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Bae" , Arjan van de Ven , Nikolay Borisov Subject: [patch V4 24/30] x86/microcode: Replace the all in one rendevouz handler References: <20231002115506.217091296@linutronix.de> MIME-Version: 1.0 Date: Mon, 2 Oct 2023 14:00:03 +0200 (CEST) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Thomas Gleixner with a new handler which just separates the control flow of primary and secondary CPUs. Signed-off-by: Thomas Gleixner --- arch/x86/kernel/cpu/microcode/core.c | 51 ++++++------------------------= ----- 1 file changed, 9 insertions(+), 42 deletions(-) --- --- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -297,7 +297,7 @@ struct microcode_ctrl { }; =20 static DEFINE_PER_CPU(struct microcode_ctrl, ucode_ctrl); -static atomic_t late_cpus_in, late_cpus_out; +static atomic_t late_cpus_in; =20 static bool wait_for_cpus(atomic_t *cnt) { @@ -333,7 +333,7 @@ static bool wait_for_ctrl(void) return false; } =20 -static __maybe_unused void load_secondary(unsigned int cpu) +static void load_secondary(unsigned int cpu) { unsigned int ctrl_cpu =3D this_cpu_read(ucode_ctrl.ctrl_cpu); enum ucode_state ret; @@ -368,7 +368,7 @@ static __maybe_unused void load_secondar this_cpu_write(ucode_ctrl.ctrl, SCTRL_DONE); } =20 -static __maybe_unused void load_primary(unsigned int cpu) +static void load_primary(unsigned int cpu) { struct cpumask *secondaries =3D topology_sibling_cpumask(cpu); enum sibling_ctrl ctrl; @@ -405,46 +405,14 @@ static __maybe_unused void load_primary( =20 static int load_cpus_stopped(void *unused) { - int cpu =3D smp_processor_id(); - enum ucode_state ret; - - /* - * Wait for all CPUs to arrive. A load will not be attempted unless all - * CPUs show up. - * */ - if (!wait_for_cpus(&late_cpus_in)) { - this_cpu_write(ucode_ctrl.result, UCODE_TIMEOUT); - return 0; - } - - /* - * On an SMT system, it suffices to load the microcode on one sibling of - * the core because the microcode engine is shared between the threads. - * Synchronization still needs to take place so that no concurrent - * loading attempts happen on multiple threads of an SMT core. See - * below. - */ - if (cpumask_first(topology_sibling_cpumask(cpu)) !=3D cpu) - goto wait_for_siblings; + unsigned int cpu =3D smp_processor_id(); =20 - ret =3D microcode_ops->apply_microcode(cpu); - this_cpu_write(ucode_ctrl.result, ret); - -wait_for_siblings: - if (!wait_for_cpus(&late_cpus_out)) - panic("Timeout during microcode update!\n"); - - /* - * At least one thread has completed update on each core. - * For others, simply call the update to make sure the - * per-cpu cpuinfo can be updated with right microcode - * revision. - */ - if (cpumask_first(topology_sibling_cpumask(cpu)) =3D=3D cpu) - return 0; + if (this_cpu_read(ucode_ctrl.ctrl_cpu) =3D=3D cpu) + load_primary(cpu); + else + load_secondary(cpu); =20 - ret =3D microcode_ops->apply_microcode(cpu); - this_cpu_write(ucode_ctrl.result, ret); + /* No point to wait here. The CPUs will all wait in stop_machine(). */ return 0; } =20 @@ -458,7 +426,6 @@ static int load_late_stop_cpus(void) pr_err("You should switch to early loading, if possible.\n"); =20 atomic_set(&late_cpus_in, num_online_cpus()); - atomic_set(&late_cpus_out, num_online_cpus()); =20 /* * Take a snapshot before the microcode update in order to compare and