On Tue, 30 Dec 2014, Quan Xu wrote:
> +int vtpm_recv(struct XenDevice *xendev, uint8_t* buf, size_t *count)
> +{
> + struct xen_vtpm_dev *vtpmdev = container_of(xendev, struct xen_vtpm_dev,
> + xendev);
> + struct tpmif_shared_page *shr = vtpmdev->shr;
> + unsigned int offset;
> +
> + if (shr->state == TPMIF_STATE_IDLE) {
> + return -ECANCELED;
> + }
> +
> + while (vtpm_status(vtpmdev) != VTPM_STATUS_IDLE) {
> + vtpm_aio_wait(vtpm_aio_ctx);
> + }
Is this really necessary to write this as a busy loop?
I think you should write it as a proper aio callback for efficiency:
QEMU is going to burn 100% of the cpu polling and not doing anything
else!
> + offset = sizeof(*shr) + 4*shr->nr_extra_pages;
> + memcpy(buf, offset + (uint8_t *)shr, shr->length);
> + *count = shr->length;
> +
> + return 0;
> +}
