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Created attachment 1191885 [details] unknown device in windows guest Description of problem: In RHEL7.3,fw_cfg device can be shown in windows guest with no driver installed which will lead to win2016 svvp test fail. RHEL7.2 qemu(qemu-kvm-rhev-2.3.0-31.el7.x86_64.) does not hit this issue. As it's too late to create such driver in rhel7.3,we hope qemu can create a flag that can be used to hide the fw_cfg device in windows guest. Version-Release number of selected component (if applicable): qemu-kvm-rhev-2.6.0-21.el7.x86_64 How reproducible: 100% Steps to Reproduce: 1.boot a windows server 2016 guest on rhel7.3 2.check in qtree (qemu) info qtree dev: fw_cfg_io, id "" iobase = 1296 (0x510) dma_iobase = 1300 (0x514) dma_enabled = true 3.check in windows guest in device manager(View-->resources by type),there is an unknown device(please check the screenshot) Actual results: There is an unknown device(please check the screenshot); When we run rhel7.3 svvp test with windows2016,it will automatically detect this device has no driver installed which will lead to svvp test fail. So I set test blocker keyword in this bug. Expected results: No unknown device shown in windows guest. Additional info: Following is Marcel's suggestion: https://bugzilla.redhat.com/show_bug.cgi?id=1246993#c14 I have some answers: The problem is not connected to the "dma-enabled" flag, but with a new feature added to the fw_cfg device: The possibility to see the fw_cfg data in the guest OS. The way they did it is by adding a node in the ACPI DSDT table for the fw_cfg device: Please see: https://lists.gnu.org/archive/html/qemu-devel/2016-02/msg04660.html for details. The way it is used in guest kernel can be seen here: https://lkml.org/lkml/2016/1/27/1650 I can confirm this is the issue, possible solutions are: - Add a Windows driver for it - Find a way to hide the device, by removing it from DSDT or using a an ACPI 'trick' to hide it from Windows guests - all that based on some property flag. I suggest to reply to the QEMU upstream thread and explain what is the exact issue for Windows guests asking for guidance.
Status update here: https://bugzilla.redhat.com/show_bug.cgi?id=1246993#c20
fw_cfg device is not shown in windows guest with https://brewweb.engineering.redhat.com/brew/taskinfo?taskID=11683896 thank you.
The less intrusive solution is to revert the patch adding the fw_cfg device to ACPI.
Fix included in qemu-kvm-rhev-2.6.0-23.el7
Reproduced the bz on qemu-kvm-rhev-2.6.0-20.el7.x86_64 and Verified it on qemu-kvm-rhev-2.6.0-23.el7.x86_64 Following is the details 1. Boot win2016 guest /usr/libexec/qemu-kvm \ -M pc \ -cpu SandyBridge \ -nodefaults -rtc base=utc \ -m 4G \ -smp 2,sockets=2,cores=1,threads=1 \ -enable-kvm \ -name rhel7.3 \ -k en-us \ -nodefaults \ -serial unix:/tmp/serial0,server,nowait \ -boot menu=on \ -qmp tcp:0:6666,server,nowait \ -vga qxl \ -vnc :2 \ -drive file=/home/bug/win2016.raw,if=none,id=drive-virtio-disk0,format=raw,cache=none,werror=stop,rerror=stop \ -device ide-hd,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 \ -monitor stdio \ 2. Check it on hmp and guest (qemu) info qtree dev: fw_cfg_io, id "" iobase = 1296 (0x510) dma_iobase = 1300 (0x514) dma_enabled = true dev: kvmclock, id "" dev: kvmvapic, id "" the unkown device disappeared in guest, please check the attachment Thanks Jing Zhao
Created attachment 1198914 [details] hide the unknown device
According to comment 7, marked it as verified
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://rhn.redhat.com/errata/RHBA-2016-2673.html