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

From: Li, ZhenHua
Date: Mon Jan 05 2015 - 21:05:45 EST

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Thank you very much for your help.

I have found there are several places need flush, and I will send a new
version
of this patchset with the flush functions.

Regards
Zhenhua

On 01/06/2015 08:18 AM, Takao Indoh wrote:
> On 2014/12/29 12:15, Li, ZhenHua wrote:
>> Hi Takao Indoh,
>>
>> Happy New Year, and thank you very much for you help. The flush is quite
> Happy new year!
>
>> a problem, as there are several places the flush function should be called,
>> I think the flush should be placed in functions like __iommu_update_old_*.
>> Created a small patch for this, it is attached.
>>
>>
>>
>> As I cannot reproduce your problems on my system, so could you please try
>> these steps?
>> 1. Apply the latest patchset, including 9/10 and 10/10, and then apply the
>> attached patch_for_flush.patch. And then test the kernel.
> No inter-remap fault, but there is still DMAR fault message.
>
>> 2. If 1 does not fix the DMAR fault problems, then it might be caused by
>> 7/10, so please *unpatch* it from the kernel (others and the attached one
>> should be patched), and then test the kernel.
> DMAR fault still occurs. I'll dig iommu driver code to find out the
> reason.
>
> Thanks,
> Takao Indoh
>
>> Regards
>> Zhenhua
>>
>> On 12/26/2014 03:27 PM, Takao Indoh wrote:
>>> On 2014/12/26 15:46, Li, ZhenHua wrote:
>>>> Hi Takao Indoh,
>>>>
>>>> Thank you very much for your testing. I will add your update in next
>>>> version.
>>>> Also I think a flush for __iommu_update_old_root_entry is also necessary.
>>>>
>>>> Currently I have no idea about your fault, does it happen before or
>>>> during its loading? Could you send me your full kernel log as an
>>>> attachment?
>>> Sure, see attached file.
>>>
>>> I removed 9/10 and 10/10 patches from my kernel to avoid panic problem I
>>> reported in previous mail, and then tested kdump. So please ignore
>>> intr-remap fault message in log file. Also please ignore stack trace
>>> starting with the following message, it's a problem of my box.
>>>
>>> Flags mismatch irq 0. 00000080 (i801_smbus) vs. 00015a00 (timer)
>>>
>>> Thanks,
>>> Takao Indoh
>>>
>>>> Regards and Merry Christmas.
>>>> Zhenhua
>>>>
>>>> On 12/26/2014 01:13 PM, Takao Indoh wrote:
>>>>> Hi Zhen-Hua,
>>>>>
>>>>> I tested your patch and found two problems.
>>>>>
>>>>> [1]
>>>>> Kenel panic occurs during 2nd kernel boot.
>>>>>
>>>>> ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
>>>>> Kernel panic - not syncing: timer doesn't work through Interrupt-remapped IO-APIC
>>>>> CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.18.0 #25
>>>>> Hardware name: FUJITSU-SV PRIMERGY BX920 S2/D3030, BIOS 080015 Rev.3D81.3030 02/10/2012
>>>>> 0000000000000002 ffff880036167d08 ffffffff815b1c6a 0000000000000000
>>>>> ffffffff817f7670 ffff880036167d88 ffffffff815b19f1 0000000000000008
>>>>> ffff880036167d98 ffff880036167d38 ffffffff810a5d2f ffff880036167d98
>>>>> Call Trace:
>>>>> [<ffffffff815b1c6a>] dump_stack+0x48/0x5e
>>>>> [<ffffffff815b19f1>] panic+0xbb/0x1fa
>>>>> [<ffffffff810a5d2f>] ? vprintk_default+0x1f/0x30
>>>>> [<ffffffff814c6a6c>] panic_if_irq_remap+0x1c/0x20
>>>>> [<ffffffff81b53985>] check_timer+0x1e7/0x5ed
