Date:	Fri, 26 Dec 2014 16:27:42 +0900
From:	Takao Indoh <indou.takao@...fujitsu.com>
To:	<zhen-hual@...com>
CC:	<dwmw2@...radead.org>, <bhe@...hat.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>
Subject: Re: [PATCH 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel

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(-)
>>>
>>
> 
> 
> 


View attachment "log.txt" of type "text/plain" (51738 bytes)

Powered by blists - more mailing lists