On Wed, Mar 20, 2024 at 11:58:57AM +0000, Daniel P. Berrangé wrote:
> On Wed, Mar 20, 2024 at 03:39:18AM -0500, Michael Roth wrote:
> > From: Brijesh Singh <brijesh.singh@xxxxxxx>
> >
> > SEV-SNP support relies on a different set of properties/state than the
> > existing 'sev-guest' object. This patch introduces the 'sev-snp-guest'
> > object, which can be used to configure an SEV-SNP guest. For example,
> > a default-configured SEV-SNP guest with no additional information
> > passed in for use with attestation:
> >
> > -object sev-snp-guest,id=sev0
> >
> > or a fully-specified SEV-SNP guest where all spec-defined binary
> > blobs are passed in as base64-encoded strings:
> >
> > -object sev-snp-guest,id=sev0, \
> > policy=0x30000, \
> > init-flags=0, \
> > id-block=YWFhYWFhYWFhYWFhYWFhCg==, \
> > id-auth=CxHK/OKLkXGn/KpAC7Wl1FSiisWDbGTEKz..., \
> > auth-key-enabled=on, \
> > host-data=LNkCWBRC5CcdGXirbNUV1OrsR28s..., \
> > guest-visible-workarounds=AA==, \
> >
> > See the QAPI schema updates included in this patch for more usage
> > details.
> >
> > In some cases these blobs may be up to 4096 characters, but this is
> > generally well below the default limit for linux hosts where
> > command-line sizes are defined by the sysconf-configurable ARG_MAX
> > value, which defaults to 2097152 characters for Ubuntu hosts, for
> > example.
> >
> > Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
> > Co-developed-by: Michael Roth <michael.roth@xxxxxxx>
> > Acked-by: Markus Armbruster <armbru@xxxxxxxxxx> (for QAPI schema)
> > Signed-off-by: Michael Roth <michael.roth@xxxxxxx>
> > ---
> > docs/system/i386/amd-memory-encryption.rst | 78 ++++++-
> > qapi/qom.json | 51 +++++
> > target/i386/sev.c | 241 +++++++++++++++++++++
> > target/i386/sev.h | 1 +
> > 4 files changed, 369 insertions(+), 2 deletions(-)
> >
>
> > +##
> > +# @SevSnpGuestProperties:
> > +#
> > +# Properties for sev-snp-guest objects. Most of these are direct arguments
> > +# for the KVM_SNP_* interfaces documented in the linux kernel source
> > +# under Documentation/virt/kvm/amd-memory-encryption.rst, which are in
> > +# turn closely coupled with the SNP_INIT/SNP_LAUNCH_* firmware commands
> > +# documented in the SEV-SNP Firmware ABI Specification (Rev 0.9).
> > +#
> > +# More usage information is also available in the QEMU source tree under
> > +# docs/amd-memory-encryption.
> > +#
> > +# @policy: the 'POLICY' parameter to the SNP_LAUNCH_START command, as
> > +# defined in the SEV-SNP firmware ABI (default: 0x30000)
> > +#
> > +# @guest-visible-workarounds: 16-byte, base64-encoded blob to report
> > +# hypervisor-defined workarounds, corresponding
> > +# to the 'GOSVW' parameter of the
> > +# SNP_LAUNCH_START command defined in the
> > +# SEV-SNP firmware ABI (default: all-zero)
> > +#
> > +# @id-block: 96-byte, base64-encoded blob to provide the 'ID Block'
> > +# structure for the SNP_LAUNCH_FINISH command defined in the
> > +# SEV-SNP firmware ABI (default: all-zero)
> > +#
> > +# @id-auth: 4096-byte, base64-encoded blob to provide the 'ID Authentication
> > +# Information Structure' for the SNP_LAUNCH_FINISH command defined
> > +# in the SEV-SNP firmware ABI (default: all-zero)
> > +#
> > +# @auth-key-enabled: true if 'id-auth' blob contains the 'AUTHOR_KEY' field
> > +# defined SEV-SNP firmware ABI (default: false)
> > +#
> > +# @host-data: 32-byte, base64-encoded, user-defined blob to provide to the
> > +# guest, as documented for the 'HOST_DATA' parameter of the
> > +# SNP_LAUNCH_FINISH command in the SEV-SNP firmware ABI
> > +# (default: all-zero)
> > +#
> > +# Since: 7.2
>
> This will be 9.1 at the earliest now.
Amazing how good I am at remembering these once I see a reply to a
schema patch I'd already hit 'send' on :)
>
> > +##
> > +{ 'struct': 'SevSnpGuestProperties',
> > + 'base': 'SevCommonProperties',
> > + 'data': {
> > + '*policy': 'uint64',
> > + '*guest-visible-workarounds': 'str',
> > + '*id-block': 'str',
> > + '*id-auth': 'str',
> > + '*auth-key-enabled': 'bool',
> > + '*host-data': 'str' } }
> > +
>
> > diff --git a/target/i386/sev.c b/target/i386/sev.c
> > index 63a220de5e..7e6dab642a 100644
> > --- a/target/i386/sev.c
> > +++ b/target/i386/sev.c
> > @@ -42,6 +42,7 @@
> >
> > OBJECT_DECLARE_SIMPLE_TYPE(SevCommonState, SEV_COMMON)
> > OBJECT_DECLARE_SIMPLE_TYPE(SevGuestState, SEV_GUEST)
> > +OBJECT_DECLARE_SIMPLE_TYPE(SevSnpGuestState, SEV_SNP_GUEST)
> >
> > struct SevCommonState {
> > X86ConfidentialGuest parent_obj;
> > @@ -87,8 +88,22 @@ struct SevGuestState {
> > bool kernel_hashes;
> > };
> >
> > +struct SevSnpGuestState {
> > + SevCommonState sev_common;
> > +
> > + /* configuration parameters */
> > + char *guest_visible_workarounds;
> > + char *id_block;
> > + char *id_auth;
> > + char *host_data;
> > +
> > + struct kvm_sev_snp_launch_start kvm_start_conf;
> > + struct kvm_sev_snp_launch_finish kvm_finish_conf;
> > +};
> > +
> > #define DEFAULT_GUEST_POLICY 0x1 /* disable debug */
> > #define DEFAULT_SEV_DEVICE "/dev/sev"
> > +#define DEFAULT_SEV_SNP_POLICY 0x30000
> >
> > #define SEV_INFO_BLOCK_GUID "00f771de-1a7e-4fcb-890e-68c77e2fb44e"
> > typedef struct __attribute__((__packed__)) SevInfoBlock {
> > @@ -1473,11 +1488,237 @@ static const TypeInfo sev_guest_info = {
> > .class_init = sev_guest_class_init,
>
> > +
> > +static char *
> > +sev_snp_guest_get_guest_visible_workarounds(Object *obj, Error **errp)
> > +{
> > + return g_strdup(SEV_SNP_GUEST(obj)->guest_visible_workarounds);
> > +}
> > +
> > +static void
> > +sev_snp_guest_set_guest_visible_workarounds(Object *obj, const char *value,
> > + Error **errp)
> > +{
> > + SevSnpGuestState *sev_snp_guest = SEV_SNP_GUEST(obj);
> > + struct kvm_sev_snp_launch_start *start = &sev_snp_guest->kvm_start_conf;
> > + g_autofree guchar *blob;
> > + gsize len;
> > +
> > + if (sev_snp_guest->guest_visible_workarounds) {
> > + g_free(sev_snp_guest->guest_visible_workarounds);
> > + }
>
> Redundant 'if' test - g_free is happy with NULL
>
> > +
> > + /* store the base64 str so we don't need to re-encode in getter */
> > + sev_snp_guest->guest_visible_workarounds = g_strdup(value);
> > +
> > + blob = qbase64_decode(sev_snp_guest->guest_visible_workarounds, -1, &len, errp);
> > + if (!blob) {
> > + return;
> > + }
> > +
> > + if (len > sizeof(start->gosvw)) {
>
> The QAPI docs said this property must be '16 bytes', so I'd
> suggest we do a strict equality test, rather than min size
> test to catch a wider set of mistakes.
Makes sense.
>
> > + error_setg(errp, "parameter length of %lu exceeds max of %lu",
> > + len, sizeof(start->gosvw));
> > + return;
> > + }
> > +
> > + memcpy(start->gosvw, blob, len);
> > +}
> > +
> > +static char *
> > +sev_snp_guest_get_id_block(Object *obj, Error **errp)
> > +{
> > + SevSnpGuestState *sev_snp_guest = SEV_SNP_GUEST(obj);
> > +
> > + return g_strdup(sev_snp_guest->id_block);
> > +}
> > +
> > +static void
> > +sev_snp_guest_set_id_block(Object *obj, const char *value, Error **errp)
> > +{
> > + SevSnpGuestState *sev_snp_guest = SEV_SNP_GUEST(obj);
> > + struct kvm_sev_snp_launch_finish *finish = &sev_snp_guest->kvm_finish_conf;
> > + gsize len;
> > +
> > + if (sev_snp_guest->id_block) {
> > + g_free(sev_snp_guest->id_block);
> > + g_free((guchar *)finish->id_block_uaddr);
> > + }
>
> Assuming 'id_block_uaddr' is also initialized to 0, when id_block
> is NULL, then you can remove the 'if' conditional.
id_block_uaddr only ever gets initialized after id_block gets
initialized via g_strdup() below, and the SevSnpGuestState struct is
zero'd during creation time so no need to worry about uninitialized
values. So I think we can indeed drop the if check.
>
> > +
> > + /* store the base64 str so we don't need to re-encode in getter */
> > + sev_snp_guest->id_block = g_strdup(value);
> > +
> > + finish->id_block_uaddr =
> > + (uint64_t)qbase64_decode(sev_snp_guest->id_block, -1, &len, errp);
> > +
> > + if (!finish->id_block_uaddr) {
> > + return;
> > + }
> > +
> > + if (len > KVM_SEV_SNP_ID_BLOCK_SIZE) {
>
> Again, lets do a strict equality test to match the documented
> required size.
>
> > + error_setg(errp, "parameter length of %lu exceeds max of %u",
> > + len, KVM_SEV_SNP_ID_BLOCK_SIZE);
> > + return;
> > + }
> > +
> > + finish->id_block_en = (len) ? 1 : 0;
> > +}
> > +
> > +static char *
> > +sev_snp_guest_get_id_auth(Object *obj, Error **errp)
> > +{
> > + SevSnpGuestState *sev_snp_guest = SEV_SNP_GUEST(obj);
> > +
> > + return g_strdup(sev_snp_guest->id_auth);
> > +}
> > +
> > +static void
> > +sev_snp_guest_set_id_auth(Object *obj, const char *value, Error **errp)
> > +{
> > + SevSnpGuestState *sev_snp_guest = SEV_SNP_GUEST(obj);
> > + struct kvm_sev_snp_launch_finish *finish = &sev_snp_guest->kvm_finish_conf;
> > + gsize len;
> > +
> > + if (sev_snp_guest->id_auth) {
> > + g_free(sev_snp_guest->id_auth);
> > + g_free((guchar *)finish->id_auth_uaddr);
> > + }
>
> Same probably redundant 'if'
Looks like it. Will address these and recurring cases below.
-Mike
>
> > +
> > + /* store the base64 str so we don't need to re-encode in getter */
> > + sev_snp_guest->id_auth = g_strdup(value);
> > +
> > + finish->id_auth_uaddr =
> > + (uint64_t)qbase64_decode(sev_snp_guest->id_auth, -1, &len, errp);
> > +
> > + if (!finish->id_auth_uaddr) {
> > + return;
> > + }
> > +
> > + if (len > KVM_SEV_SNP_ID_AUTH_SIZE) {
>
> Equality test.
>
> > + error_setg(errp, "parameter length of %lu exceeds max of %u",
> > + len, KVM_SEV_SNP_ID_AUTH_SIZE);
> > + return;
> > + }
> > +}
> > +
> > +static bool
> > +sev_snp_guest_get_auth_key_en(Object *obj, Error **errp)
> > +{
> > + SevSnpGuestState *sev_snp_guest = SEV_SNP_GUEST(obj);
> > +
> > + return !!sev_snp_guest->kvm_finish_conf.auth_key_en;
> > +}
> > +
> > +static void
> > +sev_snp_guest_set_auth_key_en(Object *obj, bool value, Error **errp)
> > +{
> > + SevSnpGuestState *sev_snp_guest = SEV_SNP_GUEST(obj);
> > +
> > + sev_snp_guest->kvm_finish_conf.auth_key_en = value;
> > +}
> > +
> > +static char *
> > +sev_snp_guest_get_host_data(Object *obj, Error **errp)
> > +{
> > + SevSnpGuestState *sev_snp_guest = SEV_SNP_GUEST(obj);
> > +
> > + return g_strdup(sev_snp_guest->host_data);
> > +}
> > +
> > +static void
> > +sev_snp_guest_set_host_data(Object *obj, const char *value, Error **errp)
> > +{
> > + SevSnpGuestState *sev_snp_guest = SEV_SNP_GUEST(obj);
> > + struct kvm_sev_snp_launch_finish *finish = &sev_snp_guest->kvm_finish_conf;
> > + g_autofree guchar *blob;
> > + gsize len;
> > +
> > + if (sev_snp_guest->host_data) {
> > + g_free(sev_snp_guest->host_data);
> > + }
>
> Redundant 'if'
>
> > +
> > + /* store the base64 str so we don't need to re-encode in getter */
> > + sev_snp_guest->host_data = g_strdup(value);
> > +
> > + blob = qbase64_decode(sev_snp_guest->host_data, -1, &len, errp);
> > +
> > + if (!blob) {
> > + return;
> > + }
> > +
> > + if (len > sizeof(finish->host_data)) {
>
> Equality test
>
> > + error_setg(errp, "parameter length of %lu exceeds max of %lu",
> > + len, sizeof(finish->host_data));
> > + return;
> > + }
> > +
> > + memcpy(finish->host_data, blob, len);
> > +}
> > +
> > +static void
> > +sev_snp_guest_class_init(ObjectClass *oc, void *data)
> > +{
> > + object_class_property_add(oc, "policy", "uint64",
> > + sev_snp_guest_get_policy,
> > + sev_snp_guest_set_policy, NULL, NULL);
> > + object_class_property_add_str(oc, "guest-visible-workarounds",
> > + sev_snp_guest_get_guest_visible_workarounds,
> > + sev_snp_guest_set_guest_visible_workarounds);
> > + object_class_property_add_str(oc, "id-block",
> > + sev_snp_guest_get_id_block,
> > + sev_snp_guest_set_id_block);
> > + object_class_property_add_str(oc, "id-auth",
> > + sev_snp_guest_get_id_auth,
> > + sev_snp_guest_set_id_auth);
> > + object_class_property_add_bool(oc, "auth-key-enabled",
> > + sev_snp_guest_get_auth_key_en,
> > + sev_snp_guest_set_auth_key_en);
> > + object_class_property_add_str(oc, "host-data",
> > + sev_snp_guest_get_host_data,
> > + sev_snp_guest_set_host_data);
> > +}
> > +
> > +static void
> > +sev_snp_guest_instance_init(Object *obj)
> > +{
> > + SevSnpGuestState *sev_snp_guest = SEV_SNP_GUEST(obj);
> > +
> > + /* default init/start/finish params for kvm */
> > + sev_snp_guest->kvm_start_conf.policy = DEFAULT_SEV_SNP_POLICY;
> > +}
> > +
> > +/* guest info specific to sev-snp */
> > +static const TypeInfo sev_snp_guest_info = {
> > + .parent = TYPE_SEV_COMMON,
> > + .name = TYPE_SEV_SNP_GUEST,
> > + .instance_size = sizeof(SevSnpGuestState),
> > + .class_init = sev_snp_guest_class_init,
> > + .instance_init = sev_snp_guest_instance_init,
> > +};
>
> Use the OBJECT_DEFINE_TYPE_WITH_INTERFACES macro here.
>
> > +
> > static void
> > sev_register_types(void)
> > {
> > type_register_static(&sev_common_info);
> > type_register_static(&sev_guest_info);
> > + type_register_static(&sev_snp_guest_info);
> > }
> >
> > type_init(sev_register_types);
> > diff --git a/target/i386/sev.h b/target/i386/sev.h
> > index 668374eef3..bedc667eeb 100644
> > --- a/target/i386/sev.h
> > +++ b/target/i386/sev.h
> > @@ -22,6 +22,7 @@
> >
> > #define TYPE_SEV_COMMON "sev-common"
> > #define TYPE_SEV_GUEST "sev-guest"
> > +#define TYPE_SEV_SNP_GUEST "sev-snp-guest"
> >
> > #define SEV_POLICY_NODBG 0x1
> > #define SEV_POLICY_NOKS 0x2
> > --
> > 2.25.1
> >
>
> With regards,
> Daniel
> --
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