Re: [PATCH hyperv-next v3 13/15] Drivers: hv: Support confidential VMBus channels

[ALOK TIWARI <alok.a.tiwari@xxxxxxxxxx>]

On 04-06-2025 06:13, Roman Kisel wrote:
> To run a confidential VMBus channels, one has to initialize the
> co_ring_buffers and co_external_memory fields of the channel
> structure.
>
> Advertise support upon negoatiating the version and compute
> values for those fields and initialize them.
>
> Signed-off-by: Roman Kisel <romank@xxxxxxxxxxxxxxxxxxx>
> ---
>   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..33bc29e826bd 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);
> +	if (co_ring_buffer) {
> +		if (vmbus_proto_version < VERSION_WIN10_V6_0 || !vmbus_is_confidential()) {
> +			atomic_dec(&vmbus_connection.offer_in_progress);
> +			return;
> +		}
> +	}
> +
> +	co_external_memory = is_co_external_memory(offer);
> +	if (is_co_external_memory(offer)) {

 Redundant call for is_co_external_memory()
 if(co_external_memory)

> +		if (vmbus_proto_version < VERSION_WIN10_V6_0 || !vmbus_is_confidential()) {
> +			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


Thanks,
Alok