kernel.git/drivers/xen/events, branch linux-6.8.y

xen/events: increment refcnt only if event channel is refcounted

2024-03-26T22:17:34Z

[ Upstream commit d277f9d82802223f242cd9b60c988cfdda1d6be0 ] In bind_evtchn_to_irq_chip() don't increment the refcnt of the event channel blindly. In case the event channel is NOT refcounted, issue a warning instead. Add an additional safety net by doing the refcnt increment only if the caller has specified IRQF_SHARED in the irqflags parameter. Fixes: 9e90e58c11b7 ("xen: evtchn: Allow shared registration of IRQ handers") Signed-off-by: Juergen Gross Reviewed-by: Oleksandr Tyshchenko Link: https://lore.kernel.org/r/20240313071409.25913-3-jgross@suse.com Signed-off-by: Juergen Gross Signed-off-by: Sasha Levin

xen/events: close evtchn after mapping cleanup

2024-02-13T09:12:47Z

shutdown_pirq and startup_pirq are not taking the irq_mapping_update_lock because they can't due to lock inversion. Both are called with the irq_desc->lock being taking. The lock order, however, is first irq_mapping_update_lock and then irq_desc->lock. This opens multiple races: - shutdown_pirq can be interrupted by a function that allocates an event channel: CPU0 CPU1 shutdown_pirq { xen_evtchn_close(e) __startup_pirq { EVTCHNOP_bind_pirq -> returns just freed evtchn e set_evtchn_to_irq(e, irq) } xen_irq_info_cleanup() { set_evtchn_to_irq(e, -1) } } Assume here event channel e refers here to the same event channel number. After this race the evtchn_to_irq mapping for e is invalid (-1). - __startup_pirq races with __unbind_from_irq in a similar way. Because __startup_pirq doesn't take irq_mapping_update_lock it can grab the evtchn that __unbind_from_irq is currently freeing and cleaning up. In this case even though the event channel is allocated, its mapping can be unset in evtchn_to_irq. The fix is to first cleanup the mappings and then close the event channel. In this way, when an event channel gets allocated it's potential previous evtchn_to_irq mappings are guaranteed to be unset already. This is also the reverse order of the allocation where first the event channel is allocated and then the mappings are setup. On a 5.10 kernel prior to commit 3fcdaf3d7634 ("xen/events: modify internal [un]bind interfaces"), we hit a BUG like the following during probing of NVMe devices. The issue is that during nvme_setup_io_queues, pci_free_irq is called for every device which results in a call to shutdown_pirq. With many nvme devices it's therefore likely to hit this race during boot because there will be multiple calls to shutdown_pirq and startup_pirq are running potentially in parallel. ------------[ cut here ]------------ blkfront: xvda: barrier or flush: disabled; persistent grants: enabled; indirect descriptors: enabled; bounce buffer: enabled kernel BUG at drivers/xen/events/events_base.c:499! invalid opcode: 0000 [#1] SMP PTI CPU: 44 PID: 375 Comm: kworker/u257:23 Not tainted 5.10.201-191.748.amzn2.x86_64 #1 Hardware name: Xen HVM domU, BIOS 4.11.amazon 08/24/2006 Workqueue: nvme-reset-wq nvme_reset_work RIP: 0010:bind_evtchn_to_cpu+0xdf/0xf0 Code: 5d 41 5e c3 cc cc cc cc 44 89 f7 e8 2b 55 ad ff 49 89 c5 48 85 c0 0f 84 64 ff ff ff 4c 8b 68 30 41 83 fe ff 0f 85 60 ff ff ff <0f> 0b 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 0f 1f 44 00 00 RSP: 0000:ffffc9000d533b08 EFLAGS: 00010046 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000006 RDX: 0000000000000028 RSI: 00000000ffffffff RDI: 00000000ffffffff RBP: ffff888107419680 R08: 0000000000000000 R09: ffffffff82d72b00 R10: 0000000000000000 R11: 0000000000000000 R12: 00000000000001ed R13: 0000000000000000 R14: 00000000ffffffff R15: 0000000000000002 FS: 0000000000000000(0000) GS:ffff88bc8b500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000002610001 CR4: 00000000001706e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ? show_trace_log_lvl+0x1c1/0x2d9 ? show_trace_log_lvl+0x1c1/0x2d9 ? set_affinity_irq+0xdc/0x1c0 ? __die_body.cold+0x8/0xd ? die+0x2b/0x50 ? do_trap+0x90/0x110 ? bind_evtchn_to_cpu+0xdf/0xf0 ? do_error_trap+0x65/0x80 ? bind_evtchn_to_cpu+0xdf/0xf0 ? exc_invalid_op+0x4e/0x70 ? bind_evtchn_to_cpu+0xdf/0xf0 ? asm_exc_invalid_op+0x12/0x20 ? bind_evtchn_to_cpu+0xdf/0xf0 ? bind_evtchn_to_cpu+0xc5/0xf0 set_affinity_irq+0xdc/0x1c0 irq_do_set_affinity+0x1d7/0x1f0 irq_setup_affinity+0xd6/0x1a0 irq_startup+0x8a/0xf0 __setup_irq+0x639/0x6d0 ? nvme_suspend+0x150/0x150 request_threaded_irq+0x10c/0x180 ? nvme_suspend+0x150/0x150 pci_request_irq+0xa8/0xf0 ? __blk_mq_free_request+0x74/0xa0 queue_request_irq+0x6f/0x80 nvme_create_queue+0x1af/0x200 nvme_create_io_queues+0xbd/0xf0 nvme_setup_io_queues+0x246/0x320 ? nvme_irq_check+0x30/0x30 nvme_reset_work+0x1c8/0x400 process_one_work+0x1b0/0x350 worker_thread+0x49/0x310 ? process_one_work+0x350/0x350 kthread+0x11b/0x140 ? __kthread_bind_mask+0x60/0x60 ret_from_fork+0x22/0x30 Modules linked in: ---[ end trace a11715de1eee1873 ]--- Fixes: d46a78b05c0e ("xen: implement pirq type event channels") Cc: stable@vger.kernel.org Co-debugged-by: Andrew Panyakin Signed-off-by: Maximilian Heyne Reviewed-by: Juergen Gross Link: https://lore.kernel.org/r/20240124163130.31324-1-mheyne@amazon.de Signed-off-by: Juergen Gross

