Manos Pitsidianakis <manos.pitsidiana...@linaro.org> writes:
> A hang was observed when running a small kernel that exercised VIRTIO
> GPU under TCG. This is an edge-case and won't happen under typical
> conditions.
>
> When unmapping a blob object, its MemoryRegion's freeing is deferred to
> the RCU thread. The hang's cause was determined to be a busy main loop
> not allowing for the RCU thread to run because the kernel did not setup
> any timers or had any interrupts on the way. While fixing the RCU thread
> to run even if the guest CPU spins is a solution, it's easier to fix the
> reason why the MemoryRegion isn't freed from the main loop instead.
>
> While at it, also restructure the 3 stage cleanup to immediately respond
> to the guest if the MR happened to have had no other reference.
>
> PS: The hang can be reproduced by running this unikernel with TCG
>
> https://git.codelinaro.org/manos.pitsidianakis/virtio-tests/-/tree/8c0ebe9395827e24aa5711186d499bf5de87cf63/virtio-test-suite
Hmm these seems to regress the virtio-gpu tests:
๐10:18:49 alex@toolbox:qemu.git/builds/virtio-gpu on ๎ HEAD (ae021f8)
(REBASING 4/9) [$+?] took 7s
โ echo $LD_LIBRARY_PATH
/home/alex/lsrc/qemu.git/builds/extra.libs/install/lib
/home/alex/lsrc/qemu.git/builds/extra.libs/install/lib/x86_64-linux-gnu
๐10:18:54 alex@toolbox:qemu.git/builds/virtio-gpu on ๎ HEAD (ae021f8)
(REBASING 4/9) [$+?]
โ echo $PKG_CONFIG_PATH
/home/alex/lsrc/qemu.git/builds/extra.libs/install/lib/pkgconfig
/home/alex/lsrc/qemu.git/builds/extra.libs/install/lib/x86_64-linux-gnu/pkgconfig/
๐10:18:58 alex@toolbox:qemu.git/builds/virtio-gpu on ๎ HEAD (ae021f8)
(REBASING 4/9) [$+?]
โ head config.log
# QEMU configure log Wed Apr 9 10:01:50 UTC 2025
# Configured with: '../../configure' '--disable-docs' '--enable-virglrenderer'
'--target-list=aarch64-softmmu,x86_64-softmmu' '--enable-debug' '--skip-meson'
#
cc -c -o config-temp/qemu-conf.o config-temp/qemu-conf.c
cc -c -o config-temp/qemu-conf.o config-temp/qemu-conf.c
config-temp/qemu-conf.c:2:2: error: #error __i386__ not defined
2 | #error __i386__ not defined
| ^~~~~
cc -c -o config-temp/qemu-conf.o config-temp/qemu-conf.c
๐10:19:02 alex@toolbox:qemu.git/builds/virtio-gpu on ๎ HEAD (ae021f8)
(REBASING 4/9) [$+?]
โ make -j30
/home/alex/lsrc/qemu.git/builds/virtio-gpu/pyvenv/bin/meson introspect
--targets --tests --benchmarks |
/home/alex/lsrc/qemu.git/builds/virtio-gpu/pyvenv/bin/python3 -B
scripts/mtest2make.py > Makefile.mtest
[1/19] Generating qemu-version.h with a custom command (wrapped by meson to
capture output)
๐10:19:09 alex@toolbox:qemu.git/builds/virtio-gpu on ๎ HEAD (ae021f8)
(REBASING 4/9) [$+?]
