Hi Jean, Pull Kevin in. Not sure why he was removed from cc list. On 07/24/2018 07:30 PM, Jean-Philippe Brucker wrote: > Hi Baolu, > > On 24/07/18 03:22, Lu Baolu wrote: >> Hi, >> >> On 07/23/2018 12:44 PM, Liu, Yi L wrote: >>>> From: Lu Baolu [mailto:baolu.lu@xxxxxxxxxxxxxxx] >>>> Sent: Sunday, July 22, 2018 2:09 PM >>>> >>>> With the Intel IOMMU supporting PASID granularity isolation and protection, a >>>> mediated device could be isolated and protected by an IOMMU unit. We need to >>>> allocate a new group instead of a PCI group. >>> Existing vfio mdev framework also allocates an iommu group for mediate device. >>> >>> mdev_probe() >>> |_ mdev_attach_iommu() >>> |_ iommu_group_alloc() >> When external components ask iommu to allocate a group for a device, >> it will call pci_device_group in Intel IOMMU driver's @device_group >> callback. In another word, current Intel IOMMU driver doesn't aware >> the mediated device and treat all devices as PCI ones. This patch >> extends the @device_group call back to make it aware of a mediated >> device. > I agree that allocating two groups for an mdev seems strange, and in my > opinion we shouldn't export the notion of mdev to IOMMU drivers. > Otherwise each driver will have to add its own "dev_is_mdev()" special > cases, which will get messy in the long run. Besides, the macro is > currently private, and to be exported it should be wrapped in > symbol_get/put(mdev_bus_type). I agree with you. It should be better if we can make it in a driver agnostic way. > > There is another way: as we're planning to add a generic pasid_alloc() > function to the IOMMU API, the mdev module itself could allocate a > default PASID for each mdev by calling pasid_alloc() on the mdev's > parent, and then do map()/unmap() with that PASID. This way we don't > have to add IOMMU ops to the mdev bus, everything can still be done > using the ops of the parent. And IOMMU drivers "only" have to implement > PASID ops, which will be reused by drivers other than mdev. A quick question when I thinking about this is how to allocate a domain for the mediated device who uses the default pasid for DMA transactions? Best regards, Lu Baolu > > The allocated PASID also needs to be installed into the parent device. > If the mdev module knows the PASID, we can do that by adding > set_pasid(mdev, pasid) and clear_pasid(mdev, pasid) operations to > mdev_parent_ops. > > Thanks, > Jean > >
