• Peter Zijlstra (Intel)'s avatar
    sched/smt: Make sched_smt_present track topology · 01659361
    Peter Zijlstra (Intel) authored
    commit c5511d03
    
     upstream
    
    Currently the 'sched_smt_present' static key is enabled when at CPU bringup
    SMT topology is observed, but it is never disabled. However there is demand
    to also disable the key when the topology changes such that there is no SMT
    present anymore.
    
    Implement this by making the key count the number of cores that have SMT
    enabled.
    
    In particular, the SMT topology bits are set before interrrupts are enabled
    and similarly, are cleared after interrupts are disabled for the last time
    and the CPU dies.
    Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
    Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
    Reviewed-by: default avatarIngo Molnar <mingo@kernel.org>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Jiri Kosina <jkosina@suse.cz>
    Cc: Tom Lendacky <thomas.lendacky@amd.com>
    Cc: Josh Poimboeuf <jpoimboe@redhat.com>
    Cc: Andrea Arcangeli <aarcange@redhat.com>
    Cc: David Woodhouse <dwmw@amazon.co.uk>
    Cc: Tim Chen <tim.c.chen@linux.intel.com>
    Cc: Andi Kleen <ak@linux.intel.com>
    Cc: Dave Hansen <dave.hansen@intel.com>
    Cc: Casey Schaufler <casey.schaufler@intel.com>
    Cc: Asit Mallick <asit.k.mallick@intel.com>
    Cc: Arjan van de Ven <arjan@linux.intel.com>
    Cc: Jon Masters <jcm@redhat.com>
    Cc: Waiman Long <longman9394@gmail.com>
    Cc: Greg KH <gregkh@linuxfoundation.org>
    Cc: Dave Stewart <david.c.stewart@intel.com>
    Cc: Kees Cook <keescook@chromium.org>
    Cc: stable@vger.kernel.org
    Link: https://lkml.kernel.org/r/20181125185004.246110444@linutronix.de
    
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    01659361
core.c 166 KB