Kyösti Mälkki (kyosti.malkki@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@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@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); - } } - }