概括一下我的情况，我目前正在运行 Ubuntu MATE。几天前，我决定通过 KVM 和 Windows 10 运行游戏虚拟机来玩 Master Chief 系列。在这样做的时候，我意识到它使用自己的显示器（我想将我的两个大显示器都连接到我的 GPU）和输入设备，而且如果我想同时运行 CPU 密集型应用程序（例如浏览器），它会使我的主机操作系统严重滞后。
因此，我决定利用多个虚拟机，只使用一个小型的专用主机操作系统（可能是带有 XFCE 的 Debian），并在 Windows 虚拟机旁边创建一个 Ubuntu MATE 虚拟机作为我的“工作站”PC。我可以在我的大屏幕上浏览和工作，而不必担心窥镜或弄乱电缆之类的事情。此外，我可以暂停该虚拟机以运行 Windows 虚拟机并节省资源，至少我是这么理解的。Linux 虚拟机不需要强大的显卡，因为我不会在上面玩游戏，我只是使用 GPU 直通来轻松使用我的大显示器。请告诉我这是不是一个坏主意，或者是否有更好的方法。
我假设这将有效，因为可以在多个虚拟机上使用 GPU 直通，只要虚拟机不同时运行（我认为暂停或休眠的虚拟机“未运行”），它就可以工作。如果这可能会导致问题，请告诉我。
我的 Windows 10 运行良好（偶尔会卡顿，整体性能还算合理，但速度可以更快），在我的大型显示器上显示效果很好，使用游戏鼠标和键盘也很好。它与 GPU Passthrough 配合得很好。
然而，我的主力虚拟机却出了问题。
我在客户机上安装了 Ubuntu MATE，并在虚拟机管理器中设置了 GPU 直通。但它从未显示在我的显示器上，我只能使用虚拟机管理器中的图形控制台来查看它。
当我在客户端上运行 screenfetch 时，它会报告我的 GPU 为llvmpipe (LLVM 9.0, 256 bits)
lspci -k显示我的 PCI-E 显卡正在使用nvidia内核驱动程序。我使用的是“附加驱动程序”中选择的版本 435。我也nvidia proprietary driver metapackage试过了，但没有成功。nouveau
我怀疑 Ubuntu MATE 没有使用正确的显示驱动程序。在显示设置中，它只知道一个名为“虚拟 1”的“未知”显示器。
当我运行时，nvidia-settings我收到错误ERROR: An internal driver error occurred，并且 NVidia 控制面板窗口完全空白，没有任何控件。我最初怀疑 NVIDIA 故意拒绝在虚拟机上工作，Windows 就是这种情况，所以我在其 XML 文件中添加了标准部分以隐藏 nvidia，即这个
<hyperv>
<vendor_id state='on' value='whatever'/>
</hyperv>
我注意到“启动序列”（带有点的绿色 Ubuntu MATE 符号）经常出现在大显示器上，但是当操作系统正常启动时它们会丢失信号。
这是我的 ubuntu MATE 客户机的 XML 文件：
<domain type='kvm'>
<name>ubuntu-mate-workstation</name>
<uuid>bd317e3a-61a0-468e-ac1b-aa260de83c67</uuid>
<metadata>
<libosinfo:libosinfo xmlns:libosinfo="http://libosinfo.org/xmlns/libvirt/domain/1.0">
<libosinfo:os id="http://ubuntu.com/ubuntu/18.04"/>
</libosinfo:libosinfo>
</metadata>
<memory unit='KiB'>8192000</memory>
<currentMemory unit='KiB'>8192000</currentMemory>
<vcpu placement='static'>2</vcpu>
<os>
<type arch='x86_64' machine='pc-q35-4.0'>hvm</type>
<loader readonly='yes' type='pflash'>/usr/share/OVMF/OVMF_CODE.fd</loader>
<nvram>/var/lib/libvirt/qemu/nvram/ubuntu-mate-workstation_VARS.fd</nvram>
<bootmenu enable='yes'/>
</os>
<features>
<acpi/>
<apic/>
<hyperv>
<vendor_id state='on' value='whatever'/>
</hyperv>
<vmport state='off'/>
</features>
<cpu mode='host-model' check='partial'>
<model fallback='allow'/>
</cpu>
<clock offset='utc'>
<timer name='rtc' tickpolicy='catchup'/>
<timer name='pit' tickpolicy='delay'/>
<timer name='hpet' present='no'/>
</clock>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>destroy</on_crash>
<pm>
<suspend-to-mem enabled='no'/>
<suspend-to-disk enabled='no'/>
</pm>
<devices>
<emulator>/usr/bin/qemu-system-x86_64</emulator>
<disk type='file' device='disk'>
<driver name='qemu' type='qcow2'/>
<source file='/var/lib/libvirt/images/ubuntu-mate-workstation.qcow2'/>
<target dev='vda' bus='virtio'/>
<boot order='1'/>
<address type='pci' domain='0x0000' bus='0x03' slot='0x00' function='0x0'/>
</disk>
<disk type='file' device='cdrom'>
<driver name='qemu' type='raw'/>
<target dev='sda' bus='sata'/>
<readonly/>
<boot order='2'/>
<address type='drive' controller='0' bus='0' target='0' unit='0'/>
</disk>
<controller type='usb' index='0' model='ich9-ehci1'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x7'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci1'>
<master startport='0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x0' multifunction='on'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci2'>
<master startport='2'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x1'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci3'>
<master startport='4'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x2'/>
</controller>
<controller type='sata' index='0'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
</controller>
<controller type='pci' index='0' model='pcie-root'/>
<controller type='pci' index='1' model='pcie-root-port'>
<model name='pcie-root-port'/>
<target chassis='1' port='0x10'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0' multifunction='on'/>
</controller>
<controller type='pci' index='2' model='pcie-root-port'>
<model name='pcie-root-port'/>
<target chassis='2' port='0x11'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x1'/>
</controller>
<controller type='pci' index='3' model='pcie-root-port'>
<model name='pcie-root-port'/>
<target chassis='3' port='0x12'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x2'/>
</controller>
<controller type='pci' index='4' model='pcie-root-port'>
<model name='pcie-root-port'/>
<target chassis='4' port='0x13'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x3'/>
</controller>
<controller type='pci' index='5' model='pcie-root-port'>
<model name='pcie-root-port'/>
<target chassis='5' port='0x14'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x4'/>
</controller>
<controller type='pci' index='6' model='pcie-root-port'>
<model name='pcie-root-port'/>
<target chassis='6' port='0x15'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x5'/>
</controller>
<controller type='pci' index='7' model='pcie-root-port'>
<model name='pcie-root-port'/>
<target chassis='7' port='0x16'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x6'/>
</controller>
<controller type='virtio-serial' index='0'>
<address type='pci' domain='0x0000' bus='0x02' slot='0x00' function='0x0'/>
</controller>
<interface type='network'>
<mac address='52:54:00:d7:41:1e'/>
<source network='default'/>
<model type='virtio'/>
<address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
</interface>
<serial type='pty'>
<target type='isa-serial' port='0'>
<model name='isa-serial'/>
</target>
</serial>
<console type='pty'>
<target type='serial' port='0'/>
</console>
<channel type='unix'>
<target type='virtio' name='org.qemu.guest_agent.0'/>
<address type='virtio-serial' controller='0' bus='0' port='1'/>
</channel>
<channel type='spicevmc'>
<target type='virtio' name='com.redhat.spice.0'/>
<address type='virtio-serial' controller='0' bus='0' port='2'/>
</channel>
<input type='tablet' bus='usb'>
<address type='usb' bus='0' port='1'/>
</input>
<input type='mouse' bus='ps2'/>
<input type='keyboard' bus='ps2'/>
<graphics type='spice' autoport='yes'>
<listen type='address'/>
<image compression='off'/>
<gl enable='no' rendernode='/dev/dri/by-path/pci-0000:00:02.0-render'/>
</graphics>
<sound model='ich9'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x1b' function='0x0'/>
</sound>
<video>
<model type='virtio' heads='1' primary='yes'>
<acceleration accel3d='yes'/>
</model>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
</video>
<hostdev mode='subsystem' type='pci' managed='yes'>
<source>
<address domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
</source>
<address type='pci' domain='0x0000' bus='0x06' slot='0x00' function='0x0'/>
</hostdev>
<hostdev mode='subsystem' type='pci' managed='yes'>
<source>
<address domain='0x0000' bus='0x01' slot='0x00' function='0x1'/>
</source>
<address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/>
</hostdev>
<redirdev bus='usb' type='spicevmc'>
<address type='usb' bus='0' port='2'/>
