On Wed, Dec 13, 2017 at 04:32:10PM +0100, Auger Eric wrote: > Hi, > > On 13/12/17 16:04, Auger Eric wrote: > > Hi Peter, > > > > On 13/12/17 07:49, Peter Xu wrote: > >> On Tue, Dec 12, 2017 at 12:59:39PM -0700, Alex Williamson wrote: > >>> The vfio_info_add_capability() helper requires the caller to pass a > >>> capability ID, which it then uses to fill in header fields, assuming > >>> hard coded versions. This makes for an awkward and rigid interface. > >>> The only thing we want this helper to do is allocate sufficient > >>> space in the caps buffer and chain this capability into the list. > >>> Reduce it to that simple task. > >>> > >>> Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx> > >> > >> Reviewed-by: Peter Xu <peterx@xxxxxxxxxx> > >> > >> Though during review I had a question related to the function > >> msix_sparse_mmap_cap(): Is it possible that one PCI device BAR is very > >> small (e.g., 4K) that only contains the MSI-X table (and another small > >> PBA area)? If so, should we just mark that region unmappable instead > >> of setting vfio_region_info_cap_sparse_mmap.nr_areas to 1 in > >> msix_sparse_mmap_cap()? > >> > >> /* If MSI-X table is aligned to the start or end, only one area */ > >> if (((vdev->msix_offset & PAGE_MASK) == 0) || > >> (PAGE_ALIGN(vdev->msix_offset + vdev->msix_size) >= end)) > >> nr_areas = 1; > >> > >> Thanks, > >> > > if I understand the code correctly, if the MSI-X table exactly matches > > the BAR, a sparse mmap region is reported with offset/size = 0. Is that > > correct? > > > > Thanks > > > > Eric > > > looks fixed by > > [RFC PATCH kernel] vfio-pci: Fix sparse capability when no parts of MSIX > BAR can be mapped > > Sorry for the noise. Hi, Eric, Thanks for the link anyways. :) -- Peter Xu
