Re: [RFC Part2 PATCH 02/30] x86/sev-snp: add RMP entry lookup helpers

[Brijesh Singh]

On 4/15/21 2:50 PM, Borislav Petkov wrote:
> On Thu, Apr 15, 2021 at 01:08:09PM -0500, Brijesh Singh wrote:
>> This is from Family 19h Model 01h Rev B01. The processor which
>> introduces the SNP feature. Yes, I have already upload the PPR on the BZ.
>>
>> The PPR is also available at AMD: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.amd.com%2Fen%2Fsupport%2Ftech-docs&data=04%7C01%7Cbrijesh.singh%40amd.com%7Ca20ef8e85fca49875f4b08d90047b837%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637541130354491050%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=MosOIntXEk6ikXpIFd89XkZPb8H6oO25y2mP2l82blU%3D&reserved=0
> Please add the link in the bugzilla to the comments here - this is the
> reason why stuff is being uploaded in the first place, because those
> vendor sites tend to change and those links become stale with time.

Will do.


>
>> I guess I was trying to shorten the name. I am good with struct rmpentry;
> Yes please - typedefs are used only in very specific cases.
>
>> All those magic numbers are documented in the PPR.
> We use defines - not magic numbers. For example
>
> #define RMPTABLE_ENTRIES_OFFSET 0x4000
>
> The 8 is probably
>
> PAGE_SHIFT - RMPENTRY_SHIFT
>
> because you have GPA bits [50:12] and an RMP entry is 16 bytes, i.e., 1 << 4.
>
> With defines it is actually clear what the computation is doing - with
> naked numbers not really.

Sure, I will add macros to make it more readable.