Re: [PATCH v12 00/25] Linux RISC-V AIA Support

[Andrea Parri <parri.andrea@gmail.com>]

Hi Anup,

I understand that some refactoring is in progress, but I don't see the
report below; adding it here hoping that it can be useful towards v13.
(Unfortunately, I didn't have enough time to debug this yet...)


>   irqchip/sifive-plic: Convert PLIC driver into a platform driver

I'm seeing the following LOCKDEP warning with this series, bisected to
the commit above.  This is a defconfig + PROVE_LOCKING=y build, booted
using -machine virt,aia=none.

[    0.953473] ========================================================
[    0.953704] WARNING: possible irq lock inversion dependency detected
[    0.953955] 6.8.0-rc1-00039-gd9b9d6eb987f #1122 Not tainted
[    0.954224] --------------------------------------------------------
[    0.954444] swapper/0/0 just changed the state of lock:
[    0.954664] ffffaf808109d0c8 (&irq_desc_lock_class){-...}-{2:2}, at: handle_fasteoi_irq+0x24/0x1da
[    0.955699] but this lock took another, HARDIRQ-unsafe lock in the past:
[    0.955942]  (&handler->enable_lock){+.+.}-{2:2}
[    0.955974] 
               
               and interrupts could create inverse lock ordering between them.

[    0.956507] 
               other info that might help us debug this:
[    0.956775]  Possible interrupt unsafe locking scenario:

[    0.956998]        CPU0                    CPU1
[    0.957247]        ----                    ----
[    0.957439]   lock(&handler->enable_lock);
[    0.957607]                                local_irq_disable();
[    0.957793]                                lock(&irq_desc_lock_class);
[    0.958021]                                lock(&handler->enable_lock);
[    0.958246]   <Interrupt>
[    0.958342]     lock(&irq_desc_lock_class);
[    0.958501] 
                *** DEADLOCK ***

