Hi, Tony, On Tue, Sep 28, 2021 at 06:06:52PM -0700, Luck, Tony wrote: > >> fpregs_lock(); > > > > I'm afraid we may hit the same locking issue when we send IPI to notify > > another task to modify its > > PASID state. Here the API is called to modify another running task's PASID > > state as well without a right lock. > > fpregs_lock() is not enough to deal with this, I'm afraid. > > We don't send IPI any more to change PASID state. The only place that the > current patch series touches the PASID MSR is in the #GP fault handler.
It's safe for the helpers to handle the PASID case (modifying the current task's PASID state in #GP). But the helpers seem to be generic. They take "task" as a parameter and handle the task as non-current case. So the helpers are not for PASID only. They may be used by others to modify a running task's FPU state. But It's not safe to do so. At least need some comments/restriction for the helpers to be used on a running task? Thanks. -Fenghua _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
