Messages in this thread | | | Date | Wed, 18 Oct 2023 09:00:25 -0300 | From | Jason Gunthorpe <> | Subject | Re: [PATCH 0/5] mlx5 ConnectX diagnostic misc driver |
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On Wed, Oct 18, 2023 at 10:31:23AM +0200, Greg Kroah-Hartman wrote: > On Wed, Oct 18, 2023 at 01:19:36AM -0700, Saeed Mahameed wrote: > > Historically a userspace program was used that accessed the PCI register > > and config space directly through /sys/bus/pci/.../XXX and could operate > > these debugging interfaces in parallel with the running driver. > > This approach is incompatible with secure boot and kernel lockdown so this > > driver provides a secure and restricted interface to that. > > Why not just write a UIO driver for this hardware then?
The old mechanism relied on direct config space and sometimes mmio access to the PCI device. We did a security analysis and concluded that approach could not provide the required security for what our customers want from the secure boot and lockdown modes. We cannot allow a lockdown userspace direct access to those device registers.
So, it was redesigned to be RPC driven instead of having direct HW access. The RPCs allow the device to provide the required level of security.
This new misc driver does not expose any HW registers or interrupts to userspace, so it does not seem like a fit for UIO.
Jason
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