From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.16]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 115731B7E1; Wed, 7 Feb 2024 11:35:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.16 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707305750; cv=none; b=X8LKmiOzYL3j5aALyHfUN9KooQZ+WpS09/NTbyAKrz9v4uxLjXmvAG0CtjW+QhFi83edY5jCyTvHOv6RAidS5kKK1psHsHp3tY0Bo2U1sZ7EPoNqu6VIT8ygVdKoIsEbcMNStl94ohpFtua2b69UPGVQLUPhuJ70TaB18M3+kug= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707305750; c=relaxed/simple; bh=0YPkjMO46SfT4+DaDWi2AKdkqPLqA1uaOj6h7G+eQuo=; h=From:Date:To:cc:Subject:In-Reply-To:Message-ID:References: MIME-Version:Content-Type; b=n18KMlI6akMKCRRoL0W4MyomnLLELxZxY8zeT7zbvqhvK7CtOW8VR2xlosln1HAA35YbC/nalskyU+gnLHIpTV7nUNQQz3+5PTm/r4GexyzNRwWFR7D49pxQiaWnlTX5Cu2eGl4GvycS4/AxUJLtDhDwVjPPIu0dw9rTw40p1dQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=none smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=Xm9ig6zZ; arc=none smtp.client-ip=198.175.65.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="Xm9ig6zZ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1707305749; x=1738841749; h=from:date:to:cc:subject:in-reply-to:message-id: references:mime-version; bh=0YPkjMO46SfT4+DaDWi2AKdkqPLqA1uaOj6h7G+eQuo=; b=Xm9ig6zZWyh5yCEDHgnsrdObet4lL0vMZFo/epPEhZQKjQeIebldP40P T4jXpWMiElWiDYVUJMiYYMgx1M4U2G8HQES56iP35cho3xPsw1IDWo8BL 9tJE48pMAKyeFOGYWtB/Se/o9qiQh+ttmCGnDEubpMUl9ognOl6q1zJRj lk4Z7Y81uk9nU7BU9D2WzRQISqdV8FDAB9HfzC4NwaM4R46ZQ4OLWUsS1 0cyYYh7mkP3d4cDvAsJu4Us4Qcq1Ej7EzU5sH4q1wYXtlRK6yAkgas76x kmLymY/XkfFjb9vD1XlPKkHoVcV4AxHwipQOrbOhWVmo7KLgHp9IIScnv g==; X-IronPort-AV: E=McAfee;i="6600,9927,10976"; a="1121916" X-IronPort-AV: E=Sophos;i="6.05,250,1701158400"; d="scan'208";a="1121916" Received: from orviesa003.jf.intel.com ([10.64.159.143]) by orvoesa108.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Feb 2024 03:35:48 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.05,250,1701158400"; d="scan'208";a="5938646" Received: from ijarvine-desk1.ger.corp.intel.com (HELO localhost) ([10.246.51.96]) by ORVIESA003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Feb 2024 03:35:45 -0800 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Wed, 7 Feb 2024 13:35:38 +0200 (EET) To: Smita Koralahalli cc: linux-pci@vger.kernel.org, LKML , Bjorn Helgaas , Mahesh J Salgaonkar , Lukas Wunner , Yazen Ghannam Subject: Re: [PATCH v8] PCI/DPC: Ignore Surprise Down error on hot removal In-Reply-To: <20240207111256.110982-1-Smita.KoralahalliChannabasappa@amd.com> Message-ID: References: <20240207111256.110982-1-Smita.KoralahalliChannabasappa@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII On Wed, 7 Feb 2024, Smita Koralahalli wrote: > According to PCIe r6.0 sec 6.7.6 [1], async removal with DPC may result in > surprise down error. This error is expected and is just a side-effect of > async remove. > > Ignore surprise down error generated as a side-effect of async remove. > Typically, this error is benign as the pciehp handler invoked by PDC > or/and DLLSC alongside DPC, de-enumerates and brings down the device > appropriately. But the error messages might confuse users. Get rid of > these irritating log messages with a 1s delay while pciehp waits for > dpc recovery. dpc -> DPC. > The implementation is as follows: On an async remove a DPC is triggered > along with a Presence Detect State change and/or DLL State Change. > Determine it's an async remove by checking for DPC Trigger Status in DPC > Status Register and Surprise Down Error Status in AER Uncorrected Error > Status to be non-zero. If true, treat the DPC event as a side-effect of > async remove, clear the error status registers and continue with hot-plug > tear down routines. If not, follow the existing routine to handle AER and > DPC errors. > > Please note that, masking Surprise Down Errors was explored as an > alternative approach, but left due to the odd behavior that masking only > avoids the interrupt, but still records an error per PCIe r6.0.1 Section > 6.2.3.2.2. That stale error is going to be reported the next time some > error other than Surprise Down is handled. > > Dmesg before: > > pcieport 0000:00:01.4: DPC: containment event, status:0x1f01 source:0x0000 > pcieport 0000:00:01.4: DPC: unmasked uncorrectable error detected > pcieport 0000:00:01.4: PCIe Bus Error: severity=Uncorrected (Fatal), type=Transaction Layer, (Receiver ID) > pcieport 0000:00:01.4: device [1022:14ab] error status/mask=00000020/04004000 > pcieport 0000:00:01.4: [ 5] SDES (First) > nvme nvme2: frozen state error detected, reset controller > pcieport 0000:00:01.4: DPC: Data Link Layer Link Active not set in 1000 msec > pcieport 0000:00:01.4: AER: subordinate device reset failed > pcieport 