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[PATCH] hw/virtio: Update vring after modifying its queue size

Philippe Mathieu-Daudé posted 1 patch 2 years, 7 months ago
Test checkpatch passed
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/qemu tags/patchew/20210825224256.1750286-1-philmd@redhat.com
hw/virtio/virtio.c | 1 +
1 file changed, 1 insertion(+)
[PATCH] hw/virtio: Update vring after modifying its queue size
Posted by Philippe Mathieu-Daudé 2 years, 7 months ago 
When a ring queue size is modified, we need to call
virtio_queue_update_rings() to re-init the memory region
caches. Otherwise the region might have outdated memory
size, and later load/store access might trigger an
assertion, such:

  qemu-system-i386: include/exec/memory_ldst_cached.h.inc:30: uint16_t address_space_lduw_le_cached(MemoryRegionCache *, hwaddr, MemTxAttrs, MemTxResult *):
  Assertion `addr < cache->len && 2 <= cache->len - addr' failed.
  Thread 1 "qemu-system-i38" received signal SIGABRT, Aborted.
  0x00007ffff4d312a2 in raise () from /lib64/libc.so.6
  (gdb) bt
  #1  0x00007ffff4d1a8a4 in abort () at /lib64/libc.so.6
  #4  0x0000555558f2b8ec in address_space_lduw_le_cached (cache=0x61300010a7c0, addr=134, attrs=..., result=0x0) at include/exec/memory_ldst_cached.h.inc:30
  #5  0x0000555558f2ac6b in lduw_le_phys_cached (cache=0x61300010a7c0, addr=134) at include/exec/memory_ldst_phys.h.inc:67
  #6  0x0000555558f2a3cd in virtio_lduw_phys_cached (vdev=0x62d00003a680, cache=0x61300010a7c0, pa=134) at include/hw/virtio/virtio-access.h:166
  #7  0x0000555558f300ea in vring_avail_ring (vq=0x7fffdd55d8a0, i=65) at hw/virtio/virtio.c:326
  #8  0x0000555558f33b10 in vring_get_used_event (vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:332
  #9  0x0000555558f33677 in virtio_split_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2471
  #10 0x0000555558f1859f in virtio_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2523
  #11 0x0000555558f188cc in virtio_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2565
  #12 0x0000555557c2bd52 in virtio_input_handle_sts (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/input/virtio-input.c:100
  #13 0x0000555558f16df7 in virtio_queue_notify (vdev=0x62d00003a680, n=1) at hw/virtio/virtio.c:2363
  #14 0x00005555583f45c0 in virtio_pci_notify_write (opaque=0x62d000032400, addr=7, val=0, size=1) at hw/virtio/virtio-pci.c:1369
  #15 0x0000555558b80b04 in memory_region_write_accessor (mr=0x62d000033190, addr=7, value=0x7fffffff8eb0, size=1, shift=0, mask=255, attrs=...) at softmmu/memory.c:492

Reported-by: Qiuhao Li <Qiuhao.Li@outlook.com>
Fixes: ab223c9518e ("virtio: allow virtio-1 queue layout")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/302
BugLink: https://bugs.launchpad.net/qemu/+bug/1913510
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 hw/virtio/virtio.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 874377f37a7..04ffe5f420e 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -2255,6 +2255,7 @@ void virtio_queue_set_num(VirtIODevice *vdev, int n, int num)
         return;
     }
     vdev->vq[n].vring.num = num;
+    virtio_queue_update_rings(vdev, n);
 }
 
 VirtQueue *virtio_vector_first_queue(VirtIODevice *vdev, uint16_t vector)
-- 
2.31.1
Re: [PATCH] hw/virtio: Update vring after modifying its queue size
Posted by Jason Wang 2 years, 7 months ago 
On Thu, Aug 26, 2021 at 6:43 AM Philippe Mathieu-Daudé
<philmd@redhat.com> wrote:
>
> When a ring queue size is modified, we need to call
> virtio_queue_update_rings() to re-init the memory region
> caches. Otherwise the region might have outdated memory
> size, and later load/store access might trigger an
> assertion, such:
>
>   qemu-system-i386: include/exec/memory_ldst_cached.h.inc:30: uint16_t address_space_lduw_le_cached(MemoryRegionCache *, hwaddr, MemTxAttrs, MemTxResult *):
>   Assertion `addr < cache->len && 2 <= cache->len - addr' failed.
>   Thread 1 "qemu-system-i38" received signal SIGABRT, Aborted.
>   0x00007ffff4d312a2 in raise () from /lib64/libc.so.6
>   (gdb) bt
>   #1  0x00007ffff4d1a8a4 in abort () at /lib64/libc.so.6
>   #4  0x0000555558f2b8ec in address_space_lduw_le_cached (cache=0x61300010a7c0, addr=134, attrs=..., result=0x0) at include/exec/memory_ldst_cached.h.inc:30
>   #5  0x0000555558f2ac6b in lduw_le_phys_cached (cache=0x61300010a7c0, addr=134) at include/exec/memory_ldst_phys.h.inc:67
>   #6  0x0000555558f2a3cd in virtio_lduw_phys_cached (vdev=0x62d00003a680, cache=0x61300010a7c0, pa=134) at include/hw/virtio/virtio-access.h:166
>   #7  0x0000555558f300ea in vring_avail_ring (vq=0x7fffdd55d8a0, i=65) at hw/virtio/virtio.c:326
>   #8  0x0000555558f33b10 in vring_get_used_event (vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:332
>   #9  0x0000555558f33677 in virtio_split_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2471
>   #10 0x0000555558f1859f in virtio_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2523
>   #11 0x0000555558f188cc in virtio_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2565
>   #12 0x0000555557c2bd52 in virtio_input_handle_sts (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/input/virtio-input.c:100
>   #13 0x0000555558f16df7 in virtio_queue_notify (vdev=0x62d00003a680, n=1) at hw/virtio/virtio.c:2363
>   #14 0x00005555583f45c0 in virtio_pci_notify_write (opaque=0x62d000032400, addr=7, val=0, size=1) at hw/virtio/virtio-pci.c:1369
>   #15 0x0000555558b80b04 in memory_region_write_accessor (mr=0x62d000033190, addr=7, value=0x7fffffff8eb0, size=1, shift=0, mask=255, attrs=...) at softmmu/memory.c:492
>
> Reported-by: Qiuhao Li <Qiuhao.Li@outlook.com>
> Fixes: ab223c9518e ("virtio: allow virtio-1 queue layout")
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/302
> BugLink: https://bugs.launchpad.net/qemu/+bug/1913510
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  hw/virtio/virtio.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 874377f37a7..04ffe5f420e 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -2255,6 +2255,7 @@ void virtio_queue_set_num(VirtIODevice *vdev, int n, int num)
>          return;
>      }
>      vdev->vq[n].vring.num = num;
> +    virtio_queue_update_rings(vdev, n);
>  }
>

Spec said:

"
The driver MUST configure the other virtqueue fields before enabling
the virtqueue with queue_enable.
"

So I think we should forbid the num to be changed if the virtqueue is ready?

Thanks

>  VirtQueue *virtio_vector_first_queue(VirtIODevice *vdev, uint16_t vector)
> --
> 2.31.1
>
Re: [PATCH] hw/virtio: Update vring after modifying its queue size
Posted by Philippe Mathieu-Daudé 2 years, 7 months ago 
On 8/26/21 5:28 AM, Jason Wang wrote:
> On Thu, Aug 26, 2021 at 6:43 AM Philippe Mathieu-Daudé
> <philmd@redhat.com> wrote:
>>
>> When a ring queue size is modified, we need to call
>> virtio_queue_update_rings() to re-init the memory region
>> caches. Otherwise the region might have outdated memory
>> size, and later load/store access might trigger an
>> assertion, such:
>>
>>   qemu-system-i386: include/exec/memory_ldst_cached.h.inc:30: uint16_t address_space_lduw_le_cached(MemoryRegionCache *, hwaddr, MemTxAttrs, MemTxResult *):
>>   Assertion `addr < cache->len && 2 <= cache->len - addr' failed.
>>   Thread 1 "qemu-system-i38" received signal SIGABRT, Aborted.
>>   0x00007ffff4d312a2 in raise () from /lib64/libc.so.6
>>   (gdb) bt
>>   #1  0x00007ffff4d1a8a4 in abort () at /lib64/libc.so.6
>>   #4  0x0000555558f2b8ec in address_space_lduw_le_cached (cache=0x61300010a7c0, addr=134, attrs=..., result=0x0) at include/exec/memory_ldst_cached.h.inc:30
>>   #5  0x0000555558f2ac6b in lduw_le_phys_cached (cache=0x61300010a7c0, addr=134) at include/exec/memory_ldst_phys.h.inc:67
>>   #6  0x0000555558f2a3cd in virtio_lduw_phys_cached (vdev=0x62d00003a680, cache=0x61300010a7c0, pa=134) at include/hw/virtio/virtio-access.h:166
>>   #7  0x0000555558f300ea in vring_avail_ring (vq=0x7fffdd55d8a0, i=65) at hw/virtio/virtio.c:326
>>   #8  0x0000555558f33b10 in vring_get_used_event (vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:332
>>   #9  0x0000555558f33677 in virtio_split_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2471
>>   #10 0x0000555558f1859f in virtio_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2523
>>   #11 0x0000555558f188cc in virtio_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2565
>>   #12 0x0000555557c2bd52 in virtio_input_handle_sts (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/input/virtio-input.c:100
>>   #13 0x0000555558f16df7 in virtio_queue_notify (vdev=0x62d00003a680, n=1) at hw/virtio/virtio.c:2363
>>   #14 0x00005555583f45c0 in virtio_pci_notify_write (opaque=0x62d000032400, addr=7, val=0, size=1) at hw/virtio/virtio-pci.c:1369
>>   #15 0x0000555558b80b04 in memory_region_write_accessor (mr=0x62d000033190, addr=7, value=0x7fffffff8eb0, size=1, shift=0, mask=255, attrs=...) at softmmu/memory.c:492
>>
>> Reported-by: Qiuhao Li <Qiuhao.Li@outlook.com>
>> Fixes: ab223c9518e ("virtio: allow virtio-1 queue layout")
>> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/302
>> BugLink: https://bugs.launchpad.net/qemu/+bug/1913510
>> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>> ---
>>  hw/virtio/virtio.c | 1 +
>>  1 file changed, 1 insertion(+)
>>
>> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
>> index 874377f37a7..04ffe5f420e 100644
>> --- a/hw/virtio/virtio.c
>> +++ b/hw/virtio/virtio.c
>> @@ -2255,6 +2255,7 @@ void virtio_queue_set_num(VirtIODevice *vdev, int n, int num)
>>          return;
>>      }
>>      vdev->vq[n].vring.num = num;
>> +    virtio_queue_update_rings(vdev, n);
>>  }
>>
> 
> Spec said:
> 
> "
> The driver MUST configure the other virtqueue fields before enabling
> the virtqueue with queue_enable.
> "
> 
> So I think we should forbid the num to be changed if the virtqueue is ready?

