[dpdk-dev] [PATCH v3 2/7] net/vmxnet3: introduce generalized cmd interface

[Shrikrishna Khare <skhare@vmware.com>]

Shared memory is used to exchange information between the vmxnet3 driver
and the emulation. In order to request emulation to perform a task, the
driver first populates specific fields in this shared memory and then
issues corresponding command by writing to the command register(CMD). The
layout of the shared memory was defined by vmxnet3 version 1 and cannot
be extended for every new command without breaking backward compatibility.

To address this problem, in vmxnet3 version 3, the emulation repurposed
a reserved field in the shared memory to represent command information
instead. For new commands, the driver first populates the command
information field in the shared memory and then issues the command. The
emulation interprets the data written to the command information
depending on the type of the command. This patch exposes this capability
to the driver.

Signed-off-by: Shrikrishna Khare <skhare@vmware.com>
Acked-by: Yong Wang <yongwang@vmware.com>
Acked-by: Jin Heo <heoj@vmware.com>
---
 drivers/net/vmxnet3/base/vmxnet3_defs.h | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/drivers/net/vmxnet3/base/vmxnet3_defs.h b/drivers/net/vmxnet3/base/vmxnet3_defs.h
index 68ae8b6..7484b84 100644
--- a/drivers/net/vmxnet3/base/vmxnet3_defs.h
+++ b/drivers/net/vmxnet3/base/vmxnet3_defs.h
@@ -109,6 +109,7 @@ typedef enum {
    VMXNET3_CMD_STOP_EMULATION,
    VMXNET3_CMD_LOAD_PLUGIN,
    VMXNET3_CMD_ACTIVATE_VF,
+   VMXNET3_CMD_RESERVED3,
 
    VMXNET3_CMD_FIRST_GET = 0xF00D0000,
    VMXNET3_CMD_GET_QUEUE_STATUS = VMXNET3_CMD_FIRST_GET,
@@ -695,12 +696,41 @@ Vmxnet3_RxQueueDesc;
 
 typedef
 #include "vmware_pack_begin.h"
+struct Vmxnet3_SetPolling {
+   uint8 enablePolling;
+}
+#include "vmware_pack_end.h"
+Vmxnet3_SetPolling;
+
+/*
+ * If the command data <= 16 bytes, use the shared memory direcly.
+ * Otherwise, use the variable length configuration descriptor.
+ */
+typedef
+#include "vmware_pack_begin.h"
+union Vmxnet3_CmdInfo {
+   Vmxnet3_VariableLenConfDesc varConf;
+   Vmxnet3_SetPolling          setPolling;
+   __le64                      data[2];
+}
+#include "vmware_pack_end.h"
+Vmxnet3_CmdInfo;
+
+typedef
+#include "vmware_pack_begin.h"
 struct Vmxnet3_DriverShared {
    __le32               magic;
    __le32               pad; /* make devRead start at 64-bit boundaries */
    Vmxnet3_DSDevRead    devRead;
    __le32               ecr;
-   __le32               reserved[5];
+   __le32               reserved;
+
+   union {
+      __le32            reserved1[4];
+      Vmxnet3_CmdInfo   cmdInfo; /* only valid in the context of executing the
+				  * relevant command
+				  */
+   } cu;
 }
 #include "vmware_pack_end.h"
 Vmxnet3_DriverShared;
-- 
2.6.2