On Tue, Dec 06, 2022 at 07:54:02PM +0000, Michael Kelley (LINUX) wrote: > Exactly correct. Ok, thanks. Let's put that in the commit message and get rid of the "subsequent patch" wording as patch order in git is ambiguous. IOW, something like this: Current code always maps the IO-APIC as shared (decrypted) in a confidential VM. But Hyper-V guest VMs on AMD SEV-SNP with vTOM enabled use a paravisor running in VMPL0 to emulate the IO-APIC. In such a case, the IO-APIC must be accessed as private (encrypted) because the paravisor emulates the IO-APIC in the lower half of the vTOM where all accesses must be encrypted. Add a new CC attribute which determines how the IO-APIC MMIO mapping should be established depending on the platform the kernel is running on as a guest. Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette