Change in coreboot[master]: cpu/x86/lapic: Fix choice X2APIC_ONLY

[Kyösti Mälkki (Code Review)]

Kyösti Mälkki has submitted this change. ( https://review.coreboot.org/c/coreboot/+/60213 )

Change subject: cpu/x86/lapic: Fix choice X2APIC_ONLY
......................................................................

cpu/x86/lapic: Fix choice X2APIC_ONLY

When sending self an IPI, some instructions may be processed
before IPI is serviced. Spend some time doing nothing, to
avoid entering a printk() and acquiring console_lock and
dead-locking.

Change-Id: I78070ae91e78c11c3e3aa225e5673d4667d6f7bb
Signed-off-by: Kyösti Mälkki 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/60213
Tested-by: build bot (Jenkins) 
Reviewed-by: Angel Pons 
Reviewed-by: Arthur Heymans 
---
M src/include/cpu/x86/lapic.h
1 file changed, 8 insertions(+), 0 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Arthur Heymans: Looks good to me, approved
  Angel Pons: Looks good to me, but someone else must approve

diff --git a/src/include/cpu/x86/lapic.h b/src/include/cpu/x86/lapic.h
index c1603f2..e131d2e 100644
--- a/src/include/cpu/x86/lapic.h
+++ b/src/include/cpu/x86/lapic.h
@@ -145,8 +145,16 @@

static __always_inline void lapic_send_ipi_self(uint32_t icrlow)
 {
+	int i = 1000;
+
    /* LAPIC_DEST_SELF does not support all delivery mode -fields. */
    lapic_send_ipi(icrlow, lapicid());
+
+	/* In case of X2APIC force a short delay, to prevent deadlock in a case
+	 * the immediately following code acquires some lock, like with printk().
+	 */
+	while (CONFIG(X2APIC_ONLY) && i--)
+		cpu_relax();
 }

static __always_inline void lapic_send_ipi_others(uint32_t icrlow)