Hi, Will
On 2021/4/2 上午1:11, Will Deacon wrote:
On Thu, Apr 01, 2021 at 05:47:19PM +0200, Jean-Philippe Brucker wrote:
The SMMU provides a Stall model for handling page faults in platform
devices. It is similar to PCIe PRI, but doesn't require devices to have
their own translation cache. Instead, faulting transactions are parked
and the OS is given a chance to fix the page tables and retry the
transaction.
Enable stall for devices that support it (opt-in by firmware). When an
event corresponds to a translation error, call the IOMMU fault handler.
If the fault is recoverable, it will call us back to terminate or
continue the stall.
Which hardware is this useful for? Stalling adds a fair amount of complexity
to the driver, so I don't think we should support it unless we're likely to
see platforms that both implement it and do something useful with it.
I have tested the stall mode on Hisilicon Kunpeng920 board, as well as
using drivers/misc/uacce/uacce.c.
Thanks
