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x86/microcode: Allow late microcode loading with SMT disabled

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The kernel unnecessarily prevents late microcode loading when SMT is
disabled.  It should be safe to allow it if all the primary threads are
online.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
This commit is contained in:
Josh Poimboeuf 2018-08-10 08:31:10 +01:00 committed by David Woodhouse
parent e24f14b0ff
commit 07d981ad4c
1 changed files with 12 additions and 4 deletions
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16
arch/x86/kernel/cpu/microcode/core.c
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@ -509,12 +509,20 @@ static struct platform_device *microcode_pdev;
static int check_online_cpus(void)
{
if (num_online_cpus() == num_present_cpus())
return 0;
unsigned int cpu;
pr_err("Not all CPUs online, aborting microcode update.\n");
/*
* Make sure all CPUs are online. It's fine for SMT to be disabled if
* all the primary threads are still online.
*/
for_each_present_cpu(cpu) {
if (topology_is_primary_thread(cpu) && !cpu_online(cpu)) {
pr_err("Not all CPUs online, aborting microcode update.\n");
return -EINVAL;
}
}
return -EINVAL;
return 0;
}
static atomic_t late_cpus_in;