[RFC v2 PATCH 09/13] KVM: Introduce kvm_memfd_invalidate_range

[Chao Peng]

Invalidate on fd-based memslot can reuse the code from existing MMU
notifier.

Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
---
 include/linux/kvm_host.h |  3 +++
 virt/kvm/kvm_main.c      | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 925c4d9f0a31..f0fd32f6eab3 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1883,4 +1883,7 @@ static inline void kvm_handle_signal_exit(struct kvm_vcpu 
*vcpu)
 /* Max number of entries allowed for each kvm dirty ring */
 #define  KVM_DIRTY_RING_MAX_ENTRIES  65536
 
+int kvm_memfd_invalidate_range(struct kvm *kvm, struct inode *inode,
+                              unsigned long start, unsigned long end);
+
 #endif
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index d9a6890dd18a..090afbadb03f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -811,6 +811,35 @@ static int kvm_init_mmu_notifier(struct kvm *kvm)
        return mmu_notifier_register(&kvm->mmu_notifier, current->mm);
 }
 
+int kvm_memfd_invalidate_range(struct kvm *kvm, struct inode *inode,
+                              unsigned long start, unsigned long end)
+{
+       int ret;
+       const struct kvm_useraddr_range useraddr_range = {
+               .start          = start,
+               .end            = end,
+               .pte            = __pte(0),
+               .handler        = kvm_unmap_gfn_range,
+               .on_lock        = (void *)kvm_null_fn,
+               .flush_on_ret   = true,
+               .may_block      = false,
+       };
+
+
+       /* Prevent memslot modification */
+       spin_lock(&kvm->mn_invalidate_lock);
+       kvm->mn_active_invalidate_count++;
+       spin_unlock(&kvm->mn_invalidate_lock);
+
+       ret = __kvm_handle_useraddr_range(kvm, &useraddr_range);
+
+       spin_lock(&kvm->mn_invalidate_lock);
+       kvm->mn_active_invalidate_count--;
+       spin_unlock(&kvm->mn_invalidate_lock);
+
+       return ret;
+}
+
 #else  /* !(CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER) */
 
 static int kvm_init_mmu_notifier(struct kvm *kvm)
@@ -818,6 +847,12 @@ static int kvm_init_mmu_notifier(struct kvm *kvm)
        return 0;
 }
 
+int kvm_memfd_invalidate_range(struct kvm *kvm, struct inode *inode,
+                              unsigned long start, unsigned long end)
+{
+       return 0;
+}
+
 #endif /* CONFIG_MMU_NOTIFIER && KVM_ARCH_WANT_MMU_NOTIFIER */
 
 #ifdef CONFIG_HAVE_KVM_PM_NOTIFIER
-- 
2.17.1