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x86/microcode: Allow late microcode loading with SMT disabled 

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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14
arch/x86/kernel/cpu/microcode/core.c
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@ -509,13 +509,21 @@ static struct platform_device *microcode_pdev;
static int check_online_cpus(void)
{
if (num_online_cpus() == num_present_cpus())
return 0;
unsigned int cpu;
/*
* 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 0;
}
static atomic_t late_cpus_in;
static atomic_t late_cpus_out;