Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [PATCH v1] x86/apic: Fix kernel panic when "intremap=off" and "x2apic_phys" are set | Date | Mon, 19 Jun 2023 18:31:55 +0200 |
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On Sat, Jun 17 2023 at 02:52, Dheeraj Kumar Srivastava wrote: > x2APIC mode requires "Interrupt Remapping" to be enabled and the > "physical x2apic" driver can be used only when x2APIC mode is enabled. > However when "intremap=off" and "x2apic_phys" kernel command line > parameters are passed, "physical x2apic" driver is being used even when > x2APIC mode is disabled ("intremap=off" disables x2APIC mode). > This results in the below kernel panic: > > unchecked MSR access error: RDMSR from 0x80f at rIP: 0xffffffff87eab4ec > (native_read_msr+0xc/0x40) > Call Trace: > <TASK> > native_apic_msr_read+0x1f/0x30 > setup_local_APIC+0x4e/0x380 > ? zen_untrain_ret+0x1/0x1 > ? enable_IR_x2apic+0xe8/0x250 > apic_intr_mode_init+0x4c/0x120 > x86_late_time_init+0x28/0x40 > start_kernel+0x626/0xa80 > x86_64_start_reservations+0x1c/0x30 > x86_64_start_kernel+0xbf/0x110 > secondary_startup_64_no_verify+0x10b/0x10b > </TASK> > > This is due to an incorrect conditional check in x2apic_phys_probe(). > Fix it here by returning 0 when "x2apic_mode" is not set in > x2apic_phys_probe(). This now prevents default_setup_apic_routing() from > selecting "physical x2apic" driver. > > Fixes: 9ebd680bd029 ("x86, apic: Use probe routines to simplify apic selection") > Reviewed-by: Kishon Vijay Abraham I <kvijayab@amd.com> > Reviewed-by: Vasant Hegde <vasant.hegde@amd.com> > Signed-off-by: Dheeraj Kumar Srivastava <dheerajkumar.srivastava@amd.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
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