On Fri, Aug 13, 2021 at 11:59:22AM -0500, Tom Lendacky wrote:

While the name suggests this is intended mainly for guests, it will
also be used for host memory encryption checks in place of sme_active().

Which suggest that the name is not good to start with.  Maybe protected
hardware, system or platform might be a better choice?

+static inline bool prot_guest_has(unsigned int attr)
+{
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+	if (sme_me_mask)
+		return amd_prot_guest_has(attr);
+#endif
+
+	return false;
+}

Shouldn't this be entirely out of line?

+/* 0x800 - 0x8ff reserved for AMD */
+#define PATTR_SME			0x800
+#define PATTR_SEV			0x801
+#define PATTR_SEV_ES			0x802

Why do we need reservations for a purely in-kernel namespace?

And why are you overoading a brand new generic API with weird details
of a specific implementation like this?