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

From: Randy Dunlap
Date: Wed Aug 20 2025 - 18:45:58 EST




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]
?

> + * Note, SEV-ES may effectively be disabled if all ASIDs from
> + * the joint range are assigned to SEV-SNP.
> + */
--
~Randy