On Sun, Oct 09, 2016 at 03:41:43PM +0800, Xiaoguang Chen wrote:
> When a memory slot is being moved or removed users of page track
> can be notified. So users can drop write-protection for the pages
> in that memory slot.
>
> This notifier type is needed by KVMGT to sync up its shadow page
> table when memory slot is being moved or removed.
Hi Xiaoguang,
How is this supposed to be used by the kvmgt?
Thanks,
Neo
>
> Reviewed-by: Xiao Guangrong <guangrong.xiao@xxxxxxxxx>
> Signed-off-by: Chen Xiaoguang <xiaoguang.chen@xxxxxxxxx>
> ---
> arch/x86/include/asm/kvm_page_track.h | 9 +++++++++
> arch/x86/kvm/page_track.c | 25 +++++++++++++++++++++++++
> arch/x86/kvm/x86.c | 2 +-
> 3 files changed, 35 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/include/asm/kvm_page_track.h b/arch/x86/include/asm/kvm_page_track.h
> index c2b8d24..5f66597 100644
> --- a/arch/x86/include/asm/kvm_page_track.h
> +++ b/arch/x86/include/asm/kvm_page_track.h
> @@ -32,6 +32,14 @@ struct kvm_page_track_notifier_node {
> */
> void (*track_write)(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new,
> int bytes);
> + /*
> + * It is called when memory slot is being moved or removed
> + * users can drop write-protection for the pages in that memory slot
> + *
> + * @kvm: the kvm where memory slot being moved or removed
> + * @slot: the memory slot being moved or removed
> + */
> + void (*track_flush_slot)(struct kvm *kvm, struct kvm_memory_slot *slot);
> };
>
> void kvm_page_track_init(struct kvm *kvm);
> @@ -58,4 +66,5 @@ kvm_page_track_unregister_notifier(struct kvm *kvm,
> struct kvm_page_track_notifier_node *n);
> void kvm_page_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new,
> int bytes);
> +void kvm_page_track_flush_slot(struct kvm *kvm, struct kvm_memory_slot *slot);
> #endif
> diff --git a/arch/x86/kvm/page_track.c b/arch/x86/kvm/page_track.c
> index b431539..e79bb25 100644
> --- a/arch/x86/kvm/page_track.c
> +++ b/arch/x86/kvm/page_track.c
> @@ -225,3 +225,28 @@ void kvm_page_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new,
> n->track_write(vcpu, gpa, new, bytes);
> srcu_read_unlock(&head->track_srcu, idx);
> }
> +
> +/*
> + * Notify the node that memory slot is being removed or moved so that it can
> + * drop write-protection for the pages in the memory slot.
> + *
> + * The node should figure out it has any write-protected pages in this slot
> + * by itself.
> + */
> +void kvm_page_track_flush_slot(struct kvm *kvm, struct kvm_memory_slot *slot)
> +{
> + struct kvm_page_track_notifier_head *head;
> + struct kvm_page_track_notifier_node *n;
> + int idx;
> +
> + head = &kvm->arch.track_notifier_head;
> +
> + if (hlist_empty(&head->track_notifier_list))
> + return;
> +
> + idx = srcu_read_lock(&head->track_srcu);
> + hlist_for_each_entry_rcu(n, &head->track_notifier_list, node)
> + if (n->track_flush_slot)
> + n->track_flush_slot(kvm, slot);
> + srcu_read_unlock(&head->track_srcu, idx);
> +}
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 87f5dbb..f8ae90c 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8278,7 +8278,7 @@ void kvm_arch_flush_shadow_all(struct kvm *kvm)
> void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
> struct kvm_memory_slot *slot)
> {
> - kvm_mmu_invalidate_zap_all_pages(kvm);
> + kvm_page_track_flush_slot(kvm, slot);
> }
>
> static inline bool kvm_vcpu_has_events(struct kvm_vcpu *vcpu)
> --
> 1.9.1
>
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