Re: [Xen-devel] [PATCH v3 0/4] x86/iommu: PVH Dom0 workarounds for missing RMRR entries

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Tue, Aug 07, 2018 at 08:29:49AM -0600, Tamas K Lengyel wrote:
> On Tue, Aug 7, 2018 at 8:04 AM Roger Pau Monne <roger.pau@xxxxxxxxxx> wrote:
> >
> > Hello,
> >
> > The following series implement a workaround for missing RMRR
> > entries for a PVH Dom0. It's based on the iommu_inclusive_mapping VTd
> > option.
> >
> > The PVH workaround identity maps all regions marked as reserved in the
> > memory map.
> >
> > Note that this workaround is enabled by default on Intel hardware. It's
> > also available to AMD hardware, although it's disabled by default in
> > that case.
> >
> > The series can be found at:
> >
> > git://xenbits.xen.org/people/royger/xen.git iommu_inclusive_v3
> >
> > Thanks, Roger.
> > Roger Pau Monne (4):
> >   iommu: introduce dom0-iommu option
> >   iommu: make iommu_inclusive_mapping a suboption of dom0-iommu
> >   dom0/pvh: change the order of the MMCFG initialization
> >   x86/iommu: add reserved dom0-iommu option to map reserved memory
> >     ranges
> >
> >  docs/misc/xen-command-line.markdown         | 47 +++++++++++
> >  xen/arch/x86/hvm/dom0_build.c               |  9 ++-
> >  xen/arch/x86/hvm/io.c                       |  5 ++
> >  xen/arch/x86/x86_64/mm.c                    |  3 +-
> >  xen/drivers/passthrough/amd/iommu_init.c    |  2 +-
> >  xen/drivers/passthrough/amd/pci_amd_iommu.c | 11 ++-
> >  xen/drivers/passthrough/arm/iommu.c         |  4 +
> >  xen/drivers/passthrough/iommu.c             | 62 +++++++++++++--
> >  xen/drivers/passthrough/vtd/extern.h        |  2 -
> >  xen/drivers/passthrough/vtd/iommu.c         | 25 +++---
> >  xen/drivers/passthrough/vtd/x86/vtd.c       | 58 +-------------
> >  xen/drivers/passthrough/x86/iommu.c         | 87 +++++++++++++++++++++
> >  xen/include/asm-x86/hvm/io.h                |  3 +
> >  xen/include/xen/iommu.h                     |  8 +-
> >  14 files changed, 240 insertions(+), 86 deletions(-)
> >
> > --
> 
> Hi Roger,
> I gave this branch a spin on a Dell XPS laptop booting UEFI with Linux
> 4.18-rc8. I was able to get dom0 to boot with PVH but the physical
> keyboard of the laptop stopped working, it works no problem with just
> Linux 4.18-rc8 or PV dom0, so I had to plug in a USB keyboard. After
> running for a minute or two the system starts to slow down to the
> point where it becomes unresponsive. The xl dmesg log is filled with
> this error:
> 
> (XEN) [VT-D]iommu.c:919: iommu_fault_status: Fault Overflow
> (XEN) [VT-D]iommu.c:921: iommu_fault_status: Primary Pending Fault
> (XEN) [VT-D]DMAR:[DMA Read] Request device [0000:00:02.0] fault addr
> 4625f3a000, iommu reg = ffff82c00181c000
> (XEN) [VT-D]DMAR: reason 06 - PTE Read access is not set
> (XEN) print_vtd_entries: iommu #0 dev 0000:00:02.0 gmfn 4625f3a

Is the gmfn always the same (0x4625f3a)?

> (XEN)     root_entry[00] = 273a18001
> (XEN)     context[10] = 2_27ba35001
> (XEN)     l4[000] = 9c0000027ba34107
> (XEN)     l3[118] = 8000000000000000
> (XEN)     l3[118] not present

Can you also paste the full xl dmesg log? I'm specially interested in
the memory map of the machine which is printed quite early during Xen
boot.

Thanks, Roger.

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