On Thu, Aug 29, 2024 at 12:28 AM Michael S. Tsirkin <m...@redhat.com> wrote:
>
> On Thu, Aug 22, 2024 at 09:08:46PM +0600, Dorjoy Chowdhury wrote:
> > Nitro Secure Module (NSM)[1] device is used in AWS Nitro Enclaves[2]
> > for stripped down TPM functionality like cryptographic attestation.
> > The requests to and responses from NSM device are CBOR[3] encoded.
> >
> > This commit adds support for NSM device in QEMU. Although related to
> > AWS Nitro Enclaves, the virito-nsm device is independent and can be
> > used in other machine types as well. The libcbor[4] library has been
> > used for the CBOR encoding and decoding functionalities.
> >
> > [1]
> > https://lists.oasis-open.org/archives/virtio-comment/202310/msg00387.html
> > [2] https://docs.aws.amazon.com/enclaves/latest/user/nitro-enclave.html
> > [3] http://cbor.io/
> > [4] https://libcbor.readthedocs.io/en/latest/
> >
> > Signed-off-by: Dorjoy Chowdhury <dorjoychy...@gmail.com>
> > ---
> > MAINTAINERS | 10 +
> > hw/virtio/Kconfig | 5 +
> > hw/virtio/cbor-helpers.c | 326 ++++++
> > hw/virtio/meson.build | 6 +
> > hw/virtio/virtio-nsm-pci.c | 73 ++
> > hw/virtio/virtio-nsm.c | 1638 ++++++++++++++++++++++++++++++
> > include/hw/virtio/cbor-helpers.h | 46 +
> > include/hw/virtio/virtio-nsm.h | 59 ++
> > meson.build | 2 +
> > 9 files changed, 2165 insertions(+)
[...]
> > +static void handle_input(VirtIODevice *vdev, VirtQueue *vq)
> > +{
> > + g_autofree VirtQueueElement *out_elem = NULL;
> > + g_autofree VirtQueueElement *in_elem = NULL;
> > + VirtIONSM *vnsm = VIRTIO_NSM(vdev);
> > + Error *err = NULL;
> > +
> > + out_elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
> > + if (!out_elem) {
> > + /* nothing in virtqueue */
> > + return;
> > + }
> > +
> > + if (out_elem->out_num != 1) {
> > + virtio_error(vdev, "Expected one request buffer first in
> > virtqueue");
> > + goto cleanup;
> > + }
>
> Seems to assume request in a single s/g element?
> We generally avoid this kind of thing.
>
> Applies equally elsewheree.
>
Thank you for reviewing. I think I did it this way (first virqueue_pop
gives out_elem with out_num == 1 and the next virtqueue_pop gives
in_elem with in_num == 1) after seeing what the virqueue contains
(using printfs) when running in a VM and sending some NSM requests and
I noticed the above. Can you give me a bit more details about what
this should be like? Is there any existing virtio device code I can
look at for example?
Thanks!
> > +
> > + in_elem = virtqueue_pop(vq, sizeof(VirtQueueElement));
> > + if (!in_elem) {
> > + virtio_error(vdev, "Expected response buffer after request buffer "
> > + "in virtqueue");
> > + goto cleanup;
> > + }
> > + if (in_elem->in_num != 1) {
> > + virtio_error(vdev, "Expected one response buffer after request
> > buffer "
> > + "in virtqueue");
> > + goto cleanup;
> > + }
> > +
> > + if (!get_nsm_request_response(vnsm, out_elem->out_sg, in_elem->in_sg,
> > + &err)) {
> > + error_report_err(err);
> > + virtio_error(vdev, "Failed to get NSM request response");
> > + goto cleanup;
> > + }
> > +
> > + virtqueue_push(vq, out_elem, 0);
> > + virtqueue_push(vq, in_elem, in_elem->in_sg->iov_len);
> > + virtio_notify(vdev, vq);
> > + return;
> > +
> > + cleanup:
> > + if (out_elem) {
> > + virtqueue_detach_element(vq, out_elem, 0);
> > + }
> > + if (in_elem) {
> > + virtqueue_detach_element(vq, in_elem, 0);
> > + }
> > + return;
> > +}
> > +
> > +static uint64_t get_features(VirtIODevice *vdev, uint64_t f, Error **errp)
> > +{
> > + return f;
> > +}
> > +
[...]
Regards,
Dorjoy
