[PATCH v7 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel
Li, ZhenHua
zhen-hual at hp.com
Wed Jan 7 00:52:28 PST 2015
Well, that's quite good news.
Looking forward Takao's testing on his system.
Regards
Zhenhua
On 01/07/2015 04:28 PM, Baoquan He wrote:
> 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 at redhat.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 at redhat.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 at gmail.com>
>>>>> Signed-off-by: Li, Zhen-Hua <zhen-hual at hp.com>
>>>>> Signed-off-by: Takao Indoh <indou.takao at jp.fujitsu.com>
>>>>> Tested-by: Baoquan He <bhe at redhat.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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