Re: [PATCH V1 17/20] accel/amdxdna: Link SR-IOV VFs for power management sequencing

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [High] pm: device link between PF and VF permanently lost on first VF unbind
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commit 2785e7a8d2421554408eee0ed2983e10f0090091
Author: David Zhang <yidong.zhang@amd.com>

accel/amdxdna: Link SR-IOV VFs for power management sequencing

This commit adds PM device links between the Physical Function (PF) and
Virtual Functions (VFs) when SR-IOV is enabled. This ensures proper PM
sequencing so that VFs are suspended before the PF, and the PF is
resumed before VFs.

> diff --git a/drivers/accel/amdxdna/aie4_sriov.c b/drivers/accel/amdxdna/aie4_sriov.c
> index 0eea28f626763..bfea6ff00ec04 100644
> --- a/drivers/accel/amdxdna/aie4_sriov.c
> +++ b/drivers/accel/amdxdna/aie4_sriov.c

[ ... ]

> +static int aie4_link_vf(struct amdxdna_dev *xdna, struct pci_dev *pdev_vf)
> +{
> +	struct pci_dev *pdev_pf = to_pci_dev(xdna->ddev.dev);
> +	struct device_link *link;
> +
> +	link = device_link_add(&pdev_vf->dev,   /* consumer = VF */
> +			       &pdev_pf->dev,   /* supplier = PF */
> +			       DL_FLAG_PM_RUNTIME | DL_FLAG_AUTOREMOVE_CONSUMER);

[Severity: High]
Could this device link be permanently lost on the first VF driver unbind?

The DL_FLAG_AUTOREMOVE_CONSUMER flag automatically deletes the device link
when the consumer (VF) driver unbinds. Since the link is only created by the
PF driver during aie4_sriov_start() when SR-IOV is first enabled, it appears
it won't be recreated if a driver is subsequently re-bound to the VF.

If an administrator unbinds and rebinds a VF driver, would the missing
PM device link allow the PM core to runtime-suspend the PF while the
newly-bound VF is actively using it? Removing DL_FLAG_AUTOREMOVE_CONSUMER
might ensure the link remains tied to the device lifecycle instead.

> +	if (!link) {
> +		XDNA_ERR(xdna, "Failed to link VF %s", pci_name(pdev_vf));
> +		return -EINVAL;
> +	}
> +
> +	XDNA_DBG(xdna, "Linked VF %s", pci_name(pdev_vf));
> +	return 0;
> +}

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Sashiko AI review · https://sashiko.dev/#/patchset/20260930033233.1727265-1-yidong.zhang@amd.com?part=17