centos-3.10-i686-fix-pcid-bug17925.patch
https://bugs.centos.org/view.php?id=17925
When booting a recent 32-bit i686 kernel on a multi-cpu system with 'pcid' cpu feature, only the boot cpu is correctly initialized. The other cpu's fail to initialize, resulting in a badly running or crashing kernel.
The reason is two missing patches present in vanilla upstream kernels:
x86/mm: Disable PCID on 32-bit kernels
x86/mm/32: Move setup_clear_cpu_cap(X86_FEATURE_PCID) earlier
Submitted-by: Jerome Borsboom
Applied-by: Akemi Yagi <toracat@centos.org>
--- a/arch/x86/kernel/cpu/common.c 2020-10-21 10:17:08.000000000 -0700
+++ b/arch/x86/kernel/cpu/common.c 2020-12-09 22:10:47.945329193 -0800
@@ -1131,6 +1131,14 @@ static void __init early_identify_cpu(st
this_cpu->c_bsp_init(c);
cpu_set_bug_bits(c);
+
+#ifdef CONFIG_X86_32
+ /*
+ * Regardless of whether PCID is enumerated, the SDM says
+ * that it can't be enabled in 32-bit mode.
+ */
+ setup_clear_cpu_cap(X86_FEATURE_PCID);
+#endif
}
void __init early_cpu_init(void)