Re: [RFC PATCH v1 09/28] x86/efi: Access EFI data as encrypted when SEV is active
From: Borislav Petkov <hidden>
Date: 2016-09-22 17:27:48
Also in:
kvm, linux-crypto, linux-efi, lkml
On Thu, Sep 22, 2016 at 07:08:50PM +0200, Paolo Bonzini wrote:
That's not how I read it. I just figured that the BIOS has some magic things high in the physical address space and if you reduce the physical address space the BIOS (which is called from e.g. EFI runtime services) would have problems with that.
Yeah, I had to ask about that myself and Tom will have it explained better in the next version. The reduction in physical address space happens when SME enabled because you need a couple of bits in the PTE with which to say which key has encrypted that page. So it is an indelible part of the SME machinery. Btw, section "7.10 Secure Memory Encryption" has an initial writeup: http://support.amd.com/TechDocs/24593.pdf Now that I skim over it, it doesn't mention the BIOS thing but that'll be updated. HTH. -- Regards/Gruss, Boris. SUSE Linux GmbH, GF: Felix ImendA?rffer, Jane Smithard, Graham Norton, HRB 21284 (AG NA 1/4 rnberg) -- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>