Alright. virtio_pci_common_write() doesn't report errors although.
Re: [PATCH] hw/virtio: Update vring after modifying its queue size
Posted by Philippe Mathieu-Daudé 2 years, 7 months ago 
On 8/26/21 10:40 AM, Philippe Mathieu-Daudé wrote:
> On 8/26/21 5:28 AM, Jason Wang wrote:
>> On Thu, Aug 26, 2021 at 6:43 AM Philippe Mathieu-Daudé
>> <philmd@redhat.com> wrote:
>>>
>>> When a ring queue size is modified, we need to call
>>> virtio_queue_update_rings() to re-init the memory region
>>> caches. Otherwise the region might have outdated memory
>>> size, and later load/store access might trigger an
>>> assertion, such:
>>>
>>>   qemu-system-i386: include/exec/memory_ldst_cached.h.inc:30: uint16_t address_space_lduw_le_cached(MemoryRegionCache *, hwaddr, MemTxAttrs, MemTxResult *):
>>>   Assertion `addr < cache->len && 2 <= cache->len - addr' failed.
>>>   Thread 1 "qemu-system-i38" received signal SIGABRT, Aborted.
>>>   0x00007ffff4d312a2 in raise () from /lib64/libc.so.6
>>>   (gdb) bt
>>>   #1  0x00007ffff4d1a8a4 in abort () at /lib64/libc.so.6
>>>   #4  0x0000555558f2b8ec in address_space_lduw_le_cached (cache=0x61300010a7c0, addr=134, attrs=..., result=0x0) at include/exec/memory_ldst_cached.h.inc:30
>>>   #5  0x0000555558f2ac6b in lduw_le_phys_cached (cache=0x61300010a7c0, addr=134) at include/exec/memory_ldst_phys.h.inc:67
>>>   #6  0x0000555558f2a3cd in virtio_lduw_phys_cached (vdev=0x62d00003a680, cache=0x61300010a7c0, pa=134) at include/hw/virtio/virtio-access.h:166
>>>   #7  0x0000555558f300ea in vring_avail_ring (vq=0x7fffdd55d8a0, i=65) at hw/virtio/virtio.c:326
>>>   #8  0x0000555558f33b10 in vring_get_used_event (vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:332
>>>   #9  0x0000555558f33677 in virtio_split_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2471
>>>   #10 0x0000555558f1859f in virtio_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2523
>>>   #11 0x0000555558f188cc in virtio_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2565
>>>   #12 0x0000555557c2bd52 in virtio_input_handle_sts (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/input/virtio-input.c:100
>>>   #13 0x0000555558f16df7 in virtio_queue_notify (vdev=0x62d00003a680, n=1) at hw/virtio/virtio.c:2363
>>>   #14 0x00005555583f45c0 in virtio_pci_notify_write (opaque=0x62d000032400, addr=7, val=0, size=1) at hw/virtio/virtio-pci.c:1369
>>>   #15 0x0000555558b80b04 in memory_region_write_accessor (mr=0x62d000033190, addr=7, value=0x7fffffff8eb0, size=1, shift=0, mask=255, attrs=...) at softmmu/memory.c:492
>>>
>>> Reported-by: Qiuhao Li <Qiuhao.Li@outlook.com>
>>> Fixes: ab223c9518e ("virtio: allow virtio-1 queue layout")
>>> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/302
>>> BugLink: https://bugs.launchpad.net/qemu/+bug/1913510
>>> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
>>> ---
>>>  hw/virtio/virtio.c | 1 +
>>>  1 file changed, 1 insertion(+)
>>>
>>> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
>>> index 874377f37a7..04ffe5f420e 100644
>>> --- a/hw/virtio/virtio.c
>>> +++ b/hw/virtio/virtio.c
>>> @@ -2255,6 +2255,7 @@ void virtio_queue_set_num(VirtIODevice *vdev, int n, int num)
>>>          return;
>>>      }
>>>      vdev->vq[n].vring.num = num;
>>> +    virtio_queue_update_rings(vdev, n);
>>>  }
>>>
>>
>> Spec said:
>>
>> "
>> The driver MUST configure the other virtqueue fields before enabling
>> the virtqueue with queue_enable.
>> "
>>
>> So I think we should forbid the num to be changed if the virtqueue is ready?

