Re: [PATCH v9 2/2] KVM: SEV: Add SEV-SNP CipherTextHiding support

[Kim Phillips <kim.phillips@amd.com>]

On 8/21/25 5:58 AM, Kalra, Ashish wrote:
> On 8/21/2025 5:30 AM, Kim Phillips wrote:
>> On 8/20/25 6:23 PM, Kalra, Ashish wrote:
>>> On 8/20/2025 5:45 PM, Randy Dunlap wrote:
>>>> On 8/20/25 1:50 PM, Ashish Kalra wrote:
>>>>> @@ -3064,10 +3070,32 @@ void __init sev_hardware_setup(void)
>>>>>    out:
>>>>>        if (sev_enabled) {
>>>>>            init_args.probe = true;
>>>>> +
>>>>> +        if (sev_is_snp_ciphertext_hiding_supported())
>>>>> +            init_args.max_snp_asid = min(nr_ciphertext_hiding_asids,
>>>>> +                             min_sev_asid - 1);
>>>>> +
>>>>>            if (sev_platform_init(&init_args))
>>>>>                sev_supported = sev_es_supported = sev_snp_supported = false;
>>>>>            else if (sev_snp_supported)
>>>>>                sev_snp_supported = is_sev_snp_initialized();
>>>>> +
>>>>> +        if (sev_snp_supported)
>>>>> +            nr_ciphertext_hiding_asids = init_args.max_snp_asid;
>>>>> +
>>>>> +        /*
>>>>> +         * If ciphertext hiding is enabled, the joint SEV-ES/SEV-SNP
>>>>> +         * ASID range is partitioned into separate SEV-ES and SEV-SNP
>>>>> +         * ASID ranges, with the SEV-SNP range being [1..max_snp_asid]
>>>>> +         * and the SEV-ES range being [max_snp_asid..max_sev_es_asid].
>>>>                                        [max_snp_asid + 1..max_sev_es_asid]
>>>> ?
>>> Yes.
>> So why wouldn't you have left Sean's original "(max_snp_asid..max_sev_es_asid]" as-is?
>>
>> Kim
>>
> Because that i believe is a typo and the correct SEV-ES range is [max_snp_asid + 1..max_sev_es_asid].

It's not, though.

[max_snp_asid..max_sev_es_asid]

and

(max_snp_asid..max_sev_es_asid]

are two completely different things.


You also modified Sean's Documentation/ changes.  A consistent "joint 
SEV-ES+SEV-SNP" is preferred.

Thanks,

Kim