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[192.55.54.38]) by smtp.gmail.com with ESMTPSA id b127sm7481963pfb.143.2020.10.09.12.48.09 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 09 Oct 2020 12:48:11 -0700 (PDT) From: "Sean V Kelley" To: "Bjorn Helgaas" Cc: "Sean V Kelley" , bhelgaas@google.com, Jonathan.Cameron@huawei.com, rafael.j.wysocki@intel.com, ashok.raj@intel.com, tony.luck@intel.com, sathyanarayanan.kuppuswamy@intel.com, qiuxu.zhuo@intel.com, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v8 11/14] PCI/RCEC: Add RCiEP's linked RCEC to AER/ERR Date: Fri, 09 Oct 2020 12:48:07 -0700 X-Mailer: MailMate (1.13.2r5673) Message-ID: <5D41DFBA-CF5D-4DFD-A6B2-A28B621CB228@intel.com> In-Reply-To: References: <20201009175745.GA3489710@bjorn-Precision-5520> <41B2B0A9-80B0-41DA-9FF3-A5D9465E6E08@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On 9 Oct 2020, at 11:53, Sean V Kelley wrote: > On 9 Oct 2020, at 11:34, Sean V Kelley wrote: > >> On 9 Oct 2020, at 11:26, Sean V Kelley wrote: >> >>> Hi Bjorn, >>> >>> On 9 Oct 2020, at 10:57, Bjorn Helgaas wrote: >>> >>>> On Fri, Oct 02, 2020 at 11:47:32AM -0700, Sean V Kelley wrote: >>>>> From: Qiuxu Zhuo >>>>> >>>>> When attempting error recovery for an RCiEP associated with an >>>>> RCEC device, >>>>> there needs to be a way to update the Root Error Status, the >>>>> Uncorrectable >>>>> Error Status and the Uncorrectable Error Severity of the parent >>>>> RCEC. >>>>> In some non-native cases in which there is no OS visible device >>>>> associated with the RCiEP, there is nothing to act upon as the >>>>> firmware >>>>> is acting before the OS. So add handling for the linked 'rcec' in >>>>> AER/ERR >>>>> while taking into account non-native cases. >>>>> >>>>> Co-developed-by: Sean V Kelley >>>>> Signed-off-by: Sean V Kelley >>>>> Signed-off-by: Qiuxu Zhuo >>>>> Reviewed-by: Jonathan Cameron >>>>> --- >>>>> drivers/pci/pcie/aer.c | 9 +++++---- >>>>> drivers/pci/pcie/err.c | 39 >>>>> ++++++++++++++++++++++++++++----------- >>>>> 2 files changed, 33 insertions(+), 15 deletions(-) >>>>> >>>>> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c >>>>> index 65dff5f3457a..dccdba60b5d9 100644 >>>>> --- a/drivers/pci/pcie/aer.c >>>>> +++ b/drivers/pci/pcie/aer.c >>>>> @@ -1358,17 +1358,18 @@ static int aer_probe(struct pcie_device >>>>> *dev) >>>>> static pci_ers_result_t aer_root_reset(struct pci_dev *dev) >>>>> { >>>>> int aer = dev->aer_cap; >>>>> + int rc = 0; >>>>> u32 reg32; >>>>> - int rc; >>>>> - >>>>> >>>>> /* Disable Root's interrupt in response to error messages */ >>>>> pci_read_config_dword(dev, aer + PCI_ERR_ROOT_COMMAND, ®32); >>>>> reg32 &= ~ROOT_PORT_INTR_ON_MESG_MASK; >>>>> pci_write_config_dword(dev, aer + PCI_ERR_ROOT_COMMAND, reg32); >>>>> >>>>> - rc = pci_bus_error_reset(dev); >>>>> - pci_info(dev, "Root Port link has been reset\n"); >>>>> + if (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_EC) { >>>>> + rc = pci_bus_error_reset(dev); >>>>> + pci_info(dev, "Root Port link has been reset\n"); >>>>> + } >>>>> >>>>> /* Clear Root Error Status */ >>>>> pci_read_config_dword(dev, aer + PCI_ERR_ROOT_STATUS, ®32); >>>>> diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c >>>>> index 38abd7984996..956ad4c86d53 100644 >>>>> --- a/drivers/pci/pcie/err.c >>>>> +++ b/drivers/pci/pcie/err.c >>>>> @@ -149,7 +149,8 @@ static int