diff --git a/arch/x86/include/asm/kvm_page_track.h b/arch/x86/include/asm/kvm_page_track.h index 5520040682d1d69335f42e2288601941ba5259ff..e363e3040ba49c5120c0bfee601a674cbdd794ce 100644 --- a/arch/x86/include/asm/kvm_page_track.h +++ b/arch/x86/include/asm/kvm_page_track.h @@ -10,4 +10,11 @@ void kvm_page_track_free_memslot(struct kvm_memory_slot *free, struct kvm_memory_slot *dont); int kvm_page_track_create_memslot(struct kvm_memory_slot *slot, unsigned long npages); + +void kvm_slot_page_track_add_page(struct kvm *kvm, + struct kvm_memory_slot *slot, gfn_t gfn, + enum kvm_page_track_mode mode); +void kvm_slot_page_track_remove_page(struct kvm *kvm, + struct kvm_memory_slot *slot, gfn_t gfn, + enum kvm_page_track_mode mode); #endif diff --git a/arch/x86/kvm/page_track.c b/arch/x86/kvm/page_track.c index 8c396d08c0a4a7ed52f938a275c9e46b6c8b0f06..cd76bc31896809e1c5bfd584b6e9c71edbbd8b46 100644 --- a/arch/x86/kvm/page_track.c +++ b/arch/x86/kvm/page_track.c @@ -50,3 +50,88 @@ int kvm_page_track_create_memslot(struct kvm_memory_slot *slot, kvm_page_track_free_memslot(slot, NULL); return -ENOMEM; } + +static inline bool page_track_mode_is_valid(enum kvm_page_track_mode mode) +{ + if (mode < 0 || mode >= KVM_PAGE_TRACK_MAX) + return false; + + return true; +} + +static void update_gfn_track(struct kvm_memory_slot *slot, gfn_t gfn, + enum kvm_page_track_mode mode, short count) +{ + int index, val; + + index = gfn_to_index(gfn, slot->base_gfn, PT_PAGE_TABLE_LEVEL); + + val = slot->arch.gfn_track[mode][index]; + + if (WARN_ON(val + count < 0 || val + count > USHRT_MAX)) + return; + + slot->arch.gfn_track[mode][index] += count; +} + +/* + * add guest page to the tracking pool so that corresponding access on that + * page will be intercepted. + * + * It should be called under the protection both of mmu-lock and kvm->srcu + * or kvm->slots_lock. + * + * @kvm: the guest instance we are interested in. + * @slot: the @gfn belongs to. + * @gfn: the guest page. + * @mode: tracking mode, currently only write track is supported. + */ +void kvm_slot_page_track_add_page(struct kvm *kvm, + struct kvm_memory_slot *slot, gfn_t gfn, + enum kvm_page_track_mode mode) +{ + + if (WARN_ON(!page_track_mode_is_valid(mode))) + return; + + update_gfn_track(slot, gfn, mode, 1); + + /* + * new track stops large page mapping for the + * tracked page. + */ + kvm_mmu_gfn_disallow_lpage(slot, gfn); + + if (mode == KVM_PAGE_TRACK_WRITE) + if (kvm_mmu_slot_gfn_write_protect(kvm, slot, gfn)) + kvm_flush_remote_tlbs(kvm); +} + +/* + * remove the guest page from the tracking pool which stops the interception + * of corresponding access on that page. It is the opposed operation of + * kvm_slot_page_track_add_page(). + * + * It should be called under the protection both of mmu-lock and kvm->srcu + * or kvm->slots_lock. + * + * @kvm: the guest instance we are interested in. + * @slot: the @gfn belongs to. + * @gfn: the guest page. + * @mode: tracking mode, currently only write track is supported. + */ +void kvm_slot_page_track_remove_page(struct kvm *kvm, + struct kvm_memory_slot *slot, gfn_t gfn, + enum kvm_page_track_mode mode) +{ + if (WARN_ON(!page_track_mode_is_valid(mode))) + return; + + update_gfn_track(slot, gfn, mode, -1); + + /* + * allow large page mapping for the tracked page + * after the tracker is gone. + */ + kvm_mmu_gfn_allow_lpage(slot, gfn); +}