</redirdev>
<redirdev bus='usb' type='spicevmc'>
<address type='usb' bus='0' port='3'/>
</redirdev>
<memballoon model='virtio'>
<address type='pci' domain='0x0000' bus='0x04' slot='0x00' function='0x0'/>
</memballoon>
<rng model='virtio'>
<backend model='random'>/dev/urandom</backend>
<address type='pci' domain='0x0000' bus='0x05' slot='0x00' function='0x0'/>
</rng>
</devices>
</domain>
这是我的 Windows 机器的 XML
<domain type='kvm'>
<name>win10</name>
<uuid>dda109fe-ba6d-45b1-833f-4b479895262f</uuid>
<metadata>
<libosinfo:libosinfo xmlns:libosinfo="http://libosinfo.org/xmlns/libvirt/domain/1.0">
<libosinfo:os id="http://microsoft.com/win/10"/>
</libosinfo:libosinfo>
</metadata>
<memory unit='KiB'>12800000</memory>
<currentMemory unit='KiB'>12800000</currentMemory>
<vcpu placement='static'>4</vcpu>
<os>
<type arch='x86_64' machine='pc-q35-4.0'>hvm</type>
<loader readonly='yes' type='pflash'>/usr/share/OVMF/OVMF_CODE.fd</loader>
<nvram>/var/lib/libvirt/qemu/nvram/win10_VARS.fd</nvram>
<bootmenu enable='yes'/>
</os>
<features>
<acpi/>
<apic/>
<hyperv>
<relaxed state='on'/>
<vapic state='on'/>
<spinlocks state='on' retries='8191'/>
<vendor_id state='on' value='whatever'/>
</hyperv>
<kvm>
<hidden state='on'/>
</kvm>
<vmport state='off'/>
</features>
<cpu mode='host-model' check='partial'>
<model fallback='allow'/>
</cpu>
<clock offset='localtime'>
<timer name='rtc' tickpolicy='catchup'/>
<timer name='pit' tickpolicy='delay'/>
<timer name='hpet' present='no'/>
<timer name='hypervclock' present='yes'/>
</clock>
<on_poweroff>destroy</on_poweroff>
<on_reboot>restart</on_reboot>
<on_crash>destroy</on_crash>
<pm>
<suspend-to-mem enabled='no'/>
<suspend-to-disk enabled='no'/>
</pm>
<devices>
<emulator>/usr/bin/qemu-system-x86_64</emulator>
<disk type='file' device='disk'>
<driver name='qemu' type='qcow2' cache='writeback'/>
<source file='/var/lib/libvirt/images/win10.qcow2'/>
<target dev='vda' bus='virtio'/>
<boot order='2'/>
<address type='pci' domain='0x0000' bus='0x08' slot='0x00' function='0x0'/>
</disk>
<disk type='file' device='cdrom'>
<driver name='qemu' type='raw'/>
<source file='/home/paul/Downloads/virtio-win-0.1.171.iso'/>
<target dev='sdb' bus='sata'/>
<readonly/>
<boot order='3'/>
<address type='drive' controller='0' bus='0' target='0' unit='1'/>
</disk>
<disk type='file' device='cdrom'>
<driver name='qemu' type='raw'/>
<source file='/media/paul/YEE/Installers/OS Images/Windows 10 x64 November 2019/Win10_1909_English_x64.iso'/>
<target dev='sdc' bus='sata'/>
<readonly/>
<boot order='1'/>
<address type='drive' controller='0' bus='0' target='0' unit='2'/>
</disk>
<controller type='usb' index='0' model='qemu-xhci' ports='15'>
<address type='pci' domain='0x0000' bus='0x02' slot='0x00' function='0x0'/>
</controller>
<controller type='sata' index='0'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
</controller>
<controller type='pci' index='0' model='pcie-root'/>
<controller type='pci' index='1' model='pcie-root-port'>
<model name='pcie-root-port'/>
<target chassis='1' port='0x10'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0' multifunction='on'/>
</controller>
<controller type='pci' index='2' model='pcie-root-port'>
<model name='pcie-root-port'/>
<target chassis='2' port='0x11'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x1'/>
</controller>
<controller type='pci' index='3' model='pcie-root-port'>
<model name='pcie-root-port'/>
<target chassis='3' port='0x12'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x2'/>
