EHCI cpage is out of range with qemu ehci controller - SeaBIOS

21 Mar 2022


      Hi all,
I experienced an error about ehci current page on qemu + seabios v1.14:
cpage out of range (5)
processing error - resetting ehci HC
We know that the EHCI spec defines valid range of ehci cpage to 0-4, But 
here is a 5, Obviously it's an issue.
I added a EHCI controller, and attached a usb mass storage to the EHCI 
controller as boot device:
host:~# qemu-system-x86_64 \
   -accel kvm \
   -bios /home/test/projects/seabios/out/bios.bin \
   -m 4096 \
   -device usb-ehci \
   -blockdev 
driver=file,read-only=on,filename=/isos/openSUSE-Tumbleweed-GNOME-Live-x86_64-Snapshot20220314-Media.iso,node-name=iso 
\
   -device usb-storage,drive=iso,bootindex=0
The issue is not 100% reproducible, I run the test 15 times with above 
steps, the issue occurs 1 or 2 times.
The qemu version seems doesn't matter, I used to use qemu 5.2, 6.0 and 
latest git master, Got the same test result.
It seems that the issue was introduced since seabios v1.14, It can be 
reproduced on latest seabios git master as well, It can't be reproduced 
on seabios 1.13 or older.
The seabios commit b3fa8577 "kvm: add support for reading tsc frequency 
from kvmclock" seems to be the suspect.
Thanks,
Lin