[tip: x86/apic] x86/acpi: Dont invoke topology_register_apic() for XEN PV

[tip-bot2 for Thomas Gleixner]

The following commit has been merged into the x86/apic branch of tip:

Commit-ID:     cab8e164a49c0ee5c9acb7edec33d76422d831bf
Gitweb:        https://git.kernel.org/tip/cab8e164a49c0ee5c9acb7edec33d76422d831bf
Author:        Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate:    Tue, 13 Feb 2024 22:05:43 +01:00
Committer:     Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitterDate: Thu, 15 Feb 2024 22:07:42 +01:00

x86/acpi: Dont invoke topology_register_apic() for XEN PV

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@xxxxxxxxxxxxx>
Tested-by: Michael Kelley <mhklinux@xxxxxxxxxxx>
Tested-by: Sohil Mehta <sohil.mehta@xxxxxxxxx>
Link: https://lore.kernel.org/r/20240213210251.885489468@xxxxxxxxxxxxx



---
 arch/x86/kernel/acpi/boot.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 42799d5..df741fb 100644
--- 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>
@@ -166,7 +168,8 @@ static int __init acpi_parse_madt(struct acpi_table_header *table)
 
 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)
@@ -1087,7 +1090,8 @@ static int __init early_acpi_parse_madt_lapic_addr_ovr(void)
 		return count;
 	}
 
-	register_lapic_address(acpi_lapic_addr);
+	if (!xen_pv_domain())
+		register_lapic_address(acpi_lapic_addr);
 
 	return count;
 }