Re: [PATCH] KVM: x86/mmu: Add capability to zap only sptes for the affected memslot

[Alex Williamson <alex.williamson@redhat.com>]

On Thu, 23 Jul 2020 08:57:11 -0700
Sean Christopherson <sean.j.christopherson@intel.com> wrote:

> On Tue, Jul 21, 2020 at 10:00:36AM -0600, Alex Williamson wrote:
> > On Mon, 20 Jul 2020 20:03:19 -0700
> > Sean Christopherson <sean.j.christopherson@intel.com> wrote:
> >   
> > > +Weijiang
> > > 
> > > On Mon, Jul 13, 2020 at 12:06:50PM -0700, Sean Christopherson wrote:  
> > > > The only ideas I have going forward are to:
> > > > 
> > > >   a) Reproduce the bug outside of your environment and find a resource that
> > > >      can go through the painful bisection.    
> > > 
> > > We're trying to reproduce the original issue in the hopes of biesecting, but
> > > have not yet discovered the secret sauce.  A few questions:
> > > 
> > >   - Are there any known hardware requirements, e.g. specific flavor of GPU?  
> > 
> > I'm using an old GeForce GT635, I don't think there's anything special
> > about this card.  
> 
> Would you be able to provide your QEMU command line?  Or at least any
> potentially relevant bits?  Still no luck reproducing this on our end.

XML:

<domain type='kvm'>
  <name>GeForce</name>
  <uuid>2b417d4b-f25b-4522-a5be-e105f032f99c</uuid>
  <memory unit='KiB'>4194304</memory>
  <currentMemory unit='KiB'>4194304</currentMemory>
  <memoryBacking>
    <hugepages/>
  </memoryBacking>
  <vcpu placement='static'>4</vcpu>
  <cputune>
    <vcpupin vcpu='0' cpuset='3'/>
    <vcpupin vcpu='1' cpuset='7'/>
    <vcpupin vcpu='2' cpuset='2'/>
    <vcpupin vcpu='3' cpuset='6'/>
    <emulatorpin cpuset='0,4'/>
  </cputune>
  <os>
    <type arch='x86_64' machine='pc-i440fx-5.0'>hvm</type>
    <loader readonly='yes' type='pflash'>/usr/share/edk2/ovmf/OVMF_CODE.fd</loader>
    <nvram template='/usr/share/edk2/ovmf/OVMF_VARS.fd'>/var/lib/libvirt/qemu/nvram/GeForce_VARS.fd</nvram>
    <bootmenu enable='yes'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <pae/>
    <hyperv>
      <relaxed state='on'/>
      <vapic state='on'/>
      <spinlocks state='on' retries='8191'/>
      <vendor_id state='on' value='KeenlyKVM'/>
    </hyperv>
    <kvm>
      <hidden state='on'/>
    </kvm>
    <vmport state='off'/>
  </features>
  <cpu mode='custom' match='exact' check='none'>
    <model fallback='allow'>IvyBridge-IBRS</model>
    <topology sockets='1' dies='1' cores='4' threads='1'/>
  </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>restart</on_crash>
  <devices>
    <emulator>/usr/local/bin/qemu-system-x86_64</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2' cache='none'/>
      <source file='/mnt/ssd/GeForce.qcow2'/>
      <target dev='sda' bus='scsi'/>
      <boot order='2'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
    <controller type='scsi' index='0' model='virtio-scsi'>
      <driver queues='4'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </controller>
    <controller type='pci' index='0' model='pci-root'/>
    <controller type='usb' index='0' model='nec-xhci'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x08' function='0x0'/>
    </controller>
    <interface type='direct'>
      <mac address='52:54:00:60:ef:ac'/>
      <source dev='enp4s0' mode='bridge'/>
      <model type='virtio'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>
    <input type='mouse' bus='ps2'/>
    <input type='keyboard' bus='ps2'/>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <source>
        <address domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
      </source>
      <rom bar='on'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </hostdev>
    <hostdev mode='subsystem' type='pci' managed='yes'>
      <source>
        <address domain='0x0000' bus='0x01' slot='0x00' function='0x1'/>
      </source>
      <rom bar='off'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </hostdev>
    <memballoon model='none'/>
  </devices>
</domain>

