From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 015D6C4332B for ; Sat, 21 Mar 2020 19:12:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C7B892072C for ; Sat, 21 Mar 2020 19:12:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727761AbgCUTMv (ORCPT ); Sat, 21 Mar 2020 15:12:51 -0400 Received: from mga06.intel.com ([134.134.136.31]:4567 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727028AbgCUTMv (ORCPT ); Sat, 21 Mar 2020 15:12:51 -0400 IronPort-SDR: BF5uw76TWSpmJxU09thk8Rga+09mJZDkusnxTEn3SaqeAcxZxSGDysE4Je6pOjXMgHW2+z6esi NLND2S5j8ACA== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Mar 2020 12:12:50 -0700 IronPort-SDR: LEGngsaaDdt6kb5w+R52hg45Dzy0hFhk3Ck92J3u+FrpKnfuQtr4UDreSOVg9rQ4FlkgxuE9Gt SLzGcxHyB8IQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.72,289,1580803200"; d="scan'208";a="419063818" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.202]) by orsmga005.jf.intel.com with ESMTP; 21 Mar 2020 12:12:50 -0700 Date: Sat, 21 Mar 2020 12:12:50 -0700 From: Sean Christopherson To: Peter Xu Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, "Michael S . Tsirkin" , Vitaly Kuznetsov , Yan Zhao , "Dr . David Alan Gilbert" , Christophe de Dinechin , Alex Williamson , Jason Wang , Kevin Tian , Paolo Bonzini Subject: Re: [PATCH v7 06/14] KVM: Make dirty ring exclusive to dirty bitmap log Message-ID: <20200321191250.GB13851@linux.intel.com> References: <20200318163720.93929-1-peterx@redhat.com> <20200318163720.93929-7-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200318163720.93929-7-peterx@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 18, 2020 at 12:37:12PM -0400, Peter Xu wrote: > There's no good reason to use both the dirty bitmap logging and the > new dirty ring buffer to track dirty bits. We should be able to even > support both of them at the same time, but it could complicate things > which could actually help little. Let's simply make it the rule > before we enable dirty ring on any arch, that we don't allow these two > interfaces to be used together. > > The big world switch would be KVM_CAP_DIRTY_LOG_RING capability > enablement. That's where we'll switch from the default dirty logging > way to the dirty ring way. As long as kvm->dirty_ring_size is setup > correctly, we'll once and for all switch to the dirty ring buffer mode > for the current virtual machine. > > Signed-off-by: Peter Xu > --- > Documentation/virt/kvm/api.rst | 7 +++++++ > virt/kvm/kvm_main.c | 12 ++++++++++++ > 2 files changed, 19 insertions(+) > > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst > index 99ee9cfc20c4..8f3a83298d3f 100644 > --- a/Documentation/virt/kvm/api.rst > +++ b/Documentation/virt/kvm/api.rst > @@ -6202,3 +6202,10 @@ make sure all the existing dirty gfns are flushed to the dirty rings. > > The dirty ring can gets full. When it happens, the KVM_RUN of the > vcpu will return with exit reason KVM_EXIT_DIRTY_LOG_FULL. > + > +NOTE: the KVM_CAP_DIRTY_LOG_RING capability and the new ioctl Leave off "new", it'll be stale a few months/years from now. > +KVM_RESET_DIRTY_RINGS are exclusive to the existing KVM_GET_DIRTY_LOG Did you mean "mutually exclusive with"? "exclusive to" would mean they can only be used by KVM_GET_DIRTY_LOG with doesn't match the next sentence. > +interface. After enabling KVM_CAP_DIRTY_LOG_RING with an acceptable > +dirty ring size, the virtual machine will switch to the dirty ring > +tracking mode, and KVM_GET_DIRTY_LOG, KVM_CLEAR_DIRTY_LOG ioctls will > +stop working. > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 54a1e893d17b..b289d3bddd5c 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -1352,6 +1352,10 @@ int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log, > unsigned long n; > unsigned long any = 0; > > + /* Dirty ring tracking is exclusive to dirty log tracking */ > + if (kvm->dirty_ring_size) > + return -EINVAL; > + > *memslot = NULL; > *is_dirty = 0; > > @@ -1413,6 +1417,10 @@ static int kvm_get_dirty_log_protect(struct kvm *kvm, struct kvm_dirty_log *log) > unsigned long *dirty_bitmap_buffer; > bool flush; > > + /* Dirty ring tracking is exclusive to dirty log tracking */ > + if (kvm->dirty_ring_size) > + return -EINVAL; > + > as_id = log->slot >> 16; > id = (u16)log->slot; > if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS) > @@ -1521,6 +1529,10 @@ static int kvm_clear_dirty_log_protect(struct kvm *kvm, > unsigned long *dirty_bitmap_buffer; > bool flush; > > + /* Dirty ring tracking is exclusive to dirty log tracking */ > + if (kvm->dirty_ring_size) > + return -EINVAL; > + > as_id = log->slot >> 16; > id = (u16)log->slot; > if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_USER_MEM_SLOTS) > -- > 2.24.1 >