From: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@xxxxxxx>
[ Upstream commit 85d38d5810e285d5aec7fb5283107d1da70c12a9 ]
When booting with "intremap=off" and "x2apic_phys" on the kernel command
line, the physical x2APIC driver ends up being used even when x2APIC
mode is disabled ("intremap=off" disables x2APIC mode). This happens
because the first compound condition check in x2apic_phys_probe() is
false due to x2apic_mode == 0 and so the following one returns true
after default_acpi_madt_oem_check() having already selected the physical
x2APIC driver.
This results in the following panic:
kernel BUG at arch/x86/kernel/apic/io_apic.c:2409!
invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.4.0-rc2-ver4.1rc2 #2
Hardware name: Dell Inc. PowerEdge R6515/07PXPY, BIOS 2.3.6 07/06/2021
RIP: 0010:setup_IO_APIC+0x9c/0xaf0
Call Trace:
<TASK>
? native_read_msr
apic_intr_mode_init
x86_late_time_init
start_kernel
x86_64_start_reservations
x86_64_start_kernel
secondary_startup_64_no_verify
</TASK>
which is:
setup_IO_APIC:
apic_printk(APIC_VERBOSE, "ENABLING IO-APIC IRQs\n");
for_each_ioapic(ioapic)
BUG_ON(mp_irqdomain_create(ioapic));
Return 0 to denote that x2APIC has not been enabled when probing the
physical x2APIC driver.
[ bp: Massage commit message heavily. ]
Fixes: 9ebd680bd029 ("x86, apic: Use probe routines to simplify apic selection")
Signed-off-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@xxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Reviewed-by: Kishon Vijay Abraham I <kvijayab@xxxxxxx>
Reviewed-by: Vasant Hegde <vasant.hegde@xxxxxxx>
Reviewed-by: Cyrill Gorcunov <gorcunov@xxxxxxxxx>
Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230616212236.1389-1-dheerajkumar.srivastava@xxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
arch/x86/kernel/apic/x2apic_phys.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/apic/x2apic_phys.c b/arch/x86/kernel/apic/x2apic_phys.c
index 6bde05a86b4ed..896bc41cb2ba7 100644
--- a/arch/x86/kernel/apic/x2apic_phys.c
+++ b/arch/x86/kernel/apic/x2apic_phys.c
@@ -97,7 +97,10 @@ static void init_x2apic_ldr(void)
static int x2apic_phys_probe(void)
{
- if (x2apic_mode && (x2apic_phys || x2apic_fadt_phys()))
+ if (!x2apic_mode)
+ return 0;
+
+ if (x2apic_phys || x2apic_fadt_phys())
return 1;
return apic == &apic_x2apic_phys;
--
2.39.2