[    0.958715] no locks held by swapper/0/0.
[    0.958870] 
               the shortest dependencies between 2nd lock and 1st lock:
[    0.959152]  -> (&handler->enable_lock){+.+.}-{2:2} {
[    0.959372]     HARDIRQ-ON-W at:
[    0.959522]                       __lock_acquire+0x884/0x1f5c
[    0.959745]                       lock_acquire+0xf0/0x292
[    0.959913]                       _raw_spin_lock+0x2c/0x40
[    0.960090]                       plic_probe+0x322/0x65c
[    0.960257]                       platform_probe+0x4e/0x92
[    0.960432]                       really_probe+0x82/0x210
[    0.960598]                       __driver_probe_device+0x5c/0xd0
[    0.960784]                       driver_probe_device+0x2c/0xb0
[    0.960964]                       __driver_attach+0x72/0x10a
[    0.961151]                       bus_for_each_dev+0x60/0xac
[    0.961330]                       driver_attach+0x1a/0x22
[    0.961496]                       bus_add_driver+0xd4/0x19e
[    0.961666]                       driver_register+0x3e/0xd8
[    0.961835]                       __platform_driver_register+0x1c/0x24
[    0.962030]                       plic_driver_init+0x1a/0x22
[    0.962201]                       do_one_initcall+0x80/0x268
[    0.962371]                       kernel_init_freeable+0x296/0x300
[    0.962554]                       kernel_init+0x1e/0x10a
[    0.962713]                       ret_from_fork+0xe/0x1c
[    0.962884]     SOFTIRQ-ON-W at:
[    0.962994]                       __lock_acquire+0x89e/0x1f5c
[    0.963169]                       lock_acquire+0xf0/0x292
[    0.963336]                       _raw_spin_lock+0x2c/0x40
[    0.963497]                       plic_probe+0x322/0x65c
[    0.963664]                       platform_probe+0x4e/0x92
[    0.963849]                       really_probe+0x82/0x210
[    0.964054]                       __driver_probe_device+0x5c/0xd0
[    0.964255]                       driver_probe_device+0x2c/0xb0
[    0.964428]                       __driver_attach+0x72/0x10a
[    0.964603]                       bus_for_each_dev+0x60/0xac
[    0.964777]                       driver_attach+0x1a/0x22
[    0.964943]                       bus_add_driver+0xd4/0x19e
[    0.965343]                       driver_register+0x3e/0xd8
[    0.965527]                       __platform_driver_register+0x1c/0x24
[    0.965732]                       plic_driver_init+0x1a/0x22
[    0.965908]                       do_one_initcall+0x80/0x268
[    0.966078]                       kernel_init_freeable+0x296/0x300
[    0.966268]                       kernel_init+0x1e/0x10a
[    0.966436]                       ret_from_fork+0xe/0x1c
[    0.966599]     INITIAL USE at:
[    0.966716]                      __lock_acquire+0x3fc/0x1f5c
[    0.966891]                      lock_acquire+0xf0/0x292
[    0.967048]                      _raw_spin_lock+0x2c/0x40
[    0.967206]                      plic_probe+0x322/0x65c
[    0.967360]                      platform_probe+0x4e/0x92
[    0.967522]                      really_probe+0x82/0x210
[    0.967678]                      __driver_probe_device+0x5c/0xd0
[    0.967853]                      driver_probe_device+0x2c/0xb0
[    0.968025]                      __driver_attach+0x72/0x10a
[    0.968185]                      bus_for_each_dev+0x60/0xac
[    0.968348]                      driver_attach+0x1a/0x22
[    0.968513]                      bus_add_driver+0xd4/0x19e
[    0.968678]                      driver_register+0x3e/0xd8
[    0.968839]                      __platform_driver_register+0x1c/0x24
[    0.969035]                      plic_driver_init+0x1a/0x22
[    0.969239]                      do_one_initcall+0x80/0x268
[    0.969431]                      kernel_init_freeable+0x296/0x300
[    0.969610]                      kernel_init+0x1e/0x10a
[    0.969766]                      ret_from_fork+0xe/0x1c
[    0.969936]   }
[    0.970010]   ... key      at: [<ffffffff824f4138>] __key.2+0x0/0x10
[    0.970224]   ... acquired at:
[    0.970353]    lock_acquire+0xf0/0x292
[    0.970482]    _raw_spin_lock+0x2c/0x40
[    0.970609]    plic_irq_enable+0x7e/0x140
[    0.970739]    irq_enable+0x2c/0x60
[    0.970882]    __irq_startup+0x58/0x60
[    0.971008]    irq_startup+0x5e/0x13c
[    0.971126]    __setup_irq+0x4de/0x5da
[    0.971248]    request_threaded_irq+0xcc/0x12e
[    0.971394]    vm_find_vqs+0x62/0x50a
[    0.971518]    probe_common+0xfe/0x1d2
[    0.971635]    virtrng_probe+0xc/0x14
[    0.971751]    virtio_dev_probe+0x154/0x1fc
[    0.971878]    really_probe+0x82/0x210
[    0.972008]    __driver_probe_device+0x5c/0xd0
[    0.972147]    driver_probe_device+0x2c/0xb0
[    0.972280]    __driver_attach+0x72/0x10a
[    0.972407]    bus_for_each_dev+0x60/0xac
[    0.972540]    driver_attach+0x1a/0x22
[    0.972656]    bus_add_driver+0xd4/0x19e
[    0.972777]    driver_register+0x3e/0xd8
[    0.972896]    register_virtio_driver+0x1c/0x2a
[    0.973049]    virtio_rng_driver_init+0x18/0x20
[    0.973236]    do_one_initcall+0x80/0x268
[    0.973399]    kernel_init_freeable+0x296/0x300
[    0.973540]    kernel_init+0x1e/0x10a
[    0.973658]    ret_from_fork+0xe/0x1c

[    0.973858] -> (&irq_desc_lock_class){-...}-{2:2} {
[    0.974036]    IN-HARDIRQ-W at:
[    0.974142]                     __lock_acquire+0xa82/0x1f5c
[    0.974309]                     lock_acquire+0xf0/0x292
[    0.974467]                     _raw_spin_lock+0x2c/0x40
[    0.974625]                     handle_fasteoi_irq+0x24/0x1da
[    0.974794]                     generic_handle_domain_irq+0x1c/0x2a
[    0.974982]                     plic_handle_irq+0x7e/0xf0
[    0.975143]                     generic_handle_domain_irq+0x1c/0x2a
[    0.975329]                     riscv_intc_irq+0x2e/0x46
[    0.975488]                     handle_riscv_irq+0x4a/0x74
[    0.975652]                     call_on_irq_stack+0x32/0x40
[    0.975817]    INITIAL USE at:
[    0.975923]                    __lock_acquire+0x3fc/0x1f5c
[    0.976087]                    lock_acquire+0xf0/0x292
[    0.976244]                    _raw_spin_lock_irqsave+0x3a/0x64
[    0.976423]                    __irq_get_desc_lock+0x5a/0x84
[    0.976594]                    irq_modify_status+0x2a/0x106
[    0.976764]                    irq_set_percpu_devid+0x62/0x78
[    0.976939]                    riscv_intc_domain_map+0x1e/0x54
[    0.977133]                    irq_domain_associate_locked+0x42/0xe4
[    0.977363]                    irq_create_mapping_affinity+0x98/0xd4
[    0.977570]                    sbi_ipi_init+0x70/0x142
[    0.977744]                    init_IRQ+0xfe/0x11a
[    0.977906]                    start_kernel+0x4ae/0x790
[    0.978082]  }
[    0.978151]  ... key      at: [<ffffffff824bbee0>] irq_desc_lock_class+0x0/0x10
[    0.978389]  ... acquired at:
[    0.978494]    mark_lock+0x3fe/0x8c2
[    0.978624]    __lock_acquire+0xa82/0x1f5c
[    0.978766]    lock_acquire+0xf0/0x292
[    0.978897]    _raw_spin_lock+0x2c/0x40
[    0.979029]    handle_fasteoi_irq+0x24/0x1da
[    0.979171]    generic_handle_domain_irq+0x1c/0x2a
[    0.979326]    plic_handle_irq+0x7e/0xf0
[    0.979460]    generic_handle_domain_irq+0x1c/0x2a
[    0.979618]    riscv_intc_irq+0x2e/0x46
[    0.979751]    handle_riscv_irq+0x4a/0x74
[    0.979888]    call_on_irq_stack+0x32/0x40