>>>>> [<ffffffff8129bd9d>] ? radix_tree_lookup+0xd/0x10
>>>>> [<ffffffff81b5413b>] setup_IO_APIC+0x261/0x292
>>>>> [<ffffffff81b50302>] native_smp_prepare_cpus+0x214/0x25d
>>>>> [<ffffffff81b41c65>] kernel_init_freeable+0x1dc/0x28c
>>>>> [<ffffffff815aaf00>] ? rest_init+0x80/0x80
>>>>> [<ffffffff815aaf0e>] kernel_init+0xe/0xf0
>>>>> [<ffffffff815b5d2c>] ret_from_fork+0x7c/0xb0
>>>>> [<ffffffff815aaf00>] ? rest_init+0x80/0x80
>>>>> ---[ end Kernel panic - not syncing: timer doesn't work through Interrupt-remapped IO-APIC
>>>>>
>>>>>
>>>>> This panic seems to be related to unflushed cache. I confirmed this
>>>>> problem was fixed by the following patch.
>>>>>
>>>>> --- a/drivers/iommu/intel_irq_remapping.c
>>>>> +++ b/drivers/iommu/intel_irq_remapping.c
>>>>> @@ -200,8 +200,13 @@ static int modify_irte(int irq, struct irte *irte_modified)
>>>>> set_64bit(&irte->high, irte_modified->high);
>>>>>
>>>>> #ifdef CONFIG_CRASH_DUMP
>>>>> - if (is_kdump_kernel())
>>>>> + if (is_kdump_kernel()) {
>>>>> __iommu_update_old_irte(iommu, index);
>>>>> + __iommu_flush_cache(iommu,
>>>>> + iommu->ir_table->base_old_virt +
>>>>> + index * sizeof(struct irte),
>>>>> + sizeof(struct irte));
>>>>> + }
>>>>> #endif
>>>>> __iommu_flush_cache(iommu, irte, sizeof(*irte));
>>>>>
>>>>>
>>>>> [2]
>>>>> Some DMAR error messages are still found in 2nd kernel boot.
>>>>>
>>>>> dmar: DRHD: handling fault status reg 2
>>>>> dmar: DMAR:[DMA Write] Request device [01:00.0] fault addr ffded000
>>>>> DMAR:[fault reason 01] Present bit in root entry is clear
>>>>>
>>>>> I confiremd your commit 1a2262 was already applied. Any idea?
>>>>>
>>>>> Thanks,
>>>>> Takao Indoh
>>>>>
>>>>>
>>>>> On 2014/12/22 18:15, 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 last of Bill's patchset:
>>>>>> https://lkml.org/lkml/2014/10/21/134
>>>>>> https://lkml.org/lkml/2014/12/15/121
>>>>>>
>>>>>> 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;
>>>>>>
>>>>>> This patchset should be applied with this one together:
>>>>>> https://lkml.org/lkml/2014/11/5/43
>>>>>> x86/iommu: fix incorrect bit operations in setting values
>>>>>>
>>>>>> Bill Sumner (5):
>>>>>> iommu/vt-d: Update iommu_attach_domain() and its callers
>>>>>> iommu/vt-d: Items required for kdump
>>>>>> iommu/vt-d: data types and functions used for kdump
>>>>>> iommu/vt-d: Add domain-id functions
>>>>>> iommu/vt-d: enable kdump support in iommu module
>>>>>>
>>>>>> Li, Zhen-Hua (10):
>>>>>> 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/vtd: assign new page table for dma_map
>>>>>> iommu/vt-d: Copy functions for irte
>>>>>> iommu/vt-d: Use old irte in kdump kernel
>>>>>>
>>>>>> drivers/iommu/intel-iommu.c | 1050 +++++++++++++++++++++++++++++++++--
>>>>>> drivers/iommu/intel_irq_remapping.c | 99 +++-
>>>>>> include/linux/intel-iommu.h | 18 +
>>>>>> 3 files changed, 1123 insertions(+), 44 deletions(-)
>>>>>>
>>>>
>

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Next message: Chen, Fan: "Re: [PATCH] eventfd: fix trivial typos in function eventfd_signal() comment"
Previous message: John Stultz: "Re: frequent lockups in 3.18rc4"
In reply to: Takao Indoh: "Re: [PATCH 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel"
Next in thread: Baoquan He: "Re: [PATCH 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel"
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