Re: [Qemu-devel] [PATCH v2 10/13] target/i386: sev: add support to load incoming encrypted page

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

* Singh, Brijesh (brijesh.singh@amd.com) wrote:
> The sev_load_incoming_page() provide the implementation to read the
> incoming guest private pages from the socket and load it into the guest
> memory. The routines uses the RECEIVE_START command to create the
> incoming encryption context on the first call then uses the
> RECEIEVE_UPDATE_DATA command to load the encrypted pages into the guest
> memory. After migration is completed, we issue the RECEIVE_FINISH command
> to transition the SEV guest to the runnable state so that it can be
> executed.
> 
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>
> ---
>  accel/kvm/kvm-all.c      |   1 +
>  target/i386/sev.c        | 126 ++++++++++++++++++++++++++++++++++++++-
>  target/i386/trace-events |   3 +
>  3 files changed, 129 insertions(+), 1 deletion(-)
> 
> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> index a9fb447248..7f94dba6f9 100644
> --- a/accel/kvm/kvm-all.c
> +++ b/accel/kvm/kvm-all.c
> @@ -1793,6 +1793,7 @@ static int kvm_init(MachineState *ms)
>  
>          kvm_state->memcrypt_encrypt_data = sev_encrypt_data;
>          kvm_state->memcrypt_save_outgoing_page = sev_save_outgoing_page;
> +        kvm_state->memcrypt_load_incoming_page = sev_load_incoming_page;
>      }
>  
>      ret = kvm_arch_init(ms, s);
> diff --git a/target/i386/sev.c b/target/i386/sev.c
> index 28b36c8035..09a62d6f88 100644
> --- a/target/i386/sev.c
> +++ b/target/i386/sev.c
> @@ -708,13 +708,34 @@ sev_launch_finish(SEVState *s)
>      }
>  }
>  
> +static int
> +sev_receive_finish(SEVState *s)
> +{
> +    int error, ret = 1;
> +
> +    trace_kvm_sev_receive_finish();
> +    ret = sev_ioctl(s->sev_fd, KVM_SEV_RECEIVE_FINISH, 0, &error);
> +    if (ret) {
> +        error_report("%s: RECEIVE_FINISH ret=%d fw_error=%d '%s'",
> +                __func__, ret, error, fw_error_to_str(error));
> +        goto err;
> +    }
> +
> +    sev_set_guest_state(SEV_STATE_RUNNING);
> +err:
> +    return ret;
> +}
> +
> +
>  static void
>  sev_vm_state_change(void *opaque, int running, RunState state)
>  {
>      SEVState *s = opaque;
>  
>      if (running) {
> -        if (!sev_check_state(SEV_STATE_RUNNING)) {
> +        if (sev_check_state(SEV_STATE_RECEIVE_UPDATE)) {
> +            sev_receive_finish(s);
> +        } else if (!sev_check_state(SEV_STATE_RUNNING)) {
>              sev_launch_finish(s);
>          }
>      }
> @@ -1065,6 +1086,109 @@ int sev_save_outgoing_page(void *handle, QEMUFile *f, uint8_t *ptr,
>      return sev_send_update_data(s, f, ptr, sz, bytes_sent);
>  }
>  
> +static int
> +sev_receive_start(QSevGuestInfo *sev, QEMUFile *f)
> +{
> +    int ret = 1;
> +    int fw_error;
> +    struct kvm_sev_receive_start *start;
> +    gchar *session = NULL, *pdh_cert = NULL;
> +
> +    start = g_new0(struct kvm_sev_receive_start, 1);

Same as the send patch; these are tiny so may as well be on the stack

> +    /* get SEV guest handle */
> +    start->handle = object_property_get_int(OBJECT(sev), "handle",
> +            &error_abort);
> +
> +    /* get the source policy */
> +    start->policy = qemu_get_be32(f);
> +
> +    /* get source PDH key */
> +    start->pdh_len = qemu_get_be32(f);

You might want to bound the sizes of pdh_len and session_len
on reading; if the migration stream is badly corrupt you could
end up allocating and then trying to read a few GB ofjunk off the wire.

> +    pdh_cert = g_new(gchar, start->pdh_len);
> +    qemu_get_buffer(f, (uint8_t *)pdh_cert, start->pdh_len);
> +    start->pdh_uaddr = (unsigned long)pdh_cert;
> +
> +    /* get source session data */
> +    start->session_len = qemu_get_be32(f);
> +    session = g_new(gchar, start->session_len);
> +    qemu_get_buffer(f, (uint8_t *)session, start->session_len);
> +    start->session_uaddr = (unsigned long)session;
> +
> +    trace_kvm_sev_receive_start(start->policy, session, pdh_cert);
> +
> +    ret = sev_ioctl(sev_state->sev_fd, KVM_SEV_RECEIVE_START, start, &fw_error);
> +    if (ret < 0) {
> +        error_report("Error RECEIVE_START ret=%d fw_error=%d '%s'",
> +                ret, fw_error, fw_error_to_str(fw_error));
> +        goto err;
> +    }
> +
> +    object_property_set_int(OBJECT(sev), start->handle, "handle", &error_abort);
> +    sev_set_guest_state(SEV_STATE_RECEIVE_UPDATE);
> +err:
> +    g_free(start);
> +    g_free(session);
> +    g_free(pdh_cert);
> +
> +    return ret;
> +}
> +
> +static int sev_receive_update_data(QEMUFile *f, uint8_t *ptr)
> +{
> +    int ret = 1, fw_error = 0;
> +    gchar *hdr = NULL, *trans = NULL;
> +    struct kvm_sev_receive_update_data *update;
> +
> +    update = g_new0(struct kvm_sev_receive_update_data, 1);

Similar comments to the _start function

> +    /* get packet header */
> +    update->hdr_len = qemu_get_be32(f);
> +    hdr = g_new(gchar, update->hdr_len);
> +    qemu_get_buffer(f, (uint8_t *)hdr, update->hdr_len);
> +    update->hdr_uaddr = (unsigned long)hdr;
> +
> +    /* get transport buffer */
> +    update->trans_len = qemu_get_be32(f);
> +    trans = g_new(gchar, update->trans_len);
> +    update->trans_uaddr = (unsigned long)trans;
> +    qemu_get_buffer(f, (uint8_t *)update->trans_uaddr, update->trans_len);
> +
> +    update->guest_uaddr = (unsigned long) ptr;
> +    update->guest_len = update->trans_len;
> +
> +    trace_kvm_sev_receive_update_data(trans, ptr, update->guest_len,
> +            hdr, update->hdr_len);
> +
> +    ret = sev_ioctl(sev_state->sev_fd, KVM_SEV_RECEIVE_UPDATE_DATA,
> +                    update, &fw_error);
> +    if (ret) {
> +        error_report("Error RECEIVE_UPDATE_DATA ret=%d fw_error=%d '%s'",
> +                ret, fw_error, fw_error_to_str(fw_error));
> +        goto err;
> +    }
> +err:
> +    g_free(trans);
> +    g_free(update);
> +    g_free(hdr);
> +    return ret;
> +}
> +
> +int sev_load_incoming_page(void *handle, QEMUFile *f, uint8_t *ptr)
> +{
> +    SEVState *s = (SEVState *)handle;
> +
> +    /* If this is first buffer and SEV is not in recieiving state then
> +     * use RECEIVE_START command to create a encryption context.
> +     */
> +    if (!sev_check_state(SEV_STATE_RECEIVE_UPDATE) &&
> +        sev_receive_start(s->sev_info, f)) {
> +        return 1;
> +    }
> +
> +    return sev_receive_update_data(f, ptr);
> +}
> +
>  static void
>  sev_register_types(void)
>  {
> diff --git a/target/i386/trace-events b/target/i386/trace-events
> index b41516cf9f..609752cca7 100644
> --- a/target/i386/trace-events
> +++ b/target/i386/trace-events
> @@ -18,3 +18,6 @@ kvm_sev_launch_finish(void) ""
>  kvm_sev_send_start(uint64_t pdh, int l1, uint64_t plat, int l2, uint64_t amd, int l3) "pdh 0x%" PRIx64 " len %d plat 0x%" PRIx64 " len %d amd 0x%" PRIx64 " len %d"
>  kvm_sev_send_update_data(void *src, void *dst, int len) "guest %p trans %p len %d"
>  kvm_sev_send_finish(void) ""
> +kvm_sev_receive_start(int policy, void *session, void *pdh) "policy 0x%x session %p pdh %p"
> +kvm_sev_receive_update_data(void *src, void *dst, int len, void *hdr, int hdr_len) "guest %p trans %p len %d hdr %p hdr_len %d"
> +kvm_sev_receive_finish(void) ""
> -- 
> 2.17.1
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK