Re: [RFC 00/10] Process-local memory allocations for hiding KVM secrets

[Andy Lutomirski]

> 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 itâs an uphill battle.