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-rw-r--r--virt/kvm/kvm_main.c64
1 files changed, 44 insertions, 20 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index a83ca63d26fc..64c5dc37c6a1 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -719,6 +719,24 @@ static struct kvm_memslots *install_new_memslots(struct kvm *kvm,
}
/*
+ * KVM_SET_USER_MEMORY_REGION ioctl allows the following operations:
+ * - create a new memory slot
+ * - delete an existing memory slot
+ * - modify an existing memory slot
+ * -- move it in the guest physical memory space
+ * -- just change its flags
+ *
+ * Since flags can be changed by some of these operations, the following
+ * differentiation is the best we can do for __kvm_set_memory_region():
+ */
+enum kvm_mr_change {
+ KVM_MR_CREATE,
+ KVM_MR_DELETE,
+ KVM_MR_MOVE,
+ KVM_MR_FLAGS_ONLY,
+};
+
+/*
* Allocate some memory and give it an address in the guest physical address
* space.
*
@@ -737,6 +755,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
struct kvm_memory_slot old, new;
struct kvm_memslots *slots = NULL, *old_memslots;
bool old_iommu_mapped;
+ enum kvm_mr_change change;
r = check_memory_region_flags(mem);
if (r)
@@ -780,17 +799,30 @@ int __kvm_set_memory_region(struct kvm *kvm,
old_iommu_mapped = old.npages;
- /*
- * Disallow changing a memory slot's size or changing anything about
- * zero sized slots that doesn't involve making them non-zero.
- */
r = -EINVAL;
- if (npages && old.npages && npages != old.npages)
- goto out;
- if (!npages && !old.npages)
+ if (npages) {
+ if (!old.npages)
+ change = KVM_MR_CREATE;
+ else { /* Modify an existing slot. */
+ if ((mem->userspace_addr != old.userspace_addr) ||
+ (npages != old.npages))
+ goto out;
+
+ if (base_gfn != old.base_gfn)
+ change = KVM_MR_MOVE;
+ else if (new.flags != old.flags)
+ change = KVM_MR_FLAGS_ONLY;
+ else { /* Nothing to change. */
+ r = 0;
+ goto out;
+ }
+ }
+ } else if (old.npages) {
+ change = KVM_MR_DELETE;
+ } else /* Modify a non-existent slot: disallowed. */
goto out;
- if ((npages && !old.npages) || (base_gfn != old.base_gfn)) {
+ if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) {
/* Check for overlaps */
r = -EEXIST;
kvm_for_each_memslot(slot, kvm->memslots) {
@@ -808,20 +840,12 @@ int __kvm_set_memory_region(struct kvm *kvm,
new.dirty_bitmap = NULL;
r = -ENOMEM;
-
- /*
- * Allocate if a slot is being created. If modifying a slot,
- * the userspace_addr cannot change.
- */
- if (!old.npages) {
+ if (change == KVM_MR_CREATE) {
new.user_alloc = user_alloc;
new.userspace_addr = mem->userspace_addr;
if (kvm_arch_create_memslot(&new, npages))
goto out_free;
- } else if (npages && mem->userspace_addr != old.userspace_addr) {
- r = -EINVAL;
- goto out_free;
}
/* Allocate page dirty bitmap if needed */
@@ -830,7 +854,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
goto out_free;
}
- if (!npages || base_gfn != old.base_gfn) {
+ if ((change == KVM_MR_DELETE) || (change == KVM_MR_MOVE)) {
r = -ENOMEM;
slots = kmemdup(kvm->memslots, sizeof(struct kvm_memslots),
GFP_KERNEL);
@@ -881,7 +905,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
* slots (size changes, userspace addr changes) is disallowed above,
* so any other attribute changes getting here can be skipped.
*/
- if (npages) {
+ if (change != KVM_MR_DELETE) {
if (old_iommu_mapped &&
((new.flags ^ old.flags) & KVM_MEM_READONLY)) {
kvm_iommu_unmap_pages(kvm, &old);
@@ -896,7 +920,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
}
/* actual memory is freed via old in kvm_free_physmem_slot below */
- if (!npages) {
+ if (change == KVM_MR_DELETE) {
new.dirty_bitmap = NULL;
memset(&new.arch, 0, sizeof(new.arch));
}