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

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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