linux-kernel - Re: [PATCH] nvme: Don't fail to resume if NSIDs change

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Message-id: <040c5788-1a7b-26ea-23cc-ba239c76efa9@augustwikerfors.se>
Date:   Mon, 31 Jul 2023 21:54:39 +0200
From:   August Wikerfors <git@...ustwikerfors.se>
To:     Keith Busch <kbusch@...nel.org>
Cc:     Mario Limonciello <mario.limonciello@....com>, axboe@...com,
        hch@....de, sagi@...mberg.me, linux-nvme@...ts.infradead.org,
        linux-kernel@...r.kernel.org, nilskruse97@...il.com,
        David.Chang@....com
Subject: Re: [PATCH] nvme: Don't fail to resume if NSIDs change

On 2023-07-31 21:10, Keith Busch wrote:
> On Mon, Jul 31, 2023 at 01:51:03PM -0500, Mario Limonciello wrote:
>> Samsung PM9B1 has problems after resume because NSID has changed.
>> This has been reported in the past on OEM varities of PM9B1 parts
>> and fixed by firmware updates on 'some' of those parts.
>>
>> However this same issue also happens on 'retail' PM9B1 parts which
>> Samsung has not released firmware updates for.
>>
>> As the check has been relaxed at startup for multiple disks with
>> duplicate NSIDs with commit ac522fc6c3165 ("nvme: don't reject
>> probe due to duplicate IDs for single-ported PCIe devices") also
>> relax the check that runs on resume for NSIDs and mark them bogus
>> if this occurs on resume.
> 
> How could the driver tell the difference between the device needing a
> quirk compared to a rapid delete-create-attach namespace sequence?
> Proceeding with the namespace now may get dirty writes intended for the
> previous namespace, corrupting the new one.
> 
> The commit you mentioned tries to constrain allowing duplication where
> we can reasonably assume the quirk is needed. If we need to do similiar
> for this condition, one possible constraint might be that the device
> doesn't report OACS bit 3 (Namespace Management).

It looks like that would work for the PM9B1:
> $ sudo nvme id-ctrl -H /dev/nvme0
> [...] > oacs      : 0x17
>   [10:10] : 0   Lockdown Command and Feature Not Supported
>   [9:9] : 0     Get LBA Status Capability Not Supported
>   [8:8] : 0     Doorbell Buffer Config Not Supported
>   [7:7] : 0     Virtualization Management Not Supported
>   [6:6] : 0     NVMe-MI Send and Receive Not Supported
>   [5:5] : 0     Directives Not Supported
>   [4:4] : 0x1   Device Self-test Supported
>   [3:3] : 0     NS Management and Attachment Not Supported
>   [2:2] : 0x1   FW Commit and Download Supported
>   [1:1] : 0x1   Format NVM Supported
>   [0:0] : 0x1   Security Send and Receive Supported

Regards,
August Wikerfors