x86/cpu/amd: Don't clear RDSEED32 bit on znver5

1Naim · 1Naim · commit 0d31fb228ed0 · 2026-04-13T21:33:31.000+08:00
It seems that even after 6 months there still exists a system that
hasn't updated their microcode to fix this. Instead of removing the
detection altogether, keep the warning but don't clear the cpuid bit so
that we can spread awareness and have people update their microcode
revision.

Signed-off-by: Eric Naim &lt;dnaim@cachyos.org&gt;
diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
@@ -1032,11 +1032,8 @@ static const struct x86_cpu_id zen5_rdseed_microcode[] = {
 
 static void init_amd_zen5(struct cpuinfo_x86 *c)
 {
-	if (!x86_match_min_microcode_rev(zen5_rdseed_microcode)) {
-		clear_cpu_cap(c, X86_FEATURE_RDSEED);
-		msr_clear_bit(MSR_AMD64_CPUID_FN_7, 18);
-		pr_emerg_once("RDSEED32 is broken. Disabling the corresponding CPUID bit.\n");
-	}
+	if (!x86_match_min_microcode_rev(zen5_rdseed_microcode))
+		pr_emerg_once("RDSEED32 is broken. Please update your firmware.\n");
 }
 
 static void init_amd(struct cpuinfo_x86 *c)

Original file line number	Diff line number	Diff line change
`@@ -1032,11 +1032,8 @@ static const struct x86_cpu_id zen5_rdseed_microcode[] = {`
`1032`	`1032`
`1033`	`1033`	`static void init_amd_zen5(struct cpuinfo_x86 *c)`
`1034`	`1034`	`{`
`1035`		`- if (!x86_match_min_microcode_rev(zen5_rdseed_microcode)) {`
`1036`		`- clear_cpu_cap(c, X86_FEATURE_RDSEED);`
`1037`		`- msr_clear_bit(MSR_AMD64_CPUID_FN_7, 18);`
`1038`		`- pr_emerg_once("RDSEED32 is broken. Disabling the corresponding CPUID bit.\n");`
`1039`		`- }`
	`1035`	`+ if (!x86_match_min_microcode_rev(zen5_rdseed_microcode))`
	`1036`	`+ pr_emerg_once("RDSEED32 is broken. Please update your firmware.\n");`
`1040`	`1037`	`}`
`1041`	`1038`
`1042`	`1039`	`static void init_amd(struct cpuinfo_x86 *c)`