From: Keith Busch <kbusch@kernel.org>
To: Nilay Shroff <nilay@linux.ibm.com>
Cc: axboe@fb.com, hch@lst.de, sagi@grimberg.me,
linux-nvme@lists.infradead.org, linux-block@vger.kernel.org,
gjoyce@linux.ibm.com
Subject: Re: [PATCH RESEND] nvme-pci: Fix EEH failure on ppc after subsystem reset
Date: Tue, 27 Feb 2024 11:29:16 -0700 [thread overview]
Message-ID: <Zd4p_E8cPFpr1M--@kbusch-mbp> (raw)
In-Reply-To: <20240209050342.406184-1-nilay@linux.ibm.com>
On Fri, Feb 09, 2024 at 10:32:16AM +0530, Nilay Shroff wrote:
> If the nvme subsyetm reset causes the loss of communication to the nvme
> adapter then EEH could potnetially recover the adapter. The detection of
> comminication loss to the adapter only happens when the nvme driver
> attempts to read an MMIO register.
>
> The nvme subsystem reset command writes 0x4E564D65 to NSSR register and
> schedule adapter reset.In the case nvme subsystem reset caused the loss
> of communication to the nvme adapter then either IO timeout event or
> adapter reset handler could detect it. If IO timeout even could detect
> loss of communication then EEH handler is able to recover the
> communication to the adapter. This change was implemented in 651438bb0af5
> (nvme-pci: Fix EEH failure on ppc). However if the adapter communication
> loss is detected in nvme reset work handler then EEH is unable to
> successfully finish the adapter recovery.
>
> This patch ensures that,
> - nvme driver reset handler would observer pci channel was offline after
> a failed MMIO read and avoids marking the controller state to DEAD and
> thus gives a fair chance to EEH handler to recover the nvme adapter.
>
> - if nvme controller is already in RESETTNG state and pci channel frozen
> error is detected then nvme driver pci-error-handler code sends the
> correct error code (PCI_ERS_RESULT_NEED_RESET) back to the EEH handler
> so that EEH handler could proceed with the pci slot reset.
A subsystem reset takes the link down. I'm pretty sure the proper way to
recover from it requires pcie hotplug support.
next prev parent reply other threads:[~2024-02-27 18:29 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-09 5:02 [PATCH RESEND] nvme-pci: Fix EEH failure on ppc after subsystem reset Nilay Shroff
2024-02-22 21:00 ` Greg Joyce
[not found] ` <2c76725c-7bb6-4827-b45a-dbe1acbefba7@imap.linux.ibm.com>
2024-02-27 18:14 ` Nilay Shroff
2024-02-27 18:29 ` Keith Busch [this message]
2024-02-28 11:19 ` Nilay Shroff
2024-02-29 12:27 ` Nilay Shroff
2024-03-06 11:20 ` Nilay Shroff
2024-03-06 15:19 ` Keith Busch
2024-03-08 15:41 ` Keith Busch
2024-03-09 14:29 ` Nilay Shroff
2024-03-09 15:44 ` Keith Busch
2024-03-09 19:05 ` Nilay Shroff
2024-03-11 4:41 ` Keith Busch
2024-03-11 12:58 ` Nilay Shroff
2024-03-12 14:30 ` Keith Busch
2024-03-13 11:59 ` Nilay Shroff
2024-03-22 5:02 ` Nilay Shroff
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