From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751712Ab2LWIzU (ORCPT ); Sun, 23 Dec 2012 03:55:20 -0500 Received: from mx1.redhat.com ([209.132.183.28]:5207 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751412Ab2LWIzR (ORCPT ); Sun, 23 Dec 2012 03:55:17 -0500 Date: Sun, 23 Dec 2012 10:55:06 +0200 From: Gleb Natapov To: Alex Williamson Cc: kvm@vger.kernel.org, yoshikawa_takuya_b1@lab.ntt.co.jp, mtosatti@redhat.com, linux-kernel@vger.kernel.org, takuya.yoshikawa@gmail.com Subject: Re: [PATCH] kvm: Fix memory slot generation updates Message-ID: <20121223085506.GM17584@redhat.com> References: <20121221151959.3641.75215.stgit@bling.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20121221151959.3641.75215.stgit@bling.home> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 21, 2012 at 08:20:16AM -0700, Alex Williamson wrote: > 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 Applied, thanks. What about this small cleanup on to of the patch: diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 14cbae8..e45c20c 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -702,6 +702,17 @@ static int check_memory_region_flags(struct kvm_userspace_memory_region *mem) return 0; } +static struct kvm_memslots *install_new_memslots(struct kvm *kvm, + struct kvm_memslots *slots, struct kvm_memory_slot *new) +{ + struct kvm_memslots *old_memslots = kvm->memslots; + + update_memslots(slots, new, kvm->memslots->generation); + rcu_assign_pointer(kvm->memslots, slots); + synchronize_srcu_expedited(&kvm->srcu); + return old_memslots; +} + /* * Allocate some memory and give it an address in the guest physical address * space. @@ -820,11 +831,8 @@ int __kvm_set_memory_region(struct kvm *kvm, slot = id_to_memslot(slots, mem->slot); slot->flags |= KVM_MEMSLOT_INVALID; - update_memslots(slots, NULL, kvm->memslots->generation); + old_memslots = install_new_memslots(kvm, slots, NULL); - old_memslots = kvm->memslots; - rcu_assign_pointer(kvm->memslots, slots); - synchronize_srcu_expedited(&kvm->srcu); /* slot was deleted or moved, clear iommu mapping */ kvm_iommu_unmap_pages(kvm, &old); /* From this point no new shadow pages pointing to a deleted, @@ -868,10 +876,7 @@ int __kvm_set_memory_region(struct kvm *kvm, memset(&new.arch, 0, sizeof(new.arch)); } - update_memslots(slots, &new, kvm->memslots->generation); - old_memslots = kvm->memslots; - rcu_assign_pointer(kvm->memslots, slots); - synchronize_srcu_expedited(&kvm->srcu); + old_memslots = install_new_memslots(kvm, slots, &new); kvm_arch_commit_memory_region(kvm, mem, old, user_alloc); -- Gleb.