[RFC PATCH 1/5] nvme-pci: add function nvme_submit_vf_cmd to issue admin commands for VF driver.

[Lei Rao]

The new function nvme_submit_vf_cmd() helps the host VF driver to issue
VF admin commands. It's helpful in some cases that the host NVMe driver
does not control VF's admin queue. For example, in the virtualization
device pass-through case, the VF controller's admin queue is governed
by the Guest NVMe driver. Host VF driver relies on PF device's admin
queue to control VF devices like vendor-specific live migration commands.

Signed-off-by: Lei Rao <lei.rao@xxxxxxxxx>
Signed-off-by: Yadong Li <yadong.li@xxxxxxxxx>
Signed-off-by: Chaitanya Kulkarni <kch@xxxxxxxxxx>
Reviewed-by: Eddie Dong <eddie.dong@xxxxxxxxx>
Reviewed-by: Hang Yuan <hang.yuan@xxxxxxxxx>
---
 drivers/nvme/host/pci.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 488ad7dabeb8..3d9c54d8e7fc 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -3585,6 +3585,24 @@ static struct pci_driver nvme_driver = {
 	.err_handler	= &nvme_err_handler,
 };
 
+int nvme_submit_vf_cmd(struct pci_dev *dev, struct nvme_command *cmd,
+			      size_t *result, void *buffer, unsigned int bufflen)
+{
+	struct nvme_dev *ndev = NULL;
+	union nvme_result res = { };
+	int ret;
+
+	ndev = pci_iov_get_pf_drvdata(dev, &nvme_driver);
+	if (IS_ERR(ndev))
+		return PTR_ERR(ndev);
+	ret = __nvme_submit_sync_cmd(ndev->ctrl.admin_q, cmd, &res, buffer, bufflen,
+			      NVME_QID_ANY, 0, 0);
+	if (ret >= 0 && result)
+		*result = le32_to_cpu(res.u32);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(nvme_submit_vf_cmd);
+
 static int __init nvme_init(void)
 {
 	BUILD_BUG_ON(sizeof(struct nvme_create_cq) != 64);
-- 
2.34.1