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[RFC] hw/virtio: Do not access vring cache if queue is not ready

Message ID 20210825200953.1684541-1-philmd@redhat.com
State New
Headers show
Series [RFC] hw/virtio: Do not access vring cache if queue is not ready | expand

Commit Message

Philippe Mathieu-Daudé Aug. 25, 2021, 8:09 p.m. UTC 
Do not intent to access the vring MemoryRegion cache if
the queue is not ready (no vring available).

This fixes issue #301:

  qemu-system-i386: include/exec/memory_ldst_cached.h.inc:77: void address_space_stw_le_cached(MemoryRegionCache *, hwaddr, uint16_t, MemTxAttrs, MemTxResult *):
  Assertion `addr < cache->len && 2 <= cache->len - addr' failed.
  Thread 1 "qemu-system-i38" received signal SIGABRT, Aborted.
  (gdb) bt
  #1  0x00007ffff4d1a8a4 in abort () at /lib64/libc.so.6
  #4  0x0000555558f2a122 in address_space_stw_le_cached (cache=0x61300010bb70, addr=516, val=0, attrs=..., result=0x0) at include/exec/memory_ldst_cached.h.inc:77
  #5  0x0000555558f2964c in stw_le_phys_cached (cache=0x61300010bb70, addr=516, val=0) at include/exec/memory_ldst_phys.h.inc:109
  #6  0x0000555558f28da8 in virtio_stw_phys_cached (vdev=0x62d00004e680, cache=0x61300010bb70, pa=516, value=0) at include/hw/virtio/virtio-access.h:196
  #7  0x0000555558f287dc in vring_set_avail_event (vq=0x7fff5d23e800, val=0) at hw/virtio/virtio.c:428
  #8  0x0000555558efabb7 in virtio_queue_split_set_notification (vq=0x7fff5d23e800, enable=1) at hw/virtio/virtio.c:437
  #9  0x0000555558ef9f3c in virtio_queue_set_notification (vq=0x7fff5d23e800, enable=1) at hw/virtio/virtio.c:498
  #10 0x0000555558c94786 in virtio_blk_handle_vq (s=0x62d00004e680, vq=0x7fff5d23e800) at hw/block/virtio-blk.c:795
  #11 0x0000555558cb96c2 in virtio_blk_data_plane_handle_output (vdev=0x62d00004e680, vq=0x7fff5d23e800) at hw/block/dataplane/virtio-blk.c:165
  #12 0x0000555558f35937 in virtio_queue_notify_aio_vq (vq=0x7fff5d23e800) at hw/virtio/virtio.c:2323
  #13 0x0000555558f264b3 in virtio_queue_host_notifier_aio_read (n=0x7fff5d23e87c) at hw/virtio/virtio.c:3532
  #14 0x0000555559a9cd3e in aio_dispatch_handler (ctx=0x613000063000, node=0x60d000008f40) at util/aio-posix.c:329
  #15 0x0000555559a963ae in aio_dispatch_handlers (ctx=0x613000063000) at util/aio-posix.c:372
  #16 0x0000555559a95f82 in aio_dispatch (ctx=0x613000063000) at util/aio-posix.c:382

and  #302:

  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: Cheolwoo Myung <cwmyung@snu.ac.kr>
Reported-by: Qiuhao Li <Qiuhao.Li@outlook.com>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/301
BugLink: https://bugs.launchpad.net/qemu/+bug/1910941
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>
---
Could be more readable to use virtio_queue_ready()

RFC because I have no clue about this hot path code,
I simply looked at the backtraces.
---
 hw/virtio/virtio.c | 82 +++++++++++++++++++++++++++++++++++++---------
 1 file changed, 66 insertions(+), 16 deletions(-)

