On Tue, 7 Jun 2022 at 16:30, Jon Hunter <jonathanh@xxxxxxxxxx> wrote: > > > On 24/05/2022 18:03, Russell King (Oracle) wrote: > > On Tue, May 24, 2022 at 03:50:17PM +0100, Jon Hunter wrote: > >> Hi Ard, > >> > >> On 28/03/2022 14:47, Ard Biesheuvel wrote: > >>> The Spectre-BHB mitigations were inadvertently left disabled for > >>> Cortex-A15, due to the fact that cpu_v7_bugs_init() is not called in > >>> that case. So fix that. > >>> > >>> Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx> > >>> --- > >>> arch/arm/mm/proc-v7-bugs.c | 1 + > >>> 1 file changed, 1 insertion(+) > >>> > >>> diff --git a/arch/arm/mm/proc-v7-bugs.c b/arch/arm/mm/proc-v7-bugs.c > >>> index 06dbfb968182..fb9f3eb6bf48 100644 > >>> --- a/arch/arm/mm/proc-v7-bugs.c > >>> +++ b/arch/arm/mm/proc-v7-bugs.c > >>> @@ -288,6 +288,7 @@ void cpu_v7_ca15_ibe(void) > >>> { > >>> if (check_spectre_auxcr(this_cpu_ptr(&spectre_warned), BIT(0))) > >>> cpu_v7_spectre_v2_init(); > >>> + cpu_v7_spectre_bhb_init(); > >>> } > >>> void cpu_v7_bugs_init(void) > >> > >> > >> Since this patch has been merged, I am seeing a ton of messages when booting > >> Linux on tegra124-jetson-tk1 ... > >> > >> [ 1233.327547] CPU0: Spectre BHB: using loop workaround > >> [ 1233.327795] CPU1: Spectre BHB: using loop workaround > >> [ 1233.328270] CPU1: Spectre BHB: using loop workaround > > > > Now that you mention this, I vaguely remember some email on the list a > > while ago about this being caused by something like cpuidle - but I'm > > unable to find it now. > > > >> [0] https://lore.kernel.org/linux-arm-kernel/20220519161310.1489625-1-dmitry.osipenko@xxxxxxxxxxxxx/T/ > > > > That was probably it. > > > > We can't really do this for the other print, because the system status > > can change as a result of CPUs being brought online. :( > > > > Does it make sense to only print the message if/when the method changes > as opposed to every time the CPUs are brought online? That way, there > would still be at least one print showing the current method. I believe > that is what Ard had proposed. > A fix for this issue is already in linux-next: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=bafa10435c4f34f4b9bda8fc7ee6e4330ebca3ea