Re: [PATCH v11 0/10] iommu/vt-d: Fix intel vt-d faults in kdump kernel

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

Hi Joerg,

Testing from HP: passed.
Testing from He Baoquan(Redhat): passed

The problem that dmar fault came again when running v10 with latest
kernel is fixed.
And I think there is no need to update the code to a new version now.

So please tell me if there are still any code need to be changed.

Thanks
Zhenhua

On 05/13/2015 09:54 AM, Li, ZhenHua wrote:
> One thing must be pointed out:
> There is a known issue that hpsa driver cannot work well in kdump
> kernel. And this patchset is not intended to fix this problem.
>
> So this patchset cannot work with HP smart array devices which need hpsa
> driver.
>
> On 05/11/2015 05:52 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, copy data from the old ones
>> that
>>     used by the old kernel.
>> 5. Keep using the old page tables before driver is loaded.
>> 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 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
>>      https://lkml.org/lkml/2015/1/6/1166
>>      https://lkml.org/lkml/2015/1/12/35
>>      https://lkml.org/lkml/2015/3/19/33
>>      https://lkml.org/lkml/2015/4/10/135
>>
>> Changelog[v11]:
>>      1. Fix some conflicts with the latest upstream kernel.
>>         Add flush in iommu_context_addr
>>
>> Changelog[v10]:
>>      1. Do not use CONFIG_CRASH_DUMP and is_kdump_kernel().
>>         Use one flag which stores the te and ir status in last kernel:
>>             iommu->pre_enabled_trans
>>             iommu->pre_enabled_ir
>>
>> Changelog[v9]:
>>      1. Add new function iommu_attach_domain_with_id.
>>      2. Do not copy old page tables, keep using the old ones.
>>      3. Remove functions:
>>             intel_iommu_did_to_domain_values_entry
>>             intel_iommu_get_dids_from_old_kernel
>>             device_to_domain_id
>>             copy_page_addr
>>             copy_page_table
>>             copy_context_entry
>>             copy_context_entry_table
>>      4. Add new function device_to_existing_context_entry.
>>
>> Changelog[v8]:
>>      1. Add a missing __iommu_flush_cache in function copy_page_table.
>>
>> 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@redhat.com]
>>            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@redhat.com> helps testing this patchset.
>> Takao Indoh <indou.takao@jp.fujitsu.com> gives valuable suggestions.
>>
>> Li, Zhen-Hua (10):
>>    iommu/vt-d: New function to attach domain with id
>>    iommu/vt-d: Items required for kdump
>>    iommu/vt-d: Function to get existing context entry
>>    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
>>
>>   drivers/iommu/intel-iommu.c         | 536
>> ++++++++++++++++++++++++++++++++++--
>>   drivers/iommu/intel_irq_remapping.c |  96 ++++++-
>>   include/linux/intel-iommu.h         |  16 ++
>>   3 files changed, 623 insertions(+), 25 deletions(-)
>>
>