From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.10]) (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 648238F44; Wed, 17 Jan 2024 05:26:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.10 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705469179; cv=none; b=otj/ugnNVkbgDHjpQEhTvj9LYiw4pU7wKOHMmyTVvmPhgzR5m/w2JOlnBhC0njY+wu9r+MTWEt4J3lih/pYd06MT6fZE8dy7cJ3I1vJdQJoKozfLNB1oNbwQUAjeDoksYzFFfBwGfgbN70edjpdWETHl5vauTQGofXdIziBkVjo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705469179; c=relaxed/simple; bh=9dZSmX0shpaQGEKsBa2DYCgCjL8t5oUpfPA8H9uFExo=; h=DKIM-Signature:X-IronPort-AV:X-IronPort-AV:Received:X-ExtLoop1: X-IronPort-AV:Received:Message-ID:Date:MIME-Version:User-Agent: Subject:To:Cc:References:From:In-Reply-To:Content-Type: Content-Transfer-Encoding; 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bh=9dZSmX0shpaQGEKsBa2DYCgCjL8t5oUpfPA8H9uFExo=; b=JuHcnV16pWq3x42hhUHvkExHGDM0tzNLdGtukDZLn9otRV44W6PR5F1j Zi59DkgQR9EQsNEHIi+bNlzGpHfjL438R9EyeLmgFFFuT93ARSWNXHWLP G/xSLdnmsrY5tDc4PNBEKK3lJQdy4eMtwO/Y+M8A6+TMoFC3NDPwEXdUY Ep1FLg7pn2GnxPzmFB5k0E1BNR2GoRJvj05YE8Xbr/xQwROPFetaCff2h mmZVKzeS9Fp+swwonXW/63pqGMQHuI+8ew5A1rGA8xFeiWJFORVHYxvEw VxC+xGLbFjP1J87c8fQF7LfK5DmZRNukde+4kHOdcp/GQIkWfytBaxMWg g==; X-IronPort-AV: E=McAfee;i="6600,9927,10955"; a="7465064" X-IronPort-AV: E=Sophos;i="6.05,200,1701158400"; d="scan'208";a="7465064" Received: from orviesa001.jf.intel.com ([10.64.159.141]) by fmvoesa104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Jan 2024 21:26:16 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.05,200,1701158400"; d="scan'208";a="32712014" Received: from zhaohaif-mobl.ccr.corp.intel.com (HELO [10.254.209.39]) ([10.254.209.39]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Jan 2024 21:26:13 -0800 Message-ID: <42f7848a-0262-4871-b5dc-0e87beebfd11@linux.intel.com> Date: Wed, 17 Jan 2024 13:26:10 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH v10 0/5] fix vt-d hard lockup when hotplug ATS capable device To: Baolu Lu , kevin.tian@intel.com, bhelgaas@google.com, dwmw2@infradead.org, will@kernel.org, robin.murphy@arm.com, lukas@wunner.de Cc: linux-pci@vger.kernel.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org References: <20231228170206.720675-1-haifeng.zhao@linux.intel.com> <1a2a4069-c737-4a3c-a2f6-cce06823331b@linux.intel.com> <3ee904e9-8a93-4bd9-8df7-6294885589e4@linux.intel.com> From: Ethan Zhao In-Reply-To: <3ee904e9-8a93-4bd9-8df7-6294885589e4@linux.intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 1/17/2024 11:24 AM, Baolu Lu wrote: > On 2024/1/15 15:58, Ethan Zhao wrote: >> -static int qi_check_fault(struct intel_iommu *iommu, int index, int >> wait_index) >> +static int qi_check_fault(struct intel_iommu *iommu, int index, int >> wait_index, >> +                  pci_dev *target_pdev) >>   { >>          u32 fault; >>          int head, tail; >> +       u64 iqe_err, ice_sid; >>          struct q_inval *qi = iommu->qi; >>          int shift = qi_shift(iommu); >> >>          if (qi->desc_status[wait_index] == QI_ABORT) >>                  return -EAGAIN; >> >> +       /* >> +        * If the ATS invalidation target device is gone this moment >> (surprise >> +        * removed, died, no response) don't try this request again. >> this >> +        * request will not get valid result anymore. but the request >> was >> +        * already submitted to hardware and we predict to get a ITE in >> +        * followed batch of request, if so, it will get handled then. >> +        */ > > We can't leave the ITE triggered by this request for the next one, which > has no context about why this happened. Perhaps move below code down to > the segment that handles ITEs. Here, the invalidation request has been issued to hardware but target device gone, we can't loop and wait for the ITE for this request to happen, and we bail out here because we hold lock_irqsave lock , the ITE still could happen with later batch request in the future,  though it is not triggered by that request, but it could still be cleaned/handled. move it to the fault() segment ?,there means ITE already happened, no need to check target presence anymore. did I miss something about the context lost ? > > Another concern is about qi_dump_fault(), which pr_err's the fault > message as long as the register is set. Some faults are predictable, > such as cache invalidation for surprise-removed devices. Unconditionally > reporting errors with pr_err() may lead the user to believe that a more > serious hardware error has occurred. Probably we can refine this part of > the code as well. Agree, may refine them in seperated series ? loop and always retry IQE, ICE don't make sense per my understanding.  if IQE happened retry it will always reproduce the fault, because request is the same. we could fix them together in other patches. Thanks, Ethan > > Others look sane to me. > >> +       if (target_pdev && !pci_device_is_present(target_pdev)) >> +               return -EINVAL; >> + >>          fault = readl(iommu->reg + DMAR_FSTS_REG); >>          if (fault & (DMA_FSTS_IQE | DMA_FSTS_ITE | DMA_FSTS_ICE)) >>                  qi_dump_fault(iommu, fault); >> @@ -1315,6 +1327,13 @@ static int qi_check_fault(struct intel_iommu >> *iommu, int index, int wait_index) >>                  tail = readl(iommu->reg + DMAR_IQT_REG); >>                  tail = ((tail >> shift) - 1 + QI_LENGTH) % QI_LENGTH; >> >> +               /* >> +                * SID field is valid only when the ITE field is Set >> in FSTS_REG >> +                * see Intel VT-d spec r4.1, section 11.4.9.9 >> +                */ >> +               iqe_err = dmar_readq(iommu->reg + DMAR_IQER_REG); >> +               ice_sid = DMAR_IQER_REG_ITESID(iqe_err); >> + >>                  writel(DMA_FSTS_ITE, iommu->reg + DMAR_FSTS_REG); >>                  pr_info("Invalidation Time-out Error (ITE) cleared\n"); >> >> @@ -1324,6 +1343,16 @@ static int qi_check_fault(struct intel_iommu >> *iommu, int index, int wait_index) >>                          head = (head - 2 + QI_LENGTH) % QI_LENGTH; >>                  } while (head != tail); >> >> +               /* >> +                * If got ITE, we need to check if the sid of ITE is >> the same as >> +                * current ATS invalidation target device, if yes, >> don't try this >> +                * request anymore, the target device has a response >> time beyound >> +                * expected. 0 value of ice_sid means old device, no >> ice_sid value. >> +                */ >> +               if (target_pdev && ice_sid && ice_sid == >> +                   pci_dev_id(pci_physfn(target_pdev)) >> +                               return -ETIMEDOUT; >> + >>                  if (qi->desc_status[wait_index] == QI_ABORT) >>                          return -EAGAIN; >>          } > > Best regards, > baolu