On Wed, Jan 23, 2019 at 05:45:24PM +1100, Benjamin Herrenschmidt wrote: > On Tue, 2019-01-22 at 16:26 +1100, Paul Mackerras wrote: > > On Mon, Jan 07, 2019 at 08:10:05PM +0100, Cédric Le Goater wrote: > > > Clear the ESB pages from the VMA of the IRQ being pass through to the > > > guest and let the fault handler repopulate the VMA when the ESB pages > > > are accessed for an EOI or for a trigger. > > > > Why do we want to do this? > > > > I don't see any possible advantage to removing the PTEs from the > > userspace mapping. You'll need to explain further. > > Afaik bcs we change the mapping to point to the real HW irq ESB page > instead of the "IPI" that was there at VM init time. So that makes it sound like there is a whole lot going on that hasn't even been hinted at in the patch descriptions... It sounds like we need a good description of how all this works and fits together somewhere under Documentation/. In any case we need much more informative patch descriptions. I realize that it's all currently in Cedric's head, but I bet that in two or three years' time when we come to try to debug something, it won't be in anyone's head... Paul.
