On Fri, Jul 04, 2014 at 09:11:50AM +0000, David Laight wrote: > > I might be missing something, but we are talking of MSI address space > > here, aren't we? I am not getting how we could end up with a 'write' > > to a random kernel location when a unclaimed MSI vector sent. We could > > only expect a spurious interrupt at worst, which is handled and reported. > > > > Anyway, as I described in my reply to Bjorn, this is not a concern IMO. > > I'm thinking of the following - which might be MSI-X ? > 1) Hardware requests some interrupts and tells the host the BAR (and offset) > where the 'vectors' should be written. > 2) To raise an interrupt the hardware uses the 'vector' as the address > of a normal PCIe write cycle. > > So if the hardware requests 4 interrupts, but the driver (believing it > will only use 3) only write 3 vectors, and then the hardware uses the > 4th vector it can write to a random location. > > Debugging that would be hard! MSI base address is kind of hardcoded for a platform. A combination of MSI base address, PCI function number and MSI vector makes a PCI host to raise interrupt on a CPU. I might be inaccurate in details, but the scenario you described is impossible AFAICT. > David > > > -- Regards, Alexander Gordeev agordeev@xxxxxxxxxx
