Re: [RFC v2 26/32] x86/mm: Move force_dma_unencrypted() to common code

[Andi Kleen]

On 5/17/2021 3:32 PM, Kuppuswamy, Sathyanarayanan wrote:
> On 5/17/21 11:37 AM, Sean Christopherson wrote:
> > > Just remember, a "common framework" doesn't mean that it can't be 
> > > backed
> > > by extremely arch-specific mechanisms.
> > >
> > > For instance, there's a lot of pkey-specific code in mm/mprotect.c.  It
> > > still gets optimized away on x86 with all the goodness of X86_FEATUREs.
> > Ya, exactly.  Ideally, generic code shouldn't have to differentiate 
> > between SEV,
> > SEV-ES, SEV-SNP, TDX, etc..., a vanilla "bool 
> > is_protected_guest(void)" should
> > suffice.  Under the hood, x86's implementation for 
> > is_protected_guest() can be
> > boot_cpu_has() checks (if we want).
>
> What about the use case of protected_guest_has(flag)? Do you want to 
> call it with
> with X86_FEATURE_* flags outside arch/x86 code ?


I don't think we need any flags in the generic code. Just a simple bool 
is enough.


-Andi