[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH for 4.5] x86/VPMU: Clear last_vcpu when destroying VPMU
On Fri, Dec 12, 2014 at 04:20:48PM -0500, Boris Ostrovsky wrote: > We need to make sure that last_vcpu is not pointing to VCPU whose > VPMU is being destroyed. Otherwise we may try dereference it in > the future, when VCPU is gone. > > Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> Release-Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> > --- > xen/arch/x86/hvm/vpmu.c | 22 ++++++++++++++++++++++ > 1 files changed, 22 insertions(+), 0 deletions(-) > > This needs to be backported to 4.3 and 4.4 as well > > diff --git a/xen/arch/x86/hvm/vpmu.c b/xen/arch/x86/hvm/vpmu.c > index 1df74c2..6d39680 100644 > --- a/xen/arch/x86/hvm/vpmu.c > +++ b/xen/arch/x86/hvm/vpmu.c > @@ -247,10 +247,32 @@ void vpmu_initialise(struct vcpu *v) > } > } > > +static void vpmu_clear_last(void *arg) > +{ > + struct vcpu *v = (struct vcpu *)arg; > + > + if ( this_cpu(last_vcpu) == v ) > + this_cpu(last_vcpu) = NULL; > +} > + > void vpmu_destroy(struct vcpu *v) > { > struct vpmu_struct *vpmu = vcpu_vpmu(v); > > + if ( vpmu_is_set(vpmu, VPMU_CONTEXT_ALLOCATED) ) > + { > + /* Need to clear last_vcpu in case it points to v */ > + if ( vpmu->last_pcpu != smp_processor_id() ) > + on_selected_cpus(cpumask_of(vpmu->last_pcpu), > + vpmu_clear_last, (void *)v, 1); > + else > + { > + local_irq_disable(); > + vpmu_clear_last((void *)v); > + local_irq_enable(); > + } > + } > + > if ( vpmu->arch_vpmu_ops && vpmu->arch_vpmu_ops->arch_vpmu_destroy ) > vpmu->arch_vpmu_ops->arch_vpmu_destroy(v); > } > -- > 1.7.1 > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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