What about virtio_queue_set_addr() and virtio_queue_set_align()?
Re: [PATCH] hw/virtio: Update vring after modifying its queue size
Posted by Michael S. Tsirkin 2 years, 7 months ago 
On Thu, Aug 26, 2021 at 05:16:03PM +0200, Philippe Mathieu-Daudé wrote:
> On 8/26/21 10:40 AM, Philippe Mathieu-Daudé wrote:
> > On 8/26/21 5:28 AM, Jason Wang wrote:
> >> On Thu, Aug 26, 2021 at 6:43 AM Philippe Mathieu-Daudé
> >> <philmd@redhat.com> wrote:
> >>>
> >>> When a ring queue size is modified, we need to call
> >>> virtio_queue_update_rings() to re-init the memory region
> >>> caches. Otherwise the region might have outdated memory
> >>> size, and later load/store access might trigger an
> >>> assertion, such:
> >>>
> >>>   qemu-system-i386: include/exec/memory_ldst_cached.h.inc:30: uint16_t address_space_lduw_le_cached(MemoryRegionCache *, hwaddr, MemTxAttrs, MemTxResult *):
> >>>   Assertion `addr < cache->len && 2 <= cache->len - addr' failed.
> >>>   Thread 1 "qemu-system-i38" received signal SIGABRT, Aborted.
> >>>   0x00007ffff4d312a2 in raise () from /lib64/libc.so.6
> >>>   (gdb) bt
> >>>   #1  0x00007ffff4d1a8a4 in abort () at /lib64/libc.so.6
> >>>   #4  0x0000555558f2b8ec in address_space_lduw_le_cached (cache=0x61300010a7c0, addr=134, attrs=..., result=0x0) at include/exec/memory_ldst_cached.h.inc:30
> >>>   #5  0x0000555558f2ac6b in lduw_le_phys_cached (cache=0x61300010a7c0, addr=134) at include/exec/memory_ldst_phys.h.inc:67
> >>>   #6  0x0000555558f2a3cd in virtio_lduw_phys_cached (vdev=0x62d00003a680, cache=0x61300010a7c0, pa=134) at include/hw/virtio/virtio-access.h:166
> >>>   #7  0x0000555558f300ea in vring_avail_ring (vq=0x7fffdd55d8a0, i=65) at hw/virtio/virtio.c:326
> >>>   #8  0x0000555558f33b10 in vring_get_used_event (vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:332
> >>>   #9  0x0000555558f33677 in virtio_split_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2471
> >>>   #10 0x0000555558f1859f in virtio_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2523
> >>>   #11 0x0000555558f188cc in virtio_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2565
> >>>   #12 0x0000555557c2bd52 in virtio_input_handle_sts (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/input/virtio-input.c:100
> >>>   #13 0x0000555558f16df7 in virtio_queue_notify (vdev=0x62d00003a680, n=1) at hw/virtio/virtio.c:2363
> >>>   #14 0x00005555583f45c0 in virtio_pci_notify_write (opaque=0x62d000032400, addr=7, val=0, size=1) at hw/virtio/virtio-pci.c:1369
> >>>   #15 0x0000555558b80b04 in memory_region_write_accessor (mr=0x62d000033190, addr=7, value=0x7fffffff8eb0, size=1, shift=0, mask=255, attrs=...) at softmmu/memory.c:492
> >>>
> >>> Reported-by: Qiuhao Li <Qiuhao.Li@outlook.com>
> >>> Fixes: ab223c9518e ("virtio: allow virtio-1 queue layout")
> >>> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/302
> >>> BugLink: https://bugs.launchpad.net/qemu/+bug/1913510
> >>> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> >>> ---
> >>>  hw/virtio/virtio.c | 1 +
> >>>  1 file changed, 1 insertion(+)
> >>>
> >>> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> >>> index 874377f37a7..04ffe5f420e 100644
> >>> --- a/hw/virtio/virtio.c
> >>> +++ b/hw/virtio/virtio.c
> >>> @@ -2255,6 +2255,7 @@ void virtio_queue_set_num(VirtIODevice *vdev, int n, int num)
> >>>          return;
> >>>      }
> >>>      vdev->vq[n].vring.num = num;
> >>> +    virtio_queue_update_rings(vdev, n);
> >>>  }
> >>>
> >>
> >> Spec said:
> >>
> >> "
> >> The driver MUST configure the other virtqueue fields before enabling
> >> the virtqueue with queue_enable.
> >> "
> >>
> >> So I think we should forbid the num to be changed if the virtqueue is ready?
> 
> What about virtio_queue_set_addr() and virtio_queue_set_align()?

