From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765330AbdAJPGS (ORCPT ); Tue, 10 Jan 2017 10:06:18 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:60004 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031146AbdAJNlq (ORCPT ); Tue, 10 Jan 2017 08:41:46 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Myron Stowe , Joseph Szczypek , Don Brace , Baoquan He , Dave Young , Xunlei Pang , Joerg Roedel Subject: [PATCH 4.4 077/101] iommu/vt-d: Flush old iommu caches for kdump when the device gets context mapped Date: Tue, 10 Jan 2017 14:37:30 +0100 Message-Id: <20170110131525.757716796@linuxfoundation.org> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20170110131522.493717794@linuxfoundation.org> References: <20170110131522.493717794@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xunlei Pang commit aec0e86172a79eb5e44aff1055bb953fe4d47c59 upstream. We met the DMAR fault both on hpsa P420i and P421 SmartArray controllers under kdump, it can be steadily reproduced on several different machines, the dmesg log is like: HP HPSA Driver (v 3.4.16-0) hpsa 0000:02:00.0: using doorbell to reset controller hpsa 0000:02:00.0: board ready after hard reset. hpsa 0000:02:00.0: Waiting for controller to respond to no-op DMAR: Setting identity map for device 0000:02:00.0 [0xe8000 - 0xe8fff] DMAR: Setting identity map for device 0000:02:00.0 [0xf4000 - 0xf4fff] DMAR: Setting identity map for device 0000:02:00.0 [0xbdf6e000 - 0xbdf6efff] DMAR: Setting identity map for device 0000:02:00.0 [0xbdf6f000 - 0xbdf7efff] DMAR: Setting identity map for device 0000:02:00.0 [0xbdf7f000 - 0xbdf82fff] DMAR: Setting identity map for device 0000:02:00.0 [0xbdf83000 - 0xbdf84fff] DMAR: DRHD: handling fault status reg 2 DMAR: [DMA Read] Request device [02:00.0] fault addr fffff000 [fault reason 06] PTE Read access is not set hpsa 0000:02:00.0: controller message 03:00 timed out hpsa 0000:02:00.0: no-op failed; re-trying After some debugging, we found that the fault addr is from DMA initiated at the driver probe stage after reset(not in-flight DMA), and the corresponding pte entry value is correct, the fault is likely due to the old iommu caches of the in-flight DMA before it. Thus we need to flush the old cache after context mapping is setup for the device, where the device is supposed to finish reset at its driver probe stage and no in-flight DMA exists hereafter. I'm not sure if the hardware is responsible for invalidating all the related caches allocated in the iommu hardware before, but seems not the case for hpsa, actually many device drivers have problems in properly resetting the hardware. Anyway flushing (again) by software in kdump kernel when the device gets context mapped which is a quite infrequent operation does little harm. With this patch, the problematic machine can survive the kdump tests. CC: Myron Stowe CC: Joseph Szczypek CC: Don Brace CC: Baoquan He CC: Dave Young Fixes: 091d42e43d21 ("iommu/vt-d: Copy translation tables from old kernel") Fixes: dbcd861f252d ("iommu/vt-d: Do not re-use domain-ids from the old kernel") Fixes: cf484d0e6939 ("iommu/vt-d: Mark copied context entries") Signed-off-by: Xunlei Pang Tested-by: Don Brace Signed-off-by: Joerg Roedel Signed-off-by: Greg Kroah-Hartman --- drivers/iommu/intel-iommu.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) --- a/drivers/iommu/intel-iommu.c +++ b/drivers/iommu/intel-iommu.c @@ -1993,6 +1993,25 @@ static int domain_context_mapping_one(st if (context_present(context)) goto out_unlock; + /* + * For kdump cases, old valid entries may be cached due to the + * in-flight DMA and copied pgtable, but there is no unmapping + * behaviour for them, thus we need an explicit cache flush for + * the newly-mapped device. For kdump, at this point, the device + * is supposed to finish reset at its driver probe stage, so no + * in-flight DMA will exist, and we don't need to worry anymore + * hereafter. + */ + if (context_copied(context)) { + u16 did_old = context_domain_id(context); + + if (did_old >= 0 && did_old < cap_ndoms(iommu->cap)) + iommu->flush.flush_context(iommu, did_old, + (((u16)bus) << 8) | devfn, + DMA_CCMD_MASK_NOBIT, + DMA_CCMD_DEVICE_INVL); + } + pgd = domain->pgd; context_clear_entry(context);