On 4/9/25 23:54, John Levon wrote: > On Wed, Apr 09, 2025 at 11:51:09PM +0800, Tomita Moeko wrote: > >> On 4/9/25 21:48, John Levon wrote: >>> Add these helpers that access config space and return an -errno style >>> return. >>> >>> Signed-off-by: John Levon <john.le...@nutanix.com> >>> --- >>> hw/vfio/pci.c | 134 ++++++++++++++++++++++++++++++++++---------------- >>> 1 file changed, 91 insertions(+), 43 deletions(-) >>> >>> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c >>> index ddeee33aa9..c3842d2f8d 100644 >>> --- a/hw/vfio/pci.c >>> +++ b/hw/vfio/pci.c >>> @@ -964,6 +964,28 @@ static void vfio_pci_load_rom(VFIOPCIDevice *vdev) >>> } >>> } >>> >>> +/* "Raw" read of underlying config space. */ >>> +static int vfio_pci_config_space_read(VFIOPCIDevice *vdev, off_t offset, >>> + uint32_t size, void *data) >> >> Returning ssize_t here might be better here to avoid casting issues, >> though we would never read/write something exceeds INT32_MAX. > > I considered this (and the later helpers in the patch), but most of the > existing > code already uses int. Happy to look at fixing the callers too (e.g. > vfio_msi_setup()) if that's everyone's preference. > > regards > john
I checked the code, caller casts return of pread/pwrite to int because the `count` argument, bytes read/write at most, they passed does not exceed int. Given that uint32_t can exceed int, returning ssize_t here and let callers to determine cast or not is better I believe. Thanks, Moeko
