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Fri, 14 Jun 2024 09:51:14 +0000 Message-ID: <72d9ab72-8b19-455e-a1db-d2bca9754bbf@suse.de> Date: Fri, 14 Jun 2024 11:51:14 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 1/1] nvme-pci : Fix EEH failure on ppc after subsystem reset To: Nilay Shroff , kbusch@kernel.org Cc: linux-nvme@lists.infradead.org, hch@lst.de, sagi@grimberg.me, gjoyce@linux.ibm.com, axboe@fb.com References: <20240604091523.1422027-1-nilay@linux.ibm.com> <20240604091523.1422027-2-nilay@linux.ibm.com> Content-Language: en-US From: Hannes Reinecke In-Reply-To: <20240604091523.1422027-2-nilay@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Spamd-Result: default: False [-4.29 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-0.999]; MIME_GOOD(-0.10)[text/plain]; XM_UA_NO_VERSION(0.01)[]; RCPT_COUNT_SEVEN(0.00)[7]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_TLS_ALL(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; MIME_TRACE(0.00)[0:+]; FROM_HAS_DN(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_DN_SOME(0.00)[] X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240614_025117_298729_8B8BCD31 X-CRM114-Status: GOOD ( 18.33 ) X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On 6/4/24 11:10, Nilay Shroff wrote: > The NVMe subsystem reset command when executed may cause the loss of > the NVMe adapter communication with kernel. And the only way today > to recover the adapter is to either re-enumerate the pci bus or > hotplug NVMe disk or reboot OS. > > The PPC architecture supports mechanism called EEH (enhanced error > handling) which allows pci bus errors to be cleared and a pci card to > be rebooted, without having to physically hotplug NVMe disk or reboot > the OS. > > In the current implementation when user executes the nvme subsystem > reset command and if kernel loses the communication with NVMe adapter > then subsequent read/write to the PCIe config space of the device > would fail. Failing to read/write to PCI config space makes NVMe > driver assume the permanent loss of communication with the device and > so driver marks the NVMe controller dead and frees all resources > associate to that controller. As the NVMe controller goes dead, the > EEH recovery can't succeed. > > This patch helps fix this issue so that after user executes subsystem > reset command if the communication with the NVMe adapter is lost and > EEH recovery is initiated then we allow the EEH recovery to forward > progress and gives the EEH thread a fair chance to recover the > adapter. If in case, the EEH thread couldn't recover the adapter > communication then it sets the pci channel state of the erring > adapter to "permanent failure" and removes the device. > > Signed-off-by: Nilay Shroff > --- > drivers/nvme/host/core.c | 1 + > drivers/nvme/host/pci.c | 21 ++++++++++++++++++--- > 2 files changed, 19 insertions(+), 3 deletions(-) > Looks odd, but I cannot see a better way out here. Reviewed-by: Hannes Reinecke Cheers, Hannes -- Dr. Hannes Reinecke Kernel Storage Architect hare@suse.de +49 911 74053 688 SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 36809 (AG Nürnberg), GF: Ivo Totev, Andrew McDonald, Werner Knoblich