linux-kernel - Re: [PATCH v9 29/43] x86/boot: Add Confidential Computing type to setup

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Date:   Fri, 4 Feb 2022 11:41:18 -0600
From:   Brijesh Singh <brijesh.singh@....com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     brijesh.singh@....com, x86@...nel.org,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        linux-efi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-coco@...ts.linux.dev, linux-mm@...ck.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Joerg Roedel <jroedel@...e.de>,
        Tom Lendacky <thomas.lendacky@....com>,
        "H. Peter Anvin" <hpa@...or.com>, Ard Biesheuvel <ardb@...nel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Jim Mattson <jmattson@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Sergio Lopez <slp@...hat.com>, Peter Gonda <pgonda@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Srinivas Pandruvada <srinivas.pandruvada@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Dov Murik <dovmurik@...ux.ibm.com>,
        Tobin Feldman-Fitzthum <tobin@....com>,
        Michael Roth <michael.roth@....com>,
        Vlastimil Babka <vbabka@...e.cz>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Andi Kleen <ak@...ux.intel.com>,
        "Dr . David Alan Gilbert" <dgilbert@...hat.com>,
        brijesh.ksingh@...il.com, tony.luck@...el.com, marcorr@...gle.com,
        sathyanarayanan.kuppuswamy@...ux.intel.com
Subject: Re: [PATCH v9 29/43] x86/boot: Add Confidential Computing type to
 setup_data


On 2/4/22 10:21 AM, Borislav Petkov wrote:
> On Fri, Jan 28, 2022 at 11:17:50AM -0600, Brijesh Singh wrote:
>> +/*
>> + * AMD SEV Confidential computing blob structure. The structure is
>> + * defined in OVMF UEFI firmware header:
>> + * https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Ftianocore%2Fedk2%2Fblob%2Fmaster%2FOvmfPkg%2FInclude%2FGuid%2FConfidentialComputingSevSnpBlob.h&amp;data=04%7C01%7Cbrijesh.singh%40amd.com%7C334b7454d7a541f3497d08d9e7fa796c%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637795885258984697%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000&amp;sdata=XNPvA7re7WHpAgzeuOC%2Buu0ql18P6KOIbP5ZriFsxEY%3D&amp;reserved=0
> So looking at that typedef struct CONFIDENTIAL_COMPUTING_SNP_BLOB_LOCATION there:
>
> typedef struct {
>   UINT32    Header;
>   UINT16    Version;
>   UINT16    Reserved1;
>   UINT64    SecretsPhysicalAddress;
>   UINT32    SecretsSize;
>   UINT64    CpuidPhysicalAddress;
>   UINT32    CpuidLSize;
> } CONFIDENTIAL_COMPUTING_SNP_BLOB_LOCATION;
>
>> + */
>> +#define CC_BLOB_SEV_HDR_MAGIC	0x45444d41
>> +struct cc_blob_sev_info {
>> +	u32 magic;
> That's called "Header" there.

I will rename it to keep it consistent with OVMF header.


>> +	u16 version;
>> +	u16 reserved;
>> +	u64 secrets_phys;
>> +	u32 secrets_len;
>> +	u32 rsvd1;
> You've added that member for padding but the fw blob one doesn't have
> it.
>
> But if we get a blob from the firmware and the structure layout differs,
> how is this supposed to even work?
>
>> +	u64 cpuid_phys;
>> +	u32 cpuid_len;
>> +	u32 rsvd2;
> That one too.
>
> Or are you going to change the blob layout in ovmf too, to match?

Yes, that's the plan. I have tested my OVMF with v9 and everything looks
good at the runtime. Will send OVMF patch to match the blob layout.