Messages in this thread | | | Date | Thu, 2 Sep 2021 13:26:56 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH Part1 v5 34/38] x86/sev: Add snp_msg_seqno() helper |
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On Mon, Aug 30, 2021 at 10:07:39AM -0500, Brijesh Singh wrote: > The SNP firmware spec says that counter must begin with the 1.
So put that in the comment and explain what 0 is: magic or invalid or whatnot and why is that so and that it is spec-ed this way, etc.
Just having it there without a reasoning makes one wonder whether that's some arbitrary limitation or so.
> During the GHCB writing the seqno use to be 32-bit value and hence the GHCB > spec choose the 32-bit value but recently the SNP firmware changed it from > the 32 to 64. So, now we are left with the option of limiting the sequence > number to 32-bit. If we go beyond 32-bit then all we can do is fail the > call. If we pass the value of zero then FW will fail the call.
That sounds weird again. So make it 64-bit like the FW and fix the spec.
> I just choose the smaller name but I have no issues matching with the spec. > Also those keys does not have anything to do with the VMPL level. The > secrets page provides 4 different keys and they are referred as vmpck0..3 > and each of them have a sequence numbers associated with it. > > In GHCB v3 we probably need to rework the structure name.
You can point to the spec section so that readers can find the struct layout there.
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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