On 2014-01-27 20:14, Jan Kiszka wrote: > apic_icr_write and its users in smpboot.c were apparently written under > the assumption that this code would only run during early boot. But > nowadays we also execute it when onlining a CPU later on while the > system is fully running. That will make wakeup_cpu_via_init_nmi and, > thus, also native_apic_icr_write run in plain process context. If we > migrate the caller to a different CPU at the wrong time or interrupt it > and write to ICR/ICR2 to send unrelated IPIs, we can end up sending > INIT, SIPI or NMIs to wrong CPUs. > > Fix this by disabling interrupts during the write to the ICR halves and > disable preemption around waiting for ICR availability and using it. > > Signed-off-by: Jan Kiszka <[email protected]> > --- > arch/x86/kernel/apic/apic.c | 4 ++++ > arch/x86/kernel/smpboot.c | 11 +++++++++-- > 2 files changed, 13 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c > index 7f26c9a..06f90b8 100644 > --- a/arch/x86/kernel/apic/apic.c > +++ b/arch/x86/kernel/apic/apic.c > @@ -283,8 +283,12 @@ u32 native_safe_apic_wait_icr_idle(void) > > void native_apic_icr_write(u32 low, u32 id) > { > + unsigned long flags; > + > + local_irq_save(flags); > apic_write(APIC_ICR2, SET_APIC_DEST_FIELD(id)); > apic_write(APIC_ICR, low); > + local_irq_restore(flags); > } > > u64 native_apic_icr_read(void) > diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c > index a32da80..37e11e5 100644 > --- a/arch/x86/kernel/smpboot.c > +++ b/arch/x86/kernel/smpboot.c > @@ -701,11 +701,15 @@ wakeup_cpu_via_init_nmi(int cpu, unsigned long > start_ip, int apicid, > int id; > int boot_error; > > + preempt_disable(); > + > /* > * Wake up AP by INIT, INIT, STARTUP sequence. > */ > - if (cpu) > - return wakeup_secondary_cpu_via_init(apicid, start_ip); > + if (cpu) { > + boot_error = wakeup_secondary_cpu_via_init(apicid, start_ip); > + goto out; > + } > > /* > * Wake up BSP by nmi. > @@ -725,6 +729,9 @@ wakeup_cpu_via_init_nmi(int cpu, unsigned long start_ip, > int apicid, > boot_error = wakeup_secondary_cpu_via_nmi(id, start_ip); > } > > +out: > + preempt_enable(); > + > return boot_error; > } > >
What's the status of this? Waiting for further review, or is it queued somewhere by now? Would be good to have in 3.14, and then also in stable kernels. Jan
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