On Fri, Jun 14, 2019 at 7:21 AM Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote: > > On Wed, 12 Jun 2019, Andy Lutomirski wrote: > > > On Jun 12, 2019, at 12:55 PM, Dave Hansen <dave.hansen@xxxxxxxxx> wrote: > > > > > >> On 6/12/19 10:08 AM, Marius Hillenbrand wrote: > > >> This patch series proposes to introduce a region for what we call > > >> process-local memory into the kernel's virtual address space. > > > > > > It might be fun to cc some x86 folks on this series. They might have > > > some relevant opinions. ;) > > > > > > A few high-level questions: > > > > > > Why go to all this trouble to hide guest state like registers if all the > > > guest data itself is still mapped? > > > > > > Where's the context-switching code? Did I just miss it? > > > > > > We've discussed having per-cpu page tables where a given PGD is only in > > > use from one CPU at a time. I *think* this scheme still works in such a > > > case, it just adds one more PGD entry that would have to context-switched. > > > > Fair warning: Linus is on record as absolutely hating this idea. He might > > change his mind, but it’s an uphill battle. > > Yes I know, but as a benefit we could get rid of all the GSBASE horrors in > the entry code as we could just put the percpu space into the local PGD. > I have personally suggested this to Linus on a couple of occasions, and he seemed quite skeptical.
