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

[Kuppuswamy, Sathyanarayanan]

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 ?


--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer