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Commit 07d981ad authored by Josh Poimboeuf's avatar Josh Poimboeuf Committed by David Woodhouse
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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: default avatarJosh Poimboeuf <jpoimboe@redhat.com>
Acked-by: default avatarBorislav Petkov <bp@suse.de>
Signed-off-by: default avatarDavid Woodhouse <dwmw@amazon.co.uk>
parent e24f14b0

arch/x86/kernel/cpu/microcode/core.c

+12 −4
Original line number Diff line number Diff line
@@ -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;