On Tue, May 25, 2021 at 09:16:30AM -0400, Tony Krowiak wrote: > > > On 5/24/21 10:37 AM, Jason J. Herne wrote: > > On 5/21/21 3:36 PM, Tony Krowiak wrote: > > > The function pointer to the handler that processes interception of the > > > PQAP instruction is contained in the mdev. If the mdev is removed and > > > its storage de-allocated during the processing of the PQAP instruction, > > > the function pointer could get wiped out before the function is called > > > because there is currently nothing that controls access to it. > > > > > > This patch introduces two new functions: > > > * The kvm_arch_crypto_register_hook() function registers a function > > > pointer > > > for processing intercepted crypto instructions. > > > * The kvm_arch_crypto_register_hook() function un-registers a function > > > pointer that was previously registered. > > > > Typo: You meant kvm_arch_crypto_UNregister_hook() in the second bullet. > > > > > > Just one overall observation on this one. The whole hook system seems > > kind of over-engineered if this is our only use for it. It looks like a > > kvm_s390_crypto_hook is meant to link a specific module with a function > > pointer. Do we really need this concept? > > > > I think a simpler design could be to just place a mutex and a function > > pointer in the kvm_s390_crypto struct. Then you can grab the mutex in > > vfio_ap_ops.c when registering/unregistering. You would also grab the > > mutex in priv.c when calling the function pointer. What I am suggesting > > is essentially the exact same scheme you have implemented here, but > > simpler and with less infrastructure. > > That would be great, however; when I implemented something similar, it > resulted in a > lockdep splat between the lock used to protect the hook and the > matrix_dev->lock used to > protect updates to matrix_mdev (including the freeing thereof). After > pulling what little hair > I have left out, this seemed like a reasonable solution, over-engineered > though it may be. > If somebody has a simpler solution, I'm all ears. Why can't you put the locks in the right order? It looked trivial, I'm confused. Jason
