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=-4.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,RDNS_NONE,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_NONE,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:32904 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729887AbgCKPtB (ORCPT ); Wed, 11 Mar 2020 11:49:01 -0400 Received: by mail-qk1-f199.google.com with SMTP id b82so1739534qkc.11 for ; Wed, 11 Mar 2020 08:48:54 -0700 (PDT) Date: Wed, 11 Mar 2020 11:48:50 -0400 From: Peter Xu To: Sean Christopherson Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Yan Zhao , Jason Wang , Alex Williamson , Vitaly Kuznetsov , "Dr . David Alan Gilbert" , Christophe de Dinechin , "Michael S . Tsirkin" , Kevin Tian , Paolo Bonzini Subject: Re: [PATCH v6 02/14] KVM: Cache as_id in kvm_memory_slot Message-ID: <20200311154850.GE479302@xz-x1> References: <20200309214424.330363-1-peterx@redhat.com> <20200309214424.330363-3-peterx@redhat.com> <20200310144858.GA7600@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20200310144858.GA7600@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: On Tue, Mar 10, 2020 at 07:48:59AM -0700, Sean Christopherson wrote: > On Mon, Mar 09, 2020 at 05:44:12PM -0400, Peter Xu wrote: > > Cache the address space ID just like the slot ID. It will be used in > > order to fill in the dirty ring entries. > > > > Suggested-by: Paolo Bonzini > > Suggested-by: Sean Christopherson > > Signed-off-by: Peter Xu > > --- > > include/linux/kvm_host.h | 1 + > > virt/kvm/kvm_main.c | 2 ++ > > 2 files changed, 3 insertions(+) > > > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > > index bcb9b2ac0791..afa0e9034881 100644 > > --- a/include/linux/kvm_host.h > > +++ b/include/linux/kvm_host.h > > @@ -346,6 +346,7 @@ struct kvm_memory_slot { > > unsigned long userspace_addr; > > u32 flags; > > short id; > > + u8 as_id; > > My vote is to store this as a u16 and remove the BUILD_BUG_ON. Using a u8 > doesn't save any memory since the compiler will pad out the struct. Sure. Indeed that BUILD_BUG_ON does not help much in this case. Thanks, > > > }; > > > > static inline unsigned long kvm_dirty_bitmap_bytes(struct kvm_memory_slot *memslot) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > > index 70f03ce0e5c1..e6484dabfc59 100644 > > --- a/virt/kvm/kvm_main.c > > +++ b/virt/kvm/kvm_main.c > > @@ -1036,6 +1036,8 @@ int __kvm_set_memory_region(struct kvm *kvm, > > > > new = old = *slot; > > > > + BUILD_BUG_ON(U8_MAX < KVM_ADDRESS_SPACE_NUM); > > + new.as_id = as_id; > > new.id = id; > > new.base_gfn = base_gfn; > > new.npages = npages; > > -- > > 2.24.1 > > > -- Peter Xu