[patch 29/53] x86/acpi: Dont invoke topology_register_apic() for XEN PV

Thomas Gleixner
2023-08-07T13:54:35Z

The MADT table for XEN/PV dom0 is not really useful and registering the
APICs is momentarily a pointless exercise because XENPV does not use an
APIC at all.

It overrides the x86_init.mpparse.parse_smp_config() callback, resets
num_processors and counts how many of them are provided by the hypervisor.

This is in the way of cleaning up the APIC registration. Prevent MADT
registration for XEN/PV temporarily until the rework is completed and
XEN/PV can use the MADT again.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/kernel/acpi/boot.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -23,6 +23,8 @@
#include <linux/serial_core.h>
#include <linux/pgtable.h>

+#include <xen/xen.h>
+
#include <asm/e820/api.h>
#include <asm/irqdomain.h>
#include <asm/pci_x86.h>
@@ -161,7 +163,8 @@ static int __init acpi_parse_madt(struct

static __init void acpi_register_lapic(u32 apic_id, u32 acpi_id, bool present)
{
- topology_register_apic(apic_id, acpi_id, present);
+ if (!xen_pv_domain())
+ topology_register_apic(apic_id, acpi_id, present);
}

static bool __init acpi_is_processor_usable(u32 lapic_flags)
@@ -1070,7 +1073,8 @@ static int __init early_acpi_parse_madt_
return count;
}

- register_lapic_address(acpi_lapic_addr);
+ if (!xen_pv_domain())
+ register_lapic_address(acpi_lapic_addr);

return count;
}