Messages in this thread | | | From | "Maciej S. Szmigiero" <> | Subject | Re: [PATCH v5.5 20/30] KVM: x86: Use nr_memslot_pages to avoid traversing the memslots array | Date | Tue, 9 Nov 2021 01:41:39 +0100 |
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On 04.11.2021 01:25, Sean Christopherson wrote: > From: Maciej S. Szmigiero <maciej.szmigiero@oracle.com> > > There is no point in recalculating from scratch the total number of pages > in all memslots each time a memslot is created or deleted. Use KVM's > cached nr_memslot_pages to compute the default max number of MMU pages. > > Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com> > [sean: use common KVM field and rework changelog accordingly] > Signed-off-by: Sean Christopherson <seanjc@google.com> > --- > arch/x86/include/asm/kvm_host.h | 1 - > arch/x86/kvm/mmu/mmu.c | 24 ------------------------ > arch/x86/kvm/x86.c | 11 ++++++++--- > 3 files changed, 8 insertions(+), 28 deletions(-) > (..) > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -11837,9 +11837,14 @@ void kvm_arch_commit_memory_region(struct kvm *kvm, > enum kvm_mr_change change) > { > if (!kvm->arch.n_requested_mmu_pages && > - (change == KVM_MR_CREATE || change == KVM_MR_DELETE)) > - kvm_mmu_change_mmu_pages(kvm, > - kvm_mmu_calculate_default_mmu_pages(kvm)); > + (change == KVM_MR_CREATE || change == KVM_MR_DELETE)) { > + unsigned long nr_mmu_pages; > + > + nr_mmu_pages = kvm->nr_memslot_pages * KVM_PERMILLE_MMU_PAGES;
Unfortunately, even if kvm->nr_memslot_pages is capped at ULONG_MAX then this value multiplied by 20 can still overflow an unsigned long variable.
Thanks, Maciej
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