Re: [Xen-users] "It's disallowed to assign <device> with shared RMRR at <address> for Dom<N>" after upgrading to 4.6

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Mon, Aug 01, 2016 at 10:09:14PM -0400, Stephen Oberholtzer wrote:
> So I finally upgraded my system -- kernel 3.16 -> 4.6, Xen 4.5 -> 4.6, qemu
> 2.1 -> 2.6, and now my HVM domain with PCI passthrough won't start.
> 
> The first issue was that xl submits a now-invalid command line to qemu for
> an empty cdrom (qemu gives a truly bizarre error message here: "Must
> specify either driver or file").  I gave up and removed the drive entirely;
> hopefully I don't need to use that drive anytime soon.
> 
> The second issue is something about shared RMRRs. Unfortunately, I can't
> seem to get a lot of information on what's going on here; something about a
> security hole?
> 

Sharing RMRR is considered unsafe so it is disallowed by default, IIRC.

> xl create fails with the message:
> 
> libxl: error: libxl_create.c:1424:domcreate_attach_pci:
> libxl_device_pci_add failed: -3
> 
> I finally found in 'xl dmesg' this line:
> 
> (XEN) [VT-D] It's disallowed to assign 0000:00:14.0 with shared RMRR at
> <address?> for Dom4.
> (XEN) XEN_DOMCTL_assign_device: assign 0000:00:14.0 to dom4 failed (-1)
> 
> Unfortunately, I can't seem to find out how to understand what's going on
> here.
> How can I view these RMRRs to find out what's being shared? (I turned on
> every option I could think of for Xen's logging, but no luck.)
> How do I make my VM work again?
> 

Try `man xl.cfg' and search for rmrr. There are some new options for pci
passthrough.


Wei.

> 
> -- 
> -- Stevie-O
> Real programmers use COPY CON PROGRAM.EXE

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