On 08/04/2010 01:30 PM, Eric W. Biederman wrote: > > This fixes a regression in 2.6.35 from 2.6.34, that is > present for select models of Intel cpus when people are > using an MP table. > > The commit cf7500c0ea133d66f8449d86392d83f840102632 > "x86, ioapic: In mpparse use mp_register_ioapic" started > calling mp_register_ioapic from MP_ioapic_info. An extremely > simple change that was obviously correct. Unfortunately > mp_register_ioapic did just a little more than the previous > hand crafted code and so we gained this call path. > > The problem call path 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) > > Which turned out to be a problem because the local apic > was not mapped, at that point, unlike the similar point > in the ACPI parsing code. > > This problem is fixed by mapping the local apic when > parsing the mptable as soon as we reasonably can. > > Looking at the number of places we setup the fixmap for > the local apic, I see some serious simplification opportunities. > For the moment except for not duplicating the setting up of the > fixmap in init_apic_mappings, I have not acted on them. > > The regression from 2.6.34 is tracked in bug > https://bugzilla.kernel.org/show_bug.cgi?id=16173 > > Cc: stable@xxxxxxxxxx > Reported-by: David Hill <hilld@xxxxxxxxxxxxxxx> > Reported-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx> > Tested-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx> > Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx> > --- > arch/x86/kernel/apic/apic.c | 2 +- > arch/x86/kernel/mpparse.c | 16 ++++++++++++++++ > 2 files changed, 17 insertions(+), 1 deletions(-) > > 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); > Acked-by: Yinghai Lu <yinghai@xxxxxxxxxx> will send out another two patches on top this one for cleanup. Yinghai -- 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
