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Message-ID: <20150107082813.GB16050@dhcp-16-116.nay.redhat.com>
Date: Wed, 7 Jan 2015 16:28:13 +0800
From: Baoquan He <bhe@...hat.com>
To: "Li, ZhenHua" <zhen-hual@...com>
Cc: dwmw2@...radead.org, indou.takao@...fujitsu.com, joro@...tes.org,
vgoyal@...hat.com, dyoung@...hat.com,
iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
linux-pci@...r.kernel.org, kexec@...ts.infradead.org,
alex.williamson@...hat.com, ddutile@...hat.com,
ishii.hironobu@...fujitsu.com, bhelgaas@...gle.com,
doug.hatch@...com, jerry.hoemann@...com, tom.vaden@...com,
li.zhang6@...com, lisa.mitchell@...com, billsumnerlinux@...il.com,
rwright@...com
Subject: Re: [PATCH v7 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel
On 01/07/15 at 01:25pm, Li, ZhenHua wrote:
> It is same as the last one I send to you yesterday.
>
> The continuous memory that needed for data in this patchset:
> RE: PAGE_SIZE, 4096 Bytes;
> IRTE: 65536 * 16 ; 1M Bytes;
>
> It should use same memory as the old versions of this patchset. The
> changes for the last version do not need more memory.
Hi Zhenhua,
It was my mistake because I didn't strip the debug info of modules, then
initramfs is bloated very big. Just now I tested the latest version, it
works well and dump is successful. No dmar fault and intr-remap fault
seen any more, good job!
Thanks
Baoquan
>
> Regards
> Zhenhua
>
> On 01/07/2015 01:02 PM, Baoquan He wrote:
> >On 01/07/15 at 12:11pm, Li, ZhenHua wrote:
> >>Many thanks to Takao Indoh and Baoquan He, for your testing on more
> >>different systems.
> >>
> >>The calling of flush functions are added to this version.
> >>
> >>The usage of __iommu_flush_cache function :
> >>1. Fixes a dump on Takao's system.
> >>2. Reduces the count of faults on Baoquan's system.
> >
> >I am testing the version you sent to me yesterday afternoon. Is that
> >different with this patchset? I found your patchset man reserve a big
> >contiguous memory region under 896M, this will cause the crashkernel
> >reservation failed when I set crashkernel=320M. The reason I increase
> >the crashkerenl reservation to 320M is 256M is not enough and cause OOM
> >when that patchset is tested.
> >
> >I am checking what happened.
> >
> >
> >Thanks
> >Baoquan
> >
> >>
> >>Regards
> >>Zhenhua
> >>
> >>On 01/07/2015 12:04 PM, Li, Zhen-Hua wrote:
> >>>This patchset is an update of Bill Sumner's patchset, implements a fix for:
> >>>If a kernel boots with intel_iommu=on on a system that supports intel vt-d,
> >>>when a panic happens, the kdump kernel will boot with these faults:
> >>>
> >>> dmar: DRHD: handling fault status reg 102
> >>> dmar: DMAR:[DMA Read] Request device [01:00.0] fault addr fff80000
> >>> DMAR:[fault reason 01] Present bit in root entry is clear
> >>>
> >>> dmar: DRHD: handling fault status reg 2
> >>> dmar: INTR-REMAP: Request device [[61:00.0] fault index 42
> >>> INTR-REMAP:[fault reason 34] Present field in the IRTE entry is clear
> >>>
> >>>On some system, the interrupt remapping fault will also happen even if the
> >>>intel_iommu is not set to on, because the interrupt remapping will be enabled
> >>>when x2apic is needed by the system.
> >>>
> >>>The cause of the DMA fault is described in Bill's original version, and the
> >>>INTR-Remap fault is caused by a similar reason. In short, the initialization
> >>>of vt-d drivers causes the in-flight DMA and interrupt requests get wrong
> >>>response.
> >>>
> >>>To fix this problem, we modifies the behaviors of the intel vt-d in the
> >>>crashdump kernel:
> >>>
> >>>For DMA Remapping:
> >>>1. To accept the vt-d hardware in an active state,
> >>>2. Do not disable and re-enable the translation, keep it enabled.
> >>>3. Use the old root entry table, do not rewrite the RTA register.
> >>>4. Malloc and use new context entry table and page table, copy data from the
> >>> old ones that used by the old kernel.
> >>>5. to use different portions of the iova address ranges for the device drivers
> >>> in the crashdump kernel than the iova ranges that were in-use at the time
> >>> of the panic.
> >>>6. After device driver is loaded, when it issues the first dma_map command,
> >>> free the dmar_domain structure for this device, and generate a new one, so
> >>> that the device can be assigned a new and empty page table.
> >>>7. When a new context entry table is generated, we also save its address to
> >>> the old root entry table.
> >>>
> >>>For Interrupt Remapping:
> >>>1. To accept the vt-d hardware in an active state,
> >>>2. Do not disable and re-enable the interrupt remapping, keep it enabled.
> >>>3. Use the old interrupt remapping table, do not rewrite the IRTA register.
> >>>4. When ioapic entry is setup, the interrupt remapping table is changed, and
> >>> the updated data will be stored to the old interrupt remapping table.
> >>>
> >>>Advantages of this approach:
> >>>1. All manipulation of the IO-device is done by the Linux device-driver
> >>> for that device.
> >>>2. This approach behaves in a manner very similar to operation without an
> >>> active iommu.
> >>>3. Any activity between the IO-device and its RMRR areas is handled by the
> >>> device-driver in the same manner as during a non-kdump boot.
