From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752305Ab2LUPVS (ORCPT ); Fri, 21 Dec 2012 10:21:18 -0500 Received: from mx1.redhat.com ([209.132.183.28]:29242 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751079Ab2LUPVN (ORCPT ); Fri, 21 Dec 2012 10:21:13 -0500 Subject: [PATCH] kvm: Fix memory slot generation updates To: kvm@vger.kernel.org, gleb@redhat.com From: Alex Williamson Cc: yoshikawa_takuya_b1@lab.ntt.co.jp, mtosatti@redhat.com, linux-kernel@vger.kernel.org, takuya.yoshikawa@gmail.com Date: Fri, 21 Dec 2012 08:20:16 -0700 Message-ID: <20121221151959.3641.75215.stgit@bling.home> User-Agent: StGit/0.16 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Previous patch "kvm: Minor memory slot optimization" overlooked the generation field of the memory slots. Re-using the original memory slots left us with with two slightly different memory slots with the same generation. To fix this, make update_memslots() take a new parameter to specify the last generation. This also makes generation management more explicit to avoid such problems in the future. Reported-by: Takuya Yoshikawa Signed-off-by: Alex Williamson --- include/linux/kvm_host.h | 3 ++- virt/kvm/kvm_main.c | 9 +++++---- 2 files changed, 7 insertions(+), 5 deletions(-) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 32fdc45..cbe0d68 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -428,7 +428,8 @@ void kvm_exit(void); void kvm_get_kvm(struct kvm *kvm); void kvm_put_kvm(struct kvm *kvm); -void update_memslots(struct kvm_memslots *slots, struct kvm_memory_slot *new); +void update_memslots(struct kvm_memslots *slots, struct kvm_memory_slot *new, + u64 last_generation); static inline struct kvm_memslots *kvm_memslots(struct kvm *kvm) { diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index bd31096..14cbae8 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -672,7 +672,8 @@ static void sort_memslots(struct kvm_memslots *slots) slots->id_to_index[slots->memslots[i].id] = i; } -void update_memslots(struct kvm_memslots *slots, struct kvm_memory_slot *new) +void update_memslots(struct kvm_memslots *slots, struct kvm_memory_slot *new, + u64 last_generation) { if (new) { int id = new->id; @@ -684,7 +685,7 @@ void update_memslots(struct kvm_memslots *slots, struct kvm_memory_slot *new) sort_memslots(slots); } - slots->generation++; + slots->generation = last_generation + 1; } static int check_memory_region_flags(struct kvm_userspace_memory_region *mem) @@ -819,7 +820,7 @@ int __kvm_set_memory_region(struct kvm *kvm, slot = id_to_memslot(slots, mem->slot); slot->flags |= KVM_MEMSLOT_INVALID; - update_memslots(slots, NULL); + update_memslots(slots, NULL, kvm->memslots->generation); old_memslots = kvm->memslots; rcu_assign_pointer(kvm->memslots, slots); @@ -867,7 +868,7 @@ int __kvm_set_memory_region(struct kvm *kvm, memset(&new.arch, 0, sizeof(new.arch)); } - update_memslots(slots, &new); + update_memslots(slots, &new, kvm->memslots->generation); old_memslots = kvm->memslots; rcu_assign_pointer(kvm->memslots, slots); synchronize_srcu_expedited(&kvm->srcu);