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SubjectRe: [PATCH V4 7/15] KVM/MMU: Flush tlb directly in the kvm_zap_gfn_range()
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On 13/10/2018 16:53, lantianyu1986@gmail.com wrote:
> + bool flush = false;
> int i;
>
> spin_lock(&kvm->mmu_lock);
> @@ -5654,18 +5655,27 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
> slots = __kvm_memslots(kvm, i);
> kvm_for_each_memslot(memslot, slots) {
> gfn_t start, end;
> + bool flush_tlb = true;
>
> start = max(gfn_start, memslot->base_gfn);
> end = min(gfn_end, memslot->base_gfn + memslot->npages);
> if (start >= end)
> continue;
>
> - slot_handle_level_range(kvm, memslot, kvm_zap_rmapp,
> - PT_PAGE_TABLE_LEVEL, PT_MAX_HUGEPAGE_LEVEL,
> - start, end - 1, true);
> + if (kvm_available_flush_tlb_with_range())
> + flush_tlb = false;

This should be moved outside the for, because it's invariant.

> + flush = slot_handle_level_range(kvm, memslot,
> + kvm_zap_rmapp, PT_PAGE_TABLE_LEVEL,
> + PT_MAX_HUGEPAGE_LEVEL, start,
> + end - 1, flush_tlb);

... and this should be "flush |= ".
> }
> }
>
> + if (flush && kvm_available_flush_tlb_with_range())
> + kvm_flush_remote_tlbs_with_address(kvm, gfn_start,
> + gfn_end - gfn_start + 1);
> +

... and this can be just if (flush), because if flush_tlb is true then
slot_handle_level_range always returns false.

Paolo

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