Same thing I guess.

-- 
MST
Re: [PATCH] hw/virtio: Update vring after modifying its queue size
Posted by Michael S. Tsirkin 2 years, 7 months ago 
On Thu, Aug 26, 2021 at 10:40:47AM +0200, Philippe Mathieu-Daudé wrote:
> On 8/26/21 5:28 AM, Jason Wang wrote:
> > On Thu, Aug 26, 2021 at 6:43 AM Philippe Mathieu-Daudé
> > <philmd@redhat.com> wrote:
> >>
> >> When a ring queue size is modified, we need to call
> >> virtio_queue_update_rings() to re-init the memory region
> >> caches. Otherwise the region might have outdated memory
> >> size, and later load/store access might trigger an
> >> assertion, such:
> >>
> >>   qemu-system-i386: include/exec/memory_ldst_cached.h.inc:30: uint16_t address_space_lduw_le_cached(MemoryRegionCache *, hwaddr, MemTxAttrs, MemTxResult *):
> >>   Assertion `addr < cache->len && 2 <= cache->len - addr' failed.
> >>   Thread 1 "qemu-system-i38" received signal SIGABRT, Aborted.
> >>   0x00007ffff4d312a2 in raise () from /lib64/libc.so.6
> >>   (gdb) bt
> >>   #1  0x00007ffff4d1a8a4 in abort () at /lib64/libc.so.6
> >>   #4  0x0000555558f2b8ec in address_space_lduw_le_cached (cache=0x61300010a7c0, addr=134, attrs=..., result=0x0) at include/exec/memory_ldst_cached.h.inc:30
> >>   #5  0x0000555558f2ac6b in lduw_le_phys_cached (cache=0x61300010a7c0, addr=134) at include/exec/memory_ldst_phys.h.inc:67
> >>   #6  0x0000555558f2a3cd in virtio_lduw_phys_cached (vdev=0x62d00003a680, cache=0x61300010a7c0, pa=134) at include/hw/virtio/virtio-access.h:166
> >>   #7  0x0000555558f300ea in vring_avail_ring (vq=0x7fffdd55d8a0, i=65) at hw/virtio/virtio.c:326
> >>   #8  0x0000555558f33b10 in vring_get_used_event (vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:332
> >>   #9  0x0000555558f33677 in virtio_split_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2471
> >>   #10 0x0000555558f1859f in virtio_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2523
> >>   #11 0x0000555558f188cc in virtio_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2565
> >>   #12 0x0000555557c2bd52 in virtio_input_handle_sts (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/input/virtio-input.c:100
> >>   #13 0x0000555558f16df7 in virtio_queue_notify (vdev=0x62d00003a680, n=1) at hw/virtio/virtio.c:2363
> >>   #14 0x00005555583f45c0 in virtio_pci_notify_write (opaque=0x62d000032400, addr=7, val=0, size=1) at hw/virtio/virtio-pci.c:1369
> >>   #15 0x0000555558b80b04 in memory_region_write_accessor (mr=0x62d000033190, addr=7, value=0x7fffffff8eb0, size=1, shift=0, mask=255, attrs=...) at softmmu/memory.c:492
> >>
> >> Reported-by: Qiuhao Li <Qiuhao.Li@outlook.com>
> >> Fixes: ab223c9518e ("virtio: allow virtio-1 queue layout")
> >> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/302
> >> BugLink: https://bugs.launchpad.net/qemu/+bug/1913510
> >> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> >> ---
> >>  hw/virtio/virtio.c | 1 +
> >>  1 file changed, 1 insertion(+)
> >>
> >> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> >> index 874377f37a7..04ffe5f420e 100644
> >> --- a/hw/virtio/virtio.c
> >> +++ b/hw/virtio/virtio.c
> >> @@ -2255,6 +2255,7 @@ void virtio_queue_set_num(VirtIODevice *vdev, int n, int num)
> >>          return;
> >>      }
> >>      vdev->vq[n].vring.num = num;
> >> +    virtio_queue_update_rings(vdev, n);
> >>  }
> >>
> > 
> > Spec said:
> > 
> > "
> > The driver MUST configure the other virtqueue fields before enabling
> > the virtqueue with queue_enable.
> > "
> > 
> > So I think we should forbid the num to be changed if the virtqueue is ready?
> 
> Alright. virtio_pci_common_write() doesn't report errors although.

It can't - just log guest error and ignore. Maybe set needs_reset ...

-- 
MST
Re: [PATCH] hw/virtio: Update vring after modifying its queue size
Posted by Stefan Hajnoczi 2 years, 7 months ago 
On Thu, Aug 26, 2021 at 12:42:56AM +0200, Philippe Mathieu-Daudé wrote:
> When a ring queue size is modified, we need to call
> virtio_queue_update_rings() to re-init the memory region
> caches. Otherwise the region might have outdated memory
> size, and later load/store access might trigger an
> assertion, such:
> 
>   qemu-system-i386: include/exec/memory_ldst_cached.h.inc:30: uint16_t address_space_lduw_le_cached(MemoryRegionCache *, hwaddr, MemTxAttrs, MemTxResult *):
>   Assertion `addr < cache->len && 2 <= cache->len - addr' failed.
>   Thread 1 "qemu-system-i38" received signal SIGABRT, Aborted.
>   0x00007ffff4d312a2 in raise () from /lib64/libc.so.6
>   (gdb) bt
>   #1  0x00007ffff4d1a8a4 in abort () at /lib64/libc.so.6
>   #4  0x0000555558f2b8ec in address_space_lduw_le_cached (cache=0x61300010a7c0, addr=134, attrs=..., result=0x0) at include/exec/memory_ldst_cached.h.inc:30
>   #5  0x0000555558f2ac6b in lduw_le_phys_cached (cache=0x61300010a7c0, addr=134) at include/exec/memory_ldst_phys.h.inc:67
>   #6  0x0000555558f2a3cd in virtio_lduw_phys_cached (vdev=0x62d00003a680, cache=0x61300010a7c0, pa=134) at include/hw/virtio/virtio-access.h:166
>   #7  0x0000555558f300ea in vring_avail_ring (vq=0x7fffdd55d8a0, i=65) at hw/virtio/virtio.c:326
>   #8  0x0000555558f33b10 in vring_get_used_event (vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:332
>   #9  0x0000555558f33677 in virtio_split_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2471
>   #10 0x0000555558f1859f in virtio_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2523
>   #11 0x0000555558f188cc in virtio_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2565
>   #12 0x0000555557c2bd52 in virtio_input_handle_sts (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/input/virtio-input.c:100
>   #13 0x0000555558f16df7 in virtio_queue_notify (vdev=0x62d00003a680, n=1) at hw/virtio/virtio.c:2363
>   #14 0x00005555583f45c0 in virtio_pci_notify_write (opaque=0x62d000032400, addr=7, val=0, size=1) at hw/virtio/virtio-pci.c:1369
>   #15 0x0000555558b80b04 in memory_region_write_accessor (mr=0x62d000033190, addr=7, value=0x7fffffff8eb0, size=1, shift=0, mask=255, attrs=...) at softmmu/memory.c:492
> 
> Reported-by: Qiuhao Li <Qiuhao.Li@outlook.com>
> Fixes: ab223c9518e ("virtio: allow virtio-1 queue layout")
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/302
> BugLink: https://bugs.launchpad.net/qemu/+bug/1913510
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  hw/virtio/virtio.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 874377f37a7..04ffe5f420e 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -2255,6 +2255,7 @@ void virtio_queue_set_num(VirtIODevice *vdev, int n, int num)
>          return;
>      }
>      vdev->vq[n].vring.num = num;
> +    virtio_queue_update_rings(vdev, n);
>  }

Can this line in hw/virtio/virtio-mmio.c be removed now?

