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

[Leon Romanovsky <leon@kernel.org>]

On Tue, Nov 03, 2026 at 12:05:41PM +0000, sashiko-bot@kernel.org wrote:
> 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
> --
> 
> 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.

The analysis looks correct to me. How was it tested?

Thanks

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