Re: [RFCv2 06/13] x86/realmode: Share trampoline area if KVM memory protection enabled

Dave Hansen
2021-04-19T16:49:21Z

On 4/16/21 8:40 AM, Kirill A. Shutemov wrote:
> /*
> - * If SME is active, the trampoline area will need to be in
> - * decrypted memory in order to bring up other processors
> + * If SME or KVM memory protection is active, the trampoline area will
> + * need to be in decrypted memory in order to bring up other processors
> * successfully. This is not needed for SEV.
> */
> - if (sme_active())
> + if (sme_active() || kvm_mem_protected())
> set_memory_decrypted((unsigned long)base, size >> PAGE_SHIFT);

Could you take a look at all the places you've added these:

if (foo() || kvm_mem_protected())
bar();

spots and see if some refactoring is in order?

I suspect that some thought about what the high-level commonalities are,
plus some thoughtful helper function names would go a long way to making
this whole thing understandable.

set_memory_decrypted() as a name needs to go. It almost needs to be
something like:

set_memory_sharing()

or something. The "sharing" would be between the kernel and devices
(for SME), or the guest kernel and host kernel for protected memory.