Migration of memory context involves moving lpage_info and mem_attr_array from source to destination VM.
Co-developed-by: Sagi Shahar sagis@google.com Signed-off-by: Sagi Shahar sagis@google.com Co-developed-by: Vishal Annapurve vannapurve@google.com Signed-off-by: Vishal Annapurve vannapurve@google.com Signed-off-by: Ackerley Tng ackerleytng@google.com --- arch/x86/kvm/x86.c | 110 +++++++++++++++++++++++++++++++++++++++ include/linux/kvm_host.h | 17 ++++++ virt/kvm/guest_mem.c | 25 +++++++++ 3 files changed, 152 insertions(+)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a1a28dd77b94..12688754c556 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -4402,6 +4402,33 @@ void kvm_unlock_two_vms(struct kvm *dst_kvm, struct kvm *src_kvm) } EXPORT_SYMBOL_GPL(kvm_unlock_two_vms);
+static int kvm_lock_vm_memslots(struct kvm *dst_kvm, struct kvm *src_kvm) +{ + int r = -EINVAL; + + if (dst_kvm == src_kvm) + return r; + + r = -EINTR; + if (mutex_lock_killable(&dst_kvm->slots_lock)) + return r; + + if (mutex_lock_killable_nested(&src_kvm->slots_lock, SINGLE_DEPTH_NESTING)) + goto unlock_dst; + + return 0; + +unlock_dst: + mutex_unlock(&dst_kvm->slots_lock); + return r; +} + +static void kvm_unlock_vm_memslots(struct kvm *dst_kvm, struct kvm *src_kvm) +{ + mutex_unlock(&src_kvm->slots_lock); + mutex_unlock(&dst_kvm->slots_lock); +} + /* * Read or write a bunch of msrs. All parameters are kernel addresses. * @@ -6325,6 +6352,78 @@ int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_event, return 0; }
+static bool memslot_configurations_match(struct kvm_memslots *src_slots, + struct kvm_memslots *dst_slots) +{ + struct kvm_memslot_iter src_iter; + struct kvm_memslot_iter dst_iter; + + kvm_for_each_memslot_pair(&src_iter, src_slots, &dst_iter, dst_slots) { + if (src_iter.slot->base_gfn != dst_iter.slot->base_gfn || + src_iter.slot->npages != dst_iter.slot->npages || + src_iter.slot->flags != dst_iter.slot->flags) + return false; + + if (kvm_slot_can_be_private(dst_iter.slot) && + !kvm_gmem_params_match(src_iter.slot, dst_iter.slot)) + return false; + } + + /* There should be no more nodes to iterate if configurations match */ + return !src_iter.node && !dst_iter.node; +} + +static int kvm_move_memory_ctxt_from(struct kvm *dst, struct kvm *src) +{ + struct kvm_memslot_iter src_iter; + struct kvm_memslot_iter dst_iter; + struct kvm_memslots *src_slots, *dst_slots; + int i; + + /* TODO: Do we also need to check consistency for as_id == SMM? */ + src_slots = __kvm_memslots(src, 0); + dst_slots = __kvm_memslots(dst, 0); + + if (!memslot_configurations_match(src_slots, dst_slots)) + return -EINVAL; + + /* + * Transferring lpage_info is an optimization, lpage_info can be rebuilt + * by the destination VM. + */ + kvm_for_each_memslot_pair(&src_iter, src_slots, &dst_iter, dst_slots) { + for (i = 1; i < KVM_NR_PAGE_SIZES; ++i) { + unsigned long ugfn = dst_iter.slot->userspace_addr >> PAGE_SHIFT; + int level = i + 1; + + /* + * If the gfn and userspace address are not aligned wrt each + * other, skip migrating lpage_info. + */ + if ((dst_iter.slot->base_gfn ^ ugfn) & + (KVM_PAGES_PER_HPAGE(level) - 1)) + continue; + + kvfree(dst_iter.slot->arch.lpage_info[i - 1]); + dst_iter.slot->arch.lpage_info[i - 1] = + src_iter.slot->arch.lpage_info[i - 1]; + src_iter.slot->arch.lpage_info[i - 1] = NULL; + } + } + +#ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES + /* + * For VMs that don't use private memory, this will just be moving an + * empty xarray pointer. + */ + dst->mem_attr_array.xa_head = src->mem_attr_array.xa_head; + src->mem_attr_array.xa_head = NULL; +#endif + + kvm_vm_dead(src); + return 0; +} + static int kvm_vm_move_enc_context_from(struct kvm *kvm, unsigned int source_fd) { int r; @@ -6351,6 +6450,14 @@ static int kvm_vm_move_enc_context_from(struct kvm *kvm, unsigned int source_fd) if (r) goto out_mark_migration_done;
