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<base href="https://bugs.freedesktop.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - KVM VFIO guest X hang with guest kernel > 4.15"
href="https://bugs.freedesktop.org/show_bug.cgi?id=109456">109456</a>
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<th>Summary</th>
<td>KVM VFIO guest X hang with guest kernel > 4.15
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<th>Product</th>
<td>DRI
</td>
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<th>Version</th>
<td>XOrg git
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<th>Hardware</th>
<td>x86-64 (AMD64)
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<th>OS</th>
<td>Linux (All)
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>medium
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<th>Component</th>
<td>DRM/AMDgpu
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<th>Assignee</th>
<td>dri-devel@lists.freedesktop.org
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<th>Reporter</th>
<td>libgradev@gmail.com
</td>
</tr></table>
<p>
<div>
<pre>Hi
Host: Arch running kernel 4.20.3 / Qemu 3.1
Guest: Ubuntu 18.04.1 (tried Ubuntu 18.10 also) with any kernel after 4.15
Driver: Happens with current stable, git from Padoka PPA and amdgpu-pro 18.50
Issue: Vega 64 passed through to guest causes X to hang on boot using 100% CPU
for one of the passed through cores for the Xorg process. X never starts with
the stopping point being 'LoadModule: "dri2"'. I cannot see any relevant errors
in Xorg.log or the KRB - though it's easily reproducible. The system is still
alive and can be ssh'd into.
Adding the nomodeset kernel option allows the guest to boot to GUI (albeit
without acceleration).
Details: With Qemu 3.0 having more than ~12GB RAM assigned to the guest causes
this behaviour. With Qemu 3.1 the amount of RAM is irrelevant - the hang always
occurs.
Believe this is related to one of the GPU reset patches added to the 4.16
kernel as the guest boots fine with Qemu 3.0/3.1 and guest kernel 4.15 (tested
up to 16GB guest RAM).</pre>
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