linux-kernel - [PATCH v1 12/26] x86/cpu: Use scanned CPUID(0x1)

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Message-ID: <20250506050437.10264-13-darwi@linutronix.de>
Date: Tue,  6 May 2025 07:04:23 +0200
From: "Ahmed S. Darwish" <darwi@...utronix.de>
To: Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Thomas Gleixner <tglx@...utronix.de>,
	Andrew Cooper <andrew.cooper3@...rix.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	John Ogness <john.ogness@...utronix.de>,
	x86@...nel.org,
	x86-cpuid@...ts.linux.dev,
	LKML <linux-kernel@...r.kernel.org>,
	"Ahmed S. Darwish" <darwi@...utronix.de>
Subject: [PATCH v1 12/26] x86/cpu: Use scanned CPUID(0x1)

Use scanned CPUID(0x1) access, instead of a direct CPUID query, at early
boot CPU detection code.

Beside the centralization benefits of the scanned CPUID API, this allows
using the auto-generated <cpuid/leaves.h> CPUID leaf data types and their
full C99 bitfields instead of performing ugly bitwise operations on CPUID
register output.

Signed-off-by: Ahmed S. Darwish <darwi@...utronix.de>
---
 arch/x86/kernel/cpu/common.c | 16 +++++++---------
 1 file changed, 7 insertions(+), 9 deletions(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index 59ddf6b074f2..a08340a5e6a5 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -895,6 +895,7 @@ void get_cpu_vendor(struct cpuinfo_x86 *c)
 void cpu_detect(struct cpuinfo_x86 *c)
 {
 	const struct leaf_0x0_0 *l0 = cpudata_cpuid(c, 0x0);
+	const struct leaf_0x1_0 *l1 = cpudata_cpuid(c, 0x1);
 
 	c->cpuid_level = l0->max_std_leaf;
 	*(u32 *)&c->x86_vendor_id[0] = l0->cpu_vendorid_0;
@@ -902,17 +903,14 @@ void cpu_detect(struct cpuinfo_x86 *c)
 	*(u32 *)&c->x86_vendor_id[8] = l0->cpu_vendorid_2;
 
 	c->x86 = 4;
-	/* Intel-defined flags: level 0x00000001 */
-	if (c->cpuid_level >= 0x00000001) {
-		u32 junk, tfms, cap0, misc;
 
-		cpuid(0x00000001, &tfms, &misc, &junk, &cap0);
-		c->x86		= x86_family(tfms);
-		c->x86_model	= x86_model(tfms);
-		c->x86_stepping	= x86_stepping(tfms);
+	if (l1) {
+		c->x86		= cpuid_family(l1);
+		c->x86_model	= cpuid_model(l1);
+		c->x86_stepping	= l1->stepping;
 
-		if (cap0 & (1<<19)) {
-			c->x86_clflush_size = ((misc >> 8) & 0xff) * 8;
+		if (l1->clflush) {
+			c->x86_clflush_size = l1->clflush_size * 8;
 			c->x86_cache_alignment = c->x86_clflush_size;
 		}
 	}
-- 
2.49.0