Re: [RFC PATCH 4/5] nvme-vfio: check if the hardware supports live migration

[Keith Busch]

On Tue, Dec 06, 2022 at 01:58:15PM +0800, Lei Rao wrote:
> +static bool nvmevf_check_migration(struct pci_dev *pdev)
> +{
> +	struct nvme_command c = { };
> +	struct nvme_id_ctrl *id;
> +	u8 live_mig_support;
> +	int ret;
> +
> +	c.identify.opcode = nvme_admin_identify;
> +	c.identify.cns = NVME_ID_CNS_CTRL;
> +
> +	id = kmalloc(sizeof(struct nvme_id_ctrl), GFP_KERNEL);
> +	if (!id)
> +		return false;
> +
> +	ret = nvme_submit_vf_cmd(pdev, &c, NULL, id, sizeof(struct nvme_id_ctrl));
> +	if (ret) {
> +		dev_warn(&pdev->dev, "Get identify ctrl failed (ret=0x%x)\n", ret);
> +		goto out;
> +	}
> +
> +	live_mig_support = id->vs[0];

Considering this is a vendor specific region, it seems rather presumptuous to
assume this byte means "live migration supported".