This issue still exist in Ubuntu 20.02 5.4.0-18-generic (28 Mar 2020). For the one who still struggling this is a workaround works for me.
My UAS USB3 external storage: Bus 002 Device 003: ID 152d:0583 JMicron Technology Corp. / JMicron USA Technology Corp. JEYI External The warning message in dmesg: [ 5895.913004] sd 0:0:0:0: [sda] Optimal transfer size 33553920 bytes not a multiple of physical block size (4096 bytes) if this usb is passed to qemu/kvm vm, dmesg will shows and the vm hangs(can not boot): [ 6971.972846] sd 1:0:0:0: [sdb] Synchronize Cache(10) failed: Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK Disable the UAS for this device will fix this, and also you lost the TRIM/DISCARD ability for this device. sudo modprobe -rv uas;sleep 1;sudo modprobe -v usb-storage quirks=357d:7788:u,152d:0583:u;sudo modprobe -v uas source: https://unix.stackexchange.com/questions/239782/connection- problem-with-usb3-external-storage-on-linux-uas-driver-problem ** Changed in: libvirt (Ubuntu) Status: Expired => New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1815588 Title: speed mismatch trying to attach usb device to guest vm To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1815588/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