Comments

Philippe Mathieu-Daudé Aug. 25, 2021, 8:36 p.m. UTC | #1 
On 8/25/21 10:09 PM, Philippe Mathieu-Daudé wrote:
> Do not intent to access the vring MemoryRegion cache if
> the queue is not ready (no vring available).
> 
> This fixes issue #301:
> 
>   qemu-system-i386: include/exec/memory_ldst_cached.h.inc:77: void address_space_stw_le_cached(MemoryRegionCache *, hwaddr, uint16_t, MemTxAttrs, MemTxResult *):
>   Assertion `addr < cache->len && 2 <= cache->len - addr' failed.
>   Thread 1 "qemu-system-i38" received signal SIGABRT, Aborted.
>   (gdb) bt
>   #1  0x00007ffff4d1a8a4 in abort () at /lib64/libc.so.6
>   #4  0x0000555558f2a122 in address_space_stw_le_cached (cache=0x61300010bb70, addr=516, val=0, attrs=..., result=0x0) at include/exec/memory_ldst_cached.h.inc:77
>   #5  0x0000555558f2964c in stw_le_phys_cached (cache=0x61300010bb70, addr=516, val=0) at include/exec/memory_ldst_phys.h.inc:109
>   #6  0x0000555558f28da8 in virtio_stw_phys_cached (vdev=0x62d00004e680, cache=0x61300010bb70, pa=516, value=0) at include/hw/virtio/virtio-access.h:196
>   #7  0x0000555558f287dc in vring_set_avail_event (vq=0x7fff5d23e800, val=0) at hw/virtio/virtio.c:428
>   #8  0x0000555558efabb7 in virtio_queue_split_set_notification (vq=0x7fff5d23e800, enable=1) at hw/virtio/virtio.c:437
>   #9  0x0000555558ef9f3c in virtio_queue_set_notification (vq=0x7fff5d23e800, enable=1) at hw/virtio/virtio.c:498
>   #10 0x0000555558c94786 in virtio_blk_handle_vq (s=0x62d00004e680, vq=0x7fff5d23e800) at hw/block/virtio-blk.c:795
>   #11 0x0000555558cb96c2 in virtio_blk_data_plane_handle_output (vdev=0x62d00004e680, vq=0x7fff5d23e800) at hw/block/dataplane/virtio-blk.c:165
>   #12 0x0000555558f35937 in virtio_queue_notify_aio_vq (vq=0x7fff5d23e800) at hw/virtio/virtio.c:2323
>   #13 0x0000555558f264b3 in virtio_queue_host_notifier_aio_read (n=0x7fff5d23e87c) at hw/virtio/virtio.c:3532
>   #14 0x0000555559a9cd3e in aio_dispatch_handler (ctx=0x613000063000, node=0x60d000008f40) at util/aio-posix.c:329
>   #15 0x0000555559a963ae in aio_dispatch_handlers (ctx=0x613000063000) at util/aio-posix.c:372
>   #16 0x0000555559a95f82 in aio_dispatch (ctx=0x613000063000) at util/aio-posix.c:382
> 
> and  #302:
> 
>   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: Cheolwoo Myung <cwmyung@snu.ac.kr>
> Reported-by: Qiuhao Li <Qiuhao.Li@outlook.com>
> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/301
> BugLink: https://bugs.launchpad.net/qemu/+bug/1910941
> 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>
> ---
> Could be more readable to use virtio_queue_ready()
> 
> RFC because I have no clue about this hot path code,
> I simply looked at the backtraces.
> ---
>  hw/virtio/virtio.c | 82 +++++++++++++++++++++++++++++++++++++---------
>  1 file changed, 66 insertions(+), 16 deletions(-)
> 
> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> index 874377f37a7..be1ec9e05ef 100644
> --- a/hw/virtio/virtio.c
> +++ b/hw/virtio/virtio.c
> @@ -289,26 +289,38 @@ static VRingMemoryRegionCaches *vring_get_region_caches(struct VirtQueue *vq)
>  /* Called within rcu_read_lock().  */
>  static inline uint16_t vring_avail_flags(VirtQueue *vq)
>  {
> -    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
> -    hwaddr pa = offsetof(VRingAvail, flags);
> +    VRingMemoryRegionCaches *caches;
> +    hwaddr pa;
>  
> +    if (unlikely(!vq->vring.avail)) {
> +        return 0;
> +    }
> +
> +    caches = vring_get_region_caches(vq);
>      if (!caches) {
>          return 0;
>      }
>  
> +    pa = offsetof(VRingAvail, flags);
>      return virtio_lduw_phys_cached(vq->vdev, &caches->avail, pa);
>  }
>  
>  /* Called within rcu_read_lock().  */
>  static inline uint16_t vring_avail_idx(VirtQueue *vq)
>  {
> -    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
> -    hwaddr pa = offsetof(VRingAvail, idx);
> +    VRingMemoryRegionCaches *caches;
> +    hwaddr pa;
>  
> +    if (unlikely(!vq->vring.avail)) {
> +        return 0;
> +    }
> +
> +    caches = vring_get_region_caches(vq);
>      if (!caches) {
>          return 0;
>      }
>  
> +    pa = offsetof(VRingAvail, idx);
>      vq->shadow_avail_idx = virtio_lduw_phys_cached(vq->vdev, &caches->avail, pa);
>      return vq->shadow_avail_idx;
>  }
> @@ -316,13 +328,19 @@ static inline uint16_t vring_avail_idx(VirtQueue *vq)
>  /* Called within rcu_read_lock().  */
>  static inline uint16_t vring_avail_ring(VirtQueue *vq, int i)
>  {
> -    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
> -    hwaddr pa = offsetof(VRingAvail, ring[i]);
> +    VRingMemoryRegionCaches *caches;
> +    hwaddr pa;
>  
> +    if (unlikely(!vq->vring.avail)) {
> +        return 0;
> +    }
> +
> +    caches = vring_get_region_caches(vq);
>      if (!caches) {
>          return 0;
>      }
>  
> +    pa = offsetof(VRingAvail, ring[i]);
>      return virtio_lduw_phys_cached(vq->vdev, &caches->avail, pa);
>  }

