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| author | Thomas Gleixner <tglx@linutronix.de> | 2024-03-22 19:56:35 +0100 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2024-03-23 12:22:04 +0100 |
| commit | c90399fbd74a0713d5972a6d931e4a9918621e88 (patch) | |
| tree | b9d8d57bdd113baceba3b973b88c0e9bd68a1332 /arch/x86/kernel/cpu/common.c | |
| parent | kprobes/x86: Use copy_from_kernel_nofault() to read from unsafe address (diff) | |
| download | linux-c90399fbd74a0713d5972a6d931e4a9918621e88.tar.xz linux-c90399fbd74a0713d5972a6d931e4a9918621e88.zip | |
x86/cpu: Ensure that CPU info updates are propagated on UP
The boot sequence evaluates CPUID information twice:
1) During early boot
2) When finalizing the early setup right before
mitigations are selected and alternatives are patched.
In both cases the evaluation is stored in boot_cpu_data, but on UP the
copying of boot_cpu_data to the per CPU info of the boot CPU happens
between #1 and #2. So any update which happens in #2 is never propagated to
the per CPU info instance.
Consolidate the whole logic and copy boot_cpu_data right before applying
alternatives as that's the point where boot_cpu_data is in it's final
state and not supposed to change anymore.
This also removes the voodoo mb() from smp_prepare_cpus_common() which
had absolutely no purpose.
Fixes: 71eb4893cfaf ("x86/percpu: Cure per CPU madness on UP")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20240322185305.127642785@linutronix.de
Diffstat (limited to 'arch/x86/kernel/cpu/common.c')
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index ba8cf5e9ce56..5c1e6d6be267 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -2307,6 +2307,8 @@ void arch_smt_update(void) void __init arch_cpu_finalize_init(void) { + struct cpuinfo_x86 *c = this_cpu_ptr(&cpu_info); + identify_boot_cpu(); select_idle_routine(); @@ -2345,6 +2347,13 @@ void __init arch_cpu_finalize_init(void) fpu__init_system(); fpu__init_cpu(); + /* + * Ensure that access to the per CPU representation has the initial + * boot CPU configuration. + */ + *c = boot_cpu_data; + c->initialized = true; + alternative_instructions(); if (IS_ENABLED(CONFIG_X86_64)) { |