On 01/12/15 at 04:00pm, Li, ZhenHua wrote: > Comparing to v7, this version adds only a few lines code: > > In function copy_page_table, > > + __iommu_flush_cache(iommu, phys_to_virt(dma_pte_next), > + VTD_PAGE_SIZE); So this adding fixs the reported dmar fault on Takao's system, right? > > > On 01/12/2015 03:06 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 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 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 > > > >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 at 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 at redhat.com> helps testing this patchset. > >Takao Indoh <indou.takao at jp.fujitsu.com> gives valuable suggestions. > > > > 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/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 > > > >Signed-off-by: Bill Sumner <billsumnerlinux at gmail.com> > >Signed-off-by: Li, Zhen-Hua <zhen-hual at hp.com> > >Signed-off-by: Takao Indoh <indou.takao at jp.fujitsu.com> > >Tested-by: Baoquan He <bhe at redhat.com> > >--- > > drivers/iommu/intel-iommu.c | 1054 +++++++++++++++++++++++++++++++++-- > > drivers/iommu/intel_irq_remapping.c | 104 +++- > > include/linux/intel-iommu.h | 18 + > > 3 files changed, 1134 insertions(+), 42 deletions(-) > > >
