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[24.20.148.49]) by smtp.gmail.com with ESMTPSA id p5sm7174801qte.95.2020.10.09.15.07.20 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 09 Oct 2020 15:07:21 -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 15:07:18 -0700 X-Mailer: MailMate (1.13.2r5673) Message-ID: <56145784-8C7B-4206-B172-997F8D8C97D5@intel.com> In-Reply-To: <20201009213011.GA3504871@bjorn-Precision-5520> References: <20201009213011.GA3504871@bjorn-Precision-5520> 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-kernel@vger.kernel.org On 9 Oct 2020, at 14:30, Bjorn Helgaas wrote: > On Fri, Oct 09, 2020 at 12:57:45PM -0500, 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? >> >> 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. >> >> 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. >> >> 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? > > Just as an example to make this concrete. Doesn't even compile. Okay, I tried something similar. Comments below: > > > diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c > index d6927e6535e5..e389db7cbba6 100644 > --- a/drivers/pci/pcie/aer.c > +++ b/drivers/pci/pcie/aer.c > @@ -1372,28 +1372,45 @@ 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 type = pci_pcie_type(dev); > + struct pci_dev *root; > + int aer = 0; > int rc = 0; > u32 reg32; > > - /* 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); > + if (type == PCI_EXP_TYPE_RC_END) > + root = dev->rcec; > + else > + root = dev; > + > + if (root) > + aer = root->aer_cap; Except here dev->rcec may be NULL for the non-native case. So I had a goto label to bypass what follows. I left the FLR in err.c. > > - if (pci_pcie_type(dev) != PCI_EXP_TYPE_RC_EC) { > + if (aer) { > + /* Disable Root's interrupt in response to error messages */ > + pci_read_config_dword(root, aer + PCI_ERR_ROOT_COMMAND, ®32); > + reg32 &= ~ROOT_PORT_INTR_ON_MESG_MASK; > + pci_write_config_dword(root, aer + PCI_ERR_ROOT_COMMAND, reg32); > + } > + > + if (type == PCI_EXP_TYPE_RC_EC || type == PCI_EXP_TYPE_RC_END) { > + rc = flr_on_rciep(dev); > + pci_info(dev, "has been reset (%d)\n", rc); > + } else { > rc = pci_bus_error_reset(dev); > - pci_info(dev, "Root Port link has been reset\n"); > + pci_info(dev, "Root Port link has been reset (%d)\n", rc); > } > > - /* Clear Root Error Status */ > - pci_read_config_dword(dev, aer + PCI_ERR_ROOT_STATUS, ®32); > - pci_write_config_dword(dev, aer + PCI_ERR_ROOT_STATUS, reg32); > + if (aer) { > + /* Clear Root Error Status */ > + pci_read_config_dword(root, aer + PCI_ERR_ROOT_STATUS, ®32); > + pci_write_config_dword(root, aer + PCI_ERR_ROOT_STATUS, reg32); > > - /* Enable Root Port'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); > + /* Enable Root Port's interrupt in response to error messages */ > + pci_read_config_dword(root, aer + PCI_ERR_ROOT_COMMAND, ®32); > + reg32 |= ROOT_PORT_INTR_ON_MESG_MASK; > + pci_write_config_dword(root, aer + PCI_ERR_ROOT_COMMAND, reg32); > + } > > return rc ? PCI_ERS_RESULT_DISCONNECT : PCI_ERS_RESULT_RECOVERED; > } > diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c > index 79ae1356141d..08976034a89c 100644 > --- a/drivers/pci/pcie/err.c > +++ b/drivers/pci/pcie/err.c > @@ -203,36 +203,19 @@ pci_ers_result_t pcie_do_recovery(struct pci_dev > *dev, > */ > if (type == PCI_EXP_TYPE_ROOT_PORT || > type == PCI_EXP_TYPE_DOWNSTREAM || > - type == PCI_EXP_TYPE_RC_EC) > + type == PCI_EXP_TYPE_RC_EC || > + type == PCI_EXP_TYPE_RC_END) > bridge = dev; > - else if (type == PCI_EXP_TYPE_RC_END) > - bridge = dev->rcec; > else > bridge = pci_upstream_bridge(dev); > > pci_dbg(bridge, "broadcast error_detected message\n"); > if (state == pci_channel_io_frozen) { > pci_walk_bridge(bridge, dev, report_frozen_detected, &status); We’d need to walk back the dev addition to the pci_walk_bridge() and revert to prior to the checks on dev->rcec. > - 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_subordinates(bridge); > - > - status = flr_on_rciep(dev); > - if (status != PCI_ERS_RESULT_RECOVERED) { > - pci_warn(dev, "Function Level Reset failed\n"); > - goto failed; > - } > - } else { > - status = reset_subordinates(bridge); > - if (status != PCI_ERS_RESULT_RECOVERED) { > - pci_warn(dev, "subordinate device reset failed\n"); > - goto failed; > - } > + status = reset_subordinates(bridge); > + if (status != PCI_ERS_RESULT_RECOVERED) { > + pci_warn(bridge, "subordinate device reset failed\n"); > + goto failed; > } > } else { > pci_walk_bridge(bridge, dev, report_normal_detected, &status); So this is what I experimented with for the most part but with the changes that I highlighted - addressing non-native case in the callback and also in the bridge walk. I can test it out. Thanks, Sean