[coreboot] New patch to review for coreboot: bf36231 Intel cpus: Fix deadlock on hyper-threading init
Kyösti Mälkki (kyosti.malkki@gmail.com)
gerrit at coreboot.org
Fri Mar 9 17:25:19 CET 2012
Kyösti Mälkki (kyosti.malkki at gmail.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/775
-gerrit
commit bf362311db9948925b5580a9922a58c4c8726c82
Author: Kyösti Mälkki <kyosti.malkki at gmail.com>
Date: Fri Mar 9 17:02:37 2012 +0200
Intel cpus: Fix deadlock on hyper-threading init
Only the BSP CPU was able to start its hyper-threading CPU siblings.
When an AP CPU attempts this it calls start_cpu() within start_cpu(),
deadlocking the system with start_cpu_lock.
At the time intel_sibling_init() is run, the BSP CPU is still
walking the cpu_bus linked list in lapic_cpu_init: start_other_cpus().
A sibling CPU appended at the end of this list will get started.
Also fail compile with #error if SERIAL_CPU_INIT==0, as microcode
updates on hyper-threading sibling CPUs must be serialized.
Tested with HT-enabled P4 Xeons on dual-socket604 platform.
Change-Id: I0053f58f49ed604605ce0a55e826d3e1afdc90b6
Signed-off-by: Kyösti Mälkki <kyosti.malkki at gmail.com>
---
src/cpu/intel/hyperthreading/intel_sibling.c | 22 +++++++++-------------
1 files changed, 9 insertions(+), 13 deletions(-)
diff --git a/src/cpu/intel/hyperthreading/intel_sibling.c b/src/cpu/intel/hyperthreading/intel_sibling.c
index 823d77c..e988664 100644
--- a/src/cpu/intel/hyperthreading/intel_sibling.c
+++ b/src/cpu/intel/hyperthreading/intel_sibling.c
@@ -5,6 +5,11 @@
#include <device/device.h>
#include <pc80/mc146818rtc.h>
#include <smp/spinlock.h>
+#include <assert.h>
+
+#if CONFIG_SERIAL_CPU_INIT==0
+#error Intel hyper-threading requires serialized cpu init
+#endif
static int first_time = 1;
static int disable_siblings = !CONFIG_LOGICAL_CPUS;
@@ -30,11 +35,9 @@ void intel_sibling_init(device_t cpu)
siblings = 1;
}
-#if 1
printk(BIOS_DEBUG, "CPU: %u %d siblings\n",
cpu->path.apic.apic_id,
siblings);
-#endif
/* See if I am a sibling cpu */
if (cpu->path.apic.apic_id & (siblings -1)) {
@@ -53,25 +56,18 @@ void intel_sibling_init(device_t cpu)
cpu_path.apic.apic_id = cpu->path.apic.apic_id + i;
- /* Allocate the new cpu device structure */
- new = alloc_dev(cpu->bus, &cpu_path);
+ /* Allocate new cpu device structure iff sibling CPU
+ * was not in static device tree.
+ */
+ new = alloc_find_dev(cpu->bus, &cpu_path);
if (!new) {
continue;
}
-#if 1
printk(BIOS_DEBUG, "CPU: %u has sibling %u\n",
cpu->path.apic.apic_id,
new->path.apic.apic_id);
-#endif
- /* Start the new cpu */
- if (!start_cpu(new)) {
- /* Record the error in cpu? */
- printk(BIOS_ERR, "CPU %u would not start!\n",
- new->path.apic.apic_id);
- }
}
-
}
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