0000:00:01.4: AER: device recovery failed > pcieport 0000:00:01.4: pciehp: Slot(16): Link Down > nvme2n1: detected capacity change from 1953525168 to 0 > pci 0000:04:00.0: Removing from iommu group 49 > > Dmesg after: > > pcieport 0000:00:01.4: pciehp: Slot(16): Link Down > nvme1n1: detected capacity change from 1953525168 to 0 > pci 0000:04:00.0: Removing from iommu group 37 > > [1] PCI Express Base Specification Revision 6.0, Dec 16 2021. > https://members.pcisig.com/wg/PCI-SIG/document/16609 > > Signed-off-by: Smita Koralahalli > Reviewed-by: Lukas Wunner > Reviewed-by: Kuppuswamy Sathyanarayanan > --- > v2: > Indentation is taken care. (Bjorn) > Unrelevant dmesg logs are removed. (Bjorn) > Rephrased commit message, to be clear on native vs FW-First > handling. (Bjorn and Sathyanarayanan) > Prefix changed from pciehp_ to dpc_. (Lukas) > Clearing ARI and AtomicOp Requester are performed as a part of > (de-)enumeration in pciehp_unconfigure_device(). (Lukas) > Changed to clearing all optional capabilities in DEVCTL2. > OS-First -> native. (Sathyanarayanan) > > v3: > Added error message when root port become inactive. > Modified commit description to add more details. > Rearranged code comments and function calls with no functional > change. > Additional check for is_hotplug_bridge. > dpc_completed_waitqueue to wakeup pciehp handler. > Cleared only Fatal error detected in DEVSTA. > > v4: > Made read+write conditional on "if (pdev->dpc_rp_extensions)" > for DPC_RP_PIO_STATUS. > Wrapped to 80 chars. > Code comment for clearing PCI_STATUS and PCI_EXP_DEVSTA. > Added pcie_wait_for_link() check. > Removed error message for root port inactive as the message > already existed. > Check for is_hotplug_bridge before registers read. > Section 6.7.6 of the PCIe Base Spec 6.0 -> PCIe r6.0 sec 6.7.6. > Made code comment more meaningful. > > v5: > $SUBJECT correction. > Added "Reviewed-by" tag. > No code changes. Re-spin on latest base to get Bjorn's > attention. > > v6: > Change to write 1's to clear error. (Sathyanarayanan) > > v7: > No changes. Rebasing on pci main branch as per Bjorn comments. > > v8: > Just return "status & PCI_ERR_UNC_SURPDN" instead of true and > false and allow C to handle the conversion to bool. (Ilpo) > --- > drivers/pci/pcie/dpc.c | 64 ++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 64 insertions(+) > > diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c > index 94111e438241..ba7240a2ba2f 100644 > --- a/drivers/pci/pcie/dpc.c > +++ b/drivers/pci/pcie/dpc.c > @@ -303,10 +303,74 @@ void dpc_process_error(struct pci_dev *pdev) > } > } > > +static void pci_clear_surpdn_errors(struct pci_dev *pdev) > +{ > + u32 reg32; > + > + if (pdev->dpc_rp_extensions) { > + pci_read_config_dword(pdev, pdev->dpc_cap + PCI_EXP_DPC_RP_PIO_STATUS, > + ®32); > + pci_write_config_dword(pdev, pdev->dpc_cap + PCI_EXP_DPC_RP_PIO_STATUS, > + reg32); > + } > + > + /* > + * In practice, Surprise Down errors have been observed to also set > + * error bits in the Status Register as well as the Fatal Error > + * Detected bit in the Device Status Register. > + */ > + pci_write_config_word(pdev, PCI_STATUS, 0xffff); > + > + pcie_capability_write_word(pdev, PCI_EXP_DEVSTA, PCI_EXP_DEVSTA_FED); > +} > + > +static void dpc_handle_surprise_removal(struct pci_dev *pdev) > +{ > + if (!pcie_wait_for_link(pdev, false)) { > + pci_info(pdev, "Data Link Layer Link Active not cleared in 1000 msec\n"); > + goto out; > + } > + > + if (pdev->dpc_rp_extensions && dpc_wait_rp_inactive(pdev)) > + goto out; > + > + pci_aer_raw_clear_status(pdev); > + pci_clear_surpdn_errors(pdev); > + > + pci_write_config_word(pdev, pdev->dpc_cap + PCI_EXP_DPC_STATUS, > + PCI_EXP_DPC_STATUS_TRIGGER); > + > +out: > + clear_bit(PCI_DPC_RECOVERED, &pdev->priv_flags); > + wake_up_all(&dpc_completed_waitqueue); > +} > + > +static bool dpc_is_surprise_removal(struct pci_dev *pdev) > +{ > + u16 status; > + > + if (!pdev->is_hotplug_bridge) > + return false; > + > + pci_read_config_word(pdev, pdev->aer_cap + PCI_ERR_UNCOR_STATUS, > + &status); > + > + return status & PCI_ERR_UNC_SURPDN; Thanks for the update, looks more readable now. While staring this now again, I think checking for error from pci_read_config_word() would be useful so that it cannot confused with surprise down? -- i. > +} > + > static irqreturn_t dpc_handler(int irq, void *context) > { > struct pci_dev *pdev = context; > > + /* > + * According to PCIe r6.0 sec 6.7.6, errors are an expected side effect > + * of async removal and should be ignored by software. > + */ > + if (dpc_is_surprise_removal(pdev)) { > + dpc_handle_surprise_removal(pdev); > + return IRQ_HANDLED; > + } > + > dpc_process_error(pdev); > > /* We configure DPC so it only triggers on ERR_FATAL */ >