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Date:   Tue, 6 Dec 2022 13:47:55 +0000
From:   Keith Busch <kbusch@kernel.org>
To:     Lei Rao <lei.rao@intel.com>
Cc:     axboe@fb.com, kch@nvidia.com, hch@lst.de, sagi@grimberg.me,
        alex.williamson@redhat.com, cohuck@redhat.com, jgg@ziepe.ca,
        yishaih@nvidia.com, shameerali.kolothum.thodi@huawei.com,
        kevin.tian@intel.com, mjrosato@linux.ibm.com,
        linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org,
        kvm@vger.kernel.org, eddie.dong@intel.com, yadong.li@intel.com,
        yi.l.liu@intel.com, Konrad.wilk@oracle.com, stephen@eideticom.com,
        hang.yuan@intel.com
Subject: Re: [RFC PATCH 4/5] nvme-vfio: check if the hardware supports live
 migration
Message-ID: <Y49ICyTJ/WExT+wN@kbusch-mbp>
References: <20221206055816.292304-1-lei.rao@intel.com>
 <20221206055816.292304-5-lei.rao@intel.com>
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In-Reply-To: <20221206055816.292304-5-lei.rao@intel.com>
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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".