[Bug 109456] KVM VFIO guest X hang with guest kernel > 4.15 - bugzilla-daemon

From: bugzilla-daemon@freedesktop.org
To: dri-devel@lists.freedesktop.org
Subject: [Bug 109456] KVM VFIO guest X hang with guest kernel > 4.15
Date: Fri, 25 Jan 2019 11:03:28 +0000	[thread overview]
Message-ID: <bug-109456-502@http.bugs.freedesktop.org/> (raw)

[-- Attachment #1.1: Type: text/plain, Size: 1574 bytes --]

https://bugs.freedesktop.org/show_bug.cgi?id=109456

            Bug ID: 109456
           Summary: KVM VFIO guest X hang with guest kernel > 4.15
           Product: DRI
           Version: XOrg git
          Hardware: x86-64 (AMD64)
                OS: Linux (All)
            Status: NEW
          Severity: normal
          Priority: medium
         Component: DRM/AMDgpu
          Assignee: dri-devel@lists.freedesktop.org
          Reporter: libgradev@gmail.com

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).

-- 
You are receiving this mail because:
You are the assignee for the bug.

[-- Attachment #1.2: Type: text/html, Size: 2884 bytes --]

[-- Attachment #2: Type: text/plain, Size: 160 bytes --]

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel