RE: [PATCH 3/6] Drivers: hv: vmbus: Introduce vmbus_sendpacket_getid()

Michael Kelley (LINUX)
2022-04-08T15:21:18Z

From: Andrea Parri (Microsoft) <parri.andrea@gmail.com> Sent: Wednesday, April 6, 2022 9:30 PM
>
> The function can be used to send a VMbus packet and retrieve the
> corresponding transaction ID. It will be used by hv_pci.
>
> No functional change.
>
> Suggested-by: Michael Kelley <mikelley@microsoft.com>
> Signed-off-by: Andrea Parri (Microsoft) <parri.andrea@gmail.com>
> ---
> drivers/hv/channel.c | 38 ++++++++++++++++++++++++++++++++------
> drivers/hv/hyperv_vmbus.h | 2 +-
> drivers/hv/ring_buffer.c | 14 +++++++++++---
> include/linux/hyperv.h | 7 +++++++
> 4 files changed, 51 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
> index 20fc8d50a0398..585a8084848bf 100644
> --- a/drivers/hv/channel.c
> +++ b/drivers/hv/channel.c
> @@ -1022,11 +1022,13 @@ void vmbus_close(struct vmbus_channel *channel)
> EXPORT_SYMBOL_GPL(vmbus_close);
>
> /**
> - * vmbus_sendpacket() - Send the specified buffer on the given channel
> + * vmbus_sendpacket_getid() - Send the specified buffer on the given channel
> * @channel: Pointer to vmbus_channel structure
> * @buffer: Pointer to the buffer you want to send the data from.
> * @bufferlen: Maximum size of what the buffer holds.
> * @requestid: Identifier of the request
> + * @trans_id: Identifier of the transaction associated to this request, if
> + * the send is successful; undefined, otherwise.
> * @type: Type of packet that is being sent e.g. negotiate, time
> * packet etc.
> * @flags: 0 or VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED
> @@ -1036,8 +1038,8 @@ EXPORT_SYMBOL_GPL(vmbus_close);
> *
> * Mainly used by Hyper-V drivers.
> */
> -int vmbus_sendpacket(struct vmbus_channel *channel, void *buffer,
> - u32 bufferlen, u64 requestid,
> +int vmbus_sendpacket_getid(struct vmbus_channel *channel, void *buffer,
> + u32 bufferlen, u64 requestid, u64 *trans_id,
> enum vmbus_packet_type type, u32 flags)
> {
> struct vmpacket_descriptor desc;
> @@ -1063,7 +1065,31 @@ int vmbus_sendpacket(struct vmbus_channel *channel,
> void *buffer,
> bufferlist[2].iov_base = &aligned_data;
> bufferlist[2].iov_len = (packetlen_aligned - packetlen);
>
> - return hv_ringbuffer_write(channel, bufferlist, num_vecs, requestid);
> + return hv_ringbuffer_write(channel, bufferlist, num_vecs, requestid, trans_id);
> +}
> +EXPORT_SYMBOL(vmbus_sendpacket_getid);
> +
> +/**
> + * vmbus_sendpacket() - Send the specified buffer on the given channel
> + * @channel: Pointer to vmbus_channel structure
> + * @buffer: Pointer to the buffer you want to send the data from.
> + * @bufferlen: Maximum size of what the buffer holds.
> + * @requestid: Identifier of the request
> + * @type: Type of packet that is being sent e.g. negotiate, time
> + * packet etc.
> + * @flags: 0 or VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED
> + *
> + * Sends data in @buffer directly to Hyper-V via the vmbus.
> + * This will send the data unparsed to Hyper-V.
> + *
> + * Mainly used by Hyper-V drivers.
> + */
> +int vmbus_sendpacket(struct vmbus_channel *channel, void *buffer,
> + u32 bufferlen, u64 requestid,
> + enum vmbus_packet_type type, u32 flags)
> +{
> + return vmbus_sendpacket_getid(channel, buffer, bufferlen,
> + requestid, NULL, type, flags);
> }
> EXPORT_SYMBOL(vmbus_sendpacket);
>
> @@ -1122,7 +1148,7 @@ int vmbus_sendpacket_pagebuffer(struct vmbus_channel
