[RFC KVM 15/27] kvm/isolation: keep track of VA range mapped in KVM address space

[Alexandre Chartre <alexandre.chartre@xxxxxxxxxx>]

This will be used when we have to clear mappings to ensure the same
range is cleared at the same page table level it was copied.

Signed-off-by: Alexandre Chartre <alexandre.chartre@xxxxxxxxxx>
---
 arch/x86/kvm/isolation.c |   86 ++++++++++++++++++++++++++++++++++++++++++++-
 1 files changed, 84 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/isolation.c b/arch/x86/kvm/isolation.c
index 4f1b511..c8358a9 100644
--- a/arch/x86/kvm/isolation.c
+++ b/arch/x86/kvm/isolation.c
@@ -61,6 +61,20 @@ struct pgt_directory_group {
 #define PGTD_ALIGN(entry)	\
 	((typeof(entry))(((unsigned long)(entry)) & PAGE_MASK))
 
+/*
+ * Variables to keep track of address ranges mapped into the KVM
+ * address space.
+ */
+struct kvm_range_mapping {
+	struct list_head list;
+	void *ptr;
+	size_t size;
+	enum page_table_level level;
+};
+
+static LIST_HEAD(kvm_range_mapping_list);
+static DEFINE_MUTEX(kvm_range_mapping_lock);
+
 
 struct mm_struct kvm_mm = {
 	.mm_rb			= RB_ROOT,
@@ -91,6 +105,52 @@ struct mm_struct kvm_mm = {
 static bool __read_mostly address_space_isolation;
 module_param(address_space_isolation, bool, 0444);
 
+static struct kvm_range_mapping *kvm_get_range_mapping_locked(void *ptr,
+							      bool *subset)
+{
+	struct kvm_range_mapping *range;
+
+	list_for_each_entry(range, &kvm_range_mapping_list, list) {
+		if (range->ptr == ptr) {
+			if (subset)
+				*subset = false;
+			return range;
+		}
+		if (ptr > range->ptr && ptr < range->ptr + range->size) {
+			if (subset)
+				*subset = true;
+			return range;
+		}
+	}
+
+	return NULL;
+}
+
+static struct kvm_range_mapping *kvm_get_range_mapping(void *ptr, bool *subset)
+{
+	struct kvm_range_mapping *range;
+
+	mutex_lock(&kvm_range_mapping_lock);
+	range = kvm_get_range_mapping_locked(ptr, subset);
+	mutex_unlock(&kvm_range_mapping_lock);
+
+	return range;
+}
+
+static void kvm_free_all_range_mapping(void)
+{
+	struct kvm_range_mapping *range, *range_next;
+
+	mutex_lock(&kvm_range_mapping_lock);
+
+	list_for_each_entry_safe(range, range_next,
+				 &kvm_range_mapping_list, list) {
+		list_del(&range->list);
+		kfree(range);
+	}
+
+	mutex_unlock(&kvm_range_mapping_lock);
+}
 
 static struct pgt_directory_group *pgt_directory_group_create(void)
 {
@@ -661,10 +721,30 @@ static int kvm_copy_mapping(void *ptr, size_t size, enum page_table_level level)
 {
 	unsigned long addr = (unsigned long)ptr;
 	unsigned long end = addr + ((unsigned long)size);
+	struct kvm_range_mapping *range_mapping;
+	bool subset;
+	int err;
 
 	BUG_ON(current->mm == &kvm_mm);
-	pr_debug("KERNMAP COPY addr=%px size=%lx\n", ptr, size);
-	return kvm_copy_pgd_range(&kvm_mm, current->mm, addr, end, level);
+	pr_debug("KERNMAP COPY addr=%px size=%lx level=%d\n", ptr, size, level);
+
+	range_mapping = kmalloc(sizeof(struct kvm_range_mapping), GFP_KERNEL);
+	if (!range_mapping)
+		return -ENOMEM;
+
+	err = kvm_copy_pgd_range(&kvm_mm, current->mm, addr, end, level);
+	if (err) {
+		kfree(range_mapping);
+		return err;
+	}
+
+	INIT_LIST_HEAD(&range_mapping->list);
+	range_mapping->ptr = ptr;
+	range_mapping->size = size;
+	range_mapping->level = level;
+	list_add(&range_mapping->list, &kvm_range_mapping_list);
+
+	return 0;
 }
 
 
@@ -720,6 +800,8 @@ static void kvm_isolation_uninit_mm(void)
 
 	destroy_context(&kvm_mm);
 
+	kvm_free_all_range_mapping();
+
 #ifdef CONFIG_PAGE_TABLE_ISOLATION
 	/*
 	 * With PTI, the KVM address space is defined in the user
-- 
1.7.1