Re: [PATCH rdma-next] RDMA/mana_ib: Enable RDMA devices on the CDX bus

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] RDMA/mana_ib: NULL dma_parms in mana_ib_probe() on CDX devices
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commit 4f88c8811c923b9c16d7e0dbf8674249f05b4f08
Author: Zhiyue Qiu <zhiyueqiu@microsoft.com>

RDMA/mana_ib: Enable RDMA devices on the CDX bus

This commit enables MANA RDMA on the CDX bus by depending on the shared GDMA
core, matching CDX auxiliary devices, mapping non-PCI userspace doorbells
with pgprot_device(), and reporting the Microsoft vendor ID directly.

> diff --git a/drivers/infiniband/hw/mana/device.c b/drivers/infiniband/hw/mana/device.c
> index 62c7803ca6c60..33e47490755f6 100644
> --- a/drivers/infiniband/hw/mana/device.c
> +++ b/drivers/infiniband/hw/mana/device.c
> @@ -257,6 +257,8 @@ static void mana_ib_remove(struct auxiliary_device *adev)
>  static const struct auxiliary_device_id mana_id_table[] = {
>  	{ .name = "mana.rdma", },
>  	{ .name = "mana.eth", },
> +	{ .name = "mana_cdx.rdma", },
> +	{ .name = "mana_cdx.eth", },

[Severity: High]
When mana_ib_probe() binds to mana_cdx.rdma or mana_cdx.eth, does passing
gc->dev to ib_register_device() trigger a warning and fall back to a 64 KiB
DMA segment size limit because gc->dev->dma_parms is NULL?

In drivers/infiniband/hw/mana/device.c, mana_ib_probe() registers the IB
device with gc->dev as the dma_device:

	ret = ib_register_device(&dev->ib_dev, mana_ib_is_rnic(dev) ? "mana_%d" : "manae_%d",
				 gc->dev);

And in drivers/infiniband/core/device.c, ib_register_device() checks:

	WARN_ON(dma_device && !dma_device->dma_parms);
	device->dma_device = dma_device;

Unlike struct pci_dev, struct cdx_device does not attach a dma_parms
structure, which is noted in mana_cdx_setup_hwc_irqs() in
drivers/net/ethernet/microsoft/mana/gdma_cdx.c:

	/* The PCI path also calls dma_set_max_seg_size(), but that is
	 * deliberately omitted here: the CDX core does not attach a
	 * dma_parms to the device, so the helper would only WARN, and MANA
	 * never builds scatter-gather lists, so the limit is never read.
	 */

In addition to triggering the warning in ib_register_device() on probe,
mana_ib_create_queue() and mana_ib_reg_user_mr() build scatter-gather lists
via ib_umem_get_cq_buf_or_va() and ib_umem_get_va(), where
__ib_umem_get_va() calls ib_dma_max_seg_size() -> dma_get_max_seg_size() and
falls back to SZ_64K instead of UINT_MAX when dma_parms is NULL.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261103115032.736554-1-kotaranov@linux.microsoft.com?part=1