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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,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 D3951C43441 for ; Mon, 12 Nov 2018 09:41:11 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 59B0E223C8 for ; Mon, 12 Nov 2018 09:41:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 59B0E223C8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.ibm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 42tm3T26vTzF3VC for ; Mon, 12 Nov 2018 20:41:09 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.ibm.com Authentication-Results: lists.ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=linux.ibm.com (client-ip=148.163.158.5; helo=mx0a-001b2d01.pphosted.com; envelope-from=bharata@linux.ibm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.ibm.com Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 42tm1D1VFTzF3Sd for ; Mon, 12 Nov 2018 20:39:11 +1100 (AEDT) Received: from pps.filterd (m0098419.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.22/8.16.0.22) with SMTP id wAC9d7Rw084503 for ; Mon, 12 Nov 2018 04:39:09 -0500 Received: from e06smtp01.uk.ibm.com (e06smtp01.uk.ibm.com [195.75.94.97]) by mx0b-001b2d01.pphosted.com with ESMTP id 2nq4j4egvw-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 12 Nov 2018 04:39:08 -0500 Received: from localhost by e06smtp01.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Mon, 12 Nov 2018 09:39:01 -0000 Received: from d06av22.portsmouth.uk.ibm.com (d06av22.portsmouth.uk.ibm.com [9.149.105.58]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id wAC9cxUh53542944 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=FAIL); Mon, 12 Nov 2018 09:38:59 GMT Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A69924C04A; Mon, 12 Nov 2018 09:38:59 +0000 (GMT) Received: from d06av22.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0A6304C04E; Mon, 12 Nov 2018 09:38:58 +0000 (GMT) Received: from in.ibm.com (unknown [9.199.50.113]) by d06av22.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Mon, 12 Nov 2018 09:38:57 +0000 (GMT) Date: Mon, 12 Nov 2018 15:08:55 +0530 From: Bharata B Rao To: Paul Mackerras Subject: Re: [RFC PATCH v1 2/4] kvmppc: Add support for shared pages in HMM driver References: <20181022051837.1165-1-bharata@linux.ibm.com> <20181022051837.1165-3-bharata@linux.ibm.com> <20181030052646.GB11072@blackberry> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181030052646.GB11072@blackberry> User-Agent: Mutt/1.10.1 (2018-07-13) X-TM-AS-GCONF: 00 x-cbid: 18111209-4275-0000-0000-000002DF91DE X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18111209-4276-0000-0000-000037EC9C35 Message-Id: <20181112093855.GC17399@in.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2018-11-12_07:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=515 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1811120088 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: bharata@linux.ibm.com Cc: linuxram@us.ibm.com, kvm-ppc@vger.kernel.org, benh@linux.ibm.com, linux-mm@kvack.org, jglisse@redhat.com, aneesh.kumar@linux.vnet.ibm.com, paulus@au1.ibm.com, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tue, Oct 30, 2018 at 04:26:46PM +1100, Paul Mackerras wrote: > On Mon, Oct 22, 2018 at 10:48:35AM +0530, Bharata B Rao wrote: > > A secure guest will share some of its pages with hypervisor (Eg. virtio > > bounce buffers etc). Support shared pages in HMM driver. > > > > Signed-off-by: Bharata B Rao > > Comments below... > > > --- > > arch/powerpc/kvm/book3s_hv_hmm.c | 69 ++++++++++++++++++++++++++++++-- > > 1 file changed, 65 insertions(+), 4 deletions(-) > > > > diff --git a/arch/powerpc/kvm/book3s_hv_hmm.c b/arch/powerpc/kvm/book3s_hv_hmm.c > > index a2ee3163a312..09b8e19b7605 100644 > > --- a/arch/powerpc/kvm/book3s_hv_hmm.c > > +++ b/arch/powerpc/kvm/book3s_hv_hmm.c > > @@ -50,6 +50,7 @@ struct kvmppc_hmm_page_pvt { > > struct hlist_head *hmm_hash; > > unsigned int lpid; > > unsigned long gpa; > > + bool skip_page_out; > > }; > > > > struct kvmppc_hmm_migrate_args { > > @@ -278,6 +279,65 @@ static unsigned long kvmppc_gpa_to_hva(struct kvm *kvm, unsigned long gpa, > > return hva; > > } > > > > +/* > > + * Shares the page with HV, thus making it a normal page. > > + * > > + * - If the page is already secure, then provision a new page and share > > + * - If the page is a normal page, share the existing page > > + * > > + * In the former case, uses the HMM fault handler to release the HMM page. > > + */ > > +static unsigned long > > +kvmppc_share_page(struct kvm *kvm, unsigned long gpa, > > + unsigned long addr, unsigned long page_shift) > > +{ > > + > > + int ret; > > + struct hlist_head *list, *hmm_hash; > > + unsigned int lpid = kvm->arch.lpid; > > + unsigned long flags; > > + struct kvmppc_hmm_pfn_entry *p; > > + struct page *hmm_page, *page; > > + struct kvmppc_hmm_page_pvt *pvt; > > + unsigned long pfn; > > + > > + /* > > + * First check if the requested page has already been given to > > + * UV as a secure page. If so, ensure that we don't issue a > > + * UV_PAGE_OUT but instead directly send the page > > + */ > > + spin_lock_irqsave(&kvmppc_hmm_lock, flags); > > + hmm_hash = kvm->arch.hmm_hash; > > + list = &hmm_hash[kvmppc_hmm_pfn_hash_fn(gpa)]; > > + hlist_for_each_entry(p, list, hlist) { > > + if (p->addr == gpa) { > > + hmm_page = pfn_to_page(p->hmm_pfn); > > + get_page(hmm_page); /* TODO: Necessary ? */ > > + pvt = (struct kvmppc_hmm_page_pvt *) > > + hmm_devmem_page_get_drvdata(hmm_page); > > + pvt->skip_page_out = true; > > + put_page(hmm_page); > > + break; > > + } > > + } > > + spin_unlock_irqrestore(&kvmppc_hmm_lock, flags); > > + > > + ret = get_user_pages_fast(addr, 1, 0, &page); > > Why are we calling this with write==0? Surely in general the secure > guest will expect to be able to write to the shared page? > > Also, in general get_user_pages_fast isn't sufficient to translate a > host virtual address (derived from a guest real address) into a pfn. > See for example hva_to_pfn() in virt/kvm/kvm_main.c and the things it > does to cope with the various cases that one can hit. I can imagine > in future that the secure guest might want to establish a shared > mapping to a PCI device, for instance. I switched to using gfn_to_pfn() which should cover all the cases. > > > + if (ret != 1) > > + return H_PARAMETER; > > + > > + pfn = page_to_pfn(page); > > + if (is_zero_pfn(pfn)) { > > + put_page(page); > > + return H_SUCCESS; > > + } > > The ultravisor still needs a page to map into the guest in this case, > doesn't it? What's the point of returning without giving the > ultravisor a page to use? Yes, missed it. Regards, Bharata.