Self-NAck.

While the previous part could be OK, what follows is crap (checking
avail instead of used) so please disregard this patch.

> @@ -336,13 +354,19 @@ static inline uint16_t vring_get_used_event(VirtQueue *vq)
>  static inline void vring_used_write(VirtQueue *vq, VRingUsedElem *uelem,
>                                      int i)
>  {
> -    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
> -    hwaddr pa = offsetof(VRingUsed, ring[i]);
> +    VRingMemoryRegionCaches *caches;
> +    hwaddr pa;
>  
> +    if (unlikely(!vq->vring.avail)) {
> +        return;
> +    }
> +
> +    caches = vring_get_region_caches(vq);
>      if (!caches) {
>          return;
>      }
>  
> +    pa = offsetof(VRingUsed, ring[i]);
>      virtio_tswap32s(vq->vdev, &uelem->id);
>      virtio_tswap32s(vq->vdev, &uelem->len);
>      address_space_write_cached(&caches->used, pa, uelem, sizeof(VRingUsedElem));
> @@ -352,23 +376,35 @@ static inline void vring_used_write(VirtQueue *vq, VRingUsedElem *uelem,
>  /* Called within rcu_read_lock().  */
>  static uint16_t vring_used_idx(VirtQueue *vq)
>  {
> -    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
> -    hwaddr pa = offsetof(VRingUsed, idx);
> +    VRingMemoryRegionCaches *caches;
> +    hwaddr pa;
>  
> +    if (unlikely(!vq->vring.avail)) {
> +        return 0;
> +    }
> +
> +    caches = vring_get_region_caches(vq);
>      if (!caches) {
>          return 0;
>      }
>  
> +    pa = offsetof(VRingUsed, idx);
>      return virtio_lduw_phys_cached(vq->vdev, &caches->used, pa);
>  }
>  
>  /* Called within rcu_read_lock().  */
>  static inline void vring_used_idx_set(VirtQueue *vq, uint16_t val)
>  {
> -    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
> -    hwaddr pa = offsetof(VRingUsed, idx);
> +    VRingMemoryRegionCaches *caches;
>  
> +    if (unlikely(!vq->vring.avail)) {
> +        return;
> +    }
> +
> +    caches = vring_get_region_caches(vq);
>      if (caches) {
> +        hwaddr pa = offsetof(VRingUsed, idx);
> +
>          virtio_stw_phys_cached(vq->vdev, &caches->used, pa, val);
>          address_space_cache_invalidate(&caches->used, pa, sizeof(val));
>      }
> @@ -379,17 +415,22 @@ static inline void vring_used_idx_set(VirtQueue *vq, uint16_t val)
>  /* Called within rcu_read_lock().  */
>  static inline void vring_used_flags_set_bit(VirtQueue *vq, int mask)
>  {
> -    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
> -    VirtIODevice *vdev = vq->vdev;
> -    hwaddr pa = offsetof(VRingUsed, flags);
> +    VRingMemoryRegionCaches *caches;
> +    hwaddr pa;
>      uint16_t flags;
>  
> +    if (unlikely(!vq->vring.avail)) {
> +        return;
> +    }
> +
> +    caches = vring_get_region_caches(vq);
>      if (!caches) {
>          return;
>      }
>  
> +    pa = offsetof(VRingUsed, flags);
>      flags = virtio_lduw_phys_cached(vq->vdev, &caches->used, pa);
> -    virtio_stw_phys_cached(vdev, &caches->used, pa, flags | mask);
> +    virtio_stw_phys_cached(vq->vdev, &caches->used, pa, flags | mask);
