nvme: refine the Qemu Identify CNS quirk

Add a helper to check if we can use Identify CNS values > 1, and refine
the Qemu quirk to not apply to reported versions larger than 1.1, as the
Qemu implementation had been fixed by then.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/nvme/host/core.c

@@ -1027,6 +1027,19 @@ void nvme_stop_keep_alive(struct nvme_ctrl *ctrl)
 }
 EXPORT_SYMBOL_GPL(nvme_stop_keep_alive);
 
+/*
+ * In NVMe 1.0 the CNS field was just a binary controller or namespace
+ * flag, thus sending any new CNS opcodes has a big chance of not working.
+ * Qemu unfortunately had that bug after reporting a 1.1 version compliance
+ * (but not for any later version).
+ */
+static bool nvme_ctrl_limited_cns(struct nvme_ctrl *ctrl)
+{
+	if (ctrl->quirks & NVME_QUIRK_IDENTIFY_CNS)
+		return ctrl->vs < NVME_VS(1, 2, 0);
+	return ctrl->vs < NVME_VS(1, 1, 0);
+}
+
 static int nvme_identify_ctrl(struct nvme_ctrl *dev, struct nvme_id_ctrl **id)
 {
 	struct nvme_command c = { };
@@ -3814,8 +3827,7 @@ static void nvme_scan_work(struct work_struct *work)
 
 	mutex_lock(&ctrl->scan_lock);
 	nn = le32_to_cpu(id->nn);
-	if (ctrl->vs >= NVME_VS(1, 1, 0) &&
-	    !(ctrl->quirks & NVME_QUIRK_IDENTIFY_CNS)) {
+	if (!nvme_ctrl_limited_cns(ctrl)) {
 		if (!nvme_scan_ns_list(ctrl, nn))
 			goto out_free_id;
 	}