From: Roman Kisel <romank@xxxxxxxxxxxxxxxxxxx> Sent: Tuesday, June 3, 2025 5:44 PM
>
> When the confidential VMBus is available, the guest should post
> messages via the paravisor.
>
> Update hv_post_message() to request posting messages from the paravisor
"via the paravisor"? I'm not sure what "from the paravisor" means. And
you used "via" in the previous sentence and patch Subject.
> rather than through GHCB or TD calls.
>
> Signed-off-by: Roman Kisel <romank@xxxxxxxxxxxxxxxxxxx>
> ---
> drivers/hv/hv.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
> index e25c91eb6af5..1f7cf1244509 100644
> --- a/drivers/hv/hv.c
> +++ b/drivers/hv/hv.c
> @@ -74,7 +74,7 @@ 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()) {
Does this change make post_msg_page unnecessary when Confidential
VMBus is present? When using Confidential VMBus, the code path will be
to use a normal hypercall, which will go to the paravisor, and hence
doesn't need decrypted memory.
If my thinking is correct, the code in hv_synic_alloc() could be updated to
not allocate post_msg_page when vmbus_is_confidential().
> if (hv_isolation_type_tdx())
> status = hv_tdx_hypercall(HVCALL_POST_MESSAGE,
> virt_to_phys(aligned_msg), 0);
> --
> 2.43.0
