| From foo@baz Tue Aug 14 16:14:56 CEST 2018 |
| From: Josh Poimboeuf <jpoimboe@redhat.com> |
| Date: Fri, 10 Aug 2018 08:31:10 +0100 |
| Subject: x86/microcode: Allow late microcode loading with SMT disabled |
| |
| From: Josh Poimboeuf <jpoimboe@redhat.com> |
| |
| commit 07d981ad4cf1e78361c6db1c28ee5ba105f96cc1 upstream |
| |
| 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> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| arch/x86/kernel/cpu/microcode/core.c | 16 ++++++++++++---- |
| 1 file changed, 12 insertions(+), 4 deletions(-) |
| |
| --- a/arch/x86/kernel/cpu/microcode/core.c |
| +++ b/arch/x86/kernel/cpu/microcode/core.c |
| @@ -386,12 +386,20 @@ static struct platform_device *microcode |
| |
| 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 int reload_for_cpu(int cpu) |
