movsl_mask.mask = 7;
-		break;
-	}
 #endif
 
 	intel_smp_check(c);
@@ -563,7 +556,7 @@ static void init_intel(struct cpuinfo_x86 *c)
 #ifdef CONFIG_X86_64
 	if (c->x86 == 15)
 		c->x86_cache_alignment = c->x86_clflush_size * 2;
-	if (c->x86 == 6)
+	if (c->x86 == 6 || c->x86 > 15)
 		set_cpu_cap(c, X86_FEATURE_REP_GOOD);
 #else
 	/*
-- 
2.43.0