** Description changed: + [Impact] + Code that touches DSCR user MSR does not set dscr_inherit, which breaks DSCR restore doing context switches and inheritance when forking. DSCR is used to control cache hinting. This is caused by lack of kernel interrupt when the DSCR user MSR is written, which is controlled by FSCR which would otherwise cause a facility unavailable interrupt. + + [Test case] + apt-get source linux + cd linux-5.4.0/tools/testing/tools/selftests/powerpc/ + make -j 32 + make -C dscr run_tests + make -C ptrace run_tests + make -C tm run_tests + + Look up for "not ok" versus "ok", specially for dscr_inherit_exec_test, + ptrace-tar and tm-resched-tar. + + [Potential regression] + Manipulating DSCR might break on different machines (with DTs containing + /cpus/ibm,powerpc-cpu-features, for example). Code that does so might crash because the facility unavailable interrupt handling might be not working correctly. + + + ==================================== Issue found on 5.3.0-64.58 with P8 node modoc (passed with P9 node) - # selftests: powerpc/dscr: dscr_inherit_exec_test - # test: dscr_inherit_exec_test - # tags: git_version:unknown - # Parent DSCR 1 was not inherited over exec (kernel value) - # Child didn't exit cleanly - # failure: dscr_inherit_exec_test - not ok 5 selftests: powerpc/dscr: dscr_inherit_exec_test # exit=1 + # selftests: powerpc/dscr: dscr_inherit_exec_test + # test: dscr_inherit_exec_test + # tags: git_version:unknown + # Parent DSCR 1 was not inherited over exec (kernel value) + # Child didn't exit cleanly + # failure: dscr_inherit_exec_test + not ok 5 selftests: powerpc/dscr: dscr_inherit_exec_test # exit=1
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1888332 Title: [Potential Regression] dscr_inherit_exec_test from powerpc in ubuntu_kernel_selftests failed on B/E/F To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1888332/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
