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

Commit-ID:     173dfdce3ba8b7d54d2476f76f723438dbaff391
Gitweb:        https://git.kernel.org/tip/173dfdce3ba8b7d54d2476f76f723438dbaff391
Author:        Ahmed S. Darwish <darwi@linutronix.de>
AuthorDate:    Thu, 28 May 2026 17:37:33 +02:00
Committer:     Borislav Petkov (AMD) <bp@alien8.de>
CommitterDate: Fri, 31 Jul 2026 14:52:55 -07:00

x86/cpu: Use parsed CPUID(0x1)

On early boot CPU detection, use parsed CPUID(0x1) instead of a direct CPUID
query.

Beside the parser's centralization benefits, use the auto generated CPUID data
types, and their C99 bitfields, instead of doing ugly bitwise operations.

  [ bp: - Use a common code pattern for l1 of fetching and checking it
          right after that
	- flip the check to save an indentation level
	- align assignments vertically.
  ]

Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://patch.msgid.link/20260528153923.403473-12-darwi@linutronix.de
---
 arch/x86/kernel/cpu/common.c | 22 +++++++++++-----------
 1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index e658f76..695319f 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -943,6 +943,7 @@ void get_cpu_vendor(struct cpuinfo_x86 *c)
 void cpu_detect(struct cpuinfo_x86 *c)
 {
 	const struct leaf_0x0_0 *l0 = cpuid_leaf(c, 0x0);
+	const struct leaf_0x1_0 *l1;
 
 	c->cpuid_level = l0->max_std_leaf;
 	*(u32 *)&c->x86_vendor_id[0] = l0->cpu_vendorid_0;
@@ -950,19 +951,18 @@ 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);
+	l1 = cpuid_leaf(c, 0x1);
+	if (!l1)
+		return;
 
-		if (cap0 & (1<<19)) {
-			c->x86_clflush_size = ((misc >> 8) & 0xff) * 8;
-			c->x86_cache_alignment = c->x86_clflush_size;
-		}
+	c->x86		= cpuid_family(l1);
+	c->x86_model	= cpuid_model(l1);
+	c->x86_stepping	= l1->stepping;
+
+	if (l1->clflush) {
+		c->x86_clflush_size	= l1->clflush_size * 8;
+		c->x86_cache_alignment	= c->x86_clflush_size;
 	}
 }