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When the domain is first >>> attached we know if it requires PRI or not. At that moment the DTE >>> should be set properly, it should not be set wrong and then changed >>> later. >> >> We want to enable PPR support only after setting up the handler. > > That's backwards. It means error handling can't really be sane.. Why do you think enabling feature only when we are really going to use it backwards? > >>> (and again the whole dte setting flow needs cleaning, I think you >>> should do that before trying to build more complex stuff on top) >> >> Yeah. I want to fix few things in that path. But that's outside this series. > > I was looking at it and there are many security bugs in here now that > iommufd can change the DTE at any time. The current design assumes DMA > will be stopped and ignores the spec guidance on how to do a safe DTE > update :( What security issues are you referring? Can you elaborate? > > I'm really not comfortable with adding more stuff here until the > security issue is solved. Especially if the more stuff is drifting > further from being correct. If you can keep the updates in set_dte > then maybe with some reluctance. But not like this with random touches > to the DTE all over the place. Currently all DTE update is happening inside set_dte only (dirty bit enable is an exception that may need to moved inside set_dte). This patch just invokes that set_dte and invalidates cache. -Vasant > > I was looking at what it would take and got part way through. It is a > very similar problem to ARM and I drafted a similar solution. > > Jason