Messages in this thread | | | Date | Fri, 9 Apr 2021 18:53:02 +0200 | From | Borislav Petkov <> | Subject | Re: [RFC Part1 PATCH 11/13] x86/kernel: validate rom memory before accessing when SEV-SNP is active |
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On Wed, Mar 24, 2021 at 11:44:22AM -0500, Brijesh Singh wrote: > + /* > + * The ROM memory is not part of the E820 system RAM and is not prevalidated by the BIOS. > + * The kernel page table maps the ROM region as encrypted memory, the SEV-SNP requires > + * the all the encrypted memory must be validated before the access. > + */ > + if (sev_snp_active()) { > + unsigned long n, paddr; > + > + n = ((system_rom_resource.end + 1) - video_rom_resource.start) >> PAGE_SHIFT; > + paddr = video_rom_resource.start; > + early_snp_set_memory_private((unsigned long)__va(paddr), paddr, n); > + }
I don't like this sprinkling of SNP-special stuff that needs to be done, around the tree. Instead, pls define a function called
snp_prep_memory(unsigned long pa, unsigned int num_pages, enum operation);
or so which does all the manipulation needed and the callsites only simply unconditionally call that function so that all detail is extracted and optimized away when not config-enabled.
Thx.
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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