From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sean Christopherson Date: Fri, 07 Feb 2020 18:07:20 +0000 Subject: Re: [PATCH v5 12/19] KVM: Move memslot deletion to helper function Message-Id: <20200207180720.GH2401@linux.intel.com> List-Id: References: <20200121223157.15263-1-sean.j.christopherson@intel.com> <20200121223157.15263-13-sean.j.christopherson@intel.com> <20200206161415.GA695333@xz-x1> <20200206162818.GD13067@linux.intel.com> <20200206165116.GE695333@xz-x1> <20200207175912.GG2401@linux.intel.com> In-Reply-To: <20200207175912.GG2401@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Peter Xu Cc: Paolo Bonzini , Paul Mackerras , Christian Borntraeger , Janosch Frank , David Hildenbrand , Cornelia Huck , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Marc Zyngier , James Morse , Julien Thierry , Suzuki K Poulose , linux-mips@vger.kernel.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org, Christoffer Dall , Philippe =?iso-8859-1?Q?Mathieu-Daud=E9?= On Fri, Feb 07, 2020 at 09:59:12AM -0800, Sean Christopherson wrote: > On Thu, Feb 06, 2020 at 11:51:16AM -0500, Peter Xu wrote: > > /* > > * Make a full copy of the old memslot, the pointer will become stale > > * when the memslots are re-sorted by update_memslots() in > > * kvm_delete_memslot(), while to make the kvm_free_memslot() work as > > * expected later on, we still need the cached memory slot. > > */ > > As above, it's more subtle than just the kvm_delete_memslot() case. > > /* > * Make a full copy of the old memslot, the pointer will become stale > * when the memslots are re-sorted by update_memslots() when deleting > * or moving a memslot, and additional modifications to the old memslot > * need to be made after calling update_memslots(). > */ Actually, that's not quite correct, as the same is true for all memslot updates, and we still query @old after update_memslots() for CREATE and FLAGS. This is better. /* * Make a full copy of the old memslot, the pointer will become stale * when the memslots are re-sorted by update_memslots(), and the old * memslot needs to be referenced after calling update_memslots(), e.g. * to free its resources and for arch specific behavior. */