>      address_space_cache_invalidate(&caches->used, pa, sizeof(flags));
>  }
>  
> @@ -401,6 +442,10 @@ static inline void vring_used_flags_unset_bit(VirtQueue *vq, int mask)
>      hwaddr pa = offsetof(VRingUsed, flags);
>      uint16_t flags;
>  
> +    if (unlikely(!vq->vring.avail)) {
> +        return;
> +    }
> +
>      if (!caches) {
>          return;
>      }
> @@ -415,10 +460,15 @@ static inline void vring_set_avail_event(VirtQueue *vq, uint16_t val)
>  {
>      VRingMemoryRegionCaches *caches;
>      hwaddr pa;
> +
>      if (!vq->notification) {
>          return;
>      }
>  
> +    if (unlikely(!vq->vring.avail)) {
> +        return;
> +    }
> +
>      caches = vring_get_region_caches(vq);
>      if (!caches) {
>          return;
>
Philippe Mathieu-Daudé Aug. 25, 2021, 10:50 p.m. UTC | #2 
On 8/25/21 10:36 PM, Philippe Mathieu-Daudé wrote:
> On 8/25/21 10:09 PM, Philippe Mathieu-Daudé wrote:
>> Do not intent to access the vring MemoryRegion cache if
>> the queue is not ready (no vring available).
>>
>> This fixes issue #301:
>>
>>   qemu-system-i386: include/exec/memory_ldst_cached.h.inc:77: void address_space_stw_le_cached(MemoryRegionCache *, hwaddr, uint16_t, MemTxAttrs, MemTxResult *):
>>   Assertion `addr < cache->len && 2 <= cache->len - addr' failed.
>>   Thread 1 "qemu-system-i38" received signal SIGABRT, Aborted.
>>   (gdb) bt
>>   #1  0x00007ffff4d1a8a4 in abort () at /lib64/libc.so.6
>>   #4  0x0000555558f2a122 in address_space_stw_le_cached (cache=0x61300010bb70, addr=516, val=0, attrs=..., result=0x0) at include/exec/memory_ldst_cached.h.inc:77
>>   #5  0x0000555558f2964c in stw_le_phys_cached (cache=0x61300010bb70, addr=516, val=0) at include/exec/memory_ldst_phys.h.inc:109
>>   #6  0x0000555558f28da8 in virtio_stw_phys_cached (vdev=0x62d00004e680, cache=0x61300010bb70, pa=516, value=0) at include/hw/virtio/virtio-access.h:196
>>   #7  0x0000555558f287dc in vring_set_avail_event (vq=0x7fff5d23e800, val=0) at hw/virtio/virtio.c:428
>>   #8  0x0000555558efabb7 in virtio_queue_split_set_notification (vq=0x7fff5d23e800, enable=1) at hw/virtio/virtio.c:437
>>   #9  0x0000555558ef9f3c in virtio_queue_set_notification (vq=0x7fff5d23e800, enable=1) at hw/virtio/virtio.c:498
>>   #10 0x0000555558c94786 in virtio_blk_handle_vq (s=0x62d00004e680, vq=0x7fff5d23e800) at hw/block/virtio-blk.c:795
>>   #11 0x0000555558cb96c2 in virtio_blk_data_plane_handle_output (vdev=0x62d00004e680, vq=0x7fff5d23e800) at hw/block/dataplane/virtio-blk.c:165
>>   #12 0x0000555558f35937 in virtio_queue_notify_aio_vq (vq=0x7fff5d23e800) at hw/virtio/virtio.c:2323
>>   #13 0x0000555558f264b3 in virtio_queue_host_notifier_aio_read (n=0x7fff5d23e87c) at hw/virtio/virtio.c:3532
>>   #14 0x0000555559a9cd3e in aio_dispatch_handler (ctx=0x613000063000, node=0x60d000008f40) at util/aio-posix.c:329
>>   #15 0x0000555559a963ae in aio_dispatch_handlers (ctx=0x613000063000) at util/aio-posix.c:372