</controller>
<controller type='pci' index='4' model='pcie-root-port'>
<model name='pcie-root-port'/>
<target chassis='4' port='0x13'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x3'/>
</controller>
<controller type='pci' index='5' model='pcie-root-port'>
<model name='pcie-root-port'/>
<target chassis='5' port='0x14'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x4'/>
</controller>
<controller type='pci' index='6' model='pcie-root-port'>
<model name='pcie-root-port'/>
<target chassis='6' port='0x15'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x5'/>
</controller>
<controller type='pci' index='7' model='pcie-root-port'>
<model name='pcie-root-port'/>
<target chassis='7' port='0x16'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x6'/>
</controller>
<controller type='pci' index='8' model='pcie-root-port'>
<model name='pcie-root-port'/>
<target chassis='8' port='0x17'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x7'/>
</controller>
<controller type='virtio-serial' index='0'>
<address type='pci' domain='0x0000' bus='0x03' slot='0x00' function='0x0'/>
</controller>
<filesystem type='mount' accessmode='passthrough'>
<driver type='path' wrpolicy='immediate'/>
<source dir='/home/paul'/>
<target dir='home'/>
<address type='pci' domain='0x0000' bus='0x07' slot='0x00' function='0x0'/>
</filesystem>
<interface type='network'>
<mac address='52:54:00:6a:05:b3'/>
<source network='default'/>
<model type='e1000e'/>
<address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
</interface>
<serial type='pty'>
<target type='isa-serial' port='0'>
<model name='isa-serial'/>
</target>
</serial>
<console type='pty'>
<target type='serial' port='0'/>
</console>
<channel type='spicevmc'>
<target type='virtio' name='com.redhat.spice.0'/>
<address type='virtio-serial' controller='0' bus='0' port='1'/>
</channel>
<input type='tablet' bus='usb'>
<address type='usb' bus='0' port='1'/>
</input>
<input type='mouse' bus='ps2'/>
<input type='keyboard' bus='ps2'/>
<graphics type='spice' autoport='yes'>
<listen type='address'/>
<image compression='off'/>
</graphics>
<sound model='ich9'>
<address type='pci' domain='0x0000' bus='0x00' slot='0x1b' function='0x0'/>
</sound>
<video>
<model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1' primary='yes'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
</video>
<hostdev mode='subsystem' type='pci' managed='yes'>
<source>
<address domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
</source>
<address type='pci' domain='0x0000' bus='0x05' slot='0x00' function='0x0'/>
</hostdev>
<hostdev mode='subsystem' type='pci' managed='yes'>
<source>
<address domain='0x0000' bus='0x01' slot='0x00' function='0x1'/>
</source>
<address type='pci' domain='0x0000' bus='0x06' slot='0x00' function='0x0'/>
</hostdev>
<redirdev bus='usb' type='spicevmc'>
<address type='usb' bus='0' port='2'/>
</redirdev>
<redirdev bus='usb' type='spicevmc'>
<address type='usb' bus='0' port='3'/>
</redirdev>
<memballoon model='virtio'>
<address type='pci' domain='0x0000' bus='0x04' slot='0x00' function='0x0'/>
</memballoon>
</devices>
</domain>
答案1
您一次只能将一个特定的 PCI/PCIe 设备传递给一个 VM。您无法挂起/保存（如virsh save）带有物理 PCI 设备的 VM。您必须先关闭一个 VM，然后才能启动另一个 VM，以便在它们之间切换 PCI 设备。
如果虚拟机导致主机出现性能问题：
1) 不要将所有物理 CPU 核心分配给客户虚拟机。例如，如果主机上有 4 个核心/8 个线程，则不要将超过 3 个核心/6 个线程分配给虚拟机。
2) 将虚拟 CPU 线程固定到物理 CPU 线程。
3) 向 VM 公开 CPU 拓扑（插槽/核心/线程），以便客户机中的内核至少可以尝试在给定的 CPU 核心/线程之间合理地调度进程。
4）为虚拟机使用大页面