[PATCH 2/5] KVM: MMU: split the operations of kvm_mmu_zap_page()

[Xiao Guangrong]

Using kvm_mmu_prepare_zap_page() and kvm_mmu_commit_zap_page() to
split kvm_mmu_zap_page() function, then we can:

- traverse hlist safely
- easily to gather remote tlb flush which occurs during page zapped

Signed-off-by: Xiao Guangrong <xiaoguangr...@cn.fujitsu.com>
---
 arch/x86/include/asm/kvm_host.h |    1 +
 arch/x86/kvm/mmu.c              |   42 ++++++++++++++++++++++++++++++++++++++-
 arch/x86/kvm/x86.c              |    1 +
 3 files changed, 43 insertions(+), 1 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 0cd0f29..e4df1cf 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -388,6 +388,7 @@ struct kvm_arch {
         * Hash table of struct kvm_mmu_page.
         */
        struct list_head active_mmu_pages;
+       struct list_head invalid_mmu_pages;
        struct list_head assigned_dev_head;
        struct iommu_domain *iommu_domain;
        int iommu_flags;
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 84c705e..0c957bf 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -915,6 +915,7 @@ static int is_empty_shadow_page(u64 *spt)
 static void kvm_mmu_free_page(struct kvm *kvm, struct kvm_mmu_page *sp)
 {
        ASSERT(is_empty_shadow_page(sp->spt));
+       hlist_del(&sp->hash_link);
        list_del(&sp->link);
        __free_page(virt_to_page(sp->spt));
        if (!sp->role.direct)
@@ -1560,6 +1561,46 @@ static int mmu_zap_unsync_children(struct kvm *kvm,
        return zapped;
 }
 
+static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp)
+{
+       int ret;
+
+       trace_kvm_mmu_zap_page(sp);
+       ++kvm->stat.mmu_shadow_zapped;
+       ret = mmu_zap_unsync_children(kvm, sp);
+       kvm_mmu_page_unlink_children(kvm, sp);
+       kvm_mmu_unlink_parents(kvm, sp);
+       if (!sp->role.invalid && !sp->role.direct)
+               unaccount_shadowed(kvm, sp->gfn);
+       if (sp->unsync)
+               kvm_unlink_unsync_page(kvm, sp);
+       if (!sp->root_count)
+               /* Count self */
+               ret++;
+       else
+               kvm_reload_remote_mmus(kvm);
+
+       sp->role.invalid = 1;
+       list_move(&sp->link, &kvm->arch.invalid_mmu_pages);
+       kvm_mmu_reset_last_pte_updated(kvm);
+       return ret;
+}
+
+static void kvm_mmu_commit_zap_page(struct kvm *kvm)
+{
+       struct kvm_mmu_page *sp, *n;
+
+       if (list_empty(&kvm->arch.invalid_mmu_pages))
+               return;
+
+       kvm_flush_remote_tlbs(kvm);
+       list_for_each_entry_safe(sp, n, &kvm->arch.invalid_mmu_pages, link) {
+               WARN_ON(!sp->role.invalid);
+               if (!sp->root_count)
+                       kvm_mmu_free_page(kvm, sp);
+       }
+}
+
 static int kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp)
 {
        int ret;
@@ -1577,7 +1618,6 @@ static int kvm_mmu_zap_page(struct kvm *kvm, struct 
kvm_mmu_page *sp)
        if (!sp->root_count) {
                /* Count self */
                ret++;
-               hlist_del(&sp->hash_link);
                kvm_mmu_free_page(kvm, sp);
        } else {
                sp->role.invalid = 1;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5e5cd8d..225c3c4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5331,6 +5331,7 @@ struct  kvm *kvm_arch_create_vm(void)
        }
 
        INIT_LIST_HEAD(&kvm->arch.active_mmu_pages);
+       INIT_LIST_HEAD(&kvm->arch.invalid_mmu_pages);
        INIT_LIST_HEAD(&kvm->arch.assigned_dev_head);
 
        /* Reserve bit 0 of irq_sources_bitmap for userspace irq source */
-- 
1.6.1.2



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