From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e18.ny.us.ibm.com (e18.ny.us.ibm.com [129.33.205.208]) (using TLSv1 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id CD24C1A1E14 for ; Wed, 2 Sep 2015 11:11:31 +1000 (AEST) Received: from /spool/local by e18.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 1 Sep 2015 21:11:28 -0400 Received: from b01cxnp23034.gho.pok.ibm.com (b01cxnp23034.gho.pok.ibm.com [9.57.198.29]) by d01dlp03.pok.ibm.com (Postfix) with ESMTP id D3EC3C90042 for ; Tue, 1 Sep 2015 21:02:29 -0400 (EDT) Received: from d01av03.pok.ibm.com (d01av03.pok.ibm.com [9.56.224.217]) by b01cxnp23034.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t821BPLp53346500 for ; Wed, 2 Sep 2015 01:11:25 GMT Received: from d01av03.pok.ibm.com (localhost [127.0.0.1]) by d01av03.pok.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t821BOas005974 for ; Tue, 1 Sep 2015 21:11:25 -0400 Date: Tue, 1 Sep 2015 18:11:23 -0700 From: Nishanth Aravamudan To: Michael Ellerman Cc: Hari Bathini , Gavin Shan , Alexey Kardashevskiy , Ben Herrenschmidt , Paul Mackerras , David Gibson , Wei Yang , linuxppc-dev@lists.ozlabs.org Subject: [PATCH] powerpc/powernv/pci-ioda: fix 32-bit TCE table init in kdump kernel Message-ID: <20150902011123.GA47557@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , When attempting to kdump with the 4.2 kernel, we see for each PCI device: pci 0003:01 : [PE# 000] Assign DMA32 space pci 0003:01 : [PE# 000] Setting up 32-bit TCE table at 0..80000000 pci 0003:01 : [PE# 000] Failed to create 32-bit TCE table, err -22 PCI: Domain 0004 has 8 available 32-bit DMA segments PCI: 4 PE# for a total weight of 70 pci 0004:01 : [PE# 002] Assign DMA32 space pci 0004:01 : [PE# 002] Setting up 32-bit TCE table at 0..80000000 pci 0004:01 : [PE# 002] Failed to create 32-bit TCE table, err -22 pci 0004:0d : [PE# 005] Assign DMA32 space pci 0004:0d : [PE# 005] Setting up 32-bit TCE table at 0..80000000 pci 0004:0d : [PE# 005] Failed to create 32-bit TCE table, err -22 pci 0004:0e : [PE# 006] Assign DMA32 space pci 0004:0e : [PE# 006] Setting up 32-bit TCE table at 0..80000000 pci 0004:0e : [PE# 006] Failed to create 32-bit TCE table, err -22 pci 0004:10 : [PE# 008] Assign DMA32 space pci 0004:10 : [PE# 008] Setting up 32-bit TCE table at 0..80000000 pci 0004:10 : [PE# 008] Failed to create 32-bit TCE table, err -22 and eventually the kdump kernel fails to boot as none of the PCI devices (including the disk controller) are successfully initialized. The EINVAL response is because the DMA window (the 2GB base window) is larger than the kdump kernel's reserved memory (crashkernel=, in this case specified to be 1024M). The check in question, if ((window_size > memory_hotplug_max()) || !is_power_of_2(window_size)) is a valid sanity check for pnv_pci_ioda2_table_alloc_pages(), so adjust the caller to pass in a smaller window size if our maximum memory value is smaller than the DMA window. After this change, the PCI devices successfully set up the 32-bit TCE table and kdump succeeds. The problem was seen on a Firestone machine originally. Fixes: aca6913f5551 ("powerpc/powernv/ioda2: Introduce helpers to allocate TCE pages") Signed-off-by: Nishanth Aravamudan diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c index 85cbc96eff6c..0d7967e31169 100644 --- a/arch/powerpc/platforms/powernv/pci-ioda.c +++ b/arch/powerpc/platforms/powernv/pci-ioda.c @@ -2077,10 +2077,17 @@ static long pnv_pci_ioda2_setup_default_config(struct pnv_ioda_pe *pe) { struct iommu_table *tbl = NULL; long rc; + /* + * In memory constrained environments, e.g. kdump kernel, the + * DMA window can be larger than available memory, which will + * cause errors later. + */ + __u64 window_size = + min((u64)pe->table_group.tce32_size, memory_hotplug_max()); rc = pnv_pci_ioda2_create_table(&pe->table_group, 0, IOMMU_PAGE_SHIFT_4K, - pe->table_group.tce32_size, + window_size, POWERNV_IOMMU_DEFAULT_LEVELS, &tbl); if (rc) { pe_err(pe, "Failed to create 32-bit TCE table, err %ld",