On Wed, 26 Apr 2023 07:22:17 +0000 "Liu, Yi L" <yi.l.liu@xxxxxxxxx> wrote: > > From: Alex Williamson <alex.williamson@xxxxxxxxxx> > > Sent: Thursday, April 20, 2023 10:09 PM > [...] > > > > Whereas dev-id < 0 > > > > (== -1) is an affected device which prevents hot-reset, ex. an un-owned > > > > device, device configured within a different iommufd_ctx, or device > > > > opened outside of the vfio cdev API." Is that about right? Thanks, > > > > > > Do you mean to have separate err-code for the three possibilities? As > > > the devid is generated by iommufd and it is u32. I'm not sure if we can > > > have such err-code definition without reserving some ids in iommufd. > > > > Yes, if we're going to report the full dev-set, I think we need at > > least two unique error codes or else the user has no way to determine > > the subset of invalid dev-ids which block the reset. I think Jason is > > proposing the set of valid dev-ids are >0, a dev-id of zero indicates > > some form of non-blocking, while <0 (or maybe specifically -1) > > indicates a blocking device. I was trying to get consensus on a formal > > definition of each of those error codes in my previous reply. Thanks, > > Seems like RESETTABLE flag is not needed if we report -1 for the devices > that block hotreset. Userspace can deduce if the calling device is resettable > or not by checking if there is any -1 in the affected device list. There is some redundancy there, yes. Given the desire for a null array on the actual reset ioctl I assumed there would also be a desire to streamline the info ioctl such that userspace isn't required to parse the return array, for example maybe userspace isn't required to pass a full buffer and can get the reset availability status from only the header. Of course it's still the responsibility of userspace to know the extent of the reset. Thanks, Alex
