Messages in this thread | | | Subject | Re: [PATCH Part1 v5 34/38] x86/sev: Add snp_msg_seqno() helper | From | Brijesh Singh <> | Date | Thu, 2 Sep 2021 10:27:38 -0500 |
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On 9/2/21 6:26 AM, Borislav Petkov wrote: > 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.
Agreed, I will add a comment explaining it.
> >> 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. >
I will add comment that this for spec 0.9+.
thanks
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