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=-6.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 C991AC04A6B for ; Wed, 8 May 2019 10:43:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A5ABE20656 for ; Wed, 8 May 2019 10:43:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727205AbfEHKne (ORCPT ); Wed, 8 May 2019 06:43:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54802 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726986AbfEHKne (ORCPT ); Wed, 8 May 2019 06:43:34 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 645F1C060200; Wed, 8 May 2019 10:43:33 +0000 (UTC) Received: from gondolin (ovpn-204-161.brq.redhat.com [10.40.204.161]) by smtp.corp.redhat.com (Postfix) with ESMTP id B3FD7600D4; Wed, 8 May 2019 10:43:31 +0000 (UTC) Date: Wed, 8 May 2019 12:43:27 +0200 From: Cornelia Huck To: Eric Farman Cc: Farhan Ali , Halil Pasic , Pierre Morel , linux-s390@vger.kernel.org, kvm@vger.kernel.org Subject: Re: [PATCH 3/7] s390/cio: Split pfn_array_alloc_pin into pieces Message-ID: <20190508124327.5c496c8a.cohuck@redhat.com> In-Reply-To: <20190503134912.39756-4-farman@linux.ibm.com> References: <20190503134912.39756-1-farman@linux.ibm.com> <20190503134912.39756-4-farman@linux.ibm.com> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Wed, 08 May 2019 10:43:33 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, 3 May 2019 15:49:08 +0200 Eric Farman wrote: > The pfn_array_alloc_pin routine is doing too much. Today, it does the > alloc of the pfn_array struct and its member arrays, builds the iova > address lists out of a contiguous piece of guest memory, and asks vfio > to pin the resulting pages. > > Let's effectively revert a significant portion of commit 5c1cfb1c3948 > ("vfio: ccw: refactor and improve pfn_array_alloc_pin()") such that we > break pfn_array_alloc_pin() into its component pieces, and have one > routine that allocates/populates the pfn_array structs, and another > that actually pins the memory. In the future, we will be able to > handle scenarios where pinning memory isn't actually appropriate. > > Signed-off-by: Eric Farman > --- > drivers/s390/cio/vfio_ccw_cp.c | 72 +++++++++++++++++++++++++++--------------- > 1 file changed, 47 insertions(+), 25 deletions(-) > > diff --git a/drivers/s390/cio/vfio_ccw_cp.c b/drivers/s390/cio/vfio_ccw_cp.c > index f86da78eaeaa..b70306c06150 100644 > --- a/drivers/s390/cio/vfio_ccw_cp.c > +++ b/drivers/s390/cio/vfio_ccw_cp.c > @@ -50,28 +50,25 @@ struct ccwchain { > }; > > /* > - * pfn_array_alloc_pin() - alloc memory for PFNs, then pin user pages in memory > + * pfn_array_alloc() - alloc memory for PFNs > * @pa: pfn_array on which to perform the operation > - * @mdev: the mediated device to perform pin/unpin operations > * @iova: target guest physical address > * @len: number of bytes that should be pinned from @iova > * > - * Attempt to allocate memory for PFNs, and pin user pages in memory. > + * Attempt to allocate memory for PFN. s/PFN/PFNs/ > * > * Usage of pfn_array: > * We expect (pa_nr == 0) and (pa_iova_pfn == NULL), any field in > * this structure will be filled in by this function. > * > * Returns: > - * Number of pages pinned on success. > - * If @pa->pa_nr is not 0, or @pa->pa_iova_pfn is not NULL initially, > - * returns -EINVAL. > - * If no pages were pinned, returns -errno. > + * 0 if PFNs are allocated > + * -EINVAL if pa->pa_nr is not initially zero, or pa->pa_iova_pfn is not NULL > + * -ENOMEM if alloc failed > */ > -static int pfn_array_alloc_pin(struct pfn_array *pa, struct device *mdev, > - u64 iova, unsigned int len) > +static int pfn_array_alloc(struct pfn_array *pa, u64 iova, unsigned int len) > { > - int i, ret = 0; > + int i; > > if (!len) > return 0; > @@ -97,23 +94,33 @@ static int pfn_array_alloc_pin(struct pfn_array *pa, struct device *mdev, > for (i = 1; i < pa->pa_nr; i++) > pa->pa_iova_pfn[i] = pa->pa_iova_pfn[i - 1] + 1; > > + return 0; > +} > + > +/* > + * pfn_array_pin() - Pin user pages in memory > + * @pa: pfn_array on which to perform the operation > + * @mdev: the mediated device to perform pin operations > + * > + * Returns: > + * Number of pages pinned on success. > + * If fewer pages than requested were pinned, returns -EINVAL > + * If no pages were pinned, returns -errno. I don't really like the 'returns -errno' :) It's actually the return code of vfio_pin_pages(), and that might include -EINVAL as well. So, what about mentioning in the function description that pfn_array_pin() only succeeds if it coult pin all pages, and simply stating that it returns a negative error value on failure? > + */ > +static int pfn_array_pin(struct pfn_array *pa, struct device *mdev) > +{ > + int ret = 0; > + > ret = vfio_pin_pages(mdev, pa->pa_iova_pfn, pa->pa_nr, > IOMMU_READ | IOMMU_WRITE, pa->pa_pfn); > > - if (ret < 0) { > - goto err_out; > - } else if (ret > 0 && ret != pa->pa_nr) { > + if (ret > 0 && ret != pa->pa_nr) { > vfio_unpin_pages(mdev, pa->pa_iova_pfn, ret); > ret = -EINVAL; > - goto err_out; > } > > - return ret; > - > -err_out: > - pa->pa_nr = 0; > - kfree(pa->pa_iova_pfn); > - pa->pa_iova_pfn = NULL; > + if (ret < 0) > + pa->pa_iova = 0; > > return ret; > } (...)