Hi Chris, If we cannot always pin lr context into GGTT, the LRCA cannot be used as a context identifier for us. Then we have to consider a proper interface for i915 in VM to notify GVT-g device model.
The context creation might be OK. We can pin context first, then notify the context creation, after that, unpin the context. In GVT-g, we can get the context's guest physical addresses from GTT table, and use that to identify a guest context. But the destroy can be a problem. It does not make sense to pin context and unpin that time right? Do you have any suggestions/comments? Thanks in advance! Regards, -Zhiyuan On Thu, Aug 20, 2015 at 05:16:54PM +0800, Zhiyuan Lv wrote: > Hi Chris, > > On Thu, Aug 20, 2015 at 09:36:00AM +0100, Chris Wilson wrote: > > On Thu, Aug 20, 2015 at 03:45:21PM +0800, Zhiyuan Lv wrote: > > > Intel GVT-g will perform EXECLIST context shadowing and ring buffer > > > shadowing. The shadow copy is created when guest creates a context. > > > If a context changes its LRCA address, the hypervisor is hard to know > > > whether it is a new context or not. We always pin context objects to > > > global GTT to make life easier. > > > > Nak. Please explain why we need to workaround a bug in the host. We > > cannot pin the context as that breaks userspace (e.g. synmark) who can > > and will try to use more contexts than we have room. > > This change is only for i915 running inside a VM. Host i915 driver's > behavior will not be impacted. > > The reason we want to pin context is that our hypervisor identifies > guest contexts with their LRCA, and need LRCA unchanged during > contexts' life cycle so that shadow copy of contexts can easily find > their counterparts. If we cannot pin them, we have to consider more > complicated shadow implementation ... > > BTW Chris, are there many apps like synmark that may used up GGTT with > contexts if they are all pinned? Thanks! > > Regards, > -Zhiyuan > > > -Chris > > > > -- > > Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/intel-gfx