report_resume(struct pci_dev *dev, >>>>> void *data) >>>>> /** >>>>> * pci_walk_bridge - walk bridges potentially AER affected >>>>> * @bridge bridge which may be an RCEC with associated RCiEPs, >>>>> - * an RCiEP associated with an RCEC, or a Port. >>>>> + * or a Port. >>>>> + * @dev an RCiEP lacking an associated RCEC. >>>>> * @cb callback to be called for each device found >>>>> * @userdata arbitrary pointer to be passed to callback. >>>>> * >>>>> @@ -160,13 +161,20 @@ static int report_resume(struct pci_dev >>>>> *dev, void *data) >>>>> * If the device provided has no subordinate bus, call the >>>>> provided >>>>> * callback on the device itself. >>>>> */ >>>>> -static void pci_walk_bridge(struct pci_dev *bridge, int >>>>> (*cb)(struct pci_dev *, void *), >>>>> +static void pci_walk_bridge(struct pci_dev *bridge, struct >>>>> pci_dev *dev, >>>>> + int (*cb)(struct pci_dev *, void *), >>>>> void *userdata) >>>>> { >>>>> - if (bridge->subordinate) >>>>> + /* >>>>> + * In a non-native case where there is no OS-visible reporting >>>>> + * device the bridge will be NULL, i.e., no RCEC, no PORT. >>>>> + */ >>>>> + if (bridge && bridge->subordinate) >>>>> pci_walk_bus(bridge->subordinate, cb, userdata); >>>>> - else >>>>> + else if (bridge) >>>>> cb(bridge, userdata); >>>>> + else >>>>> + cb(dev, userdata); >>>>> } >>>>> >>>>> static pci_ers_result_t flr_on_rciep(struct pci_dev *dev) >>>>> @@ -196,16 +204,25 @@ pci_ers_result_t pcie_do_recovery(struct >>>>> pci_dev *dev, >>>>> type = pci_pcie_type(dev); >>>>> if (type == PCI_EXP_TYPE_ROOT_PORT || >>>>> type == PCI_EXP_TYPE_DOWNSTREAM || >>>>> - type == PCI_EXP_TYPE_RC_EC || >>>>> - type == PCI_EXP_TYPE_RC_END) >>>>> + type == PCI_EXP_TYPE_RC_EC) >>>>> bridge = dev; >>>>> + else if (type == PCI_EXP_TYPE_RC_END) >>>>> + bridge = dev->rcec; >>>>> else >>>>> bridge = pci_upstream_bridge(dev); >>>>> >>>>> pci_dbg(dev, "broadcast error_detected message\n"); >>>>> if (state == pci_channel_io_frozen) { >>>>> - pci_walk_bridge(bridge, report_frozen_detected, &status); >>>>> + pci_walk_bridge(bridge, dev, report_frozen_detected, &status); >>>>> if (type == PCI_EXP_TYPE_RC_END) { >>>>> + /* >>>>> + * The callback only clears the Root Error Status >>>>> + * of the RCEC (see aer.c). Only perform this for the >>>>> + * native case, i.e., an RCEC is present. >>>>> + */ >>>>> + if (bridge) >>>>> + reset_subordinate_devices(bridge); >>>> >>>> Help me understand this. There are lots of callbacks in this >>>> picture, >>>> but I guess this "callback only clears Root Error Status" must >>>> refer >>>> to aer_root_reset(), i.e., the reset_subordinate_devices pointer? >>> >>> The ‘bridge’ in this case will always be dev->rcec, the event >>> collector for the associated RC_END. And that’s what’s being >>> cleared in aer.c via aer_root_reset() as the callback. It’s also >>> being checked for native/non-native here. >>> >>>> >>>> Of course, the caller of pcie_do_recovery() supplied that pointer. >>>> And we can infer that it must be aer_root_reset(), not >>>> dpc_reset_link(), because RCECs and RCiEPs are not allowed to >>>> implement DPC. >>> >>> Correct. >>> >>>> >>>> I wish we didn't have either this assumption about what >>>> reset_subordinate_devices points to, or the assumption about what >>>> aer_root_reset() does. They both seem a little bit tenuous. >>> >>> Agree. It’s the relationship between