From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:42174 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727461AbeLMKBK (ORCPT ); Thu, 13 Dec 2018 05:01:10 -0500 Date: Thu, 13 Dec 2018 10:00:59 +0000 From: "Dr. David Alan Gilbert" To: David Hildenbrand Cc: Vivek Goyal , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, miklos@szeredi.hu, stefanha@redhat.com, sweil@redhat.com, swhiteho@redhat.com Subject: Re: [PATCH 18/52] virtio-fs: Map cache using the values from the capabilities Message-ID: <20181213100058.GC2313@work-vm> References: <20181210171318.16998-1-vgoyal@redhat.com> <20181210171318.16998-19-vgoyal@redhat.com> <20181213091320.GA2313@work-vm> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: * David Hildenbrand (david@redhat.com) wrote: > On 13.12.18 10:13, Dr. David Alan Gilbert wrote: > > * David Hildenbrand (david@redhat.com) wrote: > >> On 10.12.18 18:12, Vivek Goyal wrote: > >>> Instead of assuming we had the fixed bar for the cache, use the > >>> value from the capabilities. > >>> > >>> Signed-off-by: Dr. David Alan Gilbert > >>> --- > >>> fs/fuse/virtio_fs.c | 32 +++++++++++++++++--------------- > >>> 1 file changed, 17 insertions(+), 15 deletions(-) > >>> > >>> diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c > >>> index 60d496c16841..55bac1465536 100644 > >>> --- a/fs/fuse/virtio_fs.c > >>> +++ b/fs/fuse/virtio_fs.c > >>> @@ -14,11 +14,6 @@ > >>> #include > >>> #include "fuse_i.h" > >>> > >>> -enum { > >>> - /* PCI BAR number of the virtio-fs DAX window */ > >>> - VIRTIO_FS_WINDOW_BAR = 2, > >>> -}; > >>> - > >>> /* List of virtio-fs device instances and a lock for the list */ > >>> static DEFINE_MUTEX(virtio_fs_mutex); > >>> static LIST_HEAD(virtio_fs_instances); > >>> @@ -518,7 +513,7 @@ static int virtio_fs_setup_dax(struct virtio_device *vdev, struct virtio_fs *fs) > >>> struct dev_pagemap *pgmap; > >>> struct pci_dev *pci_dev; > >>> phys_addr_t phys_addr; > >>> - size_t len; > >>> + size_t bar_len; > >>> int ret; > >>> u8 have_cache, cache_bar; > >>> u64 cache_offset, cache_len; > >>> @@ -551,17 +546,13 @@ static int virtio_fs_setup_dax(struct virtio_device *vdev, struct virtio_fs *fs) > >>> } > >>> > >>> /* TODO handle case where device doesn't expose BAR? */ > >> > >> For virtio-pmem we decided to not go via BARs as this would effectively > >> make it only usable for virtio-pci implementers. Instead, we are going > >> to export the applicable physical device region directly (e.g. > >> phys_start, phys_size in virtio config), so it is decoupled from PCI > >> details. Doing the same for virtio-fs would allow e.g. also virtio-ccw > >> to make eventually use of this. > > > > That makes it a very odd looking PCI device; I can see that with > > virtio-pmem it makes some sense, given that it's job is to expose > > arbitrary chunks of memory. > > > > Dave > > Well, the fact that your are > > - including > - adding pci related code > > in/to fs/fuse/virtio_fs.c > > tells me that these properties might be better communicated on the > virtio layer, not on the PCI layer. > > Or do you really want to glue virtio-fs to virtio-pci for all eternity? No, these need cleaning up; and the split within the bar is probably going to change to be communicated via virtio layer rather than pci capabilities. However, I don't want to make our PCI device look odd, just to make portability to non-PCI devices - so it's right to make the split appropriately, but still to use PCI bars for what they were designed for. Dave > > -- > > Thanks, > > David / dhildenb -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK