0017925: 32-bit i686 kernel fails to boot properly or even crashes on multi-cpu systems with 'pcid' cpu feature

ID	Project	Category	View Status	Date Submitted	Last Update

0017925	CentOS-7	kernel	public	2020-12-09 12:03	2021-03-30 17:58

Reporter	Jerome Borsboom	Assigned To
Priority	normal	Severity	major	Reproducibility	always
Status	resolved	Resolution	fixed
Product Version	7.9.2009

Summary	0017925: 32-bit i686 kernel fails to boot properly or even crashes on multi-cpu systems with 'pcid' cpu feature
Description	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 diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 775f10100d7fe..c9176bae7fd8c 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -904,6 +904,14 @@ static void __init early_identify_cpu(struct cpuinfo_x86 c) setup_force_cpu_cap(X86_FEATURE_ALWAYS); fpu__init_system(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) Without this patch, the kernel will try to set the PCIDE bit in the CR4 register in start_secondary which is not allowed in 32-bit mode.
Tags	kernel

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toracat 2020-12-09 18:43 manager ~0038055	We will look into this.

toracat 2020-12-10 06:29 manager ~0038060	Patch to be added. centos-3.10-i686-fix-pcid-bug17925.patch (1,037 bytes) 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) centos-3.10-i686-fix-pcid-bug17925.patch (1,037 bytes)

toracat 2020-12-15 23:04 manager ~0038087	The patch will be applied to kernel-3.10.0-1160.11.1.el7.centos.plus.

toracat 2021-03-30 17:58 manager ~0038349	Closing as 'resolved'. If you still find the issue, please feel free to reopen.

Date Modified	Username	Field	Change
2020-12-09 12:03	Jerome Borsboom	New Issue
2020-12-09 12:03	Jerome Borsboom	Tag Attached: kernel
2020-12-09 18:43	toracat	Status	new => assigned
2020-12-09 18:43	toracat	Note Added: 0038055
2020-12-10 06:29	toracat	File Added: centos-3.10-i686-fix-pcid-bug17925.patch
2020-12-10 06:29	toracat	Note Added: 0038060
2020-12-15 23:04	toracat	Note Added: 0038087
2021-03-30 17:58	toracat	Status	assigned => resolved
2021-03-30 17:58	toracat	Resolution	open => fixed
2021-03-30 17:58	toracat	Note Added: 0038349