On Thu, Jul 7, 2022 at 2:49 PM Heinrich Schuchardt <heinrich.schuchardt@xxxxxxxxxxxxx> wrote: > > When removing the pflash driver in U-Boot the blocking occurs for virtio net. If we further remove virtio net, it occurs for virtio blk. > > The problem is not flash specific. > > Best regards > > Heinrich > > Anup Patel <apatel@xxxxxxxxxxxxxxxx> schrieb am Do., 7. Juli 2022, 07:06: >> >> On Thu, Jul 7, 2022 at 10:19 AM Bin Meng <bmeng.cn@xxxxxxxxx> wrote: >> > >> > Hi Anup, >> > >> > U-Boot S-mode payload does not boot with RISC-V KVM on the QEMU 'virt' >> > multicore machine. With QEMU TCG it can boot. >> > >> > I am using the latest v5.19-rc5 kernel, along with QEMU 7.0.0 and >> > U-Boot v2022.04: >> > >> > Reproduce steps: >> > >> > U-Boot S-mode payload is built from U-Boot v2022.04: >> > $ make qemu-riscv64_smode_defconfig; make >> > >> > The host 5.19-rc5 kernel is running on top of QEMU 7.0.0 on an x86 machine. >> > >> > Use QEMU to launch the VM: >> > # qemu-system-riscv64 -M virt -accel kvm -m 2G -smp 2 -nographic >> > -kernel u-boot -device virtio-net-device,netdev=eth0 -netdev >> > user,id=eth0,hostfwd=tcp::8022-:22 >> > >> > U-Boot gets stuck during boot, logs below: >> > >> > U-Boot 2022.04 (Jul 07 2022 - 11:23:28 +0800) >> > CPU: rv64imafdc >> > Model: riscv-virtio,qemu >> > DRAM: 2 GiB >> > Core: 17 devices, 9 uclasses, devicetree: board >> > Flash: <========== stuck here, and QEMU is completely unresponsive >> > (Ctrl+A, C is ignored) >> > >> > The kernel reports: >> > >> > [ 484.351698] INFO: task qemu-system-ris:1765 blocked for more than 120 seconds. >> > [ 484.360285] Not tainted 5.19.0-rc5-custom #1 >> > [ 484.360871] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" >> > disables this message. >> > [ 484.362560] task:qemu-system-ris state:D stack: 0 pid: 1765 ppid: >> > 1515 flags:0x00000000 >> > [ 484.363785] Call Trace: >> > [ 484.363930] [] schedule+0x50/0xb2 >> > [ 484.364758] [] schedule_timeout+0x10c/0x13c >> > [ 484.364806] [] __wait_for_common+0x148/0x226 >> > [ 484.364840] [] wait_for_completion+0x2e/0x36 >> > [ 484.364871] [] __synchronize_srcu.part.0+0x88/0xe2 >> > [ 484.364918] [] synchronize_srcu_expedited+0x3a/0x44 >> > [ 484.364952] [] kvm_swap_active_memslots+0x186/0x1ea >> > [ 484.364985] [] kvm_set_memslot+0x1fc/0x39c >> > [ 484.365014] [] __kvm_set_memory_region+0x144/0x30c >> > [ 484.365043] [] kvm_vm_ioctl+0x20a/0xc82 >> > [ 484.365075] [] sys_ioctl+0x98/0xb2 >> > [ 484.365135] [] ret_from_syscall+0x0/0x2 >> > >> > The QEMU vcpu thread backtrace is: >> > >> > #0 __GI___ioctl (fd=, request=request@entry=1075883590) at >> > ../sysdeps/unix/sysv/linux/ioctl.c:35 >> > #1 0x00aaaaaab8b916ae in kvm_vm_ioctl (s=s@entry=0xaaaaaaf1ec3e00, >> > type=type@entry=1075883590) at ../accel/kvm/kvm-all.c:3035 >> > #2 0x00aaaaaab8b93572 in kvm_set_user_memory_region >> > (slot=slot@entry=0xffffffaa5d90a0, new=new@entry=false, >> > kml=0xaaaaaaf1ec4eb0, kml=) at ../accel/kvm/kvm-all.c:379 >> > #3 0x00aaaaaab8b93862 in kvm_set_phys_mem (kml=0xaaaaaaf1ec4eb0, >> > section=section@entry=0xffffffaa513b70, add=, add@entry=false) at >> > ../accel/kvm/kvm-all.c:1413 >> > #4 0x00aaaaaab8b93a30 in kvm_region_del (listener=, >> > section=0xffffffaa513b70) at ../accel/kvm/kvm-all.c:1511 >> > #5 0x00aaaaaab8ad780c in address_space_update_topology_pass >> > (as=as@entry=0xaaaaaab90b87a0 , >> > old_view=old_view@entry=0xaaaaaaf1f42c40, >> > new_view=new_view@entry=0xffffff1c001400, adding=adding@entry=fa >> > lse) at ../softmmu/memory.c:948 >> > #6 0x00aaaaaab8ad7a2a in address_space_set_flatview >> > (as=0xaaaaaab90b87a0 ) at ../softmmu/memory.c:1050 >> > #7 0x00aaaaaab8ada508 in memory_region_transaction_commit () at >> > ../softmmu/memory.c:1103 >> > #8 0x00aaaaaab8adb6ee in memory_region_rom_device_set_romd >> > (mr=mr@entry=0xaaaaaaf22d6fe0, romd_mode=romd_mode@entry=false) at >> > ../softmmu/memory.c:2289 >> > #9 0x00aaaaaab8951e1a in pflash_write (be=0, width=1, value=240, >> > offset=0, pfl=0xaaaaaaf22d6c30) at ../hw/block/pflash_cfi01.c:451 >> > #10 pflash_mem_write_with_attrs (opaque=0xaaaaaaf22d6c30, addr=0, >> > value=, len=, attrs=...) at ../hw/block/pflash_cfi01.c:682 >> > #11 0x00aaaaaab8ad5fa2 in access_with_adjusted_size >> > (addr=addr@entry=0, value=value@entry=0xffffffaa513dc8, >> > size=size@entry=1, access_size_min=, access_size_max=, >> > access_fn=0xaaaaaab8ad7d06 < >> > memory_region_write_with_attrs_accessor>, mr=0xaaaaaaf22d6fe0, >> > attrs=...) at ../softmmu/memory.c:554 >> > #12 0x00aaaaaab8ad92ba in memory_region_dispatch_write >> > (mr=mr@entry=0xaaaaaaf22d6fe0, addr=addr@entry=0, data=, >> > data@entry=240, op=, attrs=attrs@entry=...) at >> > ../softmmu/memory.c:1521 >> > #13 0x00aaaaaab8adee88 in flatview_write_continue >> > (fv=fv@entry=0xaaaaaaf1f42c40, addr=addr@entry=536870912, >> > attrs=attrs@entry=..., ptr=ptr@entry=0xffffffab730028, >> > len=len@entry=1, addr1=, l=, >> > mr=0xaaaaaaf22d6fe0) at ../softmmu/physmem.c:2814 >> > #14 0x00aaaaaab8adf0d8 in flatview_write (fv=0xaaaaaaf1f42c40, >> > addr=536870912, attrs=..., buf=0xffffffab730028, len=len@entry=1) at >> > ../softmmu/physmem.c:2856 >> > #15 0x00aaaaaab8ae1eca in address_space_write (len=1, >> > buf=0xffffffab730028, attrs=..., addr=536870912, as=0xaaaaaab90b87a0 ) >> > at ../softmmu/physmem.c:2952 >> > #16 address_space_rw (as=0xaaaaaab90b87a0 , addr=536870912, attrs=..., >> > attrs@entry=..., buf=buf@entry=0xffffffab730028, len=1, is_write=) at >> > ../softmmu/physmem.c:2962 >> > #17 0x00aaaaaab8b94a3e in kvm_cpu_exec >> > (cpu=cpu@entry=0xaaaaaaf1ec92f0) at ../accel/kvm/kvm-all.c:2929 >> > #18 0x00aaaaaab8b95572 in kvm_vcpu_thread_fn >> > (arg=arg@entry=0xaaaaaaf1ec92f0) at ../accel/kvm/kvm-accel-ops.c:49 >> > #19 0x00aaaaaab8ca280a in qemu_thread_start (args=) at >> > ../util/qemu-thread-posix.c:556 >> > #20 0x00ffffffab2cf5a6 in start_thread (arg=) at ./nptl/pthread_create.c:442 >> > #21 0x00ffffffab31ba02 in __thread_start () at >> > ../sysdeps/unix/sysv/linux/riscv/clone.S:85 >> > >> > Based on above 2 logs, we can see the QEMU vcpu thread is blocked at KVM ioctl >> > KVM_SET_USER_MEMORY_REGION, and on the kernel side the ioctl call is >> > blocked at synchronize_srcu_expedited() so that ioctl never returns >> > back to the user land. >> > >> > If I single step the QEMU instance starting from a breakpoint at >> > pflash_write(), the ioctl call of KVM_SET_USER_MEMORY_REGION does not >> > block, and U-Boot can boot eventually. >> > >> > If I remove "-smp 2" from the QEMU command line when launching the VM, >> > U-Boot boots without any problem. Of course removing "-accel kvm" >> > works too. >> > >> > It looks to me there is a locking timing issue in the RISC-V KVM >> > kernel when an SMP guest is launched. Any ideas? >> >> To further isolate the problem, does it work if QEMU does not generate >> the pflash DT node ? No, and QEMU freezes when U-Boot tries to probe the virtio-net driver, logs below: U-Boot 2022.04 (Jul 07 2022 - 11:23:28 +0800) CPU: rv64imafdc Model: riscv-virtio,qemu DRAM: 2 GiB Core: 16 devices, 8 uclasses, devicetree: board Loading Environment from nowhere... OK In: uart@10000000 Out: uart@10000000 Err: uart@10000000 Net: <========== stuck here Here is the backtrace on the QEMU side, as you can see this time the VCPU thread is blocked at the ioctl of KVM_IOEVENTFD to KVM. #0 __GI___ioctl (fd=, request=request@entry=1077980793) at ../sysdeps/unix/sysv/linux/ioctl.c:35 #1 0x00aaaaaae53195f2 in kvm_vm_ioctl (s=0xaaaaab049a3e00, type=type@entry=1077980793) at ../accel/kvm/kvm-all.c:3035 #2 0x00aaaaaae531a7ae in kvm_set_ioeventfd_mmio (fd=, addr=, val=val@entry=0, assign=assign@entry=true, size=, datamatch=datamatch@entry=true) at ../accel/kvm/kvm-all.c:1248 #3 0x00aaaaaae531a946 in kvm_mem_ioeventfd_add (listener=, section=0xffffff8b949b00, match_data=, data=0, e=) at ../accel/kvm/kvm-all.c:1579 #4 0x00aaaaaae5260a6e in address_space_add_del_ioeventfds (fds_old_nb=0, fds_old=0x0, fds_new_nb=3, fds_new=0xfffffefc0386d0, as=0xaaaaaae58407a0 ) at ../softmmu/memory.c:793 #5 address_space_update_ioeventfds (as=0xaaaaaae58407a0 ) at ../softmmu/memory.c:854 #6 0x00aaaaaae52623bc in memory_region_transaction_commit () at ../softmmu/memory.c:1111 #7 0x00aaaaaae52b04b8 in virtio_device_start_ioeventfd_impl (vdev=0xaaaaab04e24f50) at ../hw/virtio/virtio.c:3723 #8 0x00aaaaaae51d0524 in virtio_bus_start_ioeventfd (bus=bus@entry=0xaaaaab04bf2e70) at ../hw/virtio/virtio-bus.c:229 #9 0x00aaaaaae51d47ce in virtio_mmio_start_ioeventfd (proxy=0xaaaaab04bf2a20) at ../hw/virtio/virtio-mmio.c:63 #10 virtio_mmio_write (opaque=0xaaaaab04bf2a20, offset=, value=6, size=) at ../hw/virtio/virtio-mmio.c:431 #11 0x00aaaaaae525faa4 in memory_region_write_accessor (mr=0xaaaaab04bf2d40, addr=112, value=, size=, shift=, mask=, attrs=...) at ../softmmu/memory.c:492 #12 0x00aaaaaae525dee6 in access_with_adjusted_size (addr=addr@entry=112, value=value@entry=0xffffff8b949dc8, size=size@entry=4, access_size_min=, access_size_max=, access_fn=0xaaaaaae525fa2e , mr=0xaaaaab04bf2d40, attrs=...) at ../softmmu/memory.c:554 #13 0x00aaaaaae52611fe in memory_region_dispatch_write (mr=mr@entry=0xaaaaab04bf2d40, addr=addr@entry=112, data=, data@entry=6, op=, attrs=attrs@entry=...) at ../softmmu/memory.c:1521 #14 0x00aaaaaae5266dcc in flatview_write_continue (fv=fv@entry=0xfffffefc001400, addr=addr@entry=268468336, attrs=attrs@entry=..., ptr=ptr@entry=0xffffff8cb66028, len=len@entry=4, addr1=, l=, mr=0xaaaaab04bf2d40) at ../softmmu/physmem.c:2814 #15 0x00aaaaaae526701c in flatview_write (fv=0xfffffefc001400, addr=268468336, attrs=..., buf=0xffffff8cb66028, len=len@entry=4) at ../softmmu/physmem.c:2856 #16 0x00aaaaaae5269e0e in address_space_write (len=4, buf=0xffffff8cb66028, attrs=..., addr=268468336, as=0xaaaaaae58407a0 ) at ../softmmu/physmem.c:2952 #17 address_space_rw (as=0xaaaaaae58407a0 , addr=268468336, attrs=..., attrs@entry=..., buf=buf@entry=0xffffff8cb66028, len=4, is_write=) at ../softmmu/physmem.c:2962 #18 0x00aaaaaae531c982 in kvm_cpu_exec (cpu=cpu@entry=0xaaaaab049a92f0) at ../accel/kvm/kvm-all.c:2929 #19 0x00aaaaaae531d4b6 in kvm_vcpu_thread_fn (arg=arg@entry=0xaaaaab049a92f0) at ../accel/kvm/kvm-accel-ops.c:49 #20 0x00aaaaaae542a74e in qemu_thread_start (args=) at ../util/qemu-thread-posix.c:556 #21 0x00ffffff8c7055a6 in start_thread (arg=) at ./nptl/pthread_create.c:442 #22 0x00ffffff8c751a02 in __thread_start () at ../sysdeps/unix/sysv/linux/riscv/clone.S:85 Regards, Bin
