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

["Li, ZhenHua" <zhen-hual@hp.com>]

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Hi Takao Indoh,

Happy New Year, and thank you very much for you help.  The flush is quite
 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.

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.

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(-)
>>>>
>>
>>


[-- Attachment #2: patch_for_flush.patch --]
[-- Type: text/x-patch, Size: 1435 bytes --]

diff -urp a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
--- a/drivers/iommu/intel-iommu.c	2014-12-29 10:52:02.000000000 +0800
+++ b/drivers/iommu/intel-iommu.c	2014-12-29 09:36:23.000000000 +0800
@@ -5188,6 +5188,8 @@ static void __iommu_load_old_root_entry(
 		|| (!iommu->root_entry_old_phys))
 		return;
 	memcpy(iommu->root_entry, iommu->root_entry_old_virt, PAGE_SIZE);
+
+	__iommu_flush_cache(iommu, iommu->root_entry, PAGE_SIZE);
 }
 
 /*
@@ -5220,6 +5222,8 @@ static void __iommu_update_old_root_entr
 	to = iommu->root_entry_old_virt;
 	from = iommu->root_entry;
 	memcpy(to + start, from + start, size);
+
+	__iommu_flush_cache(iommu, to + start, size);
 }
 
 /*
diff -urp a/drivers/iommu/intel_irq_remapping.c b/drivers/iommu/intel_irq_remapping.c
--- a/drivers/iommu/intel_irq_remapping.c	2014-12-29 10:52:02.000000000 +0800
+++ b/drivers/iommu/intel_irq_remapping.c	2014-12-29 09:51:52.000000000 +0800
@@ -1350,6 +1350,9 @@ static int __iommu_load_old_irte(struct
 		iommu->ir_table->base_old_virt,
 		INTR_REMAP_TABLE_ENTRIES*sizeof(struct irte));
 
+	__iommu_flush_cache(iommu, iommu->ir_table->base,
+		INTR_REMAP_TABLE_ENTRIES*sizeof(struct irte));
+
 	return 0;
 }
 
@@ -1382,6 +1385,8 @@ static int __iommu_update_old_irte(struc
 	from = iommu->ir_table->base;
 	memcpy(to + start, from + start, size);
 
+	__iommu_flush_cache(iommu, to + start, size);
+
 	return 0;
 }
 #endif /* CONFIG_CRASH_DUMP */