>>   #16 0x0000555559a95f82 in aio_dispatch (ctx=0x613000063000) at util/aio-posix.c:382
>>
>> and  #302:
>>
>>   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: Cheolwoo Myung <cwmyung@snu.ac.kr>
>> Reported-by: Qiuhao Li <Qiuhao.Li@outlook.com>
>> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/301
>> BugLink: https://bugs.launchpad.net/qemu/+bug/1910941
>> 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>
>> ---
>> Could be more readable to use virtio_queue_ready()
>>
>> RFC because I have no clue about this hot path code,
>> I simply looked at the backtraces.
>> ---
>>  hw/virtio/virtio.c | 82 +++++++++++++++++++++++++++++++++++++---------
>>  1 file changed, 66 insertions(+), 16 deletions(-)
>>
>> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
>> index 874377f37a7..be1ec9e05ef 100644
>> --- a/hw/virtio/virtio.c
>> +++ b/hw/virtio/virtio.c
>> @@ -289,26 +289,38 @@ static VRingMemoryRegionCaches *vring_get_region_caches(struct VirtQueue *vq)
>>  /* Called within rcu_read_lock().  */
>>  static inline uint16_t vring_avail_flags(VirtQueue *vq)
>>  {
>> -    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
>> -    hwaddr pa = offsetof(VRingAvail, flags);
>> +    VRingMemoryRegionCaches *caches;
>> +    hwaddr pa;
>>  
>> +    if (unlikely(!vq->vring.avail)) {
>> +        return 0;
>> +    }
>> +
>> +    caches = vring_get_region_caches(vq);
>>      if (!caches) {
>>          return 0;
>>      }
>>  
>> +    pa = offsetof(VRingAvail, flags);
>>      return virtio_lduw_phys_cached(vq->vdev, &caches->avail, pa);
>>  }
>>  
>>  /* Called within rcu_read_lock().  */
>>  static inline uint16_t vring_avail_idx(VirtQueue *vq)
>>  {
>> -    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
>> -    hwaddr pa = offsetof(VRingAvail, idx);
>> +    VRingMemoryRegionCaches *caches;
>> +    hwaddr pa;
>>  
>> +    if (unlikely(!vq->vring.avail)) {
>> +        return 0;
>> +    }
>> +
>> +    caches = vring_get_region_caches(vq);
>>      if (!caches) {
>>          return 0;
>>      }
>>  
>> +    pa = offsetof(VRingAvail, idx);
>>      vq->shadow_avail_idx = virtio_lduw_phys_cached(vq->vdev, &caches->avail, pa);
>>      return vq->shadow_avail_idx;
>>  }
>> @@ -316,13 +328,19 @@ static inline uint16_t vring_avail_idx(VirtQueue *vq)
>>  /* Called within rcu_read_lock().  */
>>  static inline uint16_t vring_avail_ring(VirtQueue *vq, int i)
>>  {
>> -    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
>> -    hwaddr pa = offsetof(VRingAvail, ring[i]);
>> +    VRingMemoryRegionCaches *caches;
>> +    hwaddr pa;
>>  
>> +    if (unlikely(!vq->vring.avail)) {
>> +        return 0;
>> +    }
>> +
>> +    caches = vring_get_region_caches(vq);
>>      if (!caches) {
>>          return 0;
>>      }
>>  
>> +    pa = offsetof(VRingAvail, ring[i]);
>>      return virtio_lduw_phys_cached(vq->vdev, &caches->avail, pa);
>>  }
> 
> Self-NAck.
> 
> While the previous part could be OK, what follows is crap (checking
> avail instead of used) so please disregard this patch.

