Re: [Xen-devel] [PATCH v16 4/9] x86: add multiboot2 protocol support for EFI platforms

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Tue, Mar 07, 2017 at 12:39:04AM +0100, Daniel Kiper wrote:
> On Wed, Feb 22, 2017 at 09:04:17AM -0800, Doug Goldstein wrote:
>
> [...]
>
> > I'm currently at ELC and then on vacation so I don't have access to any
> > of the machines currently myself. However the machine I most use to test
> > is a NUC5i5MYHE and a NUC5i3MYHE if you want to ask around if someone
> > has one internally. But that's why I gave QEMU as an example.
> >
> > I was using qemu master from a few weeks ago. I'll have to find the
> > revision for you. But the command line I use is:
> >
> > -enable-kvm -M pc-q35-2.8 -device intel-iommu -cpu host -m 2048 -smp 2
> > -drive if=pflash,format=raw,file=/tmp/tmp.EiR6ixmYzV -global
> > isa-debugcon.iobase=0x402 -debugcon file:/tmp/tmp.nuvEXUWfnA -monitor
> > stdio -chardev socket,host=127.0.0.1,port=25914,id=S0,server,nowait
> > -device isa-serial,chardev=S0 -device piix3-usb-uhci -device usb-tablet
> > -netdev id=net0,type=tap -device
> > virtio-net-pci,netdev=net0,mac=52:54:00:12:34:56 -boot order=n -device
> > qxl-vga -gdb tcp::14952
>
> Sadly, my colleagues and I are not able to reproduce the problem on any of
> machines available for us (available on the market and some development
> stuff in our labs). I did tests with QEMU (I am not able to run it with
> "-device intel-iommu" on my machine; I have to investigate this). Everything
> works. Joao did some tests on Intel NUC D34010WYK second generation.
> Everything works. So, Konrad ordered Intel NUC NUC5i3MYHE for me. I am
> waiting for delivery. Doug, could you tell me what distro, Xen, etc. you
> have installed on that NUC? I would like to test same config as yours on
> this machine.

Latest QEMU from git with intel-iommu device enabled works without any issue.
Though it looks that I found a bug in Xen IOMMU code. If I run Xen from master
in QEMU then QEMU complains and crashes:

  qemu-system-x86_64: /srv/dev/qemu/qemu_20170308/hw/i386/intel_iommu.c:1786: 
vtd_mem_write: Assertion `size == 4' failed.
  Aborted (core dumped)

So, I took a look at dma_msi_set_affinity() and found this:

  dmar_writeq(iommu->reg, DMAR_FEADDR_REG, msg.address);

It looks bogus because DMAR_FEADDR_REG is defined in spec as 32-bit wide.
So, applied this patch:

-    dmar_writeq(iommu->reg, DMAR_FEADDR_REG, msg.address);
+    dmar_writel(iommu->reg, DMAR_FEADDR_REG, msg.address_lo);
+    if (x2apic_enabled)
+        dmar_writel(iommu->reg, DMAR_FEUADDR_REG, msg.address_hi);

Ant it looks that right now everything works.

If patch make sense I can post it with proper commit message.

Daniel

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