nvmet: pci-epf: Correctly initialize CSTS when enabling the controller

The function nvmet_pci_epf_poll_cc_work() sets the NVME_CSTS_RDY bit of
the controller status register (CSTS) when nvmet_pci_epf_enable_ctrl()
returns success. However, since this function can be called several
times (e.g. if the host reboots), instead of setting the bit in
ctrl->csts, initialize this field to only have NVME_CSTS_RDY set.
Conversely, if nvmet_pci_epf_enable_ctrl() fails, make sure to clear all
bits from ctrl->csts.

To simplify nvmet_pci_epf_poll_cc_work(), initialize ctrl->csts to
NVME_CSTS_RDY directly inside nvmet_pci_epf_enable_ctrl() and clear this
field in that function as well in case of a failure. To be consistent,
move clearing the NVME_CSTS_RDY bit from ctrl->csts when the controller
is being disabled from nvmet_pci_epf_poll_cc_work() into
nvmet_pci_epf_disable_ctrl().

Fixes: 0faa0fe ("nvmet: New NVMe PCI endpoint function target driver")
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Keith Busch <kbusch@kernel.org>

Author: damien-lemoal

drivers/nvme/target/pci-epf.c

@@ -1822,14 +1822,14 @@ static int nvmet_pci_epf_enable_ctrl(struct nvmet_pci_epf_ctrl *ctrl)
 	if (ctrl->io_sqes < sizeof(struct nvme_command)) {
 		dev_err(ctrl->dev, "Unsupported I/O SQES %zu (need %zu)\n",
 			ctrl->io_sqes, sizeof(struct nvme_command));
-		return -EINVAL;
+		goto err;
 	}
 
 	ctrl->io_cqes = 1UL << nvmet_cc_iocqes(ctrl->cc);
 	if (ctrl->io_cqes < sizeof(struct nvme_completion)) {
 		dev_err(ctrl->dev, "Unsupported I/O CQES %zu (need %zu)\n",
 			ctrl->io_sqes, sizeof(struct nvme_completion));
-		return -EINVAL;
+		goto err;
 	}
 
 	/* Create the admin queue. */
@@ -1844,7 +1844,7 @@ static int nvmet_pci_epf_enable_ctrl(struct nvmet_pci_epf_ctrl *ctrl)
 				qsize, pci_addr, 0);
 	if (status != NVME_SC_SUCCESS) {
 		dev_err(ctrl->dev, "Failed to create admin completion queue\n");
-		return -EINVAL;
+		goto err;
 	}
 
 	qsize = aqa & 0x00000fff;
@@ -1854,17 +1854,22 @@ static int nvmet_pci_epf_enable_ctrl(struct nvmet_pci_epf_ctrl *ctrl)
 	if (status != NVME_SC_SUCCESS) {
 		dev_err(ctrl->dev, "Failed to create admin submission queue\n");
 		nvmet_pci_epf_delete_cq(ctrl->tctrl, 0);
-		return -EINVAL;
+		goto err;
 	}
 
 	ctrl->sq_ab = NVMET_PCI_EPF_SQ_AB;
 	ctrl->irq_vector_threshold = NVMET_PCI_EPF_IV_THRESHOLD;
 	ctrl->enabled = true;
+	ctrl->csts = NVME_CSTS_RDY;
 
 	/* Start polling the controller SQs. */
 	schedule_delayed_work(&ctrl->poll_sqs, 0);
 
 	return 0;
+
+err:
+	ctrl->csts = 0;
+	return -EINVAL;
 }
 
 static void nvmet_pci_epf_disable_ctrl(struct nvmet_pci_epf_ctrl *ctrl)
@@ -1889,6 +1894,8 @@ static void nvmet_pci_epf_disable_ctrl(struct nvmet_pci_epf_ctrl *ctrl)
 	/* Delete the admin queue last. */
 	nvmet_pci_epf_delete_sq(ctrl->tctrl, 0);
 	nvmet_pci_epf_delete_cq(ctrl->tctrl, 0);
+
+	ctrl->csts &= ~NVME_CSTS_RDY;
 }
 
 static void nvmet_pci_epf_poll_cc_work(struct work_struct *work)
@@ -1909,13 +1916,10 @@ static void nvmet_pci_epf_poll_cc_work(struct work_struct *work)
 		ret = nvmet_pci_epf_enable_ctrl(ctrl);
 		if (ret)
 			return;
-		ctrl->csts |= NVME_CSTS_RDY;
 	}
 
-	if (!nvmet_cc_en(new_cc) && nvmet_cc_en(old_cc)) {
+	if (!nvmet_cc_en(new_cc) && nvmet_cc_en(old_cc))
 		nvmet_pci_epf_disable_ctrl(ctrl);
-		ctrl->csts &= ~NVME_CSTS_RDY;
-	}
 
 	if (nvmet_cc_shn(new_cc) && !nvmet_cc_shn(old_cc)) {
 		nvmet_pci_epf_disable_ctrl(ctrl);