[    0.980110] 
               stack backtrace:
[    0.980358] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.8.0-rc1-00039-gd9b9d6eb987f #1122
[    0.980662] Hardware name: riscv-virtio,qemu (DT)
[    0.980913] Call Trace:
[    0.981042] [<ffffffff80007198>] dump_backtrace+0x1c/0x24
[    0.981246] [<ffffffff80ae020a>] show_stack+0x2c/0x38
[    0.981456] [<ffffffff80aedac4>] dump_stack_lvl+0x5a/0x7c
[    0.981648] [<ffffffff80aedafa>] dump_stack+0x14/0x1c
[    0.981813] [<ffffffff80ae17a4>] print_irq_inversion_bug.part.0+0x162/0x176
[    0.982031] [<ffffffff8007c6e6>] mark_lock+0x3fe/0x8c2
[    0.982198] [<ffffffff8007d888>] __lock_acquire+0xa82/0x1f5c
[    0.982377] [<ffffffff8007f59e>] lock_acquire+0xf0/0x292
[    0.982549] [<ffffffff80af9962>] _raw_spin_lock+0x2c/0x40
[    0.982721] [<ffffffff8008f3fe>] handle_fasteoi_irq+0x24/0x1da
[    0.982904] [<ffffffff8008a4a4>] generic_handle_domain_irq+0x1c/0x2a
[    0.983112] [<ffffffff80581dc0>] plic_handle_irq+0x7e/0xf0
[    0.983293] [<ffffffff8008a4a4>] generic_handle_domain_irq+0x1c/0x2a
[    0.983495] [<ffffffff8057fb1a>] riscv_intc_irq+0x2e/0x46
[    0.983671] [<ffffffff80aedb4c>] handle_riscv_irq+0x4a/0x74
[    0.983856] [<ffffffff80afa756>] call_on_irq_stack+0x32/0x40


When I switch to -machine virt,aia=aplic-imsic (same config as above), I
get:

[    0.971406] ============================================
[    0.971439] WARNING: possible recursive locking detected
[    0.971497] 6.8.0-rc1-00039-gd9b9d6eb987f #1122 Not tainted
[    0.971583] --------------------------------------------
[    0.971612] swapper/0/1 is trying to acquire lock:
[    0.971662] ffffaf83fefa8e78 (&lpriv->ids_lock){-...}-{2:2}, at: imsic_vector_move+0x92/0x146
[    0.971927] 
               but task is already holding lock:
[    0.971975] ffffaf83fef6ee78 (&lpriv->ids_lock){-...}-{2:2}, at: imsic_vector_move+0x86/0x146
[    0.972045] 
               other info that might help us debug this:
[    0.972085]  Possible unsafe locking scenario:

[    0.972114]        CPU0
[    0.972133]        ----
[    0.972153]   lock(&lpriv->ids_lock);
[    0.972191]   lock(&lpriv->ids_lock);
[    0.972228] 
                *** DEADLOCK ***