    case VIRTIO_MMIO_QUEUE_NUM:
        trace_virtio_mmio_queue_write(value, VIRTQUEUE_MAX_SIZE);
        virtio_queue_set_num(vdev, vdev->queue_sel, value);

        if (proxy->legacy) {
            virtio_queue_update_rings(vdev, vdev->queue_sel);
	    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Stefan
Re: [PATCH] hw/virtio: Update vring after modifying its queue size
Posted by Alexander Bulekov 2 years, 7 months ago 
On 210826 0042, Philippe Mathieu-Daudé wrote:
> When a ring queue size is modified, we need to call
> virtio_queue_update_rings() to re-init the memory region
> caches. Otherwise the region might have outdated memory
> size, and later load/store access might trigger an
> assertion, such:
> 
>   qemu-system-i386: include/exec/memory_ldst_cached.h.inc:30: uint16_t address_space_lduw_le_cached(MemoryRegionCache *, hwaddr, MemTxAttrs, MemTxResult *):
>   Assertion `addr < cache->len && 2 <= cache->len - addr' failed.
>   Thread 1 "qemu-system-i38" received signal SIGABRT, Aborted.
>   0x00007ffff4d312a2 in raise () from /lib64/libc.so.6
>   (gdb) bt
>   #1  0x00007ffff4d1a8a4 in abort () at /lib64/libc.so.6
>   #4  0x0000555558f2b8ec in address_space_lduw_le_cached (cache=0x61300010a7c0, addr=134, attrs=..., result=0x0) at include/exec/memory_ldst_cached.h.inc:30
>   #5  0x0000555558f2ac6b in lduw_le_phys_cached (cache=0x61300010a7c0, addr=134) at include/exec/memory_ldst_phys.h.inc:67
>   #6  0x0000555558f2a3cd in virtio_lduw_phys_cached (vdev=0x62d00003a680, cache=0x61300010a7c0, pa=134) at include/hw/virtio/virtio-access.h:166
>   #7  0x0000555558f300ea in vring_avail_ring (vq=0x7fffdd55d8a0, i=65) at hw/virtio/virtio.c:326
>   #8  0x0000555558f33b10 in vring_get_used_event (vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:332
>   #9  0x0000555558f33677 in virtio_split_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2471
>   #10 0x0000555558f1859f in virtio_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2523
>   #11 0x0000555558f188cc in virtio_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2565
>   #12 0x0000555557c2bd52 in virtio_input_handle_sts (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/input/virtio-input.c:100
>   #13 0x0000555558f16df7 in virtio_queue_notify (vdev=0x62d00003a680, n=1) at hw/virtio/virtio.c:2363
>   #14 0x00005555583f45c0 in virtio_pci_notify_write (opaque=0x62d000032400, addr=7, val=0, size=1) at hw/virtio/virtio-pci.c:1369
>   #15 0x0000555558b80b04 in memory_region_write_accessor (mr=0x62d000033190, addr=7, value=0x7fffffff8eb0, size=1, shift=0, mask=255, attrs=...) at softmmu/memory.c:492
> 
> Reported-by: Qiuhao Li <Qiuhao.Li@outlook.com>
> Fixes: ab223c9518e ("virtio: allow virtio-1 queue layout")
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/302
> BugLink: https://bugs.launchpad.net/qemu/+bug/1913510

OSS-Fuzz found ways to trigger assertion failure for virtio-{rng,
serial, scsi, balloon, 9p}. Would it be useful to have qtest reproducers
for these?

