diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
index 5fcdfbb792bd..864d62e94614 100644
--- a/arch/x86/kernel/cpu/amd.c
+++ b/arch/x86/kernel/cpu/amd.c
@@ -549,6 +549,8 @@ static bool amd_check_tsa_microcode(void)
 	p.model		= c->x86_model;
 	p.ext_model	= c->x86_model >> 4;
 	p.stepping	= c->x86_stepping;
+	/* reserved bits are expected to be 0 in test below */
+	p.__reserved	= 0;
 
 	if (cpu_has(c, X86_FEATURE_ZEN3) ||
 	    cpu_has(c, X86_FEATURE_ZEN4)) {