Re: [PATCH] irqbypass: fix error handle when irq_bypass_register_producer() return fails

From: gchen chen
Date: Fri Oct 09 2020 - 00:29:47 EST

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Alex Williamson <alex.williamson@xxxxxxxxxx> 于2020年9月30日周三下午10:09写道：
>
>
> Please version your postings so we know which one to consider as the
> current proposal.
>
> On Wed, 30 Sep 2020 20:54:39 +0800
> guomin_chen@xxxxxxxx wrote:
>
> > From: guomin chen <guomin_chen@xxxxxxxx>
> >
> > When the producer object registration fails,In the future, due to
> > incorrect matching when unregistering, list_del(&producer->node)
> > may still be called, then trigger a BUG:
> >
> > vfio-pci 0000:db:00.0: irq bypass producer (token 0000000060c8cda5) registration fails: -16
> > vfio-pci 0000:db:00.0: irq bypass producer (token 0000000060c8cda5) registration fails: -16
> > vfio-pci 0000:db:00.0: irq bypass producer (token 0000000060c8cda5) registration fails: -16
> > ...
> > list_del corruption, ffff8f7fb8ba0828->next is LIST_POISON1 (dead000000000100)
> > ------------[ cut here ]------------
> > kernel BUG at lib/list_debug.c:47!
> > invalid opcode: 0000 [#1] SMP NOPTI
> > CPU: 29 PID: 3914 Comm: qemu-kvm Kdump: loaded Tainted: G E
> > -------- - -4.18.0-193.6.3.el8.x86_64 #1
> > Hardware name: Lenovo ThinkSystem SR650 -[7X06CTO1WW]-/-[7X06CTO1WW]-,
> > BIOS -[IVE636Z-2.13]- 07/18/2019
> > RIP: 0010:__list_del_entry_valid.cold.1+0x12/0x4c
> > Code: ce ff 0f 0b 48 89 c1 4c 89 c6 48 c7 c7 40 85 4d 88 e8 8c bc
> > ce ff 0f 0b 48 89 fe 48 89 c2 48 c7 c7 d0 85 4d 88 e8 78 bc
> > ce ff <0f> 0b 48 c7 c7 80 86 4d 88 e8 6a bc ce ff 0f 0b 48
> > 89 f2 48 89 fe
> > RSP: 0018:ffffaa9d60197d20 EFLAGS: 00010246
> > RAX: 000000000000004e RBX: ffff8f7fb8ba0828 RCX: 0000000000000000
> > RDX: 0000000000000000 RSI: ffff8f7fbf4d6a08 RDI: ffff8f7fbf4d6a08
> > RBP: 0000000000000000 R08: 000000000000084b R09: 000000000000005d
> > R10: 0000000000000000 R11: ffffaa9d60197bd0 R12: ffff8f4fbe863000
> > R13: 00000000000000c2 R14: 0000000000000000 R15: 0000000000000000
> > FS: 00007f7cb97fa700(0000) GS:ffff8f7fbf4c0000(0000)
> > knlGS:0000000000000000
> > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 00007fcf31da4000 CR3: 0000005f6d404001 CR4: 00000000007626e0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > PKRU: 55555554
> > Call Trace:
> > irq_bypass_unregister_producer+0x9b/0xf0 [irqbypass]
> > vfio_msi_set_vector_signal+0x8c/0x290 [vfio_pci]
> > ? load_fixmap_gdt+0x22/0x30
> > vfio_msi_set_block+0x6e/0xd0 [vfio_pci]
> > vfio_pci_ioctl+0x218/0xbe0 [vfio_pci]
> > ? kvm_vcpu_ioctl+0xf2/0x5f0 [kvm]
> > do_vfs_ioctl+0xa4/0x630
> > ? syscall_trace_enter+0x1d3/0x2c0
> > ksys_ioctl+0x60/0x90
> > __x64_sys_ioctl+0x16/0x20
> > do_syscall_64+0x5b/0x1a0
> > entry_SYSCALL_64_after_hwframe+0x65/0xca
> >
> > Cc: Alex Williamson <alex.williamson@xxxxxxxxxx>
> > Cc: Cornelia Huck <cohuck@xxxxxxxxxx>
> > Cc: Jiang Yi <giangyi@xxxxxxxxxx>
> > Cc: Marc Zyngier <maz@xxxxxxxxxx>
> > Cc: Peter Xu <peterx@xxxxxxxxxx>
> > Cc: Eric Auger <eric.auger@xxxxxxxxxx>
> > Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
> > Cc: Jason Wang <jasowang@xxxxxxxxxx>
> > Cc: kvm@xxxxxxxxxxxxxxx
> > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > Signed-off-by: guomin chen <guomin_chen@xxxxxxxx>
> > ---
> > drivers/vfio/pci/vfio_pci_intrs.c | 13 +++++++++++--
> > drivers/vhost/vdpa.c | 7 +++++++
> > 2 files changed, 18 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
> > index 1d9fb25..c371943 100644
> > --- a/drivers/vfio/pci/vfio_pci_intrs.c
> > +++ b/drivers/vfio/pci/vfio_pci_intrs.c
> > @@ -352,12 +352,21 @@ static int vfio_msi_set_vector_signal(struct vfio_pci_device *vdev,
> > vdev->ctx[vector].producer.token = trigger;
> > vdev->ctx[vector].producer.irq = irq;
> > ret = irq_bypass_register_producer(&vdev->ctx[vector].producer);
> > - if (unlikely(ret))
> > + if (unlikely(ret)) {
> > dev_info(&pdev->dev,
> > "irq bypass producer (token %p) registration fails: %d\n",
> > vdev->ctx[vector].producer.token, ret);
> >
> > - vdev->ctx[vector].trigger = trigger;
> > + kfree(vdev->ctx[vector].name);
> > + eventfd_ctx_put(trigger);
> > +
> > + cmd = vfio_pci_memory_lock_and_enable(vdev);
> > + free_irq(irq, trigger);
> > + vfio_pci_memory_unlock_and_restore(vdev, cmd);
> > +
> > + vdev->ctx[vector].trigger = NULL;
> > + } else
> > + vdev->ctx[vector].trigger = trigger;
> >
> > return 0;
> > }
>
> Once again, the irq bypass registration cannot cause the vector setup
> to fail, either by returning an error code or failing to configure the
> vector while returning success. It's my assertion that we simply need
> to set the producer.token to NULL on failure such that unregistering
> the producer will not generate a match, as you've done below. The
> vector still works even if this registration fails.
>
Yes, the irq bypass registration cannot cause the vector setup to fail.
But if I simply set producer.token to NULL when fails, instead of
cleaning up vector, it will trigger the following BUG:

vfio_ecap_init: 0000:db:00.0 hiding ecap 0x1e@0x310
vfio-pci 0000:db:00.0: irq bypass producer (token 000000004409229f)
registration fails: -16
------------[ cut here ]------------
kernel BUG at drivers/pci/msi.c:352!
invalid opcode: 0000 [#1] SMP NOPTI
CPU: 55 PID: 9389 Comm: qemu-kvm Kdump: loaded Tainted: G
E --------- - - 4.18.0-193.irqb.r1.el8.x86_64 #1
Hardware name: Lenovo ThinkSystem SR650 -[7X06CTO1WW]-/-[7X06CTO1WW]-,
BIOS -[IVE636Z-2.13]- 07/18/2019
RIP: 0010:free_msi_irqs+0x180/0x1b0
Code: 14 85 c0 0f 84 d5 fe ff ff 31 ed eb 0f 83 c5 01 39 6b 14 0f 86
c5 fe ff ff 8b 7b 10 01 ef e8 d7 4a c9 ff 48 83 78 70 00 74 e3
<0f> 0b 49 8d b5 b0 00 00 00 e8 e2 e3 c9 ff e9 c7 fe ff ff 48
8b 7b
RSP: 0018:ffffaeca4f4bfcd8 EFLAGS: 00010286
RAX: ffff8bec77441600 RBX: ffff8bbcdb637e40 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 00000000000001ab RDI: ffffffff8ea5b2a0
RBP: 0000000000000000 R08: ffff8bec7e746828 R09: ffff8bec7e7466a8
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8bbcde921308
R13: ffff8bbcde921000 R14: 000000000000000b R15: 0000000000000021
FS: 00007fd18d7fa700(0000) GS:ffff8bec7f6c0000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f83650024a0 CR3: 000000476e70c001 CR4: 00000000007626e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
pci_disable_msix+0xf3/0x120
pci_free_irq_vectors+0xe/0x20
vfio_msi_disable+0x89/0xd0 [vfio_pci]
vfio_pci_set_msi_trigger+0x229/0x2d0 [vfio_pci]
vfio_pci_ioctl+0x24f/0xdb0 [vfio_pci]
? pollwake+0x74/0x90
? wake_up_q+0x70/0x70
do_vfs_ioctl+0xa4/0x630
? __alloc_fd+0x33/0x140
? syscall_trace_enter+0x1d3/0x2c0
ksys_ioctl+0x60/0x90
__x64_sys_ioctl+0x16/0x20
do_syscall_64+0x5b/0x1a0
entry_SYSCALL_64_after_hwframe+0x65/0xca

> > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> > index 796fe97..4e082b8 100644
> > --- a/drivers/vhost/vdpa.c
> > +++ b/drivers/vhost/vdpa.c
> > @@ -107,6 +107,13 @@ static void vhost_vdpa_setup_vq_irq(struct vhost_vdpa *v, u16 qid)
> > vq->call_ctx.producer.token = vq->call_ctx.ctx;
> > vq->call_ctx.producer.irq = irq;
> > ret = irq_bypass_register_producer(&vq->call_ctx.producer);
> > + if (unlikely(ret)) {
> > + /*
> > + * If registration failed,
> > + * there is no need to unregister later.
> > + */
> > + vq->call_ctx.producer.token = NULL;
> > + }
> > spin_unlock(&vq->call_ctx.ctx_lock);
> > }
> >
>
> 'ret' is otherwise unused in this function, so we could simply remove
> ret and change this to
>
> if (irq_bypass_register_producer(&vq->call_ctx.producer)) {
> /* avoid generating bogus match on unregister */
> vq->call_ctx.producer.token = NULL;
> }
>
> Also please submit vfio and vdpa as separate patches so that the
> respective maintainer for each area can handle them. Thanks,
>
> Alex
>
OK, thank you, I'll submit it again in two separate patches.
Thanks Alex.

Next message: Alexandre Courbot: "Re: [PATCH v2] media: mtk-vcodec: fix builds when remoteproc is disabled"
Previous message: Dave Airlie: "[git pull] drm amdgpu fixes for 5.9 final"
Next in thread: Alex Williamson: "Re: [PATCH] irqbypass: fix error handle when irq_bypass_register_producer() return fails"
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