Messages in this thread | | | Date | Sun, 27 Sep 2009 10:54:41 +0200 | From | Avi Kivity <> | Subject | Re: [PATCH: kvm 4/5] Fix hotremove of CPUs for KVM. |
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On 09/25/2009 03:47 AM, Zachary Amsden wrote: > In the process of bringing down CPUs, the SVM / VMX structures associated > with those CPUs are not freed. This may cause leaks when unloading and > reloading the KVM module, as only the structures associated with online > CPUs are cleaned up. So, clean up all possible CPUs, not just online ones. > > Signed-off-by: Zachary Amsden<zamsden@redhat.com> > --- > arch/x86/kvm/svm.c | 2 +- > arch/x86/kvm/vmx.c | 7 +++++-- > 2 files changed, 6 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c > index 8f99d0c..13ca268 100644 > --- a/arch/x86/kvm/svm.c > +++ b/arch/x86/kvm/svm.c > @@ -525,7 +525,7 @@ static __exit void svm_hardware_unsetup(void) > { > int cpu; > > - for_each_online_cpu(cpu) > + for_each_possible_cpu(cpu) > svm_cpu_uninit(cpu); > > __free_pages(pfn_to_page(iopm_base>> PAGE_SHIFT), IOPM_ALLOC_ORDER); > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index b8a8428..603bde3 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -1350,8 +1350,11 @@ static void free_kvm_area(void) > { > int cpu; > > - for_each_online_cpu(cpu) > - free_vmcs(per_cpu(vmxarea, cpu)); > + for_each_possible_cpu(cpu) > + if (per_cpu(vmxarea, cpu)) { > + free_vmcs(per_cpu(vmxarea, cpu)); > + per_cpu(vmxarea, cpu) = NULL; > + } > } > > static __init int alloc_kvm_area(void) >
First, I'm not sure per_cpu works for possible but not actual cpus. Second, we now eagerly allocate but lazily free, leading to lots of ifs and buts. I think the code can be cleaner by eagerly allocating and eagerly freeing.
-- Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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