On Tue, Dec 10, 2024 at 08:49:40AM +0530, Aneesh Kumar K.V wrote:

Hi Dan,

Dan Williams [off-list ref] writes:

quoted

+int pci_ide_stream_setup(struct pci_dev *pdev, struct pci_ide *ide,
+			 enum pci_ide_flags flags)
+{
+	struct pci_host_bridge *hb = pci_find_host_bridge(pdev->bus);
+	struct pci_dev *rp = pcie_find_root_port(pdev);
+	int mem = 0, rc;
+
+	if (ide->stream_id < 0 || ide->stream_id > U8_MAX) {
+		pci_err(pdev, "Setup fail: Invalid stream id: %d\n", ide->stream_id);
+		return -ENXIO;
+	}
+
+	if (test_and_set_bit_lock(ide->stream_id, hb->ide_stream_ids)) {
+		pci_err(pdev, "Setup fail: Busy stream id: %d\n",
+			ide->stream_id);
+		return -EBUSY;
+	}
+

Considering we are using the hostbridge ide_stream_ids bitmap, why is
the stream_id allocation not generic? ie, any reason why a stream id alloc
like below will not work?

Should be illustrating in commit log.

"The other design detail for TSM-coordinated IDE establishment is that
the TSM manages allocation of stream-ids, this is why the stream_id is
passed in to pci_ide_stream_setup()."

This is true for Intel TDX.

Thanks,
Yilun

static int pcie_ide_sel_streamid_alloc(struct pci_dev *pdev)
{
	int stream_id;
	struct pci_host_bridge *hb;

	hb = pci_find_host_bridge(pdev->bus);

	stream_id = find_first_zero_bit(hb->ide_stream_ids, hb->nr_ide_streams);
	if (stream_id >= hb->nr_ide_streams)
		return -EBUSY;

	return stream_id;
}

-aneesh