On Tue, Jan 12, 2021 at 3:51 AM Quentin Perret <qperret@xxxxxxxxxx> wrote: > > On Monday 11 Jan 2021 at 08:45:10 (-0600), Rob Herring wrote: > > On Fri, Jan 8, 2021 at 6:16 AM Quentin Perret <qperret@xxxxxxxxxx> wrote: > > > > > > Introduce early_init_dt_add_memory_hyp() to allow KVM to conserve a copy > > > of the memory regions parsed from DT. This will be needed in the context > > > of the protected nVHE feature of KVM/arm64 where the code running at EL2 > > > will be cleanly separated from the host kernel during boot, and will > > > need its own representation of memory. > > > > What happened to doing this with memblock? > > I gave it a go, but as mentioned in v1, I ran into issues for nomap > regions. I want the hypervisor to know about these memory regions (it's > possible some of those will be given to protected guests for instance) > but these seem to be entirely removed from the memblocks when using DT: > > https://elixir.bootlin.com/linux/latest/source/drivers/of/fdt.c#L1153 > > EFI appears to do things differently, though, as it 'just' uses > memblock_mark_nomap() instead of actively removing the memblock. And that > means I could actually use the memblock API for EFI, but I'd rather > have a common solution. I tried to understand why things are done > differently but couldn't find an answer and kept things simple and > working for now. > > Is there a good reason for not using memblock_mark_nomap() with DT? If > not, I'm happy to try that. There were 2 patches to do that, but it never got resolved. See here[1]. Rob [1] https://lore.kernel.org/linux-devicetree/?q=s%3Ano-map
