> From: Alex Williamson > Sent: Thursday, May 05, 2016 1:06 AM > > > > + > > > > + ret = remap_pfn_range(vma, virtaddr, pgoff, req_size, pg_prot); > > > > > > So not supporting validate_map_request() means that the user can > > > directly mmap BARs of the host GPU and as shown below, we assume a 1:1 > > > mapping of vGPU BAR to host GPU BAR. Is that ever valid in a vGPU > > > scenario or should this callback be required? It's not clear to me how > > > the vendor driver determines what this maps to, do they compare it to > > > the physical device's own BAR addresses? > > > > I didn't quite understand too. Based on earlier discussion, do we need > > something like this, or could achieve the purpose just by leveraging > > recent sparse mmap support? > > The reason for faulting in the mmio space, if I recall correctly, is to > enable an ordering where the user driver (QEMU) can mmap regions of the > device prior to resources being allocated on the host GPU to handle > them. Sparse mmap only partially handles that, it's not dynamic. With > this faulting mechanism, the host GPU doesn't need to commit resources > until the mmap is actually accessed. Thanks, > > Alex Just double confirm. I assume this faulting mechanism can work with sparse mmap, right? Regardless of whether it's a full or partial region, this faulting mechanism would commit resource only when accessed page has MMAP flag set... Thanks Kevin -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
