On Tue, Jul 27, 2021 at 05:26:04PM -0500, Tom Lendacky via iommu wrote:

In prep for other protected virtualization technologies, introduce a
generic helper function, prot_guest_has(), that can be used to check
for specific protection attributes, like memory encryption. This is
intended to eliminate having to add multiple technology-specific checks
to the code (e.g. if (sev_active() || tdx_active())).

So common checks obviously make sense, but I really hate the stupid
multiplexer.  Having one well-documented helper per feature is much
easier to follow.

+#define PATTR_MEM_ENCRYPT		0	/* Encrypted memory */
+#define PATTR_HOST_MEM_ENCRYPT		1	/* Host encrypted memory */
+#define PATTR_GUEST_MEM_ENCRYPT		2	/* Guest encrypted memory */
+#define PATTR_GUEST_PROT_STATE		3	/* Guest encrypted state */

The kerneldoc comments on these individual helpers will give you plenty
of space to properly document what they indicate and what a (potential)
caller should do based on them.  Something the above comments completely
fail to.