On 03/13/2017 03:54 AM, Brian Starkey wrote: > On Sun, Mar 12, 2017 at 02:34:14PM +0100, Benjamin Gaignard wrote: >> 2017-03-09 18:38 GMT+01:00 Laura Abbott <labbott@xxxxxxxxxx>: >>> On 03/09/2017 02:00 AM, Benjamin Gaignard wrote: >>>> 2017-03-06 17:04 GMT+01:00 Daniel Vetter <daniel@xxxxxxxx>: >>>>> On Mon, Mar 06, 2017 at 11:58:05AM +0100, Mark Brown wrote: >>>>>> On Mon, Mar 06, 2017 at 11:40:41AM +0100, Daniel Vetter wrote: >>>>>> >>>>>>> No one gave a thing about android in upstream, so Greg KH just dumped it >>>>>>> all into staging/android/. We've discussed ION a bunch of times, recorded >>>>>>> anything we'd like to fix in staging/android/TODO, and Laura's patch >>>>>>> series here addresses a big chunk of that. >>>>>> >>>>>>> This is pretty much the same approach we (gpu folks) used to de-stage the >>>>>>> syncpt stuff. >>>>>> >>>>>> Well, there's also the fact that quite a few people have issues with the >>>>>> design (like Laurent). It seems like a lot of them have either got more >>>>>> comfortable with it over time, or at least not managed to come up with >>>>>> any better ideas in the meantime. >>>>> >>>>> See the TODO, it has everything a really big group (look at the patch for >>>>> the full Cc: list) figured needs to be improved at LPC 2015. We don't just >>>>> merge stuff because merging stuff is fun :-) >>>>> >>>>> Laurent was even in that group ... >>>>> -Daniel >>>> >>>> For me those patches are going in the right direction. >>>> >>>> I still have few questions: >>>> - since alignment management has been remove from ion-core, should it >>>> be also removed from ioctl structure ? >>> >>> Yes, I think I'm going to go with the suggestion to fixup the ABI >>> so we don't need the compat layer and as part of that I'm also >>> dropping the align argument. >>> >>>> - can you we ride off ion_handle (at least in userland) and only >>>> export a dma-buf descriptor ? >>> >>> Yes, I think this is the right direction given we're breaking >>> everything anyway. I was debating trying to keep the two but >>> moving to only dma bufs is probably cleaner. The only reason >>> I could see for keeping the handles is running out of file >>> descriptors for dma-bufs but that seems unlikely. >>>> >>>> In the future how can we add new heaps ? >>>> Some platforms have very specific memory allocation >>>> requirements (just have a look in the number of gem custom allocator in drm) >>>> Do you plan to add heap type/mask for each ? >>> >>> Yes, that was my thinking. >> >> My concern is about the policy to adding heaps, will you accept >> "customs" heap per >> platforms ? per devices ? or only generic ones ? >> If you are too strict, we will have lot of out-of-tree heaps and if >> you accept of of them >> it will be a nightmare to maintain.... >> > > Are you concerned about actual heaps (e.g. a carveout at 0x80000000 vs > a carveout at 0x60000000) or heap types? > > For heap types, I think the policy can be strict - if it's generally > useful then it should live in-tree in ion. Otherwise, it would be > out-of-tree. I'd expect most "custom" heaps to be parameterisable to > the point of being generally useful. > I'm willing to be reasonably permissive in what lives in tree. A good example would be something like a heap for the OMAP tiler which had weird hardware requirements. The associated devices that go with the heap should be well supported upstream though. > For actual heap instances, I would expect them to be communicated via > reserved-memory regions or something similar, and so the maintenance > burden is pretty low. > Yes. After the next round of review for this series I'm going to start thinking about properties for chunk and carveout heaps if nobody proposes something first. > The existing query ioctl can allow heap IDs to get assigned > dynamically at runtime, so there's no need to reserve "bit 6" for > "CUSTOM_ACME_HEAP_1" > >> Another point is how can we put secure rules (like selinux policy) on >> heaps since all the allocations >> go to the same device (/dev/ion) ? For example, until now, in Android >> we have to give the same >> access rights to all the process that use ION. >> It will become problem when we will add secure heaps because we won't >> be able to distinguish secure >> processes to standard ones or set specific policy per heaps. >> Maybe I'm wrong here but I have never see selinux policy checking an >> ioctl field but if that >> exist it could be a solution. >> > > I might be thinking of a different type of "secure", but... > > Should the security of secure heaps be enforced by OS-level > permissions? I don't know about other architectures, but at least on > arm/arm64 this is enforced in hardware; it doesn't matter who has > access to the ion heap, because only secure devices (or the CPU > running a secure process) is physically able to access the memory > backing the buffer. > > In fact, in the use-cases I know of, the process asking for the ion > allocation is not a secure process, and so we wouldn't *want* to > restrict the secure heap to be allocated from only by secure > processes. > > -Brian > >>> >>>> -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
