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=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 BC600C0044D for ; Wed, 11 Mar 2020 19:29:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9C0CE20736 for ; Wed, 11 Mar 2020 19:29:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="CsZQhdl5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731120AbgCKT3x (ORCPT ); Wed, 11 Mar 2020 15:29:53 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:23357 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1730913AbgCKT3x (ORCPT ); Wed, 11 Mar 2020 15:29:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1583954991; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=X8sydDPk2Nziuyx/YyOIFR5RvqNJQK0GeXPzyVTGcAM=; b=CsZQhdl5XIJBkEczceIUYFu2BUZ3jKyRV6fymH08Fecexx//317+qqK7GUWuK4VLpT4zdk fZkTNQ5TLd/ad58tMbEYyrvm6Cp2jgVIWe38l/GEwBsoPJ1U0kO2oUvAY4wcJgsIk4Tqgs OMBV7fxNZ9JtgS3+5PsD6jQ5sik7QGo= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-269-OS115hD8P9auQI74FymxuA-1; Wed, 11 Mar 2020 15:29:50 -0400 X-MC-Unique: OS115hD8P9auQI74FymxuA-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 8EB1A800D48; Wed, 11 Mar 2020 19:29:48 +0000 (UTC) Received: from horse.redhat.com (unknown [10.18.25.210]) by smtp.corp.redhat.com (Postfix) with ESMTP id 6E32660BF1; Wed, 11 Mar 2020 19:29:40 +0000 (UTC) Received: by horse.redhat.com (Postfix, from userid 10451) id DB87522021D; Wed, 11 Mar 2020 15:29:39 -0400 (EDT) Date: Wed, 11 Mar 2020 15:29:39 -0400 From: Vivek Goyal To: Stefan Hajnoczi Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, virtio-fs@redhat.com, miklos@szeredi.hu, dgilbert@redhat.com, mst@redhat.com, Sebastien Boeuf , kbuild test robot Subject: Re: [PATCH 04/20] virtio: Implement get_shm_region for PCI transport Message-ID: <20200311192939.GD83257@redhat.com> References: <20200304165845.3081-1-vgoyal@redhat.com> <20200304165845.3081-5-vgoyal@redhat.com> <20200310110437.GI140737@stefanha-x1.localdomain> <20200310181936.GC38440@redhat.com> <20200311173405.GI281087@stefanha-x1.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200311173405.GI281087@stefanha-x1.localdomain> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 11, 2020 at 05:34:05PM +0000, Stefan Hajnoczi wrote: > On Tue, Mar 10, 2020 at 02:19:36PM -0400, Vivek Goyal wrote: > > On Tue, Mar 10, 2020 at 11:04:37AM +0000, Stefan Hajnoczi wrote: > > > On Wed, Mar 04, 2020 at 11:58:29AM -0500, Vivek Goyal wrote: > > > > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c > > > > index 7abcc50838b8..52f179411015 100644 > > > > --- a/drivers/virtio/virtio_pci_modern.c > > > > +++ b/drivers/virtio/virtio_pci_modern.c > > > > @@ -443,6 +443,111 @@ static void del_vq(struct virtio_pci_vq_info *info) > > > > vring_del_virtqueue(vq); > > > > } > > > > > > > > +static int virtio_pci_find_shm_cap(struct pci_dev *dev, > > > > + u8 required_id, > > > > + u8 *bar, u64 *offset, u64 *len) > > > > +{ > > > > + int pos; > > > > + > > > > + for (pos = pci_find_capability(dev, PCI_CAP_ID_VNDR); > > > > > > Please fix the mixed tabs vs space indentation in this patch. > > > > Will do. There are plenty of these in this patch. > > > > > > > > > +static bool vp_get_shm_region(struct virtio_device *vdev, > > > > + struct virtio_shm_region *region, u8 id) > > > > +{ > > > > + struct virtio_pci_device *vp_dev = to_vp_device(vdev); > > > > + struct pci_dev *pci_dev = vp_dev->pci_dev; > > > > + u8 bar; > > > > + u64 offset, len; > > > > + phys_addr_t phys_addr; > > > > + size_t bar_len; > > > > + int ret; > > > > + > > > > + if (!virtio_pci_find_shm_cap(pci_dev, id, &bar, &offset, &len)) { > > > > + return false; > > > > + } > > > > + > > > > + ret = pci_request_region(pci_dev, bar, "virtio-pci-shm"); > > > > + if (ret < 0) { > > > > + dev_err(&pci_dev->dev, "%s: failed to request BAR\n", > > > > + __func__); > > > > + return false; > > > > + } > > > > + > > > > + phys_addr = pci_resource_start(pci_dev, bar); > > > > + bar_len = pci_resource_len(pci_dev, bar); > > > > + > > > > + if (offset + len > bar_len) { > > > > + dev_err(&pci_dev->dev, > > > > + "%s: bar shorter than cap offset+len\n", > > > > + __func__); > > > > + return false; > > > > + } > > > > + > > > > + region->len = len; > > > > + region->addr = (u64) phys_addr + offset; > > > > + > > > > + return true; > > > > +} > > > > > > Missing pci_release_region()? > > > > Good catch. We don't have a mechanism to call pci_relese_region() and > > virtio-mmio device's ->get_shm_region() implementation does not even > > seem to reserve the resources. > > > > So how about we leave this resource reservation to the caller. > > ->get_shm_region() just returns the addr/len pair of requested resource. > > > > Something like this patch. > > > > --- > > drivers/virtio/virtio_pci_modern.c | 8 -------- > > fs/fuse/virtio_fs.c | 13 ++++++++++--- > > 2 files changed, 10 insertions(+), 11 deletions(-) > > > > Index: redhat-linux/fs/fuse/virtio_fs.c > > =================================================================== > > --- redhat-linux.orig/fs/fuse/virtio_fs.c 2020-03-10 09:13:34.624565666 -0400 > > +++ redhat-linux/fs/fuse/virtio_fs.c 2020-03-10 14:11:10.970284651 -0400 > > @@ -763,11 +763,18 @@ static int virtio_fs_setup_dax(struct vi > > if (!have_cache) { > > dev_notice(&vdev->dev, "%s: No cache capability\n", __func__); > > return 0; > > - } else { > > - dev_notice(&vdev->dev, "Cache len: 0x%llx @ 0x%llx\n", > > - cache_reg.len, cache_reg.addr); > > } > > > > + if (!devm_request_mem_region(&vdev->dev, cache_reg.addr, cache_reg.len, > > + dev_name(&vdev->dev))) { > > + dev_warn(&vdev->dev, "could not reserve region addr=0x%llx" > > + " len=0x%llx\n", cache_reg.addr, cache_reg.len); > > + return -EBUSY; > > + } > > + > > + dev_notice(&vdev->dev, "Cache len: 0x%llx @ 0x%llx\n", cache_reg.len, > > + cache_reg.addr); > > + > > pgmap = devm_kzalloc(&vdev->dev, sizeof(*pgmap), GFP_KERNEL); > > if (!pgmap) > > return -ENOMEM; > > Index: redhat-linux/drivers/virtio/virtio_pci_modern.c > > =================================================================== > > --- redhat-linux.orig/drivers/virtio/virtio_pci_modern.c 2020-03-10 08:51:36.886565666 -0400 > > +++ redhat-linux/drivers/virtio/virtio_pci_modern.c 2020-03-10 13:43:15.168753543 -0400 > > @@ -511,19 +511,11 @@ static bool vp_get_shm_region(struct vir > > u64 offset, len; > > phys_addr_t phys_addr; > > size_t bar_len; > > - int ret; > > > > if (!virtio_pci_find_shm_cap(pci_dev, id, &bar, &offset, &len)) { > > return false; > > } > > > > - ret = pci_request_region(pci_dev, bar, "virtio-pci-shm"); > > - if (ret < 0) { > > - dev_err(&pci_dev->dev, "%s: failed to request BAR\n", > > - __func__); > > - return false; > > - } > > - > > phys_addr = pci_resource_start(pci_dev, bar); > > bar_len = pci_resource_len(pci_dev, bar); > > Do pci_resource_start()/pci_resource_len() work on a BAR where > pci_request_region() hasn't been called yet? (I haven't checked the > code, sorry...) It should. Infact, pci_request_region() itself is calling pci_resource_start() and pci_resource_len(). > > Assuming yes, then my next question is whether devm_request_mem_region() > works in both the VIRTIO PCI and MMIO cases? It should work on MMIO case as well. This basically works on /proc/iomem resource tree to reserve resources. So as long as MMIO memory range has been registered by driver in /proc/iomem, it will work. > > If yes, then this looks like a solution, though the need for > devm_request_mem_region() should be explained in the vp_get_shm_region() > doc comments so that callers remember to make that call. Or maybe it > can be included in vp_get_shm_region(). How about adding a line in include/linux/virtio_config.h right below the @get_shm_region descrition which says. "This does not reserve the resources and caller is expected to call devm_request_mem_region() or similar to reserve resources." Vivek