kernel/linux.git/drivers/xen, branch v6.1.87

xen/events: close evtchn after mapping cleanup

2024-03-06T14:45:20+00:00

commit fa765c4b4aed2d64266b694520ecb025c862c5a9 upstream. 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 Signed-off-by: Maximilian Heyne Signed-off-by: Greg Kroah-Hartman

xen/gntdev: Fix the abuse of underlying struct page in DMA-buf import

2024-02-05T20:12:58+00:00

[ Upstream commit 2d2db7d40254d5fb53b11ebd703cd1ed0c5de7a1 ] DO NOT access the underlying struct page of an sg table exported by DMA-buf in dmabuf_imp_to_refs(), this is not allowed. Please see drivers/dma-buf/dma-buf.c:mangle_sg_table() for details. Fortunately, here (for special Xen device) we can avoid using pages and calculate gfns directly from dma addresses provided by the sg table. Suggested-by: Daniel Vetter Signed-off-by: Oleksandr Tyshchenko Acked-by: Christian König Reviewed-by: Stefano Stabellini Acked-by: Daniel Vetter Link: https://lore.kernel.org/r/20240107103426.2038075-1-olekstysh@gmail.com Signed-off-by: Juergen Gross Signed-off-by: Sasha Levin

xen: simplify evtchn_do_upcall() call maze

2023-12-08T07:51:20+00:00

[ Upstream commit 37510dd566bdbff31a769cde2fa6654bccdb8b24 ] There are several functions involved for performing the functionality of evtchn_do_upcall(): - __xen_evtchn_do_upcall() doing the real work - xen_hvm_evtchn_do_upcall() just being a wrapper for __xen_evtchn_do_upcall(), exposed for external callers - xen_evtchn_do_upcall() calling __xen_evtchn_do_upcall(), too, but without any user Simplify this maze by: - removing the unused xen_evtchn_do_upcall() - removing xen_hvm_evtchn_do_upcall() as the only left caller of __xen_evtchn_do_upcall(), while renaming __xen_evtchn_do_upcall() to xen_evtchn_do_upcall() Signed-off-by: Juergen Gross Reviewed-by: Boris Ostrovsky Reviewed-by: Thomas Gleixner Signed-off-by: Juergen Gross Stable-dep-of: db2832309a82 ("x86/xen: fix percpu vcpu_info allocation") Signed-off-by: Sasha Levin

xen: Allow platform PCI interrupt to be shared

2023-12-08T07:51:20+00:00

[ Upstream commit 3e8cd711c3da6c3d724076048038cd666bdbb2b5 ] When we don't use the per-CPU vector callback, we ask Xen to deliver event channel interrupts as INTx on the PCI platform device. As such, it can be shared with INTx on other PCI devices. Set IRQF_SHARED, and make it return IRQ_HANDLED or IRQ_NONE according to whether the evtchn_upcall_pending flag was actually set. Now I can share the interrupt: 11: 82 0 IO-APIC 11-fasteoi xen-platform-pci, ens4 Drop the IRQF_TRIGGER_RISING. It has no effect when the IRQ is shared, and besides, the only effect it was having even beforehand was to trigger a debug message in both I/OAPIC and legacy PIC cases: [ 0.915441] genirq: No set_type function for IRQ 11 (IO-APIC) [ 0.951939] genirq: No set_type function for IRQ 11 (XT-PIC) Signed-off-by: David Woodhouse Reviewed-by: Juergen Gross Link: https://lore.kernel.org/r/f9a29a68d05668a3636dd09acd94d970269eaec6.camel@infradead.org Signed-off-by: Juergen Gross Stable-dep-of: db2832309a82 ("x86/xen: fix percpu vcpu_info allocation") Signed-off-by: Sasha Levin

swiotlb-xen: provide the "max_mapping_size" method

2023-12-03T06:32:11+00:00

commit bff2a2d453a1b683378b4508b86b84389f551a00 upstream. There's a bug that when using the XEN hypervisor with bios with large multi-page bio vectors on NVMe, the kernel deadlocks [1]. The deadlocks are caused by inability to map a large bio vector - dma_map_sgtable always returns an error, this gets propagated to the block layer as BLK_STS_RESOURCE and the block layer retries the request indefinitely. XEN uses the swiotlb framework to map discontiguous pages into contiguous runs that are submitted to the PCIe device. The swiotlb framework has a limitation on the length of a mapping - this needs to be announced with the max_mapping_size method to make sure that the hardware drivers do not create larger mappings. Without max_mapping_size, the NVMe block driver would create large mappings that overrun the maximum mapping size. Reported-by: Marek Marczykowski-Górecki Link: https://lore.kernel.org/stable/ZTNH0qtmint%2FzLJZ@mail-itl/ [1] Tested-by: Marek Marczykowski-Górecki Suggested-by: Christoph Hellwig Cc: stable@vger.kernel.org Signed-off-by: Keith Busch Signed-off-by: Mikulas Patocka Acked-by: Stefano Stabellini Reviewed-by: Christoph Hellwig Link: https://lore.kernel.org/r/151bef41-e817-aea9-675-a35fdac4ed@redhat.com Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman

xen/events: fix delayed eoi list handling

2023-11-28T17:07:05+00:00

[ Upstream commit 47d970204054f859f35a2237baa75c2d84fcf436 ] 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 Signed-off-by: Sasha Levin

xen-pciback: Consider INTx disabled when MSI/MSI-X is enabled

2023-11-20T10:52:01+00:00

[ Upstream commit 2c269f42d0f382743ab230308b836ffe5ae9b2ae ] Linux enables MSI-X before disabling INTx, but keeps MSI-X masked until the table is filled. Then it disables INTx just before clearing MASKALL bit. Currently this approach is rejected by xen-pciback. According to the PCIe spec, device cannot use INTx when MSI/MSI-X is enabled (in other words: enabling MSI/MSI-X implicitly disables INTx). Change the logic to consider INTx disabled if MSI/MSI-X is enabled. This applies to three places: - checking currently enabled interrupts type, - transition to MSI/MSI-X - where INTx would be implicitly disabled, - clearing INTx disable bit - which can be allowed even if MSI/MSI-X is enabled, as device should consider INTx disabled anyway in that case Fixes: 5e29500eba2a ("xen-pciback: Allow setting PCI_MSIX_FLAGS_MASKALL too") Signed-off-by: Marek Marczykowski-Górecki Acked-by: Juergen Gross Link: https://lore.kernel.org/r/20231016131348.1734721-1-marmarek@invisiblethingslab.com Signed-off-by: Juergen Gross Signed-off-by: Sasha Levin

xenbus: fix error exit in xenbus_init()

2023-11-20T10:52:01+00:00

[ Upstream commit 44961b81a9e9059b5c0443643915386db7035227 ] In case an error occurs in xenbus_init(), xen_store_domain_type should be set to XS_UNKNOWN. Fix one instance where this action is missing. Fixes: 5b3353949e89 ("xen: add support for initializing xenstore later as HVM domain") Reported-by: kernel test robot Reported-by: Dan Carpenter Link: https://lore.kernel.org/r/202304200845.w7m4kXZr-lkp@intel.com/ Signed-off-by: Juergen Gross Reviewed-by: Oleksandr Tyshchenko Link: https://lore.kernel.org/r/20230822091138.4765-1-jgross@suse.com Signed-off-by: Juergen Gross Signed-off-by: Sasha Levin

xen/events: replace evtchn_rwlock with RCU

2023-10-10T20:00:46+00:00

commit 87797fad6cce28ec9be3c13f031776ff4f104cfc upstream. In unprivileged Xen guests event handling can cause a deadlock with Xen console handling. The evtchn_rwlock and the hvc_lock are taken in opposite sequence in __hvc_poll() and in Xen console IRQ handling. Normally this is no problem, as the evtchn_rwlock is taken as a reader in both paths, but as soon as an event channel is being closed, the lock will be taken as a writer, which will cause read_lock() to block: CPU0 CPU1 CPU2 (IRQ handling) (__hvc_poll()) (closing event channel) read_lock(evtchn_rwlock) spin_lock(hvc_lock) write_lock(evtchn_rwlock) [blocks] spin_lock(hvc_lock) [blocks] read_lock(evtchn_rwlock) [blocks due to writer waiting, and not in_interrupt()] This issue can be avoided by replacing evtchn_rwlock with RCU in xen_free_irq(). Note that RCU is used only to delay freeing of the irq_info memory. There is no RCU based dereferencing or replacement of pointers involved. In order to avoid potential races between removing the irq_info reference and handling of interrupts, set the irq_info pointer to NULL only when freeing its memory. The IRQ itself must be freed at that time, too, as otherwise the same IRQ number could be allocated again before handling of the old instance would have been finished. This is XSA-441 / CVE-2023-34324. Fixes: 54c9de89895e ("xen/events: add a new "late EOI" evtchn framework") Reported-by: Marek Marczykowski-Górecki Signed-off-by: Juergen Gross Reviewed-by: Julien Grall Signed-off-by: Greg Kroah-Hartman

xen: speed up grant-table reclaim

2023-08-03T08:24:14+00:00

commit c04e9894846c663f3278a414f34416e6e45bbe68 upstream. When a grant entry is still in use by the remote domain, Linux must put it on a deferred list. Normally, this list is very short, because the PV network and block protocols expect the backend to unmap the grant first. However, Qubes OS's GUI protocol is subject to the constraints of the X Window System, and as such winds up with the frontend unmapping the window first. As a result, the list can grow very large, resulting in a massive memory leak and eventual VM freeze. To partially solve this problem, make the number of entries that the VM will attempt to free at each iteration tunable. The default is still 10, but it can be overridden via a module parameter. This is Cc: stable because (when combined with appropriate userspace changes) it fixes a severe performance and stability problem for Qubes OS users. Cc: stable@vger.kernel.org Signed-off-by: Demi Marie Obenour Reviewed-by: Juergen Gross Link: https://lore.kernel.org/r/20230726165354.1252-1-demi@invisiblethingslab.com Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman