[coreboot-gerrit] [S] Change in coreboot[master]: cpu/x86/mp_init.c: Fix the logic to add AP cpus

[Bill XIE (Code Review)]

Bill XIE has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/69215 )

Change subject: cpu/x86/mp_init.c: Fix the logic to add AP cpus
......................................................................

cpu/x86/mp_init.c: Fix the logic to add AP cpus

https://review.coreboot.org/c/coreboot/+/64340 assumes
(g_)cpu_bus->children->sibling represents the first AP cpu, but this
is not true when device tree (like mb/asus/p8x7x-series/devicetree.cb)
contains additional static lapic nodes. In such case, Linux kernel can
find one cpu unable to wake up, and an additional working cpu without
corresponding ACPI firmware node:

smpboot: Allowing 5 CPUs, 0 hotplug CPUs
    smpboot: CPU0: Intel(R) Xeon(R) CPU E3-1225 V2 @ 3.20GHz (family:
         0x6, model: 0x3a, stepping: 0x9)
    smpboot: do_boot_cpu failed(-1) to wakeup CPU#2

Now, in the end of init_bsp(), the last apic node is held on
g_last_apic, and all node representing an AP cpu should be inserted
and set up after it. The consistency lost with CB:64340 should be
restored now.

Signed-off-by: Bill XIE 
Change-Id: I1075bc52091e619ef79cbeab0a0f6b57cff1d708
---
M src/cpu/x86/mp_init.c
1 file changed, 38 insertions(+), 4 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/15/69215/1

diff --git a/src/cpu/x86/mp_init.c b/src/cpu/x86/mp_init.c
index febc30b..1aed394 100644
--- a/src/cpu/x86/mp_init.c
+++ b/src/cpu/x86/mp_init.c
@@ -172,7 +172,7 @@
    stop_this_cpu();
 }

-static struct bus *g_cpu_bus;
+static struct device *g_last_apic;

/* By the time APs call ap_init() caching has been setup, and microcode has
  * been loaded. */
@@ -184,7 +184,7 @@
    enable_lapic();
    setup_lapic_interrupts();

-	struct device *dev = g_cpu_bus->children;
+	struct device *dev = g_last_apic;
    for (unsigned int i = info->index; i > 0; i--)
    	dev = dev->sibling;

@@ -534,6 +534,7 @@
 {
    struct device_path cpu_path;
    struct cpu_info *info;
+	struct device *child;

/* Print processor name */
    fill_processor_name(processor_name);
@@ -559,6 +560,14 @@

/* Track BSP in cpu_map structures. */
    cpu_add_map_entry(info->index);
+
+	/* Find the last apic node, which may not be identical to
+	 * cpu_bus->children.
+	 */
+	for (child = info->cpu; child && child->sibling; /* */)
+		child = child->sibling;
+
+	g_last_apic = child;
    return CB_SUCCESS;
 }

@@ -584,8 +593,6 @@
    int num_cpus;
    atomic_t *ap_count;

-	g_cpu_bus = cpu_bus;
-
    if (init_bsp(cpu_bus) != CB_SUCCESS) {
    	printk(BIOS_CRIT, "Setting up BSP failed\n");
    	return CB_ERR;