> >>>4. If an IO-device has no driver in the kdump kernel, it is simply left alone.
> >>> This supports the practice of creating a special kdump kernel without
> >>> drivers for any devices that are not required for taking a crashdump.
> >>>5. Minimal code-changes among the existing mainline intel vt-d code.
> >>>
> >>>Summary of changes in this patch set:
> >>>1. Added some useful function for root entry table in code intel-iommu.c
> >>>2. Added new members to struct root_entry and struct irte;
> >>>3. Functions to load old root entry table to iommu->root_entry from the memory
> >>> of old kernel.
> >>>4. Functions to malloc new context entry table and page table and copy the data
> >>> from the old ones to the malloced new ones.
> >>>5. Functions to enable support for DMA remapping in kdump kernel.
> >>>6. Functions to load old irte data from the old kernel to the kdump kernel.
> >>>7. Some code changes that support other behaviours that have been listed.
> >>>8. In the new functions, use physical address as "unsigned long" type, not
> >>> pointers.
> >>>
> >>>Original version by Bill Sumner:
> >>> https://lkml.org/lkml/2014/1/10/518
> >>> https://lkml.org/lkml/2014/4/15/716
> >>> https://lkml.org/lkml/2014/4/24/836
> >>>
> >>>Zhenhua's updates:
> >>> https://lkml.org/lkml/2014/10/21/134
> >>> https://lkml.org/lkml/2014/12/15/121
> >>> https://lkml.org/lkml/2014/12/22/53
> >>>
> >>>Changelog[v7]:
> >>> 1. Use __iommu_flush_cache to flush the data to hardware.
> >>>
> >>>Changelog[v6]:
> >>> 1. Use "unsigned long" as type of physical address.
> >>> 2. Use new function unmap_device_dma to unmap the old dma.
> >>> 3. Some small incorrect bits order for aw shift.
> >>>
> >>>Changelog[v5]:
> >>> 1. Do not disable and re-enable traslation and interrupt remapping.
> >>> 2. Use old root entry table.
> >>> 3. Use old interrupt remapping table.
> >>> 4. New functions to copy data from old kernel, and save to old kernel mem.
> >>> 5. New functions to save updated root entry table and irte table.
> >>> 6. Use intel_unmap to unmap the old dma;
> >>> 7. Allocate new pages while driver is being loaded.
> >>>
> >>>Changelog[v4]:
> >>> 1. Cut off the patches that move some defines and functions to new files.
> >>> 2. Reduce the numbers of patches to five, make it more easier to read.
> >>> 3. Changed the name of functions, make them consistent with current context
> >>> get/set functions.
> >>> 4. Add change to function __iommu_attach_domain.
> >>>
> >>>Changelog[v3]:
> >>> 1. Commented-out "#define DEBUG 1" to eliminate debug messages.
> >>> 2. Updated the comments about changes in each version.
> >>> 3. Fixed: one-line added to Copy-Translations patch to initialize the iovad
> >>> struct as recommended by Baoquan He [bhe@...hat.com]
> >>> init_iova_domain(&domain->iovad, DMA_32BIT_PFN);
> >>>
> >>>Changelog[v2]:
> >>> The following series implements a fix for:
> >>> A kdump problem about DMA that has been discussed for a long time. That is,
> >>> when a kernel panics and boots into the kdump kernel, DMA started by the
> >>> panicked kernel is not stopped before the kdump kernel is booted and the
> >>> kdump kernel disables the IOMMU while this DMA continues. This causes the
> >>> IOMMU to stop translating the DMA addresses as IOVAs and begin to treat
> >>> them as physical memory addresses -- which causes the DMA to either:
> >>> (1) generate DMAR errors or
> >>> (2) generate PCI SERR errors or
> >>> (3) transfer data to or from incorrect areas of memory. Often this
> >>> causes the dump to fail.
> >>>
> >>>Changelog[v1]:
> >>> The original version.
> >>>
> >>>Changed in this version:
> >>>1. Do not disable and re-enable traslation and interrupt remapping.
> >>>2. Use old root entry table.
> >>>3. Use old interrupt remapping table.
> >>>4. Use "unsigned long" as physical address.
> >>>5. Use intel_unmap to unmap the old dma;
> >>>
> >>>Baoquan He <bhe@...hat.com> helps testing this patchset.
> >>>
> >>> iommu/vt-d: Update iommu_attach_domain() and its callers
> >>> iommu/vt-d: Items required for kdump
> >>> iommu/vt-d: Add domain-id functions
> >>> iommu/vt-d: functions to copy data from old mem
> >>> iommu/vt-d: Add functions to load and save old re
> >>> iommu/vt-d: datatypes and functions used for kdump
> >>> iommu/vt-d: enable kdump support in iommu module
> >>> iommu/vt-d: assign new page table for dma_map
> >>> iommu/vt-d: Copy functions for irte
> >>> iommu/vt-d: Use old irte in kdump kernel
> >>>
> >>>Signed-off-by: Bill Sumner <billsumnerlinux@...il.com>
> >>>Signed-off-by: Li, Zhen-Hua <zhen-hual@...com>
> >>>Signed-off-by: Takao Indoh <indou.takao@...fujitsu.com>
> >>>Tested-by: Baoquan He <bhe@...hat.com>
> >>>---
> >>> drivers/iommu/intel-iommu.c | 1050 +++++++++++++++++++++++++++++++++--
> >>> drivers/iommu/intel_irq_remapping.c | 104 +++-
> >>> include/linux/intel-iommu.h | 18 +
> >>> 3 files changed, 1130 insertions(+), 42 deletions(-)
> >>>
> >>
>
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