[Xen-devel] Re: [Xen-users] Re: VT-D RMRR is incorrect

[Christian Tramnitz <chris.ace@xxxxxxx>]

Ross Philipson schrieb:
> Hi folks,
>
> This sounds a lot like an issue I am working on right now. A recent 
> change to the vtd code changed the way the 1 to 1 page mapping for dom0 
> is done (look at intel_iommu_domain_init() for dom0). The change was to 
> query the e820 map for memory regions that were usable RAM and only map 
> those into the iommus for dom0. Thus reserved regions were no longer 
> mapped in. When the RMRR values do not report the correct values for 
> required 1 to 1 reserved memory regions, the needed regions do not get 
> mapped in. Thus device DMA to these regions causes vtd faults and in out 
> case a hang. It is indeed a BIOS bug; perhaps this is the same issue you 
> are seeing?
> Anyway, I am working on a workaround that I will be pushing upstream 
> this week. A parameter will allow you to include reserved memory regions 
> in the mappings. It is not ideal (less secure) but better than hanging 
> or crashing…
Hi Ross,

I tried your patch from you other post, but even with the new parameter 
enabled I still get the DMAR error messages and vt-d being disabled:
(XEN) Command line: dom0_mem=1024M iommu=1 iommu_include_reserved=1
...
(XEN) [VT-D]dmar.c:473: Host address width 39
(XEN) [VT-D]dmar.c:482: found ACPI_DMAR_DRHD
(XEN) [VT-D]dmar.c:337: dmaru->address = fbfff000
(XEN) [VT-D]dmar.c:288: found endpoint: bdf = 0:1b.0
(XEN) [VT-D]dmar.c:482: found ACPI_DMAR_DRHD
(XEN) [VT-D]dmar.c:337: dmaru->address = fbffe000
(XEN) [VT-D]dmar.c:294: found IOAPIC: bdf = f0:1f.7
(XEN) [VT-D]dmar.c:294: found IOAPIC: bdf = 0:13.0
(XEN) [VT-D]dmar.c:346: found INCLUDE_ALL
(XEN) [VT-D]dmar.c:486: found ACPI_DMAR_RMRR
(XEN) [VT-D]dmar.c:288: found endpoint: bdf = 0:1d.0
(XEN) [VT-D]dmar.c:288: found endpoint: bdf = 0:1d.1
(XEN) [VT-D]dmar.c:288: found endpoint: bdf = 0:1d.2
(XEN) [VT-D]dmar.c:288: found endpoint: bdf = 0:1d.7
(XEN) [VT-D]dmar.c:288: found endpoint: bdf = 0:1a.0
(XEN) [VT-D]dmar.c:288: found endpoint: bdf = 0:1a.1
(XEN) [VT-D]dmar.c:288: found endpoint: bdf = 0:1a.2
(XEN) [VT-D]dmar.c:288: found endpoint: bdf = 0:1a.7
(XEN) [VT-D]dmar.c:486: found ACPI_DMAR_RMRR
(XEN) [VT-D]dmar.c:376: RMRR error: base_addr bf7dc000 end_address bf7dbfff
(XEN) Failed to parse ACPI DMAR.  Disabling VT-d.


Best regards,
   Christian


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