On Wed, Sep 11, 2024 at 08:11:03PM -0300, Jason Gunthorpe wrote:
On Thu, Sep 05, 2024 at 10:53:31AM -0700, Nicolin Chen wrote:
On Thu, Sep 05, 2024 at 01:14:15PM -0300, Jason Gunthorpe wrote:
On Tue, Aug 27, 2024 at 09:59:47AM -0700, Nicolin Chen wrote:
Driver can call the iommufd_viommu_find_device() to find a device pointer using its per-viommu virtual ID. The returned device must be protected by the pair of iommufd_viommu_lock/unlock_vdev_id() function.
Put these three functions into a new viommu_api file, to build it with the IOMMUFD_DRIVER config.
Signed-off-by: Nicolin Chen nicolinc@nvidia.com
drivers/iommu/iommufd/Makefile | 2 +- drivers/iommu/iommufd/viommu_api.c | 39 ++++++++++++++++++++++++++++++ include/linux/iommufd.h | 16 ++++++++++++ 3 files changed, 56 insertions(+), 1 deletion(-) create mode 100644 drivers/iommu/iommufd/viommu_api.c
I still think this is better to just share the struct content with the driver, eventually we want to do this anyhow as the driver will want to use container_of() techniques to reach its private data.
In my mind, exposing everything to the driver is something that we have to (for driver-managed structures) v.s. we want to... Even in that case, a driver actually only need to know the size of the core structure, without touching what's inside(?).
I am a bit worried that drivers would abuse the content in the core-level structure.. Providing a set of API would encourage them to keep the core structure intact, hopefully..
This is always a tension in the kernel. If the core apis can be nice and tidy then it is a reasonable direction
But here I think we've cross some threshold where the APIs are complex, want to be inlined and really we just want to expose data not APIs to drivers.
OK. I'll think of a rework. And might need another justification for a DEFAULT type of vIOMMU object to fit in.
No need for this lock, xa_load is rcu safe against concurrent writer
I see iommufd's device.c and main.c grab xa_lock before xa_load?
That is not to protect the xa_load, it is to protect the lifetime of pointer it returns
I see. I'd drop it.
Thanks Nicolin