+ r = kvm_lock_vm_memslots(kvm, source_kvm); + if (r) + goto out_unlock; + + r = kvm_move_memory_ctxt_from(kvm, source_kvm); + if (r) + goto out_unlock_memslots; + /* * Different types of VMs will allow userspace to define if moving * encryption context should be supported. @@ -6360,6 +6467,9 @@ static int kvm_vm_move_enc_context_from(struct kvm *kvm, unsigned int source_fd) r = static_call(kvm_x86_vm_move_enc_context_from)(kvm, source_kvm); }
+out_unlock_memslots: + kvm_unlock_vm_memslots(kvm, source_kvm); +out_unlock: kvm_unlock_two_vms(kvm, source_kvm); out_mark_migration_done: kvm_mark_migration_done(kvm, source_kvm); diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 3e03eeca279f..2f44b5d294a8 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1144,6 +1144,15 @@ static inline bool kvm_memslot_iter_is_valid(struct kvm_memslot_iter *iter, gfn_ kvm_memslot_iter_is_valid(iter, end); \ kvm_memslot_iter_next(iter))
+/* Iterate over a pair of memslots in gfn order until one of the trees end */ +#define kvm_for_each_memslot_pair(iter1, slots1, iter2, slots2) \ + for (kvm_memslot_iter_start(iter1, slots1, 0), \ + kvm_memslot_iter_start(iter2, slots2, 0); \ + kvm_memslot_iter_is_valid(iter1, U64_MAX) && \ + kvm_memslot_iter_is_valid(iter2, U64_MAX); \ + kvm_memslot_iter_next(iter1), \ + kvm_memslot_iter_next(iter2)) + /* * KVM_SET_USER_MEMORY_REGION ioctl allows the following operations: * - create a new memory slot @@ -2359,6 +2368,8 @@ static inline bool kvm_mem_is_private(struct kvm *kvm, gfn_t gfn) #ifdef CONFIG_KVM_PRIVATE_MEM int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn, kvm_pfn_t *pfn, int *max_order); +bool kvm_gmem_params_match(struct kvm_memory_slot *slot1, + struct kvm_memory_slot *slot2); #else static inline int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, gfn_t gfn, @@ -2367,6 +2378,12 @@ static inline int kvm_gmem_get_pfn(struct kvm *kvm, KVM_BUG_ON(1, kvm); return -EIO; } + +static inline bool kvm_gmem_params_match(struct kvm_memory_slot *slot1, + struct kvm_memory_slot *slot2) +{ + return false; +} #endif /* CONFIG_KVM_PRIVATE_MEM */
#endif diff --git a/virt/kvm/guest_mem.c b/virt/kvm/guest_mem.c index 1b3df273f785..2f84e5c67942 100644 --- a/virt/kvm/guest_mem.c +++ b/virt/kvm/guest_mem.c @@ -686,6 +686,31 @@ int kvm_gmem_get_pfn(struct kvm *kvm, struct kvm_memory_slot *slot, } EXPORT_SYMBOL_GPL(kvm_gmem_get_pfn);
+bool kvm_gmem_params_match(struct kvm_memory_slot *slot1, + struct kvm_memory_slot *slot2) +{ + bool ret; + struct file *file1; + struct file *file2; + + if (slot1->gmem.pgoff != slot2->gmem.pgoff) + return false; + + file1 = kvm_gmem_get_file(slot1); + file2 = kvm_gmem_get_file(slot2); + + ret = (file1 && file2 && + file_inode(file1) == file_inode(file2)); + + if (file1) + fput(file1); + if (file2) + fput(file2); + + return ret; +} +EXPORT_SYMBOL_GPL(kvm_gmem_params_match); + static int kvm_gmem_init_fs_context(struct fs_context *fc) { if (!init_pseudo(fc, GUEST_MEMORY_MAGIC))