From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) (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 D0F9CF9D7; Thu, 28 Dec 2023 17:05:13 +0000 (UTC) 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="hftXHG8b" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1703783114; x=1735319114; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=jlJA6l9/LxpjxQJJdNKaR0breVRQ2CVmXJiAZTX9pxk=; b=hftXHG8bJF8GVA/joG5fRsoTyXfHX6WCq1ckjlhodRXeobv9s4MKT+jm sHrFeAj3Ho+dfdn0cYWcpTaVLEfBhxLXQVov+mg3jRP3IUzsZ0Z0XXf1J HyYq7if6XR8GblY/lS1ZYrLoQ7oSDVJ9QlC/I95UZ3mHvWEGeCF6ijyDY Z2j2mCRy2aTqk/xF2ws6UhfcXF2jO1OYwiLM5MXA/KMbhyXOdPBDfRnEx +lAgNLb+jLzXDeOfzmGlatExGfMMVZnllM79FFQh8LMTPd46c0oe6H8zK 5H4YX5BMbEr5RrbGIf/ygQBV329Ts+NoW1PSFJXREyC+3c5Tih5AxGI4k Q==; X-IronPort-AV: E=McAfee;i="6600,9927,10937"; a="10123461" X-IronPort-AV: E=Sophos;i="6.04,312,1695711600"; d="scan'208";a="10123461" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmvoesa102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Dec 2023 09:05:14 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10937"; a="848992471" X-IronPort-AV: E=Sophos;i="6.04,312,1695711600"; d="scan'208";a="848992471" Received: from ply01-vm-store.bj.intel.com ([10.238.153.201]) by fmsmga004.fm.intel.com with ESMTP; 28 Dec 2023 09:05:10 -0800 From: Ethan Zhao To: kevin.tian@intel.com, bhelgaas@google.com, baolu.lu@linux.intel.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 Subject: [RFC PATCH v10 4/5] iommu/vt-d: don't issue ATS Invalidation request when device is disconnected Date: Thu, 28 Dec 2023 12:05:03 -0500 Message-Id: <20231228170504.720794-2-haifeng.zhao@linux.intel.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20231228170504.720794-1-haifeng.zhao@linux.intel.com> References: <20231228170504.720794-1-haifeng.zhao@linux.intel.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Except those aggressive hotplug cases - surprise remove a hotplug device while its safe removal is requested and handled in process by: 1. pull it out directly. 2. turn off its power. 3. bring the link down. 4. just died there that moment. etc, in a word, 'gone' or 'disconnected'. Mostly are regular normal safe removal and surprise removal unplug. these hot unplug handling process could be optimized for fix the ATS Invalidation hang issue by calling pci_dev_is_disconnected() in function devtlb_invalidation_with_pasid() to check target device state to avoid sending meaningless ATS Invalidation request to iommu when device is gone. (see IMPLEMENTATION NOTE in PCIe spec r6.1 section 10.3.1) For safe removal, device wouldn't be removed untill the whole software handling process is done, it wouldn't trigger the hard lock up issue caused by too long ATS Invalidation timeout wait. In safe removal path, device state isn't set to pci_channel_io_perm_failure in pciehp_unconfigure_device() by checking 'presence' parameter, calling pci_dev_is_disconnected() in devtlb_invalidation_with_pasid() will return false there, wouldn't break the function. For surprise removal, device state is set to pci_channel_io_perm_failure in pciehp_unconfigure_device(), means device is already gone (disconnected) call pci_dev_is_disconnected() in devtlb_invalidation_with_pasid() will return true to break the function not to send ATS Invalidation request to the disconnected device blindly, thus avoid the further long time waiting triggers the hard lockup. safe removal & surprise removal pciehp_ist() pciehp_handle_presence_or_link_change() pciehp_disable_slot() remove_board() pciehp_unconfigure_device(presence) Tested-by: Haorong Ye Signed-off-by: Ethan Zhao --- drivers/iommu/intel/pasid.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/iommu/intel/pasid.c b/drivers/iommu/intel/pasid.c index 715943531091..3d5ed27f39ef 100644 --- a/drivers/iommu/intel/pasid.c +++ b/drivers/iommu/intel/pasid.c @@ -480,6 +480,8 @@ devtlb_invalidation_with_pasid(struct intel_iommu *iommu, if (!info || !info->ats_enabled) return; + if (pci_dev_is_disconnected(to_pci_dev(dev))) + return; /* * When PASID 0 is used, it indicates RID2PASID(DMA request w/o PASID), * devTLB flush w/o PASID should be used. For non-zero PASID under -- 2.31.1