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=-9.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_MUTT 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 6F71DC282C0 for ; Wed, 23 Jan 2019 17:41:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3FD8F21019 for ; Wed, 23 Jan 2019 17:41:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="tRvESJVn" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726849AbfAWRlu (ORCPT ); Wed, 23 Jan 2019 12:41:50 -0500 Received: from aserp2130.oracle.com ([141.146.126.79]:54480 "EHLO aserp2130.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726038AbfAWRlt (ORCPT ); Wed, 23 Jan 2019 12:41:49 -0500 Received: from pps.filterd (aserp2130.oracle.com [127.0.0.1]) by aserp2130.oracle.com (8.16.0.22/8.16.0.22) with SMTP id x0NHcf5V043881; Wed, 23 Jan 2019 17:41:44 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2018-07-02; bh=nwmrmVOztEACK777VxrEoO+sf1iUM1uzCh4D9/ju1rk=; b=tRvESJVnuCeuRfdVP88SGC6xPFVyLW2dKCCICnLtn0ytdKIFFLakKkDkt1z5AikwfSoU GRXEmotAzECfRYFdladZltF9jgWeze0brSLqGe4bqA5IjPG5MD8NZ6UeeQB7mGZrOjE2 lNDpgBBOJcakD5C2MGoIlUUI60c65DTlCyTkX5O78zzrkPMJtw3PxottOB8N1K+RsfAt P9nlF0yk9gl8w2LEINxFXNPLPWhFC5WAgH9hSXCCj9UdhNELhUZOatS9vVA+n3z/SEgY nU3D98wkSwU/28pM38LybJal/n24OkkqDyVwHx9UDcFBO/ie20zyDXtGc+cp5YCgPBbj og== Received: from aserv0022.oracle.com (aserv0022.oracle.com [141.146.126.234]) by aserp2130.oracle.com with ESMTP id 2q3sdekjch-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 23 Jan 2019 17:41:44 +0000 Received: from aserv0121.oracle.com (aserv0121.oracle.com [141.146.126.235]) by aserv0022.oracle.com (8.14.4/8.14.4) with ESMTP id x0NHfijh004204 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 23 Jan 2019 17:41:44 GMT Received: from abhmp0016.oracle.com (abhmp0016.oracle.com [141.146.116.22]) by aserv0121.oracle.com (8.14.4/8.13.8) with ESMTP id x0NHfh4W019028; Wed, 23 Jan 2019 17:41:43 GMT Received: from Konrads-MacBook-Pro.local (/75.104.64.133) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 23 Jan 2019 09:41:43 -0800 Date: Wed, 23 Jan 2019 12:41:18 -0500 From: Konrad Rzeszutek Wilk To: KarimAllah Ahmed Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, pbonzini@redhat.com, rkrcmar@redhat.com Subject: Re: [PATCH v5 04/13] KVM: Introduce a new guest mapping API Message-ID: <20190123174047.GI19289@Konrads-MacBook-Pro.local> References: <1547026933-31226-1-git-send-email-karahmed@amazon.de> <1547026933-31226-5-git-send-email-karahmed@amazon.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1547026933-31226-5-git-send-email-karahmed@amazon.de> User-Agent: Mutt/1.9.4 (2018-02-28) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9145 signatures=668682 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1901230130 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jan 09, 2019 at 10:42:04AM +0100, KarimAllah Ahmed wrote: > In KVM, specially for nested guests, there is a dominant pattern of: > > => map guest memory -> do_something -> unmap guest memory > > In addition to all this unnecessarily noise in the code due to boiler plate > code, most of the time the mapping function does not properly handle memory > that is not backed by "struct page". This new guest mapping API encapsulate > most of this boiler plate code and also handles guest memory that is not > backed by "struct page". > > The current implementation of this API is using memremap for memory that is > not backed by a "struct page" which would lead to a huge slow-down if it > was used for high-frequency mapping operations. The API does not have any > effect on current setups where guest memory is backed by a "struct page". > Further patches are going to also introduce a pfn-cache which would > significantly improve the performance of the memremap case. > > Signed-off-by: KarimAllah Ahmed > --- > v3 -> v4: > - Update the commit message. > v1 -> v2: > - Drop the caching optimization (pbonzini) > - Use 'hva' instead of 'kaddr' (pbonzini) > - Return 0/-EINVAL/-EFAULT instead of true/false. -EFAULT will be used for > AMD patch (pbonzini) > - Introduce __kvm_map_gfn which accepts a memory slot and use it (pbonzini) > - Only clear map->hva instead of memsetting the whole structure. > - Drop kvm_vcpu_map_valid since it is no longer used. > - Fix EXPORT_MODULE naming. > --- > include/linux/kvm_host.h | 9 ++++++++ > virt/kvm/kvm_main.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 62 insertions(+) > > diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h > index c38cc5e..8a2f5fa 100644 > --- a/include/linux/kvm_host.h > +++ b/include/linux/kvm_host.h > @@ -205,6 +205,13 @@ enum { > READING_SHADOW_PAGE_TABLES, > }; > > +struct kvm_host_map { > + struct page *page; > + void *hva; > + kvm_pfn_t pfn; > + kvm_pfn_t gfn; > +}; > + > /* > * Sometimes a large or cross-page mmio needs to be broken up into separate > * exits for userspace servicing. > @@ -710,7 +717,9 @@ struct kvm_memslots *kvm_vcpu_memslots(struct kvm_vcpu *vcpu); > struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn); > kvm_pfn_t kvm_vcpu_gfn_to_pfn_atomic(struct kvm_vcpu *vcpu, gfn_t gfn); > kvm_pfn_t kvm_vcpu_gfn_to_pfn(struct kvm_vcpu *vcpu, gfn_t gfn); > +int kvm_vcpu_map(struct kvm_vcpu *vcpu, gpa_t gpa, struct kvm_host_map *map); > struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn); > +void kvm_vcpu_unmap(struct kvm_host_map *map, bool dirty); > unsigned long kvm_vcpu_gfn_to_hva(struct kvm_vcpu *vcpu, gfn_t gfn); > unsigned long kvm_vcpu_gfn_to_hva_prot(struct kvm_vcpu *vcpu, gfn_t gfn, bool *writable); > int kvm_vcpu_read_guest_page(struct kvm_vcpu *vcpu, gfn_t gfn, void *data, int offset, > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 1f888a1..4d8f2e3 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -1733,6 +1733,59 @@ struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn) > } > EXPORT_SYMBOL_GPL(gfn_to_page); > > +static int __kvm_map_gfn(struct kvm_memory_slot *slot, gfn_t gfn, > + struct kvm_host_map *map) > +{ > + kvm_pfn_t pfn; > + void *hva = NULL; > + struct page *page = NULL; > + Would it make sense to check if 'map' is NULL first? Ditto on the unmap? Either way: Reviewed-by: Konrad Rzeszutek Wilk