RE: [PATCH v7 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel

From: Li, Zhen-Hua
Date: Wed Jan 07 2015 - 22:12:46 EST

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In reply to: Takao Indoh: "Re: [PATCH v7 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel"
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In your log, it seems something incorrect while copying pages.

Your last DMAR fault is:
DMAR:[fault reason 01] Present bit in root entry is clear

But this time, it is:
DMAR:[fault reason 05] PTE Write access is not set

So I think this line I added to this version , it works.
function intel_iommu_load_translation_tables, line:
__iommu_flush_cache(iommu, iommu->root_entry, PAGE_SIZE);

I checked the code, found I missed one flush in function copy_page_table.
How do you think we add one flush after this lines:

ret = copy_page_table(&dma_pte_next,
(p->val & VTD_PAGE_MASK),
shift-9, page_addr | (u << shift),
iommu, bus, devfn, dve, ppap);

+ __iommu_flush_cache(iommu, phys_to_virt(dma_pte_next),
+ VTD_PAGE_SIZE);

If this does not work, I have no ideas currently, need to dig the code more.

Regards
Zhenhua

-----Original Message-----
From: Takao Indoh [mailto:indou.takao@xxxxxxxxxxxxxx]
Sent: Thursday, January 08, 2015 9:00 AM
To: Li, Zhen-Hua; bhe@xxxxxxxxxx
Cc: dwmw2@xxxxxxxxxxxxx; joro@xxxxxxxxxx; vgoyal@xxxxxxxxxx; dyoung@xxxxxxxxxx; iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx; kexec@xxxxxxxxxxxxxxxxxxx; alex.williamson@xxxxxxxxxx; ddutile@xxxxxxxxxx; ishii.hironobu@xxxxxxxxxxxxxx; bhelgaas@xxxxxxxxxx; Hatch, Douglas B (HPS Linux PM); Hoemann, Jerry; Vaden, Tom (HP Server OS Architecture); Zhang, Li (Zoe@HPservers-Core-OE-PSC); Mitchell, Lisa (MCLinux in Fort Collins); billsumnerlinux@xxxxxxxxx; Wright, Randy (HP Servers Linux)
Subject: Re: [PATCH v7 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel

On 2015/01/07 17:52, Li, ZhenHua wrote:
> Well, that's quite good news.
> Looking forward Takao's testing on his system.

Unfortunately DMAR fault still occurs with this patch...
I attach console log.

Thanks,
Takao Indoh

>
> 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@xxxxxxxxxx]
>>>>>> 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@xxxxxxxxxx> 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@xxxxxxxxx>
>>>>>> Signed-off-by: Li, Zhen-Hua <zhen-hual@xxxxxx>
>>>>>> Signed-off-by: Takao Indoh <indou.takao@xxxxxxxxxxxxxx>
>>>>>> Tested-by: Baoquan He <bhe@xxxxxxxxxx>
>>>>>> ---
>>>>>> 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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Next message: Ezequiel Garcia: "Re: [PATCH 1/3] mtd: spi-nand framework"
Previous message: Jungseung Lee: "Re: [PATCH] kernel/module.c: Mark module state before set RO and NX regions"
In reply to: Takao Indoh: "Re: [PATCH v7 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]