x86/of: Don't use DTB for SMP setup if ACPI is enabled

There are cases when it is useful to use both ACPI and DTB provided by
the bootloader, however in such cases we should make sure to prevent
conflicts between the two. Namely, don't try to use DTB for SMP setup
if ACPI is enabled.

Precisely, this prevents at least:

- incorrectly calling register_lapic_address(APIC_DEFAULT_PHYS_BASE)
  after the LAPIC was already successfully enumerated via ACPI, causing
  noisy kernel warnings and probably potential real issues as well

- failed IOAPIC setup in the case when IOAPIC is enumerated via mptable
  instead of ACPI (e.g. with acpi=noirq), due to
  mpparse_parse_smp_config() overridden by x86_dtb_parse_smp_config()

Signed-off-by: Dmytro Maluka <dmaluka@chromium.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250105172741.3476758-2-dmaluka@chromium.org

diff --git a/arch/x86/kernel/devicetree.c b/arch/x86/kernel/devicetree.c
index 59d23cdf4ed0fa1044fdb208dd9c3e4548f4e686..dd8748c45529a8dfa13382c3b75f8f42f4b5c3f0 100644 (file)
--- a/arch/x86/kernel/devicetree.c
+++ b/arch/x86/kernel/devicetree.c
@@ -2,6 +2,7 @@
 /*
  * Architecture specific OF callbacks.
  */
+#include <linux/acpi.h>
 #include <linux/export.h>
 #include <linux/io.h>
 #include <linux/interrupt.h>
@@ -313,6 +314,6 @@ void __init x86_flattree_get_config(void)
        if (initial_dtb)
                early_memunmap(dt, map_len);
 #endif
-       if (of_have_populated_dt())
+       if (acpi_disabled && of_have_populated_dt())
                x86_init.mpparse.parse_smp_cfg = x86_dtb_parse_smp_config;
 }