Re: [RFC v2 28/32] x86/tdx: Make pages shared in ioremap()

[Kuppuswamy, Sathyanarayanan]

On 5/11/21 2:35 AM, Borislav Petkov wrote:
> Preach brother!:)
>
> /me goes and greps mailboxes...
>
> ah, do you mean this, per chance:
>
> https://lore.kernel.org/kvm/20210421144402.GB5004@xxxxxxx/
>
> ?
>
> And yes, this has "sev" in the name and dhansen makes sense to me in
> wishing to unify all the protected guest feature queries under a common
> name. And then depending on the vendor, that common name will call the
> respective vendor's helper to answer the protected guest aspect asked
> about.
>
> This way, generic code will call
>
> 	protected_guest_has()
>
> or so and be nicely abstracted away from the underlying implementation.
>
> Hohumm, yap, sounds nice to me.
>
> Thx.

I see many variants of SEV/SME related checks in the common code path
between TDX and SEV/SME. Can a generic call like
protected_guest_has(MEMORY_ENCRYPTION) or is_protected_guest()
replace all these variants?

We will not be able to test AMD related features. So I need to confirm
it with AMD code maintainers/developers before making this change.

arch/x86/include/asm/io.h:313:	if (sev_key_active() || is_tdx_guest()) {			\
arch/x86/include/asm/io.h:329:	if (sev_key_active() || is_tdx_guest()) {			\
arch/x86/kernel/pci-swiotlb.c:52:	if (sme_active() || is_tdx_guest())
arch/x86/mm/ioremap.c:96:	if (!sev_active() && !is_tdx_guest())
arch/x86/mm/pat/set_memory.c:1984:	if (!mem_encrypt_active() && !is_tdx_guest())

--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer