Re: [Qemu-devel] [PATCH v2 08/13] misc.json: add migrate-set-sev-info command

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Singh, Brijesh (brijesh.singh@amd.com) wrote:
> The command can be used by the hypervisor to specify the target Platform
> Diffie-Hellman key (PDH) and certificate chain before starting the SEV
> guest migration. The values passed through the command will be used while
> creating the outgoing encryption context.
> 
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>

I'm wondering if it would make sense to have these as migration
parameters rather than using a new command.
You could just use string parameters.
(cc'ing Eric and Daniel for interface suggestions)

> ---
>  qapi/misc-target.json  | 18 ++++++++++++++++++
>  target/i386/monitor.c  | 10 ++++++++++
>  target/i386/sev-stub.c |  5 +++++
>  target/i386/sev.c      | 11 +++++++++++
>  target/i386/sev_i386.h |  9 ++++++++-
>  5 files changed, 52 insertions(+), 1 deletion(-)
> 
> diff --git a/qapi/misc-target.json b/qapi/misc-target.json
> index a00fd821eb..938dcaea14 100644
> --- a/qapi/misc-target.json
> +++ b/qapi/misc-target.json
> @@ -266,3 +266,21 @@
>  ##
>  { 'command': 'query-gic-capabilities', 'returns': ['GICCapability'],
>    'if': 'defined(TARGET_ARM)' }
> +
> +##
> +# @migrate-set-sev-info:
> +#
> +# The command is used to provide the target host information used during the
> +# SEV guest.
> +#
> +# @pdh the target host platform diffie-hellman key encoded in base64
> +#
> +# @plat-cert the target host platform certificate chain encoded in base64
> +#
> +# @amd-cert AMD certificate chain which include ASK and OCA encoded in base64
> +#
> +# Since 4.2
> +#
> +##
> +{ 'command': 'migrate-set-sev-info',
> +  'data': { 'pdh': 'str', 'plat-cert': 'str', 'amd-cert' : 'str' }}
> diff --git a/target/i386/monitor.c b/target/i386/monitor.c
> index 1f3b532fc2..4a5f50fb45 100644
> --- a/target/i386/monitor.c
> +++ b/target/i386/monitor.c
> @@ -736,3 +736,13 @@ SevCapability *qmp_query_sev_capabilities(Error **errp)
>  
>      return data;
>  }
> +
> +void qmp_migrate_set_sev_info(const char *pdh, const char *plat_cert,
> +                              const char *amd_cert, Error **errp)
> +{
> +    if (sev_enabled()) {
> +        sev_set_migrate_info(pdh, plat_cert, amd_cert);
> +    } else {
> +        error_setg(errp, "SEV is not enabled");
> +    }
> +}
> diff --git a/target/i386/sev-stub.c b/target/i386/sev-stub.c
> index e5ee13309c..173bfa6374 100644
> --- a/target/i386/sev-stub.c
> +++ b/target/i386/sev-stub.c
> @@ -48,3 +48,8 @@ SevCapability *sev_get_capabilities(void)
>  {
>      return NULL;
>  }
> +
> +void sev_set_migrate_info(const char *pdh, const char *plat_cert,
> +                          const char *amd_cert)
> +{
> +}
> diff --git a/target/i386/sev.c b/target/i386/sev.c
> index 49baf8fef0..6c902d0be8 100644
> --- a/target/i386/sev.c
> +++ b/target/i386/sev.c
> @@ -825,6 +825,17 @@ sev_encrypt_data(void *handle, uint8_t *ptr, uint64_t len)
>      return 0;
>  }
>  
> +void sev_set_migrate_info(const char *pdh, const char *plat_cert,
> +                          const char *amd_cert)
> +{
> +    SEVState *s = sev_state;
> +
> +    s->remote_pdh = g_base64_decode(pdh, &s->remote_pdh_len);
> +    s->remote_plat_cert = g_base64_decode(plat_cert,
> +                                          &s->remote_plat_cert_len);
> +    s->amd_cert = g_base64_decode(amd_cert, &s->amd_cert_len);

What sanity checking is there that it's a valid base64 string of sane
length?

> +}
> +
>  static void
>  sev_register_types(void)
>  {
> diff --git a/target/i386/sev_i386.h b/target/i386/sev_i386.h
> index 55313441ae..3f3449b346 100644
> --- a/target/i386/sev_i386.h
> +++ b/target/i386/sev_i386.h
> @@ -39,7 +39,8 @@ extern uint32_t sev_get_cbit_position(void);
>  extern uint32_t sev_get_reduced_phys_bits(void);
>  extern char *sev_get_launch_measurement(void);
>  extern SevCapability *sev_get_capabilities(void);
> -
> +extern void sev_set_migrate_info(const char *pdh, const char *plat_cert,
> +                                 const char *amd_cert);
>  typedef struct QSevGuestInfo QSevGuestInfo;
>  typedef struct QSevGuestInfoClass QSevGuestInfoClass;
>  
> @@ -81,6 +82,12 @@ struct SEVState {
>      int sev_fd;
>      SevState state;
>      gchar *measurement;
> +    guchar *remote_pdh;
> +    size_t remote_pdh_len;
> +    guchar *remote_plat_cert;
> +    size_t remote_plat_cert_len;
> +    guchar *amd_cert;
> +    size_t amd_cert_len;
>  };
>  
>  typedef struct SEVState SEVState;
> -- 
> 2.17.1
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK