On 21/09/2018 10:22, Roman Kagan wrote:
> +typedef struct HvSintStagedMesage {
> + /* message content staged by hyperv_post_msg */
> + struct hyperv_message msg;
> + /* callback + data (r/o) to complete the processing in a BH */
> + HvSintMsgCb cb;
> + void *cb_data;
> + /* message posting status filled by cpu_post_msg */
> + int status;
> + /* passing the buck: */
> + enum {
> + /* initial state */
> + HV_STAGED_MSG_FREE,
> + /*
> + * hyperv_post_msg (e.g. in main loop) grabs the staged area (FREE ->
> + * BUSY), copies msg, and schedules cpu_post_msg on the assigned cpu
> + */
> + HV_STAGED_MSG_BUSY,
> + /*
> + * cpu_post_msg (vcpu thread) tries to copy staged msg to msg slot,
> + * notify the guest, records the status, marks the posting done (BUSY
> + * -> POSTED), and schedules sint_msg_bh BH
> + */
> + HV_STAGED_MSG_POSTED,
> + /*
> + * sint_msg_bh (BH) verifies that the posting is done, runs the
> + * callback, and starts over (POSTED -> FREE)
> + */
> + } state;
> +} HvSintStagedMesage;
s/Mesage/Message/
> + if (atomic_read(&staged_msg->state) != HV_STAGED_MSG_POSTED) {
> + /* status nor ready yet (spurious ack from guest?), ignore */
> + return;
> + }
> +
Can this actually happen? It seems scary...
Paolo