xen/events: fix error code in xen_bind_pirq_msi_to_irq()

2023-11-28T11:48:27Z

Return -ENOMEM if xen_irq_init() fails. currently the code returns an uninitialized variable or zero. Fixes: 5dd9ad32d775 ("xen/events: drop xen_allocate_irqs_dynamic()") Signed-off-by: Dan Carpenter Reviewed-by: Juergen Gross Link: https://lore.kernel.org/r/3b9ab040-a92e-4e35-b687-3a95890a9ace@moroto.mountain Signed-off-by: Juergen Gross

xen/events: remove some info_for_irq() calls in pirq handling

2023-11-15T08:51:51Z

Instead of the IRQ number user the struct irq_info pointer as parameter in the internal pirq related functions. This allows to drop some calls of info_for_irq(). Signed-off-by: Juergen Gross Reviewed-by: Oleksandr Tyshchenko Signed-off-by: Juergen Gross

xen/events: modify internal [un]bind interfaces

2023-11-15T08:29:39Z

Modify the internal bind- and unbind-interfaces to take a struct irq_info parameter. When allocating a new IRQ pass the pointer from the allocating function further up. This will reduce the number of info_for_irq() calls and make the code more efficient. Signed-off-by: Juergen Gross Reviewed-by: Oleksandr Tyshchenko Signed-off-by: Juergen Gross

xen/events: drop xen_allocate_irqs_dynamic()

2023-11-15T08:02:59Z

Instead of having a common function for allocating a single IRQ or a consecutive number of IRQs, split up the functionality into the callers of xen_allocate_irqs_dynamic(). This allows to handle any allocation error in xen_irq_init() gracefully instead of panicing the system. Let xen_irq_init() return the irq_info pointer or NULL in case of an allocation error. Additionally set the IRQ into irq_info already at allocation time, as otherwise the IRQ would be '0' (which is a valid IRQ number) until being set. Signed-off-by: Juergen Gross Reviewed-by: Oleksandr Tyshchenko Signed-off-by: Juergen Gross

xen/events: remove some simple helpers from events_base.c

2023-11-14T09:16:34Z

The helper functions type_from_irq() and cpu_from_irq() are just one line functions used only internally. Open code them where needed. At the same time modify and rename get_evtchn_to_irq() to return a struct irq_info instead of the IRQ number. Signed-off-by: Juergen Gross Reviewed-by: Oleksandr Tyshchenko Signed-off-by: Juergen Gross

xen/events: reduce externally visible helper functions

2023-11-14T08:29:28Z

get_evtchn_to_irq() has only one external user while irq_from_evtchn() provides the same functionality and is exported for a wider user base. Modify the only external user of get_evtchn_to_irq() to use irq_from_evtchn() instead and make get_evtchn_to_irq() static. evtchn_from_irq() and irq_from_virq() have a single external user and can easily be combined to a new helper irq_evtchn_from_virq() allowing to drop irq_from_virq() and to make evtchn_from_irq() static. Signed-off-by: Juergen Gross Reviewed-by: Oleksandr Tyshchenko Signed-off-by: Juergen Gross

xen/events: remove unused functions

2023-11-13T14:45:20Z

There are no users of xen_irq_from_pirq() and xen_set_irq_pending(). Remove those functions. Signed-off-by: Juergen Gross Reviewed-by: Oleksandr Tyshchenko Signed-off-by: Juergen Gross

xen/events: fix delayed eoi list handling

2023-11-13T14:21:08Z

When delaying eoi handling of events, the related elements are queued into the percpu lateeoi list. In case the list isn't empty, the elements should be sorted by the time when eoi handling is to happen. Unfortunately a new element will never be queued at the start of the list, even if it has a handling time lower than all other list elements. Fix that by handling that case the same way as for an empty list. Fixes: e99502f76271 ("xen/events: defer eoi in case of excessive number of events") Reported-by: Jan Beulich Signed-off-by: Juergen Gross Reviewed-by: Oleksandr Tyshchenko Signed-off-by: Juergen Gross