The following commit has been merged into the x86/microcode branch of tip:
Commit-ID: fc27389d6e72cf75f04a49afe851165210f8e9f3
Gitweb: https://git.kernel.org/tip/fc27389d6e72cf75f04a49afe851165210f8e9f3
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Mon, 02 Oct 2023 14:00:00 +02:00
Committer: Borislav Petkov (AMD) <bp@xxxxxxxxx>
CommitterDate: Fri, 06 Oct 2023 15:12:24 +02:00
x86/microcode: Add per CPU result state
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@xxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Link: https://lore.kernel.org/r/20231002115903.262232260@xxxxxxxxxxxxx
---
arch/x86/kernel/cpu/microcode/core.c | 114 ++++++++++++----------
arch/x86/kernel/cpu/microcode/internal.h | 1 +-
2 files changed, 68 insertions(+), 47 deletions(-)
diff --git a/arch/x86/kernel/cpu/microcode/core.c b/arch/x86/kernel/cpu/microcode/core.c
index 2b8e9b6..b72ef3b 100644
--- a/arch/x86/kernel/cpu/microcode/core.c
+++ b/arch/x86/kernel/cpu/microcode/core.c
@@ -281,6 +281,11 @@ static struct platform_device *microcode_pdev;
* 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)
@@ -303,23 +308,19 @@ 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
@@ -328,17 +329,11 @@ 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))
@@ -350,19 +345,18 @@ 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");
@@ -377,26 +371,47 @@ 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);
-
- 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);
+ microcode_ops->finalize_late_load(!updated);
+
+ 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.
*
@@ -407,9 +422,12 @@ 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) {
@@ -419,18 +437,20 @@ 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, µcode_pdev->dev)) {
case UCODE_NEW:
- return microcode_reload_late();
+ return load_late_stop_cpus();
case UCODE_NFOUND:
return -ENOENT;
default:
@@ -450,7 +470,7 @@ static ssize_t reload_store(struct device *dev,
return -EINVAL;
cpus_read_lock();
- ret = ucode_load_late_locked();
+ ret = load_late_locked();
cpus_read_unlock();
return ret ? : size;
diff --git a/arch/x86/kernel/cpu/microcode/internal.h b/arch/x86/kernel/cpu/microcode/internal.h
index a36439c..f89bbac 100644
--- 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 {
|