From 13ea525517088b20399aeb410d9fc567741ac27f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Tue, 18 Feb 2020 13:07:16 -0800 Subject: [PATCH] KVM: Reinstall old memslots if arch preparation fails Reinstall the old memslots if preparing the new memory region fails after invalidating a to-be-{re}moved memslot. Remove the superfluous 'old_memslots' variable so that it's somewhat clear that the error handling path needs to free the unused memslots, not simply the 'old' memslots. Fixes: bc6678a33d9b9 ("KVM: introduce kvm->srcu and convert kvm_set_memory_region to SRCU update") Reviewed-by: Christoffer Dall Reviewed-by: Peter Xu Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- virt/kvm/kvm_main.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 70f03ce0e5c1..6e99525d7dce 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -999,7 +999,7 @@ int __kvm_set_memory_region(struct kvm *kvm, unsigned long npages; struct kvm_memory_slot *slot; struct kvm_memory_slot old, new; - struct kvm_memslots *slots = NULL, *old_memslots; + struct kvm_memslots *slots; int as_id, id; enum kvm_mr_change change; @@ -1107,7 +1107,13 @@ int __kvm_set_memory_region(struct kvm *kvm, slot = id_to_memslot(slots, id); slot->flags |= KVM_MEMSLOT_INVALID; - old_memslots = install_new_memslots(kvm, as_id, slots); + /* + * We can re-use the old memslots, the only difference from the + * newly installed memslots is the invalid flag, which will get + * dropped by update_memslots anyway. We'll also revert to the + * old memslots if preparing the new memory region fails. + */ + slots = install_new_memslots(kvm, as_id, slots); /* From this point no new shadow pages pointing to a deleted, * or moved, memslot will be created. @@ -1117,13 +1123,6 @@ int __kvm_set_memory_region(struct kvm *kvm, * - kvm_is_visible_gfn (mmu_check_root) */ kvm_arch_flush_shadow_memslot(kvm, slot); - - /* - * We can re-use the old_memslots from above, the only difference - * from the currently installed memslots is the invalid flag. This - * will get overwritten by update_memslots anyway. - */ - slots = old_memslots; } r = kvm_arch_prepare_memory_region(kvm, &new, mem, change); @@ -1137,15 +1136,17 @@ int __kvm_set_memory_region(struct kvm *kvm, } update_memslots(slots, &new, change); - old_memslots = install_new_memslots(kvm, as_id, slots); + slots = install_new_memslots(kvm, as_id, slots); kvm_arch_commit_memory_region(kvm, mem, &old, &new, change); kvm_free_memslot(kvm, &old, &new); - kvfree(old_memslots); + kvfree(slots); return 0; out_slots: + if (change == KVM_MR_DELETE || change == KVM_MR_MOVE) + slots = install_new_memslots(kvm, as_id, slots); kvfree(slots); out_free: kvm_free_memslot(kvm, &new, &old);