Re: [PATCH v10 3/9] KVM: Extend the memslot to support fd-based private memory

Chao Peng
2022-12-21T13:47:17Z

On Tue, Dec 20, 2022 at 10:55:44AM +0100, Borislav Petkov wrote:
> On Tue, Dec 20, 2022 at 03:43:18PM +0800, Chao Peng wrote:
> > RESTRICTEDMEM is needed by TDX_HOST, not TDX_GUEST.
>
> Which basically means that RESTRICTEDMEM should simply depend on KVM.
> Because you can't know upfront whether KVM will run a TDX guest or a SNP
> guest and so on.
>
> Which then means that RESTRICTEDMEM will practically end up always
> enabled in KVM HV configs.

That's right, CONFIG_RESTRICTEDMEM is always selected for supported KVM
architectures (currently x86_64).

>
> > The only reason to add another HAVE_KVM_RESTRICTED_MEM is some code only
> > works for 64bit[*] and CONFIG_RESTRICTEDMEM is not sufficient to enforce
> > that.
>
> This is what I mean with "we have too many Kconfig items". :-\

Yes I agree. One way to remove this is probably additionally checking
CONFIG_64BIT instead.

Thanks,
Chao
>
> --
> Regards/Gruss,
> Boris.
>
> https://people.kernel.org/tglx/notes-about-netiquette