Drivers: hv: vmbus: Introduce vmbus_sendpacket_getid()

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>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/20220419122325.10078-4-parri.andrea@gmail.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 20fc8d50a03987aa5933e3255a0a3d0552924530..585a8084848bf7de236a06a09d98cd23efa92c8b 100644 (file)
--- 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 6b45c22bb717e1fe33ed4cf18e099c58c7a7d1ab..4f5b824b16cf4779fb740e70b13d2181f62fdd65 100644 (file)
--- 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 3d215d9dec433b33417f69de5513c1b231a27e36..e101b11f95e5d6b5a3d3f7237a157a2135b83247 100644 (file)
--- 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 2d085d951ee45fac149d67b8a76f83799ac364ea..7cb8718825eeb2a2973a8e859b370fa304826334 100644 (file)
--- 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,