[RFC V2 PATCH 2/8] kvm: Add HVA range operator

[Vishal Annapurve <vannapurve@google.com>]

Introduce HVA range operator so that other KVM subsystems
can operate on HVA range.

Signed-off-by: Vishal Annapurve <vannapurve@google.com>
---
 include/linux/kvm_host.h |  6 +++++
 virt/kvm/kvm_main.c      | 48 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 4508fa0e8fb6..c860e6d6408d 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -1398,6 +1398,12 @@ void *kvm_mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc);
 void kvm_mmu_updating_begin(struct kvm *kvm, gfn_t start, gfn_t end);
 void kvm_mmu_updating_end(struct kvm *kvm, gfn_t start, gfn_t end);
 
+typedef int (*kvm_hva_range_op_t)(struct kvm *kvm,
+				struct kvm_gfn_range *range, void *data);
+
+int kvm_vm_do_hva_range_op(struct kvm *kvm, unsigned long hva_start,
+		unsigned long hva_end, kvm_hva_range_op_t handler, void *data);
+
 long kvm_arch_dev_ioctl(struct file *filp,
 			unsigned int ioctl, unsigned long arg);
 long kvm_arch_vcpu_ioctl(struct file *filp,
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 7597949fe031..16cb9ab59143 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -647,6 +647,54 @@ static __always_inline int __kvm_handle_hva_range(struct kvm *kvm,
 	return (int)ret;
 }
 
+int kvm_vm_do_hva_range_op(struct kvm *kvm, unsigned long hva_start,
+		unsigned long hva_end, kvm_hva_range_op_t handler, void *data)
+{
+	int ret = 0;
+	struct kvm_gfn_range gfn_range;
+	struct kvm_memory_slot *slot;
+	struct kvm_memslots *slots;
+	int i, idx;
+
+	if (WARN_ON_ONCE(hva_end <= hva_start))
+		return -EINVAL;
+
+	idx = srcu_read_lock(&kvm->srcu);
+
+	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
+		struct interval_tree_node *node;
+
+		slots = __kvm_memslots(kvm, i);
+		kvm_for_each_memslot_in_hva_range(node, slots,
+					  hva_start, hva_end - 1) {
+			unsigned long start, end;
+
+			slot = container_of(node, struct kvm_memory_slot,
+				hva_node[slots->node_idx]);
+			start = max(hva_start, slot->userspace_addr);
+			end = min(hva_end, slot->userspace_addr +
+						  (slot->npages << PAGE_SHIFT));
+
+			/*
+			 * {gfn(page) | page intersects with [hva_start, hva_end)} =
+			 * {gfn_start, gfn_start+1, ..., gfn_end-1}.
+			 */
+			gfn_range.start = hva_to_gfn_memslot(start, slot);
+			gfn_range.end = hva_to_gfn_memslot(end + PAGE_SIZE - 1, slot);
+			gfn_range.slot = slot;
+
+			ret = handler(kvm, &gfn_range, data);
+			if (ret)
+				goto e_ret;
+		}
+	}
+
+e_ret:
+	srcu_read_unlock(&kvm->srcu, idx);
+
+	return ret;
+}
+
 static __always_inline int kvm_handle_hva_range(struct mmu_notifier *mn,
 						unsigned long start,
 						unsigned long end,
-- 
2.37.2.672.g94769d06f0-goog