the RC_END and the RC_EC. >>> >>>> >>>> We already made aer_root_reset() smart enough to check for RCECs. >>>> Can >>>> we put the FLR there, too? Then we wouldn't have this weird >>>> situation >>>> where reset_subordinate_devices() does a reset and clears error >>>> status, EXCEPT for this case where it only clears error status and >>>> we >>>> do the reset here? >>> >>> We could add the smarts to aer_root_reset() to check for an RC_END >>> in that callback and perform the clear there on its RC_EC. We just >>> wouldn’t map ‘bridge’ to dev->rcec for RC_END in >>> pcie_do_recovery() which would simplify things. >>> >>> Further, the FLR in the case of flr_on_rciep() below is specific to >>> the RCiEP itself. So it could be performed either in >>> aer_root_reset() or remain in the pcie_do_recovery(). >>> >>> That should work. >>> >>> Sean >> >> Thinking more on this, you could still pass dev->rcec to the callback >> (eventually aer_root_reset()), but you won’t have the ability to >> handle the FLR there without the pointer to the RC_END. That’s why >> I suggested passing the RC_END and checking for its RC_EC in >> aer_root_reset() if you want to also handle FLR there too from below. > > Where you get into trouble is that you don’t want to do anything in > the non-native case and shouldn’t be going to the callback. So this > would add complexity to aer_root_reset() for checking on dev->rcec == > NULL…where before you never would have invoked > reset_subordinate_devices() in the non-native case. > > Unmapping of bridge to dev->rcec in pcie_do_recovery() also causes problems for pci_walk_bridge() which pays attention to the non-native case, even making available the dev for when there is no ‘bridge’ like device. I think we may be just shifting things elsewhere despite the constraints remaining the same. So while it should work, I believe that I prefer the current approach. Sean >> >> Sean >> >>> >>> >>>> >>>>> status = flr_on_rciep(dev); >>>>> if (status != PCI_ERS_RESULT_RECOVERED) { >>>>> pci_warn(dev, "function level reset failed\n"); >>>>> @@ -219,13 +236,13 @@ pci_ers_result_t pcie_do_recovery(struct >>>>> pci_dev *dev, >>>>> } >>>>> } >>>>> } else { >>>>> - pci_walk_bridge(bridge, report_normal_detected, &status); >>>>> + pci_walk_bridge(bridge, dev, report_normal_detected, &status); >>>>> } >>>>> >>>>> if (status == PCI_ERS_RESULT_CAN_RECOVER) { >>>>> status = PCI_ERS_RESULT_RECOVERED; >>>>> pci_dbg(dev, "broadcast mmio_enabled message\n"); >>>>> - pci_walk_bridge(bridge, report_mmio_enabled, &status); >>>>> + pci_walk_bridge(bridge, dev, report_mmio_enabled, &status); >>>>> } >>>>> >>>>> if (status == PCI_ERS_RESULT_NEED_RESET) { >>>>> @@ -236,14 +253,14 @@ pci_ers_result_t pcie_do_recovery(struct >>>>> pci_dev *dev, >>>>> */ >>>>> status = PCI_ERS_RESULT_RECOVERED; >>>>> pci_dbg(dev, "broadcast slot_reset message\n"); >>>>> - pci_walk_bridge(bridge, report_slot_reset, &status); >>>>> + pci_walk_bridge(bridge, dev, report_slot_reset, &status); >>>>> } >>>>> >>>>> if (status != PCI_ERS_RESULT_RECOVERED) >>>>> goto failed; >>>>> >>>>> pci_dbg(dev, "broadcast resume message\n"); >>>>> - pci_walk_bridge(bridge, report_resume, &status); >>>>> + pci_walk_bridge(bridge, dev, report_resume, &status); >>>>> >>>>> if (type == PCI_EXP_TYPE_ROOT_PORT || >>>>> type == PCI_EXP_TYPE_DOWNSTREAM || >>>>> -- >>>>> 2.28.0 >>>>>