Gleb Natapov <gleb@xxxxxxxxxx> writes: > On Wed, Aug 04, 2010 at 10:16:08AM +0100, Tvrtko Ursulin wrote: >> >> Not the tip but 2.6.35 with earlyprintk=ttyS0,115200: >> >> [ 0.000000] Processor #0 (Bootup-CPU) >> [ 0.000000] I/O APIC #1 Version 17 at 0xFEC00000. >> [ 0.000000] BUG: unable to handle kernel paging request at ffffb030 >> [ 0.000000] IP: [<c011d136>] native_apic_mem_read+0x16/0x20 >> [ 0.000000] *pde = 00832067 *pte = 00000000 > Accessing APIC version register before APIC is mapped. Yep. I see it now. We have some of the silliest code. We only go down this path for certain revs of Intel cpus, and I double checked this change on an AMD cpu which explains why I missed hitting this case. The call path that is new in they bisected commit is: MP_ioapic_info() mp_register_ioapic() io_apic_unique_id() io_apic_get_unique_id() get_physical_broadcast() modern_apic() lapic_get_version() apic_read(APIC_LVR) Tvrtko can you test this patch and verify it fixes the kvm booting issue? This patch just maps the lapic early in the mmparse.c just like we do in acpi/boot.c when parsing the acpi tables. Eric --- diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index a96489e..c07e513 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -1606,7 +1606,7 @@ void __init init_apic_mappings(void) * acpi lapic path already maps that address in * acpi_register_lapic_address() */ - if (!acpi_lapic) + if (!acpi_lapic && !smp_found_config) set_fixmap_nocache(FIX_APIC_BASE, apic_phys); apic_printk(APIC_VERBOSE, "mapped APIC to %08lx (%08lx)\n", diff --git a/arch/x86/kernel/mpparse.c b/arch/x86/kernel/mpparse.c index d86dbf7..d7b6f7f 100644 --- a/arch/x86/kernel/mpparse.c +++ b/arch/x86/kernel/mpparse.c @@ -274,6 +274,18 @@ static void __init smp_dump_mptable(struct mpc_table *mpc, unsigned char *mpt) void __init default_smp_read_mpc_oem(struct mpc_table *mpc) { } +static void __init smp_register_lapic_address(unsigned long address) +{ + mp_lapic_addr = address; + + set_fixmap_nocache(FIX_APIC_BASE, address); + if (boot_cpu_physical_apicid == -1U) { + boot_cpu_physical_apicid = read_apic_id(); + apic_version[boot_cpu_physical_apicid] = + GET_APIC_VERSION(apic_read(APIC_LVR)); + } +} + static int __init smp_read_mpc(struct mpc_table *mpc, unsigned early) { char str[16]; @@ -295,6 +307,10 @@ static int __init smp_read_mpc(struct mpc_table *mpc, unsigned early) if (early) return 1; + /* Initialize the lapic mapping */ + if (!acpi_lapic) + smp_register_lapic_address(mpc->lapic); + if (mpc->oemptr) x86_init.mpparse.smp_read_mpc_oem(mpc); -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html