From libvirt log:

LC_ALL=C \
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin \
HOME=/var/lib/libvirt/qemu/domain-1-GeForce \
XDG_DATA_HOME=/var/lib/libvirt/qemu/domain-1-GeForce/.local/share \
XDG_CACHE_HOME=/var/lib/libvirt/qemu/domain-1-GeForce/.cache \
XDG_CONFIG_HOME=/var/lib/libvirt/qemu/domain-1-GeForce/.config \
QEMU_AUDIO_DRV=none \
/usr/local/bin/qemu-system-x86_64 \
-name guest=GeForce,debug-threads=on \
-S \
-object secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-1-GeForce/master-key.aes \
-blockdev '{"driver":"file","filename":"/usr/share/edk2/ovmf/OVMF_CODE.fd","node-name":"libvirt-pflash0-storage","auto-read-only":true,"discard":"unmap"}' \
-blockdev '{"node-name":"libvirt-pflash0-format","read-only":true,"driver":"raw","file":"libvirt-pflash0-storage"}' \
-blockdev '{"driver":"file","filename":"/var/lib/libvirt/qemu/nvram/GeForce_VARS.fd","node-name":"libvirt-pflash1-storage","auto-read-only":true,"discard":"unmap"}' \
-blockdev '{"node-name":"libvirt-pflash1-format","read-only":false,"driver":"raw","file":"libvirt-pflash1-storage"}' \
-machine pc-i440fx-5.0,accel=kvm,usb=off,vmport=off,dump-guest-core=off,pflash0=libvirt-pflash0-format,pflash1=libvirt-pflash1-format \
-cpu IvyBridge-IBRS,hv-time,hv-relaxed,hv-vapic,hv-spinlocks=0x1fff,hv-vendor-id=KeenlyKVM,kvm=off \
-m 4096 \
-mem-prealloc \
-mem-path /dev/hugepages/libvirt/qemu/1-GeForce \
-overcommit mem-lock=off \
-smp 4,sockets=1,dies=1,cores=4,threads=1 \
-uuid 2b417d4b-f25b-4522-a5be-e105f032f99c \
-display none \
-no-user-config \
-nodefaults \
-chardev socket,id=charmonitor,fd=36,server,nowait \
-mon chardev=charmonitor,id=monitor,mode=control \
-rtc base=localtime,driftfix=slew \
-global kvm-pit.lost_tick_policy=delay \
-no-hpet \
-no-shutdown \
-boot menu=on,strict=on \
-device nec-usb-xhci,id=usb,bus=pci.0,addr=0x8 \
-device virtio-scsi-pci,id=scsi0,num_queues=4,bus=pci.0,addr=0x5 \
-blockdev '{"driver":"file","filename":"/mnt/ssd/GeForce-2019-08-02.img","node-name":"libvirt-2-storage","cache":{"direct":true,"no-flush":false},"auto-read-only":true,"discard":"unmap"}' \
-blockdev '{"node-name":"libvirt-2-format","read-only":true,"cache":{"direct":true,"no-flush":false},"driver":"raw","file":"libvirt-2-storage"}' \
-blockdev '{"driver":"file","filename":"/mnt/ssd/Geforce.qcow2","node-name":"libvirt-1-storage","cache":{"direct":true,"no-flush":false},"auto-read-only":true,"discard":"unmap"}' \
-blockdev '{"node-name":"libvirt-1-format","read-only":false,"cache":{"direct":true,"no-flush":false},"driver":"qcow2","file":"libvirt-1-storage","backing":"libvirt-2-format"}' \
-device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=0,device_id=drive-scsi0-0-0-0,drive=libvirt-1-format,id=scsi0-0-0-0,bootindex=2,write-cache=on \
-netdev tap,fd=38,id=hostnet0,vhost=on,vhostfd=40 \
-device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:60:ef:ac,bus=pci.0,addr=0x3 \
-device vfio-pci,host=0000:01:00.0,id=hostdev0,bus=pci.0,addr=0x4,rombar=1 \
-device vfio-pci,host=0000:01:00.1,id=hostdev1,bus=pci.0,addr=0x6,rombar=0 \
-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \
-msg timestamp=on