-Alex

> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  hw/virtio/virtio.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 874377f37a7..04ffe5f420e 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -2255,6 +2255,7 @@ void virtio_queue_set_num(VirtIODevice *vdev, int n, int num)
>          return;
>      }
>      vdev->vq[n].vring.num = num;
> +    virtio_queue_update_rings(vdev, n);
>  }
>  
>  VirtQueue *virtio_vector_first_queue(VirtIODevice *vdev, uint16_t vector)
> -- 
> 2.31.1
>
Re: [PATCH] hw/virtio: Update vring after modifying its queue size
Posted by Philippe Mathieu-Daudé 2 years, 7 months ago 
On 8/26/21 12:42 AM, Philippe Mathieu-Daudé wrote:
> When a ring queue size is modified, we need to call
> virtio_queue_update_rings() to re-init the memory region
> caches. Otherwise the region might have outdated memory
> size, and later load/store access might trigger an
> assertion, such:
> 
>   qemu-system-i386: include/exec/memory_ldst_cached.h.inc:30: uint16_t address_space_lduw_le_cached(MemoryRegionCache *, hwaddr, MemTxAttrs, MemTxResult *):
>   Assertion `addr < cache->len && 2 <= cache->len - addr' failed.
>   Thread 1 "qemu-system-i38" received signal SIGABRT, Aborted.
>   0x00007ffff4d312a2 in raise () from /lib64/libc.so.6
>   (gdb) bt
>   #1  0x00007ffff4d1a8a4 in abort () at /lib64/libc.so.6
>   #4  0x0000555558f2b8ec in address_space_lduw_le_cached (cache=0x61300010a7c0, addr=134, attrs=..., result=0x0) at include/exec/memory_ldst_cached.h.inc:30
>   #5  0x0000555558f2ac6b in lduw_le_phys_cached (cache=0x61300010a7c0, addr=134) at include/exec/memory_ldst_phys.h.inc:67
>   #6  0x0000555558f2a3cd in virtio_lduw_phys_cached (vdev=0x62d00003a680, cache=0x61300010a7c0, pa=134) at include/hw/virtio/virtio-access.h:166
>   #7  0x0000555558f300ea in vring_avail_ring (vq=0x7fffdd55d8a0, i=65) at hw/virtio/virtio.c:326
>   #8  0x0000555558f33b10 in vring_get_used_event (vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:332
>   #9  0x0000555558f33677 in virtio_split_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2471
>   #10 0x0000555558f1859f in virtio_should_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2523
>   #11 0x0000555558f188cc in virtio_notify (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/virtio/virtio.c:2565
>   #12 0x0000555557c2bd52 in virtio_input_handle_sts (vdev=0x62d00003a680, vq=0x7fffdd55d8a0) at hw/input/virtio-input.c:100
>   #13 0x0000555558f16df7 in virtio_queue_notify (vdev=0x62d00003a680, n=1) at hw/virtio/virtio.c:2363
>   #14 0x00005555583f45c0 in virtio_pci_notify_write (opaque=0x62d000032400, addr=7, val=0, size=1) at hw/virtio/virtio-pci.c:1369
>   #15 0x0000555558b80b04 in memory_region_write_accessor (mr=0x62d000033190, addr=7, value=0x7fffffff8eb0, size=1, shift=0, mask=255, attrs=...) at softmmu/memory.c:492

Earlier call which updated vring.num:

memory_region_ops_write cpu -1 mr 0x62d000032e60 addr 0xe0004018 value
0x41 size 1 name 'virtio-pci-common-virtio-input'
Thread 1 "qemu-system-i38" hit Breakpoint 1, virtio_queue_set_num
(vdev=0x62d00003a680, n=1, num=65) at hw/virtio/virtio.c:2276
2276        if (!!num != !!vdev->vq[n].vring.num ||
(gdb) bt
#0  virtio_queue_set_num (vdev=0x62d00003a680, n=1, num=65) at
hw/virtio/virtio.c:2276
#1  0x00005555583f2a2c in virtio_pci_common_write
(opaque=0x62d000032400, addr=24, val=65, size=1) at
hw/virtio/virtio-pci.c:1297
#2  0x0000555558b81b04 in memory_region_write_accessor
(mr=0x62d000032e60, addr=24, value=0x7fffffff8eb0, size=1, shift=0,
mask=255, attrs=...) at softmmu/memory.c:492
#3  0x0000555558b81442 in access_with_adjusted_size (addr=24,
value=0x7fffffff8eb0, size=1, access_size_min=1, access_size_max=4,
access_fn=
    0x555558b81500 <memory_region_write_accessor>, mr=0x62d000032e60,
attrs=...) at softmmu/memory.c:554
#4  0x0000555558b7fd57 in memory_region_dispatch_write
(mr=0x62d000032e60, addr=24, data=65, op=MO_8, attrs=...) at
softmmu/memory.c:1504
#5  0x0000555558b513f4 in flatview_write_continue (fv=0x60600005cc00,
addr=3758112792, attrs=..., ptr=0x6020000dbb90, len=1, addr1=24, l=1,
mr=0x62d000032e60)
    at softmmu/physmem.c:2777
#6  0x0000555558b3fdd0 in flatview_write (fv=0x60600005cc00,
addr=3758112792, attrs=..., buf=0x6020000dbb90, len=1) at
softmmu/physmem.c:2817
#7  0x0000555558b3f959 in address_space_write (as=0x60800000d920,
addr=3758112792, attrs=..., buf=0x6020000dbb90, len=1) at
softmmu/physmem.c:2909

> Reported-by: Qiuhao Li <Qiuhao.Li@outlook.com>
> Fixes: ab223c9518e ("virtio: allow virtio-1 queue layout")
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/302

BTW this also fixes #300 and #301 :)

> BugLink: https://bugs.launchpad.net/qemu/+bug/1913510
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  hw/virtio/virtio.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 874377f37a7..04ffe5f420e 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -2255,6 +2255,7 @@ void virtio_queue_set_num(VirtIODevice *vdev, int n, int num)
>          return;
>      }
>      vdev->vq[n].vring.num = num;
> +    virtio_queue_update_rings(vdev, n);
>  }
>  
>  VirtQueue *virtio_vector_first_queue(VirtIODevice *vdev, uint16_t vector)
>

Patchew 2.1-devel-0870f84

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