From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Xu Date: Thu, 06 Feb 2020 16:14:15 +0000 Subject: Re: [PATCH v5 12/19] KVM: Move memslot deletion to helper function Message-Id: <20200206161415.GA695333@xz-x1> List-Id: References: <20200121223157.15263-1-sean.j.christopherson@intel.com> <20200121223157.15263-13-sean.j.christopherson@intel.com> In-Reply-To: <20200121223157.15263-13-sean.j.christopherson@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Sean Christopherson 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 =?utf-8?Q?Mathieu-Daud=C3=A9?= On Tue, Jan 21, 2020 at 02:31:50PM -0800, Sean Christopherson wrote: > Move memslot deletion into its own routine so that the success path for > other memslot updates does not need to use kvm_free_memslot(), i.e. can > explicitly destroy the dirty bitmap when necessary. This paves the way > for dropping @dont from kvm_free_memslot(), i.e. all callers now pass > NULL for @dont. > > Add a comment above the code to make a copy of the existing memslot > prior to deletion, it is not at all obvious that the pointer will become > stale during sorting and/or installation of new memslots. Could you help explain a bit on this explicit comment? I can follow up with the patch itself which looks all correct to me, but I failed to catch what this extra comment wants to emphasize... Thanks, > > Note, kvm_arch_commit_memory_region() allows an architecture to free > resources when moving a memslot or changing its flags, e.g. x86 frees > its arch specific memslot metadata during commit_memory_region(). -- Peter Xu