โ ./pyvenv/bin/meson test --setup thorough --suite func-thorough
func-aarch64-aarch64_virt_gpu -v
ninja: Entering directory `/home/alex/lsrc/qemu.git/builds/virtio-gpu'
[1/6] Generating qemu-version.h with a custom command (wrapped by meson to
capture output)
1/1 qemu:func-thorough+func-aarch64-thorough+thorough /
func-aarch64-aarch64_virt_gpu RUNNING
>>> QEMU_BUILD_ROOT=/home/alex/lsrc/qemu.git/builds/virtio-gpu G_TEST_SLOW=1
>>> QEMU_TEST_QEMU_BINARY=/home/alex/lsrc/qemu.git/builds/virtio-gpu/qemu-system-aarch64
>>>
>>> MSAN_OPTIONS=halt_on_error=1:abort_on_error=1:print_summary=1:print_stacktrace=1
>>>
>>> UBSAN_OPTIONS=halt_on_error=1:abort_on_error=1:print_summary=1:print_stacktrace=1
>>> MALLOC_PERTURB_=52
>>> PYTHONPATH=/home/alex/lsrc/qemu.git/python:/home/alex/lsrc/qemu.git/tests/functional
>>> RUST_BACKTRACE=1
>>> LD_LIBRARY_PATH=/home/alex/lsrc/qemu.git/builds/virtio-gpu/tests/tcg/plugins:/home/alex/lsrc/qemu.git/builds/virtio-gpu/contrib/plugins:/home/alex/lsrc/qemu.git/builds/extra.libs/install/lib:/home/alex/lsrc/qemu.git/builds/extra.libs/install/lib/x86_64-linux-gnu
>>> SPEED=thorough
>>> ASAN_OPTIONS=halt_on_error=1:abort_on_error=1:print_summary=1
>>> QEMU_TEST_QEMU_IMG=/home/alex/lsrc/qemu.git/builds/virtio-gpu/qemu-img
>>> MESON_TEST_ITERATION=1
>>> /home/alex/lsrc/qemu.git/builds/virtio-gpu/pyvenv/bin/python3
>>> /home/alex/lsrc/qemu.git/tests/functional/test_aarch64_virt_gpu.py
โถ 1/1
test_aarch64_virt_gpu.Aarch64VirtGPUMachine.test_aarch64_virt_with_virgl_blobs_gpu
OK
โถ 1/1
test_aarch64_virt_gpu.Aarch64VirtGPUMachine.test_aarch64_virt_with_virgl_gpu
OK
โถ 1/1
test_aarch64_virt_gpu.Aarch64VirtGPUMachine.test_aarch64_virt_with_vulkan_gpu
OK
1/1 qemu:func-thorough+func-aarch64-thorough+thorough /
func-aarch64-aarch64_virt_gpu OK 207.15s 3 subtests passed
Ok: 1
Expected Fail: 0
Fail: 0
Unexpected Pass: 0
Skipped: 0
Timeout: 0
Full log written to
/home/alex/lsrc/qemu.git/builds/virtio-gpu/meson-logs/testlog-thorough.txt
๐10:22:41 alex@toolbox:qemu.git/builds/virtio-gpu on ๎ HEAD (ae021f8)
(REBASING 4/9) [$+?] took 3m27s
โ make -j30
[1/21] Generating qemu-version.h with a custom command (wrapped by meson to
capture output)
[2/21] Compiling C object libcommon.a.p/hw_display_virtio-gpu-virgl.c.o
[3/21] Compiling C object libcommon.a.p/hw_virtio_virtio-pci.c.o
[4/21] Compiling C object qemu-vmsr-helper.p/tools_i386_qemu-vmsr-helper.c.o
[5/21] Compiling C object qemu-pr-helper.p/scsi_qemu-pr-helper.c.o
[6/21] Compiling C object qemu-io.p/qemu-io.c.o
[7/21] Linking target qemu-vmsr-helper
[8/21] Compiling C object qga/qemu-ga.p/main.c.o
[9/21] Compiling C object qemu-nbd.p/qemu-nbd.c.o
[10/21] Compiling C object libqmp.a.p/monitor_qmp-cmds-control.c.o
[11/21] Compiling C object
storage-daemon/qemu-storage-daemon.p/qemu-storage-daemon.c.o
[12/21] Linking target qemu-pr-helper
[13/21] Linking target qga/qemu-ga
[14/21] Linking target qemu-io
[15/21] Linking target qemu-nbd
[16/21] Linking target storage-daemon/qemu-storage-daemon
[17/21] Compiling C object qemu-img.p/qemu-img.c.o
[18/21] Compiling C object libcommon.a.p/system_vl.c.o
[19/21] Linking target qemu-img
[20/21] Linking target qemu-system-x86_64
[21/21] Linking target qemu-system-aarch64
๐10:23:08 alex@toolbox:qemu.git/builds/virtio-gpu on ๎
virtio/virtio-blk-fallback [$?]
