Re: [Qemu-devel] [PATCH v6 18/23] sev: emit the SEV_MEASUREMENT event

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

* Brijesh Singh (brijesh.singh@amd.com) wrote:
> During machine creation we encrypted the guest bios image, the
> LAUNCH_MEASURE command can be used to retrieve the measurement of
> the encrypted memory region. Emit the SEV_MEASUREMENT event so that
> libvirt can grab the measurement value as soon as we are done with
> creating the encrypted machine.

Can you ust clarify what happens if the libvirt has disconnected and
reconnected to qemu and so didn't see the event?  Can the reconnecting
libvirt query it and find out it's ready/not ready yet?

Dave

> Cc: Daniel P. Berrange <berrange@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: kvm@vger.kernel.org
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> ---
>  accel/kvm/sev.c        | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++
>  accel/kvm/trace-events |  1 +
>  include/sysemu/sev.h   |  1 +
>  3 files changed, 60 insertions(+)
> 
> diff --git a/accel/kvm/sev.c b/accel/kvm/sev.c
> index 1f757df725df..b78cf3144b1d 100644
> --- a/accel/kvm/sev.c
> +++ b/accel/kvm/sev.c
> @@ -19,11 +19,13 @@
>  #include "sysemu/sev.h"
>  #include "sysemu/sysemu.h"
>  #include "trace.h"
> +#include "qapi-event.h"
>  
>  #define DEFAULT_GUEST_POLICY    0x1 /* disable debug */
>  #define DEFAULT_SEV_DEVICE      "/dev/sev"
>  
>  static int sev_fd;
> +static SEVState *sev_state;
>  
>  #define SEV_FW_MAX_ERROR      0x17
>  
> @@ -418,6 +420,59 @@ err:
>      return ret;
>  }
>  
> +static void
> +sev_launch_get_measure(Notifier *notifier, void *unused)
> +{
> +    int ret, error;
> +    guchar *data;
> +    SEVState *s = sev_state;
> +    struct kvm_sev_launch_measure *measurement;
> +
> +    measurement = g_malloc0(sizeof(*measurement));
> +    if (!measurement) {
> +        return;
> +    }
> +
> +    /* query the measurement blob length */
> +    ret = sev_ioctl(KVM_SEV_LAUNCH_MEASURE, measurement, &error);
> +    if (!measurement->len) {
> +        error_report("%s: LAUNCH_MEASURE ret=%d fw_error=%d '%s'",
> +                     __func__, ret, error, fw_error_to_str(errno));
> +        goto free_measurement;
> +    }
> +
> +    data = g_malloc(measurement->len);
> +    if (s->measurement) {
> +        goto free_data;
> +    }
> +
> +    measurement->uaddr = (unsigned long)data;
> +
> +    /* get the measurement blob */
> +    ret = sev_ioctl(KVM_SEV_LAUNCH_MEASURE, measurement, &error);
> +    if (ret) {
> +        error_report("%s: LAUNCH_MEASURE ret=%d fw_error=%d '%s'",
> +                     __func__, ret, error, fw_error_to_str(errno));
> +        goto free_data;
> +    }
> +
> +    sev_set_guest_state(SEV_STATE_SECRET);
> +
> +    /* encode the measurement value and emit the event */
> +    s->measurement = g_base64_encode(data, measurement->len);
> +    trace_kvm_sev_launch_measurement(s->measurement);
> +    qapi_event_send_sev_measurement(s->measurement, &error_abort);
> +
> +free_data:
> +    g_free(data);
> +free_measurement:
> +    g_free(measurement);
> +}
> +
> +static Notifier sev_machine_done_notify = {
> +    .notify = sev_launch_get_measure,
> +};
> +
>  void *
>  sev_guest_init(const char *id)
>  {
> @@ -461,6 +516,9 @@ sev_guest_init(const char *id)
>      }
>  
>      ram_block_notifier_add(&sev_ram_notifier);
> +    qemu_add_machine_init_done_notifier(&sev_machine_done_notify);
> +
> +    sev_state = s;
>  
>      return s;
>  err:
> diff --git a/accel/kvm/trace-events b/accel/kvm/trace-events
> index c55546f36a25..51df5113ad07 100644
> --- a/accel/kvm/trace-events
> +++ b/accel/kvm/trace-events
> @@ -20,3 +20,4 @@ kvm_memcrypt_unregister_region(void *addr, size_t len) "addr %p len 0x%lu"
>  kvm_sev_change_state(char *old, char *new) "%s -> %s"
>  kvm_sev_launch_start(int policy, void *session, void *pdh) "policy 0x%x session %p pdh %p"
>  kvm_sev_launch_update_data(void *addr, uint64_t len) "addr %p len 0x%" PRIu64
> +kvm_sev_launch_measurement(const char *value) "data %s"
> diff --git a/include/sysemu/sev.h b/include/sysemu/sev.h
> index 839800efdbbf..572120c865ea 100644
> --- a/include/sysemu/sev.h
> +++ b/include/sysemu/sev.h
> @@ -63,6 +63,7 @@ typedef enum {
>  
>  struct SEVState {
>      QSevGuestInfo *sev_info;
> +    gchar *measurement;
>  };
>  
>  typedef struct SEVState SEVState;
> -- 
> 2.9.5
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK