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

Chao Peng
2021-11-19T13:49:58Z

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