โ ./pyvenv/bin/meson test --setup thorough --suite func-thorough
func-aarch64-aarch64_virt_gpu -v
ninja: Entering directory `/home/alex/lsrc/qemu.git/builds/virtio-gpu'
[1/6] Generating qemu-version.h with a custom command (wrapped by meson to
capture output)
1/1 qemu:func-thorough+func-aarch64-thorough+thorough /
func-aarch64-aarch64_virt_gpu RUNNING
>>> PYTHONPATH=/home/alex/lsrc/qemu.git/python:/home/alex/lsrc/qemu.git/tests/functional
>>> QEMU_BUILD_ROOT=/home/alex/lsrc/qemu.git/builds/virtio-gpu
>>> ASAN_OPTIONS=halt_on_error=1:abort_on_error=1:print_summary=1
>>> MESON_TEST_ITERATION=1 SPEED=thorough
>>> QEMU_TEST_QEMU_BINARY=/home/alex/lsrc/qemu.git/builds/virtio-gpu/qemu-system-aarch64
>>> G_TEST_SLOW=1
>>> UBSAN_OPTIONS=halt_on_error=1:abort_on_error=1:print_summary=1:print_stacktrace=1
>>> MALLOC_PERTURB_=7
>>> MSAN_OPTIONS=halt_on_error=1:abort_on_error=1:print_summary=1:print_stacktrace=1
>>> RUST_BACKTRACE=1
>>> LD_LIBRARY_PATH=/home/alex/lsrc/qemu.git/builds/virtio-gpu/tests/tcg/plugins:/home/alex/lsrc/qemu.git/builds/virtio-gpu/contrib/plugins:/home/alex/lsrc/qemu.git/builds/extra.libs/install/lib:/home/alex/lsrc/qemu.git/builds/extra.libs/install/lib/x86_64-linux-gnu
>>> QEMU_TEST_QEMU_IMG=/home/alex/lsrc/qemu.git/builds/virtio-gpu/qemu-img
>>> /home/alex/lsrc/qemu.git/builds/virtio-gpu/pyvenv/bin/python3
>>> /home/alex/lsrc/qemu.git/tests/functional/test_aarch64_virt_gpu.py
qemu:func-thorough+func-aarch64-thorough+thorough /
func-aarch64-aarch64_virt_gpu time out (After 480 seconds)
1/1 qemu:func-thorough+func-aarch64-thorough+thorough /
func-aarch64-aarch64_virt_gpu TIMEOUT 480.01s killed by signal
15 SIGTERM
Summary of Failures:
1/1 qemu:func-thorough+func-aarch64-thorough+thorough /
func-aarch64-aarch64_virt_gpu TIMEOUT 480.01s killed by signal 15
SIGTERM
Ok: 0
Expected Fail: 0
Fail: 0
Unexpected Pass: 0
Skipped: 0
Timeout: 1
Full log written to
/home/alex/lsrc/qemu.git/builds/virtio-gpu/meson-logs/testlog-thorough.txt
๐10:31:12 alex@toolbox:qemu.git/builds/virtio-gpu on ๎
virtio/virtio-blk-fallback [$?] took 8m [๐ด ERROR]
>
> Manos Pitsidianakis (2):
> virtio-gpu: fix hang under TCG when unmapping blob
> virtio-gpu: refactor async blob unmapping
>
> hw/display/virtio-gpu-virgl.c | 37 ++++++++++++++++++++++++-----------
> 1 file changed, 26 insertions(+), 11 deletions(-)
>
>
> base-commit: 0adf626718bc0ca9c46550249a76047f8e45da15
--
Alex Bennรฉe
Virtualisation Tech Lead @ Linaro
