From: Sean Christopherson Date: Thu, 16 Apr 2026 23:23:27 +0000 (-0700) Subject: KVM: SEV: Don't advertise support for unusable VM types X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=93d1a486e1d4f05db65b36db5fe2bca3d0257bb0;p=thirdparty%2Fkernel%2Flinux.git KVM: SEV: Don't advertise support for unusable VM types Commit 0aa6b90ef9d7 ("KVM: SVM: Add support for allowing zero SEV ASIDs") made it possible to make it impossible to use SEV VMs by not allocating them any ASIDs. Commit 6c7c620585c6 ("KVM: SEV: Add SEV-SNP CipherTextHiding support") did the same thing for SEV-ES. Do not export KVM_X86_SEV(_ES)_VM as supported types if in either of these situations, so that userspace can use them to determine what is actually supported by the current kernel configuration. Also move the buildup to a local variable so it is easier to add additional masking in future patches. Link: https://lore.kernel.org/all/aZyLIWtffvEnmtYh@google.com/ Suggested-by: Sean Christopherson Signed-off-by: Tycho Andersen (AMD) [sean: land code in sev_hardware_setup()] Reviewed-by: Tom Lendacky Tested-by: Tycho Andersen (AMD) Link: https://patch.msgid.link/20260416232329.3408497-6-seanjc@google.com Signed-off-by: Sean Christopherson --- diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index c4bbe49bb8c1..105d95034cae 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -3062,6 +3062,7 @@ void __init sev_hardware_setup(void) bool sev_snp_supported = false; bool sev_es_supported = false; bool sev_supported = false; + u32 vm_types = 0; if (!sev_enabled || !npt_enabled || !nrips) goto out; @@ -3195,24 +3196,26 @@ out: } } - if (sev_supported) - kvm_caps.supported_vm_types |= BIT(KVM_X86_SEV_VM); - if (sev_es_supported) - kvm_caps.supported_vm_types |= BIT(KVM_X86_SEV_ES_VM); + if (sev_supported && min_sev_asid <= max_sev_asid) + vm_types |= BIT(KVM_X86_SEV_VM); + if (sev_es_supported && min_sev_es_asid <= max_sev_es_asid) + vm_types |= BIT(KVM_X86_SEV_ES_VM); if (sev_snp_supported) - kvm_caps.supported_vm_types |= BIT(KVM_X86_SNP_VM); + vm_types |= BIT(KVM_X86_SNP_VM); + + kvm_caps.supported_vm_types |= vm_types; if (boot_cpu_has(X86_FEATURE_SEV)) pr_info("SEV %s (ASIDs %u - %u)\n", - sev_str_feature_state(sev_supported, min_sev_asid <= max_sev_asid), + sev_str_feature_state(sev_supported, vm_types & BIT(KVM_X86_SEV_VM)), min_sev_asid, max_sev_asid); if (boot_cpu_has(X86_FEATURE_SEV_ES)) pr_info("SEV-ES %s (ASIDs %u - %u)\n", - sev_str_feature_state(sev_es_supported, min_sev_es_asid <= max_sev_es_asid), + sev_str_feature_state(sev_es_supported, vm_types & BIT(KVM_X86_SEV_ES_VM)), min_sev_es_asid, max_sev_es_asid); if (boot_cpu_has(X86_FEATURE_SEV_SNP)) pr_info("SEV-SNP %s (ASIDs %u - %u)\n", - sev_str_feature_state(sev_snp_supported, true), + sev_str_feature_state(sev_snp_supported, vm_types & BIT(KVM_X86_SNP_VM)), min_snp_asid, max_snp_asid); sev_enabled = sev_supported;