On Tue, Jan 04, 2022 at 09:56:37AM +0800, Lu Baolu wrote: > Multiple PCI devices may be placed in the same IOMMU group because > they cannot be isolated from each other. These devices must either be > entirely under kernel control or userspace control, never a mixture. This > checks and sets DMA ownership during driver binding, and release the > ownership during driver unbinding. > > The device driver may set a new flag (no_kernel_api_dma) to skip calling > iommu_device_use_dma_api() during the binding process. For instance, the > userspace framework drivers (vfio etc.) which need to manually claim > their own dma ownership when assigning the device to userspace. > > Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> > --- > include/linux/pci.h | 5 +++++ > drivers/pci/pci-driver.c | 21 +++++++++++++++++++++ > 2 files changed, 26 insertions(+) > > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 18a75c8e615c..d29a990e3f02 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -882,6 +882,10 @@ struct module; > * created once it is bound to the driver. > * @driver: Driver model structure. > * @dynids: List of dynamically added device IDs. > + * @no_kernel_api_dma: Device driver doesn't use kernel DMA API for DMA. > + * Drivers which don't require DMA or want to manually claim the > + * owner type (e.g. userspace driver frameworks) could set this > + * flag. Again with the bikeshedding, but this name is a bit odd. Of course it's in the kernel, this is all kernel code, so you can drop that. And again, "negative" flags are rough. So maybe just "prevent_dma"? thanks, greg k-h
