[PATCH 6.6 120/142] x86/microcode: Add per CPU result state

6.6-stable review patch. If anyone has any objections, please let me know.

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From: Thomas Gleixner tglx@linutronix.de

commit 4b753955e9151ad2f722137a7bcbafda756186b3 upstream

The microcode rendezvous is purely acting on global state, which does not allow to analyze fails in a coherent way.

Introduce per CPU state where the results are written into, which allows to analyze the return codes of the individual CPUs.

Initialize the state when walking the cpu_present_mask in the online check to avoid another for_each_cpu() loop.

Enhance the result print out with that.

The structure is intentionally named ucode_ctrl as it will gain control fields in subsequent changes.

Signed-off-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Link: https://lore.kernel.org/r/20231017211723.632681010@linutronix.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kernel/cpu/microcode/core.c | 112 ++++++++++++++++++------------- arch/x86/kernel/cpu/microcode/internal.h | 1 2 files changed, 67 insertions(+), 46 deletions(-)

--- a/arch/x86/kernel/cpu/microcode/core.c +++ b/arch/x86/kernel/cpu/microcode/core.c @@ -252,6 +252,11 @@ static struct platform_device *microcode * requirement can be relaxed in the future. Right now, this is conservative * and good. */ +struct microcode_ctrl { + enum ucode_state result; +}; + +static DEFINE_PER_CPU(struct microcode_ctrl, ucode_ctrl); static atomic_t late_cpus_in, late_cpus_out;

static bool wait_for_cpus(atomic_t *cnt) @@ -274,23 +279,19 @@ static bool wait_for_cpus(atomic_t *cnt) return false; }

-/* - * Returns: - * < 0 - on error - * 0 - success (no update done or microcode was updated) - */ -static int __reload_late(void *info) +static int load_cpus_stopped(void *unused) { int cpu = smp_processor_id(); - enum ucode_state err; - int ret = 0; + 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)) - return -1; + 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 @@ -299,17 +300,11 @@ static int __reload_late(void *info) * loading attempts happen on multiple threads of an SMT core. See * below. */ - if (cpumask_first(topology_sibling_cpumask(cpu)) == cpu) - err = microcode_ops->apply_microcode(cpu); - else + if (cpumask_first(topology_sibling_cpumask(cpu)) != cpu) goto wait_for_siblings;

- if (err >= UCODE_NFOUND) { - if (err == UCODE_ERROR) { - pr_warn("Error reloading microcode on CPU %d\n", cpu); - ret = -1; - } - } + ret = microcode_ops->apply_microcode(cpu); + this_cpu_write(ucode_ctrl.result, ret);

wait_for_siblings: if (!wait_for_cpus(&late_cpus_out)) @@ -321,19 +316,18 @@ wait_for_siblings: * per-cpu cpuinfo can be updated with right microcode * revision. */ - if (cpumask_first(topology_sibling_cpumask(cpu)) != cpu) - err = microcode_ops->apply_microcode(cpu); + if (cpumask_first(topology_sibling_cpumask(cpu)) == cpu) + return 0;

- return ret; + ret = microcode_ops->apply_microcode(cpu); + this_cpu_write(ucode_ctrl.result, ret); + return 0; }

-/* - * Reload microcode late on all CPUs. Wait for a sec until they - * all gather together. - */ -static int microcode_reload_late(void) +static int load_late_stop_cpus(void) { - int old = boot_cpu_data.microcode, ret; + unsigned int cpu, updated = 0, failed = 0, timedout = 0, siblings = 0; + int old_rev = boot_cpu_data.microcode; struct cpuinfo_x86 prev_info;

pr_err("Attempting late microcode loading - it is dangerous and taints the kernel.\n"); @@ -348,26 +342,47 @@ static int microcode_reload_late(void) */ store_cpu_caps(&prev_info);

- ret = stop_machine_cpuslocked(__reload_late, NULL, cpu_online_mask); + stop_machine_cpuslocked(load_cpus_stopped, NULL, cpu_online_mask); + + /* Analyze the results */ + for_each_cpu_and(cpu, cpu_present_mask, &cpus_booted_once_mask) { + switch (per_cpu(ucode_ctrl.result, cpu)) { + case UCODE_UPDATED: updated++; break; + case UCODE_TIMEOUT: timedout++; break; + case UCODE_OK: siblings++; break; + default: failed++; break; + } + }

if (microcode_ops->finalize_late_load) - microcode_ops->finalize_late_load(ret); + microcode_ops->finalize_late_load(!updated);

- if (!ret) { - pr_info("Reload succeeded, microcode revision: 0x%x -> 0x%x\n", - old, boot_cpu_data.microcode); - microcode_check(&prev_info); - add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK); - } else { - pr_info("Reload failed, current microcode revision: 0x%x\n", - boot_cpu_data.microcode); + if (!updated) { + /* Nothing changed. */ + if (!failed && !timedout) + return 0; + pr_err("update failed: %u CPUs failed %u CPUs timed out\n", + failed, timedout); + return -EIO; } - return ret; + + add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK); + pr_info("load: updated on %u primary CPUs with %u siblings\n", updated, siblings); + if (failed || timedout) { + pr_err("load incomplete. %u CPUs timed out or failed\n", + num_online_cpus() - (updated + siblings)); + } + pr_info("revision: 0x%x -> 0x%x\n", old_rev, boot_cpu_data.microcode); + microcode_check(&prev_info); + + return updated + siblings == num_online_cpus() ? 0 : -EIO; }

/* - * Ensure that all required CPUs which are present and have been booted - * once are online. + * This function does two things: + * + * 1) Ensure that all required CPUs which are present and have been booted + * once are online. * * To pass this check, all primary threads must be online. * @@ -378,9 +393,12 @@ static int microcode_reload_late(void) * behaviour is undefined. The default play_dead() implementation on * modern CPUs uses MWAIT, which is also not guaranteed to be safe * against a microcode update which affects MWAIT. + * + * 2) Initialize the per CPU control structure */ -static bool ensure_cpus_are_online(void) +static bool setup_cpus(void) { + struct microcode_ctrl ctrl = { .result = -1, }; unsigned int cpu;

for_each_cpu_and(cpu, cpu_present_mask, &cpus_booted_once_mask) { @@ -390,18 +408,20 @@ static bool ensure_cpus_are_online(void) return false; } } + /* Initialize the per CPU state */ + per_cpu(ucode_ctrl, cpu) = ctrl; } return true; }

-static int ucode_load_late_locked(void) +static int load_late_locked(void) { - if (!ensure_cpus_are_online()) + if (!setup_cpus()) return -EBUSY;

switch (microcode_ops->request_microcode_fw(0, &microcode_pdev->dev)) { case UCODE_NEW: - return microcode_reload_late(); + return load_late_stop_cpus(); case UCODE_NFOUND: return -ENOENT; default: @@ -421,7 +441,7 @@ static ssize_t reload_store(struct devic return -EINVAL;

cpus_read_lock(); - ret = ucode_load_late_locked(); + ret = load_late_locked(); cpus_read_unlock();

return ret ? : size; --- a/arch/x86/kernel/cpu/microcode/internal.h +++ b/arch/x86/kernel/cpu/microcode/internal.h @@ -16,6 +16,7 @@ enum ucode_state { UCODE_UPDATED, UCODE_NFOUND, UCODE_ERROR, + UCODE_TIMEOUT, };

struct microcode_ops {