On Fri, Apr 20, 2018 at 12:37:08PM +0200, Borislav Petkov wrote: > Vitezslav reported a case where the > > "Timeout during microcode update!" > > panic would hit. After a deeper look, it turned out that his .config had > CONFIG_HOTPLUG_CPU disabled which practically made save_mc_for_early() a > no-op. > > When that happened, the discovered microcode patch wasn't saved into our > cache and the late loading path wouldn't find any. > > This, then, lead to early exit from __reload_late() and thus CPUs > waiting until the timeout is reached, leading to the panic. > > In hindsight, I should've made that function not return before the > post-synchronization. Oh well, I know better now... > > Reported-by: Vitezslav Samel <[email protected]>
Tested-by: Vitezslav Samel <[email protected]> > Signed-off-by: Borislav Petkov <[email protected]> > Cc: Ashok Raj <[email protected]> > Cc: <[email protected]> > Fixes: bb8c13d61a62 ("x86/microcode: Fix CPU synchronization routine") > Link: http://lkml.kernel.org/r/[email protected] > --- > arch/x86/kernel/cpu/microcode/core.c | 6 ++---- > 1 file changed, 2 insertions(+), 4 deletions(-) > > diff --git a/arch/x86/kernel/cpu/microcode/core.c > b/arch/x86/kernel/cpu/microcode/core.c > index 10c4fc2c91f8..77e201301528 100644 > --- a/arch/x86/kernel/cpu/microcode/core.c > +++ b/arch/x86/kernel/cpu/microcode/core.c > @@ -564,14 +564,12 @@ static int __reload_late(void *info) > apply_microcode_local(&err); > spin_unlock(&update_lock); > > + /* siblings return UCODE_OK because their engine got updated already */ > if (err > UCODE_NFOUND) { > pr_warn("Error reloading microcode on CPU %d\n", cpu); > - return -1; > - /* siblings return UCODE_OK because their engine got updated already */ > + ret = -1; > } else if (err == UCODE_UPDATED || err == UCODE_OK) { > ret = 1; > - } else { > - return ret; > } > > /* > -- > 2.13.0 > > SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB > 21284 (AG Nürnberg) > --
