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x86/microcode/intel: Save the microcode only after a successful late-load

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There are situations where the late microcode is loaded into memory but
is not applied:

  1) The rendezvous fails
  2) The microcode is rejected by the CPUs

If any of this happens then the pointer which was updated at firmware
load time is stale and subsequent CPU hotplug operations either fail to
update or create inconsistent microcode state.

Save the loaded microcode in a separate pointer before the late load is
attempted and when successful, update the hotplug pointer accordingly
via a new microcode_ops callback.

Remove the pointless fallback in the loader to a microcode pointer which
is never populated.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20231002115902.505491309@linutronix.de
This commit is contained in:
Thomas Gleixner
2023-10-02 13:59:44 +02:00
committed by Borislav Petkov (AMD)
parent dd5e3e3ca6
commit 2a1dada3d1
3 changed files with 20 additions and 15 deletions
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4
arch/x86/kernel/cpu/microcode/core.c
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@@ -397,6 +397,10 @@ static int microcode_reload_late(void)
store_cpu_caps(&prev_info);
ret = stop_machine_cpuslocked(__reload_late, NULL, cpu_online_mask);
if (microcode_ops->finalize_late_load)
microcode_ops->finalize_late_load(ret);
if (!ret) {
pr_info("Reload succeeded, microcode revision: 0x%x -> 0x%x\n",
old, boot_cpu_data.microcode);