On Tue, Jul 30, 2019 at 03:43:20PM +0200, Arnd Bergmann wrote: > When syncing 'for_cpu', you should not need to write back, because > there won't be any dirty cache lines. > > If you have a CPU core that does not do speculative loads, you also don't > need to invalidate here, because you have already done that in the > _for_device() case, the only reason to invalidate the CPU cache > again is if a speculative load created a stale cache line that now > shadows the data received from the device.
Yes. And that is one reason why I want to lift a set of common helpers for both the speculating and non-speculating case to the common code that just calls arch specific writeback/invalidate/writeback+invalidate helpers. It hasn't been a priotity so far, but maybe it becomes one now. Especially if I could draft someone else to help with it :)
