diff options
| -rw-r--r-- | hw/i386/pc.c | 2 | ||||
| -rw-r--r-- | qapi/qom.json | 18 | ||||
| -rw-r--r-- | target/i386/sev.c | 85 |
3 files changed, 83 insertions, 22 deletions
diff --git a/hw/i386/pc.c b/hw/i386/pc.c index 4fbc577470..c74931d577 100644 --- a/hw/i386/pc.c +++ b/hw/i386/pc.c @@ -83,7 +83,7 @@ GlobalProperty pc_compat_9_0[] = { { TYPE_X86_CPU, "x-amd-topoext-features-only", "false" }, { TYPE_X86_CPU, "x-l1-cache-per-thread", "false" }, { TYPE_X86_CPU, "guest-phys-bits", "0" }, - { "sev-guest", "legacy-vm-type", "true" }, + { "sev-guest", "legacy-vm-type", "on" }, { TYPE_X86_CPU, "legacy-multi-node", "on" }, }; const size_t pc_compat_9_0_len = G_N_ELEMENTS(pc_compat_9_0); diff --git a/qapi/qom.json b/qapi/qom.json index 8e75a419c3..7eccd2e14e 100644 --- a/qapi/qom.json +++ b/qapi/qom.json @@ -924,12 +924,16 @@ # @handle: SEV firmware handle (default: 0) # # @legacy-vm-type: Use legacy KVM_SEV_INIT KVM interface for creating the VM. -# The newer KVM_SEV_INIT2 interface syncs additional vCPU -# state when initializing the VMSA structures, which will -# result in a different guest measurement. Set this to -# maintain compatibility with older QEMU or kernel versions -# that rely on legacy KVM_SEV_INIT behavior. -# (default: false) (since 9.1) +# The newer KVM_SEV_INIT2 interface, from Linux >= 6.10, syncs +# additional vCPU state when initializing the VMSA structures, +# which will result in a different guest measurement. Set +# this to 'on' to force compatibility with older QEMU or kernel +# versions that rely on legacy KVM_SEV_INIT behavior. 'auto' +# will behave identically to 'on', but will automatically +# switch to using KVM_SEV_INIT2 if the user specifies any +# additional options that require it. If set to 'off', QEMU +# will require KVM_SEV_INIT2 unconditionally. +# (default: off) (since 9.1) # # Since: 2.12 ## @@ -939,7 +943,7 @@ '*session-file': 'str', '*policy': 'uint32', '*handle': 'uint32', - '*legacy-vm-type': 'bool' } } + '*legacy-vm-type': 'OnOffAuto' } } ## # @SevSnpGuestProperties: diff --git a/target/i386/sev.c b/target/i386/sev.c index 2ba5f51722..a1157c0ede 100644 --- a/target/i386/sev.c +++ b/target/i386/sev.c @@ -144,7 +144,7 @@ struct SevGuestState { uint32_t policy; char *dh_cert_file; char *session_file; - bool legacy_vm_type; + OnOffAuto legacy_vm_type; }; struct SevSnpGuestState { @@ -1369,6 +1369,17 @@ sev_vm_state_change(void *opaque, bool running, RunState state) } } +/* + * This helper is to examine sev-guest properties and determine if any options + * have been set which rely on the newer KVM_SEV_INIT2 interface and associated + * KVM VM types. + */ +static bool sev_init2_required(SevGuestState *sev_guest) +{ + /* Currently no KVM_SEV_INIT2-specific options are exposed via QEMU */ + return false; +} + static int sev_kvm_type(X86ConfidentialGuest *cg) { SevCommonState *sev_common = SEV_COMMON(cg); @@ -1379,14 +1390,39 @@ static int sev_kvm_type(X86ConfidentialGuest *cg) goto out; } + /* These are the only cases where legacy VM types can be used. */ + if (sev_guest->legacy_vm_type == ON_OFF_AUTO_ON || + (sev_guest->legacy_vm_type == ON_OFF_AUTO_AUTO && + !sev_init2_required(sev_guest))) { + sev_common->kvm_type = KVM_X86_DEFAULT_VM; + goto out; + } + + /* + * Newer VM types are required, either explicitly via legacy-vm-type=on, or + * implicitly via legacy-vm-type=auto along with additional sev-guest + * properties that require the newer VM types. + */ kvm_type = (sev_guest->policy & SEV_POLICY_ES) ? KVM_X86_SEV_ES_VM : KVM_X86_SEV_VM; - if (kvm_is_vm_type_supported(kvm_type) && !sev_guest->legacy_vm_type) { - sev_common->kvm_type = kvm_type; - } else { - sev_common->kvm_type = KVM_X86_DEFAULT_VM; + if (!kvm_is_vm_type_supported(kvm_type)) { + if (sev_guest->legacy_vm_type == ON_OFF_AUTO_AUTO) { + error_report("SEV: host kernel does not support requested %s VM type, which is required " + "for the set of options specified. To allow use of the legacy " + "KVM_X86_DEFAULT_VM VM type, please disable any options that are not " + "compatible with the legacy VM type, or upgrade your kernel.", + kvm_type == KVM_X86_SEV_VM ? "KVM_X86_SEV_VM" : "KVM_X86_SEV_ES_VM"); + } else { + error_report("SEV: host kernel does not support requested %s VM type. To allow use of " + "the legacy KVM_X86_DEFAULT_VM VM type, the 'legacy-vm-type' argument " + "must be set to 'on' or 'auto' for the sev-guest object.", + kvm_type == KVM_X86_SEV_VM ? "KVM_X86_SEV_VM" : "KVM_X86_SEV_ES_VM"); + } + + return -1; } + sev_common->kvm_type = kvm_type; out: return sev_common->kvm_type; } @@ -1477,14 +1513,24 @@ static int sev_common_kvm_init(ConfidentialGuestSupport *cgs, Error **errp) } trace_kvm_sev_init(); - if (x86_klass->kvm_type(X86_CONFIDENTIAL_GUEST(sev_common)) == KVM_X86_DEFAULT_VM) { + switch (x86_klass->kvm_type(X86_CONFIDENTIAL_GUEST(sev_common))) { + case KVM_X86_DEFAULT_VM: cmd = sev_es_enabled() ? KVM_SEV_ES_INIT : KVM_SEV_INIT; ret = sev_ioctl(sev_common->sev_fd, cmd, NULL, &fw_error); - } else { + break; + case KVM_X86_SEV_VM: + case KVM_X86_SEV_ES_VM: + case KVM_X86_SNP_VM: { struct kvm_sev_init args = { 0 }; ret = sev_ioctl(sev_common->sev_fd, KVM_SEV_INIT2, &args, &fw_error); + break; + } + default: + error_setg(errp, "%s: host kernel does not support the requested SEV configuration.", + __func__); + return -1; } if (ret) { @@ -2074,14 +2120,23 @@ sev_guest_set_session_file(Object *obj, const char *value, Error **errp) SEV_GUEST(obj)->session_file = g_strdup(value); } -static bool sev_guest_get_legacy_vm_type(Object *obj, Error **errp) +static void sev_guest_get_legacy_vm_type(Object *obj, Visitor *v, + const char *name, void *opaque, + Error **errp) { - return SEV_GUEST(obj)->legacy_vm_type; + SevGuestState *sev_guest = SEV_GUEST(obj); + OnOffAuto legacy_vm_type = sev_guest->legacy_vm_type; + + visit_type_OnOffAuto(v, name, &legacy_vm_type, errp); } -static void sev_guest_set_legacy_vm_type(Object *obj, bool value, Error **errp) +static void sev_guest_set_legacy_vm_type(Object *obj, Visitor *v, + const char *name, void *opaque, + Error **errp) { - SEV_GUEST(obj)->legacy_vm_type = value; + SevGuestState *sev_guest = SEV_GUEST(obj); + + visit_type_OnOffAuto(v, name, &sev_guest->legacy_vm_type, errp); } static void @@ -2107,9 +2162,9 @@ sev_guest_class_init(ObjectClass *oc, void *data) sev_guest_set_session_file); object_class_property_set_description(oc, "session-file", "guest owners session parameters (encoded with base64)"); - object_class_property_add_bool(oc, "legacy-vm-type", - sev_guest_get_legacy_vm_type, - sev_guest_set_legacy_vm_type); + object_class_property_add(oc, "legacy-vm-type", "OnOffAuto", + sev_guest_get_legacy_vm_type, + sev_guest_set_legacy_vm_type, NULL, NULL); object_class_property_set_description(oc, "legacy-vm-type", "use legacy VM type to maintain measurement compatibility with older QEMU or kernel versions."); } @@ -2125,6 +2180,8 @@ sev_guest_instance_init(Object *obj) object_property_add_uint32_ptr(obj, "policy", &sev_guest->policy, OBJ_PROP_FLAG_READWRITE); object_apply_compat_props(obj); + + sev_guest->legacy_vm_type = ON_OFF_AUTO_AUTO; } /* guest info specific sev/sev-es */ |