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[arch][x86] tighten up x86 cpu bootstrap code

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- Fix an assert in local apic code when not using x2apic and starting
  secondaries.
- Follow the spec a bit closer and wait up till a second for each
  secondary core to start.
This commit is contained in:
Travis Geiselbrecht
2025-04-06 21:13:06 -07:00
parent 3013662345
commit a8bc048648
2 changed files with 45 additions and 15 deletions
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37
platform/pc/mp.c
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@@ -11,6 +11,7 @@
#include <kernel/thread.h>
#include <kernel/vm.h>
#include <lib/acpi_lite.h>
#include <lk/err.h>
#include <lk/main.h>
#include <lk/trace.h>
#include <string.h>
@@ -35,6 +36,7 @@ struct bootstrap_args {
volatile uint32_t *boot_completed_ptr; // set by the secondary cpu when it's done
};
// called from assembly code in mp-boot.S
__NO_RETURN void secondary_entry(struct bootstrap_args *args) {
volatile uint32_t *boot_completed = args->boot_completed_ptr;
uint cpu_num = args->cpu_num;
@@ -49,7 +51,7 @@ __NO_RETURN void secondary_entry(struct bootstrap_args *args) {
x86_secondary_entry(cpu_num);
}
static void start_cpu(uint cpu_num, uint32_t apic_id, struct bootstrap_args *args) {
static status_t start_cpu(uint cpu_num, uint32_t apic_id, struct bootstrap_args *args) {
LTRACEF("cpu_num %u, apic_id %u\n", cpu_num, apic_id);
// assert that this thread is pinned to the current cpu
@@ -68,20 +70,33 @@ static void start_cpu(uint cpu_num, uint32_t apic_id, struct bootstrap_args *arg
lapic_send_init_ipi(apic_id, false);
thread_sleep(10);
// send SIPI and wait 200us
lapic_send_startup_ipi(apic_id, TRAMPOLINE_ADDRESS);
thread_sleep(1);
// send Startup IPI up to 2 times as recommended by Intel
for (int i = 0; i < 2; i++) {
lapic_send_startup_ipi(apic_id, TRAMPOLINE_ADDRESS);
// send SIPI again for good measure and wait 10ms
lapic_send_startup_ipi(apic_id, TRAMPOLINE_ADDRESS);
thread_sleep(10);
// wait for the cpu to finish booting
while (!boot_completed) {
thread_yield();
// Wait a little bit for the cpu to start before trying a second time
thread_sleep(10);
if (boot_completed) {
goto booted;
}
}
// Wait up to a second for the cpu to finish starting
for (int i = 0; i < 1000; i++) {
if (boot_completed) {
goto booted;
}
thread_sleep(10);
}
// we have failed to start this core
// TODO: handle trying to shut the core down before moving on.
printf("PC: failed to start cpu %u\n", cpu_num);
return ERR_TIMED_OUT;
booted:
LTRACEF("cpu %u booted\n", cpu_num);
return NO_ERROR;
}
struct detected_cpus {