From: Roman Kisel <romank@xxxxxxxxxxxxxxxxxxx> Sent: Monday, July 14, 2025 3:16 PM
>
> When the confidential VMBus is available, the guest should post
> messages to the paravisor.
>
> Update hv_post_message() to post messages to the paravisor rather than
> through GHCB or TD calls.
>
> Signed-off-by: Roman Kisel <romank@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Michael Kelley <mhklinux@xxxxxxxxxxx>
> ---
> drivers/hv/hv.c | 11 ++++++++++-
> 1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
> index e9ee0177d765..816f8a14ff63 100644
> --- a/drivers/hv/hv.c
> +++ b/drivers/hv/hv.c
> @@ -74,7 +74,11 @@ int hv_post_message(union hv_connection_id connection_id,
> aligned_msg->payload_size = payload_size;
> memcpy((void *)aligned_msg->payload, payload, payload_size);
>
> - if (ms_hyperv.paravisor_present) {
> + if (ms_hyperv.paravisor_present && !vmbus_is_confidential()) {
> + /*
> + * If the VMBus isn't confidential, use the CoCo-specific
> + * mechanism to communicate with the hypervisor.
> + */
> if (hv_isolation_type_tdx())
> status = hv_tdx_hypercall(HVCALL_POST_MESSAGE,
> virt_to_phys(aligned_msg), 0);
> @@ -85,6 +89,11 @@ int hv_post_message(union hv_connection_id connection_id,
> else
> status = HV_STATUS_INVALID_PARAMETER;
> } else {
> + /*
> + * If there is no paravisor, this will go to the hypervisor.
> + * In the Confidential VMBus case, there is the paravisor
> + * to which this will trap.
> + */
> status = hv_do_hypercall(HVCALL_POST_MESSAGE,
> aligned_msg, NULL);
> }
> --
> 2.43.0
