From: Roman Kisel <romank@xxxxxxxxxxxxxxxxxxx> Sent: Monday, July 14, 2025 3:16 PM
>
> To make use of Confidential VMBus channels, initialize the
> co_ring_buffers and co_external_memory fields of the channel
> structure.
>
> Advertise support upon negotiating the version and compute
> values for those fields and initialize them.
>
> Signed-off-by: Roman Kisel <romank@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Michael Kelley <mhklinux@xxxxxxxxxxx>
> ---
> drivers/hv/channel_mgmt.c | 19 +++++++++++++++++++
> drivers/hv/connection.c | 3 +++
> 2 files changed, 22 insertions(+)
>
> diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
> index ca2fe10c110a..6ae44eab1626 100644
> --- a/drivers/hv/channel_mgmt.c
> +++ b/drivers/hv/channel_mgmt.c
> @@ -1021,6 +1021,7 @@ static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
> struct vmbus_channel_offer_channel *offer;
> struct vmbus_channel *oldchannel, *newchannel;
> size_t offer_sz;
> + bool co_ring_buffer, co_external_memory;
>
> offer = (struct vmbus_channel_offer_channel *)hdr;
>
> @@ -1033,6 +1034,22 @@ static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
> return;
> }
>
> + co_ring_buffer = is_co_ring_buffer(offer);
> + co_external_memory = is_co_external_memory(offer);
> + if (!co_ring_buffer && co_external_memory) {
> + pr_err("Invalid offer relid=%d: the ring buffer isn't encrypted\n",
> + offer->child_relid);
> + return;
> + }
> + if (co_ring_buffer || co_external_memory) {
> + if (vmbus_proto_version < VERSION_WIN10_V6_0 || !vmbus_is_confidential()) {
> + pr_err("Invalid offer relid=%d: no support for confidential VMBus\n",
> + offer->child_relid);
> + atomic_dec(&vmbus_connection.offer_in_progress);
> + return;
> + }
> + }
> +
> oldchannel = find_primary_channel_by_offer(offer);
>
> if (oldchannel != NULL) {
> @@ -1111,6 +1128,8 @@ static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)
> pr_err("Unable to allocate channel object\n");
> return;
> }
> + newchannel->co_ring_buffer = co_ring_buffer;
> + newchannel->co_external_memory = co_external_memory;
>
> vmbus_setup_channel_state(newchannel, offer);
>
> diff --git a/drivers/hv/connection.c b/drivers/hv/connection.c
> index be490c598785..eeb472019d69 100644
> --- a/drivers/hv/connection.c
> +++ b/drivers/hv/connection.c
> @@ -105,6 +105,9 @@ int vmbus_negotiate_version(struct vmbus_channel_msginfo
> *msginfo, u32 version)
> vmbus_connection.msg_conn_id = VMBUS_MESSAGE_CONNECTION_ID;
> }
>
> + if (vmbus_is_confidential() && version >= VERSION_WIN10_V6_0)
> + msg->feature_flags = VMBUS_FEATURE_FLAG_CONFIDENTIAL_CHANNELS;
> +
> /*
> * shared_gpa_boundary is zero in non-SNP VMs, so it's safe to always
> * bitwise OR it
> --
> 2.43.0
