From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean-Philippe Brucker Subject: Re: [EXT] Re: [PATCH v5] iommu/virtio: Use page size bitmap supported by endpoint Date: Wed, 13 May 2020 12:45:37 +0200 Message-ID: <20200513104537.GB214296@myrica> References: <20200505093004.1935-1-bbhushan2@marvell.com> <20200505200659-mutt-send-email-mst@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org To: Bharat Bhushan Cc: "Michael S. Tsirkin" , "joro@8bytes.org" , "jasowang@redhat.com" , "virtualization@lists.linux-foundation.org" , "iommu@lists.linux-foundation.org" , "linux-kernel@vger.kernel.org" , "eric.auger.pro@gmail.com" , "eric.auger@redhat.com" List-Id: virtualization@lists.linuxfoundation.org On Wed, May 13, 2020 at 09:15:22AM +0000, Bharat Bhushan wrote: > Hi Jean, > > > -----Original Message----- > > From: Michael S. Tsirkin > > Sent: Wednesday, May 6, 2020 5:53 AM > > To: Bharat Bhushan > > Cc: jean-philippe@linaro.org; joro@8bytes.org; jasowang@redhat.com; > > virtualization@lists.linux-foundation.org; iommu@lists.linux-foundation.org; > > linux-kernel@vger.kernel.org; eric.auger.pro@gmail.com; eric.auger@redhat.com > > Subject: [EXT] Re: [PATCH v5] iommu/virtio: Use page size bitmap supported by > > endpoint [...] > > > +struct virtio_iommu_probe_pgsize_mask { > > > + struct virtio_iommu_probe_property head; > > > + __u8 reserved[4]; > > > + __le64 pgsize_bitmap; > > > +}; > > > + > > > > This is UAPI. Document the format of pgsize_bitmap please. > > I do not see uapi documentation in "Documentation" folder of other data struct in this file, am I missing something? I'm not the one requesting this change, but I'm guessing you should add a comment in this header, above pgsize_bitmap (which should actually be called page_size_mask to follow the spec). I guess I'd add: /* Same format as virtio_iommu_config::page_size_mask */ for this field, and then maybe change the comment of virtio_iommu_config, currently "/* Supported page sizes */", to something more precise such as: /* * Bitmap of supported page sizes. The least significant bit indicates the * smallest granularity and the other bits are hints indicating optimal * block sizes. */ But I don't know how much should be spelled out here, since those details are available in the spec. Thanks, Jean