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From: Eugenio Perez Martin <eperezma@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>,
	Juan Quintela <quintela@redhat.com>,
	Jason Wang <jasowang@redhat.com>,
	qemu-devel@nongnu.org, Peter Xu <peterx@redhat.com>,
	Avi Kivity <avi@redhat.com>
Subject: Re: [RFC v2 0/1] memory: Delete assertion in memory_region_unregister_iommu_notifier
Date: Fri, 3 Jul 2020 09:39:20 +0200
Message-ID: <CAJaqyWe3QoCQ7=pe7mCpa548kLRDdhhfLydtbgzX7nkSkJ6img@mail.gmail.com> (raw)
In-Reply-To: <52d97ca5-7dbd-3178-64d6-509a8f096f0b@redhat.com>

On Mon, Jun 29, 2020 at 5:05 PM Paolo Bonzini <pbonzini@redhat.com> wrote:
>
> On 26/06/20 08:41, Eugenio Pérez wrote:
> > If we examinate *entry in frame 4 of backtrace:
> > *entry = {target_as = 0x555556f6c050, iova = 0x0, translated_addr = 0x0,
> > addr_mask = 0xffffffffffffffff, perm = 0x0}
> >
> > Which (I think) tries to invalidate all the TLB registers of the device.
> >
> > Just deleting that assert is enough for the VM to start and communicate
> > using IOMMU, but maybe a better alternative is possible. We could move
> > it to the caller functions in other cases than IOMMU invalidation, or
> > make it conditional only if not invalidating.
>
> Yes, I think moving it up in the call stack is better. I cannot say
> where because the backtrace was destroyed by git (due to lines starting
> with "#").
>

Ouch, what a failure!

Pasting here for completion, sorry!

(gdb) bt
#0  0x00007ffff521370f in raise () at /lib64/libc.so.6
#1  0x00007ffff51fdb25 in abort () at /lib64/libc.so.6
#2  0x00007ffff51fd9f9 in _nl_load_domain.cold.0 () at /lib64/libc.so.6
#3  0x00007ffff520bcc6 in .annobin_assert.c_end () at /lib64/libc.so.6
#4  0x0000555555888171 in memory_region_notify_one
(notifier=0x7ffde0487fa8, entry=0x7ffde5dfe200) at
/home/qemu/memory.c:1918
#5  0x0000555555888247 in memory_region_notify_iommu
(iommu_mr=0x555556f6c0b0, iommu_idx=0, entry=...) at
/home/qemu/memory.c:1941
#6  0x0000555555951c8d in vtd_process_device_iotlb_desc
(s=0x555557609000, inv_desc=0x7ffde5dfe2d0)
    at /home/qemu/hw/i386/intel_iommu.c:2468
#7  0x0000555555951e6a in vtd_process_inv_desc (s=0x555557609000) at
/home/qemu/hw/i386/intel_iommu.c:2531
#8  0x0000555555951fa5 in vtd_fetch_inv_desc (s=0x555557609000) at
/home/qemu/hw/i386/intel_iommu.c:2563
#9  0x00005555559520e5 in vtd_handle_iqt_write (s=0x555557609000) at
/home/qemu/hw/i386/intel_iommu.c:2590
#10 0x0000555555952b45 in vtd_mem_write (opaque=0x555557609000,
addr=136, val=2688, size=4) at /home/qemu/hw/i386/intel_iommu.c:2837
#11 0x0000555555883e17 in memory_region_write_accessor
    (mr=0x555557609330, addr=136, value=0x7ffde5dfe478, size=4,
shift=0, mask=4294967295, attrs=...) at /home/qemu/memory.c:483
#12 0x000055555588401d in access_with_adjusted_size
    (addr=136, value=0x7ffde5dfe478, size=4, access_size_min=4,
access_size_max=8, access_fn=
    0x555555883d38 <memory_region_write_accessor>, mr=0x555557609330,
attrs=...) at /home/qemu/memory.c:544
#13 0x0000555555886f37 in memory_region_dispatch_write
(mr=0x555557609330, addr=136, data=2688, op=MO_32, attrs=...)
    at /home/qemu/memory.c:1476
#14 0x0000555555827a03 in flatview_write_continue
    (fv=0x7ffdd8503150, addr=4275634312, attrs=...,
ptr=0x7ffff7ff0028, len=4, addr1=136, l=4, mr=0x555557609330) at
/home/qemu/exec.c:3146
#15 0x0000555555827b48 in flatview_write (fv=0x7ffdd8503150,
addr=4275634312, attrs=..., buf=0x7ffff7ff0028, len=4)
    at /home/qemu/exec.c:3186
#16 0x0000555555827e9d in address_space_write
    (as=0x5555567ca640 <address_space_memory>, addr=4275634312,
attrs=..., buf=0x7ffff7ff0028, len=4) at /home/qemu/exec.c:3277
#17 0x0000555555827f0a in address_space_rw
    (as=0x5555567ca640 <address_space_memory>, addr=4275634312,
attrs=..., buf=0x7ffff7ff0028, len=4, is_write=true)
    at /home/qemu/exec.c:3287
#18 0x000055555589b633 in kvm_cpu_exec (cpu=0x555556b65640) at
/home/qemu/accel/kvm/kvm-all.c:2511
#19 0x0000555555876ba8 in qemu_kvm_cpu_thread_fn (arg=0x555556b65640)
at /home/qemu/cpus.c:1284
#20 0x0000555555dafff1 in qemu_thread_start (args=0x555556b8c3b0) at
util/qemu-thread-posix.c:521
#21 0x00007ffff55a62de in start_thread () at /lib64/libpthread.so.0
#22 0x00007ffff52d7e83 in clone () at /lib64/libc.so.6

