On 05.06.20 10:55, Alex Shi wrote: > > > 在 2020/1/9 下午9:48, David Hildenbrand 写道: >> Ping, >> >> I'd love to get some feedback on >> >> a) The remaining MM bits from MM folks (especially, patch #6 and #8). >> b) The general virtio infrastructure (esp. uapi in patch #2) from virtio >> folks. >> >> I'm planning to send a proper v1 (!RFC) once I have all necessary MM >> acks. In the meanwhile, I will do more testing and minor reworks (e.g., >> fix !CONFIG_NUMA compilation). > > > Hi David, > > Thanks for your work! > > I am trying your https://github.com/davidhildenbrand/linux.git virtio-mem-v5 > which works fine for me, but just a 'DMA error' happens when a vm start with > less than 2GB memory, Do I missed sth? Please use the virtio-mem-v4 branch for now, v5 is still under construction (and might be scrapped completely if v4 goes upstream as is). Looks like a DMA issue. Your're hotplugging 1GB, which should not really eat too much memory. There was a similar issue reported by Hui in [1], which boiled down to wrong usage of the swiotlb parameter. In such cases you should always try to reproduce with hotplug of a sam-sized DIMM. E.g., hotplugging a 1GB DIMM should result in the same issue. What does your .config specify for CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE? I'll try to reproduce with v4 briefly. [1] https://lkml.kernel.org/r/9708F43A-9BD2-4377-8EE8-7FB1D95C6F69@xxxxxxxxxxxxxxxxx > > Thanks > Alex > > > (qemu) qom-set vm0 requested-size 1g > (qemu) [ 26.560026] virtio_mem virtio0: plugged size: 0x0 > [ 26.560648] virtio_mem virtio0: requested size: 0x40000000 > [ 26.561730] systemd-journald[167]: no db file to read /run/udev/data/+virtio:virtio0: No such file or directory > [ 26.563138] systemd-journald[167]: no db file to read /run/udev/data/+virtio:virtio0: No such file or directory > [ 26.569122] Built 1 zonelists, mobility grouping on. Total pages: 513141 > [ 26.570039] Policy zone: Normal > > (qemu) [ 32.175838] e1000 0000:00:03.0: swiotlb buffer is full (sz: 81 bytes), total 0 (slots), used 0 (slots) > [ 32.176922] e1000 0000:00:03.0: TX DMA map failed > [ 32.177488] e1000 0000:00:03.0: swiotlb buffer is full (sz: 81 bytes), total 0 (slots), used 0 (slots) > [ 32.178535] e1000 0000:00:03.0: TX DMA map failed > > my qemu command is like this: > qemu-system-x86_64 --enable-kvm \ > -m 2G,maxmem=16G -kernel /root/linux-next/$1/arch/x86/boot/bzImage \ > -smp 4 \ > -append "earlyprintk=ttyS0 root=/dev/sda1 console=ttyS0 debug psi=1 nokaslr ignore_loglevel" \ > -hda /root/CentOS-7-x86_64-Azure-1703.qcow2 \ > -net user,hostfwd=tcp::2222-:22 -net nic -s \ > -object memory-backend-ram,id=mem0,size=3G \ > -device virtio-mem-pci,id=vm0,memdev=mem0,node=0,requested-size=0M \ > --nographic > > -- Thanks, David / dhildenb