> *channel,
> bufferlist[2].iov_base = &aligned_data;
> bufferlist[2].iov_len = (packetlen_aligned - packetlen);
>
> - return hv_ringbuffer_write(channel, bufferlist, 3, requestid);
> + return hv_ringbuffer_write(channel, bufferlist, 3, requestid, NULL);
> }
> EXPORT_SYMBOL_GPL(vmbus_sendpacket_pagebuffer);
>
> @@ -1160,7 +1186,7 @@ int vmbus_sendpacket_mpb_desc(struct vmbus_channel
> *channel,
> bufferlist[2].iov_base = &aligned_data;
> bufferlist[2].iov_len = (packetlen_aligned - packetlen);
>
> - return hv_ringbuffer_write(channel, bufferlist, 3, requestid);
> + return hv_ringbuffer_write(channel, bufferlist, 3, requestid, NULL);
> }
> EXPORT_SYMBOL_GPL(vmbus_sendpacket_mpb_desc);
>
> diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
> index 3a1f007b678a0..64c0b9cbe183b 100644
> --- a/drivers/hv/hyperv_vmbus.h
> +++ b/drivers/hv/hyperv_vmbus.h
> @@ -181,7 +181,7 @@ void hv_ringbuffer_cleanup(struct hv_ring_buffer_info
> *ring_info);
>
> int hv_ringbuffer_write(struct vmbus_channel *channel,
> const struct kvec *kv_list, u32 kv_count,
> - u64 requestid);
> + u64 requestid, u64 *trans_id);
>
> int hv_ringbuffer_read(struct vmbus_channel *channel,
> void *buffer, u32 buflen, u32 *buffer_actual_len,
> diff --git a/drivers/hv/ring_buffer.c b/drivers/hv/ring_buffer.c
> index 3d215d9dec433..e101b11f95e5d 100644
> --- a/drivers/hv/ring_buffer.c
> +++ b/drivers/hv/ring_buffer.c
> @@ -283,7 +283,7 @@ void hv_ringbuffer_cleanup(struct hv_ring_buffer_info
> *ring_info)
> /* Write to the ring buffer. */
> int hv_ringbuffer_write(struct vmbus_channel *channel,
> const struct kvec *kv_list, u32 kv_count,
> - u64 requestid)
> + u64 requestid, u64 *trans_id)
> {
> int i;
> u32 bytes_avail_towrite;
> @@ -294,7 +294,7 @@ int hv_ringbuffer_write(struct vmbus_channel *channel,
> unsigned long flags;
> struct hv_ring_buffer_info *outring_info = &channel->outbound;
> struct vmpacket_descriptor *desc = kv_list[0].iov_base;
> - u64 rqst_id = VMBUS_NO_RQSTOR;
> + u64 __trans_id, rqst_id = VMBUS_NO_RQSTOR;
>
> if (channel->rescind)
> return -ENODEV;
> @@ -353,7 +353,15 @@ int hv_ringbuffer_write(struct vmbus_channel *channel,
> }
> }
> desc = hv_get_ring_buffer(outring_info) + old_write;
> - desc->trans_id = (rqst_id == VMBUS_NO_RQSTOR) ? requestid : rqst_id;
> + __trans_id = (rqst_id == VMBUS_NO_RQSTOR) ? requestid : rqst_id;
> + /*
> + * Ensure the compiler doesn't generate code that reads the value of
> + * the transaction ID from the ring buffer, which is shared with the
> + * Hyper-V host and subject to being changed at any time.
> + */
> + WRITE_ONCE(desc->trans_id, __trans_id);
> + if (trans_id)
> + *trans_id = __trans_id;
>
> /* Set previous packet start */
> prev_indices = hv_get_ring_bufferindices(outring_info);
> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> index fe2e0179ed51e..a7cb596d893b1 100644
> --- a/include/linux/hyperv.h
> +++ b/include/linux/hyperv.h
> @@ -1161,6 +1161,13 @@ extern int vmbus_open(struct vmbus_channel *channel,
>
> extern void vmbus_close(struct vmbus_channel *channel);
>
> +extern int vmbus_sendpacket_getid(struct vmbus_channel *channel,
> + void *buffer,
> + u32 bufferLen,
> + u64 requestid,
> + u64 *trans_id,
> + enum vmbus_packet_type type,
> + u32 flags);
> extern int vmbus_sendpacket(struct vmbus_channel *channel,
> void *buffer,
> u32 bufferLen,
> --
> 2.25.1

Reviewed-by: Michael Kelley <mikelley@microsoft.com>