>-----Original Message----- >From: Neo Jia [mailto:cjia@xxxxxxxxxx] >Sent: Sunday, October 09, 2016 4:32 PM >To: Chen, Xiaoguang <xiaoguang.chen@xxxxxxxxx> >Cc: kvm@xxxxxxxxxxxxxxx; pbonzini@xxxxxxxxxx; Xiao, Guangrong ><guangrong.xiao@xxxxxxxxx>; Song, Jike <jike.song@xxxxxxxxx>; Kirti Wankhede ><kwankhede@xxxxxxxxxx> >Subject: Re: [PATCH 1/2] KVM: page track: add a new notifier type: >track_flush_slot > >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? Hi Neo, This is related to KVMGT device model. For KVMGT some ram will be allocated and used as ppgtt page table and the page table is write protected. We use page track to implement write protect. But get problem while memslot is moved or removed. We must clear the write protect for the pages in the memslot or there will be errors while ppgtt do cleanup. So KVMGT must register the track_flush_slot to get notified while memslot is moved or removed. > >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 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe kvm" in the >> body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at >> http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
