diff options
| -rw-r--r-- | virt/kvm/kvm_main.c | 64 |
1 files changed, 44 insertions, 20 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index a83ca63..64c5dc3 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)); } |