(gdb) frame 4
#4  0x0000555555888171 in memory_region_notify_one
(notifier=0x7ffde0487fa8, entry=0x7ffde5dfe200) at
/home/qemu/memory.c:1918
1918        assert(entry->iova >= notifier->start && entry_end <=
notifier->end);
(gdb) p *entry
$1 = {target_as = 0x555556f6c050, iova = 0, translated_addr = 0,
addr_mask = 18446744073709551615, perm = IOMMU_NONE}

Thanks!

> Paolo
>
> > Any comment would be appreciated. Thanks!
> >
> > Guest kernel version: kernel-3.10.0-1151.el7.x86_64
> >
> > Bug reference: https://bugs.launchpad.net/qemu/+bug/1885175
> >
> > v2: Actually delete assertion instead of just commenting out using C99
> >
> > Eugenio Pérez (1):
> >   memory: Delete assertion in memory_region_unregister_iommu_notifier
> >
> >  memory.c | 2 --
> >  1 file changed, 2 deletions(-)
> >
>



  reply index

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-26  6:41 Eugenio Pérez
2020-06-26  6:41 ` [RFC v2 1/1] " Eugenio Pérez
2020-06-26 21:29   ` Peter Xu
2020-06-27  7:26     ` Yan Zhao
2020-06-27 12:57       ` Peter Xu
2020-06-28  1:36         ` Yan Zhao
2020-06-28  7:03     ` Jason Wang
2020-06-28 14:47       ` Peter Xu
2020-06-29  5:51         ` Jason Wang
2020-06-29 13:34           ` Peter Xu
2020-06-30  2:41             ` Jason Wang
2020-06-30  8:29               ` Jason Wang
2020-06-30  9:21                 ` Michael S. Tsirkin
2020-06-30  9:23                   ` Jason Wang
2020-06-30 15:20                     ` Peter Xu
2020-07-01  8:11                       ` Jason Wang
2020-07-01 12:16                         ` Peter Xu
2020-07-01 12:30                           ` Jason Wang
2020-07-01 12:41                             ` Peter Xu
2020-07-02  3:00                               ` Jason Wang
2020-06-30 15:39               ` Peter Xu
2020-07-01  8:09                 ` Jason Wang
2020-07-02  3:01                   ` Jason Wang
2020-07-02 15:45                     ` Peter Xu
2020-07-03  7:24                       ` Jason Wang
2020-07-03 13:03                         ` Peter Xu
2020-07-07  8:03                           ` Jason Wang
2020-07-07 19:54                             ` Peter Xu
2020-07-08  5:42                               ` Jason Wang
2020-07-08 14:16                                 ` Peter Xu
2020-07-09  5:58                                   ` Jason Wang
2020-07-09 14:10                                     ` Peter Xu
2020-07-10  6:34                                       ` Jason Wang
2020-07-10 13:30                                         ` Peter Xu
2020-07-13  4:04                                           ` Jason Wang
2020-07-16  1:00                                             ` Peter Xu
2020-07-16  2:54                                               ` Jason Wang
2020-07-17 14:18                                                 ` Peter Xu
2020-07-20  4:02                                                   ` Jason Wang
2020-07-20 13:03                                                     ` Peter Xu
2020-07-21  6:20                                                       ` Jason Wang
2020-07-21 15:10                                                         ` Peter Xu
2020-08-03 16:00                         ` Eugenio Pérez
2020-08-04 20:30                           ` Peter Xu
2020-08-05  5:45                             ` Jason Wang
2020-06-29 15:05 ` [RFC v2 0/1] " Paolo Bonzini
2020-07-03  7:39   ` Eugenio Perez Martin [this message]
2020-07-03 10:10     ` Paolo Bonzini

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