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Message-ID: <20230912065502.082789879@linutronix.de>
Date: Tue, 12 Sep 2023 09:58:16 +0200 (CEST)
From: Thomas Gleixner <tglx@...utronix.de>
To: LKML <linux-kernel@...r.kernel.org>
Cc: x86@...nel.org, Borislav Petkov <bp@...en8.de>,
"Chang S. Bae" <chang.seok.bae@...el.com>,
Arjan van de Ven <arjan@...ux.intel.com>,
Nikolay Borisov <nik.borisov@...e.com>
Subject: [patch V3 21/30] x86/microcode: Add per CPU result state
From: Thomas Gleixner <tglx@...utronix.de>
The microcode rendevouz 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@...utronix.de>
---
arch/x86/kernel/cpu/microcode/core.c | 108 ++++++++++++++++++-------------
arch/x86/kernel/cpu/microcode/internal.h | 1
2 files changed, 65 insertions(+), 44 deletions(-)
---
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -324,6 +324,11 @@ static struct platform_device *microcode
* requirement can be relaxed in the future. Right now, this is conservative
* and good.
*/
+struct ucode_ctrl {
+ enum ucode_state result;
+};
+
+static DEFINE_PER_CPU(struct ucode_ctrl, ucode_ctrl);
static atomic_t late_cpus_in, late_cpus_out;
static bool wait_for_cpus(atomic_t *cnt)
@@ -344,23 +349,19 @@ 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 ucode_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
@@ -369,17 +370,11 @@ 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))
@@ -391,19 +386,18 @@ static int __reload_late(void *info)
* 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 ucode_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");
@@ -418,26 +412,47 @@ static int microcode_reload_late(void)
*/
store_cpu_caps(&prev_info);
- ret = stop_machine_cpuslocked(__reload_late, NULL, cpu_online_mask);
+ stop_machine_cpuslocked(ucode_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("Microcode 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("Microcode load: updated on %u primary CPUs with %u siblings\n", updated, siblings);
+ if (failed || timedout) {
+ pr_err("Microcode load incomplete. %u CPUs timed out or failed\n",
+ num_online_cpus() - (updated + siblings));
+ }
+ pr_info("Microcode 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.
*
@@ -448,9 +463,12 @@ static int microcode_reload_late(void)
* behaviour is undefined. The default play_dead() implementation on
* modern CPUs is using 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 ucode_setup_cpus(void)
{
+ struct ucode_ctrl ctrl = { .result = -1, };
unsigned int cpu;
for_each_cpu_and(cpu, cpu_present_mask, &cpus_booted_once_mask) {
@@ -460,6 +478,8 @@ static bool ensure_cpus_are_online(void)
return false;
}
}
+ /* Initialize the per CPU state */
+ per_cpu(ucode_ctrl, cpu) = ctrl;
}
return true;
}
@@ -468,13 +488,13 @@ static int ucode_load_late_locked(void)
{
int ret;
- if (!ensure_cpus_are_online())
+ if (!ucode_setup_cpus())
return -EBUSY;
ret = microcode_ops->request_microcode_fw(0, µcode_pdev->dev);
if (ret != UCODE_NEW)
return ret == UCODE_NFOUND ? -ENOENT : -EBADFD;
- return microcode_reload_late();
+ return ucode_load_late_stop_cpus();
}
static ssize_t reload_store(struct device *dev,
--- 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 {
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