[    0.972258]  May be due to missing lock nesting notation

[    0.972306] 6 locks held by swapper/0/1:
[    0.972338]  #0: ffffaf8081f65970 (&dev->mutex){....}-{3:3}, at: __driver_attach+0x6a/0x10a
[    0.972413]  #1: ffffaf808217c240 (&desc->request_mutex){+.+.}-{3:3}, at: __setup_irq+0xa2/0x5da
[    0.972492]  #2: ffffaf808217c0c8 (&irq_desc_lock_class){....}-{2:2}, at: __setup_irq+0xbe/0x5da
[    0.972555]  #3: ffffffff81892ac0 (mask_lock){....}-{2:2}, at: irq_setup_affinity+0x38/0xc6
[    0.972617]  #4: ffffffff81892a80 (tmp_mask_lock){....}-{2:2}, at: irq_do_set_affinity+0x3a/0x164
[    0.972681]  #5: ffffaf83fef6ee78 (&lpriv->ids_lock){-...}-{2:2}, at: imsic_vector_move+0x86/0x146
[    0.972753] 
               stack backtrace:
[    0.972852] CPU: 3 PID: 1 Comm: swapper/0 Not tainted 6.8.0-rc1-00039-gd9b9d6eb987f #1122
[    0.972900] Hardware name: riscv-virtio,qemu (DT)
[    0.972987] Call Trace:
[    0.973019] [<ffffffff80007198>] dump_backtrace+0x1c/0x24
[    0.973054] [<ffffffff80ae020a>] show_stack+0x2c/0x38
[    0.973083] [<ffffffff80aedac4>] dump_stack_lvl+0x5a/0x7c
[    0.973112] [<ffffffff80aedafa>] dump_stack+0x14/0x1c
[    0.973139] [<ffffffff8007ad5e>] print_deadlock_bug+0x282/0x328
[    0.973168] [<ffffffff8007e15c>] __lock_acquire+0x1356/0x1f5c
[    0.973198] [<ffffffff8007f59e>] lock_acquire+0xf0/0x292
[    0.973225] [<ffffffff80af9adc>] _raw_spin_lock_irqsave+0x3a/0x64
[    0.973255] [<ffffffff80581210>] imsic_vector_move+0x92/0x146
[    0.973285] [<ffffffff80581a04>] imsic_irq_set_affinity+0x8e/0xc6
[    0.973315] [<ffffffff8008c86a>] irq_do_set_affinity+0x142/0x164
[    0.973345] [<ffffffff8008cc22>] irq_setup_affinity+0x68/0xc6
[    0.973374] [<ffffffff8008fa82>] irq_startup+0x72/0x13c
[    0.973401] [<ffffffff8008d40c>] __setup_irq+0x4de/0x5da
[    0.973430] [<ffffffff8008d5d4>] request_threaded_irq+0xcc/0x12e
[    0.973460] [<ffffffff806346d8>] vp_find_vqs_msix+0x114/0x376
[    0.973491] [<ffffffff80634970>] vp_find_vqs+0x36/0x136
[    0.973518] [<ffffffff80633280>] vp_modern_find_vqs+0x16/0x4e
[    0.973547] [<ffffffff80ab31f8>] p9_virtio_probe+0x8e/0x31c
[    0.973576] [<ffffffff8062d982>] virtio_dev_probe+0x154/0x1fc
[    0.973605] [<ffffffff80693738>] really_probe+0x82/0x210
[    0.973632] [<ffffffff80693922>] __driver_probe_device+0x5c/0xd0
[    0.973661] [<ffffffff806939c2>] driver_probe_device+0x2c/0xb0
[    0.973690] [<ffffffff80693b46>] __driver_attach+0x72/0x10a
[    0.973718] [<ffffffff8069191a>] bus_for_each_dev+0x60/0xac
[    0.973746] [<ffffffff80693164>] driver_attach+0x1a/0x22
[    0.973773] [<ffffffff80692ade>] bus_add_driver+0xd4/0x19e
[    0.973801] [<ffffffff8069487e>] driver_register+0x3e/0xd8
[    0.973829] [<ffffffff8062d1ce>] register_virtio_driver+0x1c/0x2a
[    0.973858] [<ffffffff80c3da52>] p9_virtio_init+0x36/0x56
[    0.973887] [<ffffffff800028fe>] do_one_initcall+0x80/0x268
[    0.973915] [<ffffffff80c01144>] kernel_init_freeable+0x296/0x300
[    0.973944] [<ffffffff80af05dc>] kernel_init+0x1e/0x10a
[    0.973972] [<ffffffff80afa716>] ret_from_fork+0xe/0x1c


FWIW, the full Qemu command I used was as follows:

	sudo /home/andrea/Downloads/qemu/build/qemu-system-riscv64 \
		-append "root=/dev/root rw rootfstype=9p rootflags=version=9p2000.L,trans=virtio,cache=mmap,access=any raid=noautodetect security=none loglevel=7" \
		-cpu rv64,sv57=off,svadu=off,svnapot=off \
		-device virtio-net-device,netdev=net0 \
		-device virtio-rng-device,rng=rng0 \
		-device virtio-9p-pci,fsdev=root,mount_tag=/dev/root \
		-fsdev local,id=root,path=/home/andrea/Downloads/jammy/,security_model=none \
		-kernel /home/andrea/linux/arch/riscv/boot/Image \
		-m 16G \
		-machine virt,aia=<either "none" or "aplic-imsic"> \
		-monitor telnet:127.0.0.1:55555,server,nowait \
		-netdev user,id=net0,host=10.0.2.10,hostfwd=tcp::10022-:22 \
		-nographic \
		-object rng-random,filename=/dev/urandom,id=rng0 \
		-serial mon:stdio \
		-smp 5


  Andrea

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