Previous part is also crap :/
Stefan Hajnoczi Aug. 26, 2021, 7:45 a.m. UTC | #3 
On Thu, Aug 26, 2021 at 12:50:34AM +0200, Philippe Mathieu-Daudé wrote:
> On 8/25/21 10:36 PM, Philippe Mathieu-Daudé wrote:
> > On 8/25/21 10:09 PM, Philippe Mathieu-Daudé wrote:
> >> Do not intent to access the vring MemoryRegion cache if
> >> the queue is not ready (no vring available).
> >>
> >> This fixes issue #301:
> >>
> >>   qemu-system-i386: include/exec/memory_ldst_cached.h.inc:77: void address_space_stw_le_cached(MemoryRegionCache *, hwaddr, uint16_t, MemTxAttrs, MemTxResult *):
> >>   Assertion `addr < cache->len && 2 <= cache->len - addr' failed.
> >>   Thread 1 "qemu-system-i38" received signal SIGABRT, Aborted.
> >>   (gdb) bt
> >>   #1  0x00007ffff4d1a8a4 in abort () at /lib64/libc.so.6
> >>   #4  0x0000555558f2a122 in address_space_stw_le_cached (cache=0x61300010bb70, addr=516, val=0, attrs=..., result=0x0) at include/exec/memory_ldst_cached.h.inc:77
> >>   #5  0x0000555558f2964c in stw_le_phys_cached (cache=0x61300010bb70, addr=516, val=0) at include/exec/memory_ldst_phys.h.inc:109
> >>   #6  0x0000555558f28da8 in virtio_stw_phys_cached (vdev=0x62d00004e680, cache=0x61300010bb70, pa=516, value=0) at include/hw/virtio/virtio-access.h:196
> >>   #7  0x0000555558f287dc in vring_set_avail_event (vq=0x7fff5d23e800, val=0) at hw/virtio/virtio.c:428
> >>   #8  0x0000555558efabb7 in virtio_queue_split_set_notification (vq=0x7fff5d23e800, enable=1) at hw/virtio/virtio.c:437
> >>   #9  0x0000555558ef9f3c in virtio_queue_set_notification (vq=0x7fff5d23e800, enable=1) at hw/virtio/virtio.c:498
> >>   #10 0x0000555558c94786 in virtio_blk_handle_vq (s=0x62d00004e680, vq=0x7fff5d23e800) at hw/block/virtio-blk.c:795
> >>   #11 0x0000555558cb96c2 in virtio_blk_data_plane_handle_output (vdev=0x62d00004e680, vq=0x7fff5d23e800) at hw/block/dataplane/virtio-blk.c:165
> >>   #12 0x0000555558f35937 in virtio_queue_notify_aio_vq (vq=0x7fff5d23e800) at hw/virtio/virtio.c:2323
> >>   #13 0x0000555558f264b3 in virtio_queue_host_notifier_aio_read (n=0x7fff5d23e87c) at hw/virtio/virtio.c:3532
> >>   #14 0x0000555559a9cd3e in aio_dispatch_handler (ctx=0x613000063000, node=0x60d000008f40) at util/aio-posix.c:329
> >>   #15 0x0000555559a963ae in aio_dispatch_handlers (ctx=0x613000063000) at util/aio-posix.c:372
> >>   #16 0x0000555559a95f82 in aio_dispatch (ctx=0x613000063000) at util/aio-posix.c:382
> >>
> >> and  #302:
> >>
> >>   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: Cheolwoo Myung <cwmyung@snu.ac.kr>
> >> Reported-by: Qiuhao Li <Qiuhao.Li@outlook.com>
> >> Resolves: https://gitlab.com/qemu-project/qemu/-/issues/301
> >> BugLink: https://bugs.launchpad.net/qemu/+bug/1910941
> >> 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>
> >> ---
> >> Could be more readable to use virtio_queue_ready()
> >>
> >> RFC because I have no clue about this hot path code,
> >> I simply looked at the backtraces.
> >> ---
> >>  hw/virtio/virtio.c | 82 +++++++++++++++++++++++++++++++++++++---------
> >>  1 file changed, 66 insertions(+), 16 deletions(-)
> >>
> >> diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
> >> index 874377f37a7..be1ec9e05ef 100644
> >> --- a/hw/virtio/virtio.c
> >> +++ b/hw/virtio/virtio.c
> >> @@ -289,26 +289,38 @@ static VRingMemoryRegionCaches *vring_get_region_caches(struct VirtQueue *vq)
> >>  /* Called within rcu_read_lock().  */
> >>  static inline uint16_t vring_avail_flags(VirtQueue *vq)
> >>  {
> >> -    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
> >> -    hwaddr pa = offsetof(VRingAvail, flags);
> >> +    VRingMemoryRegionCaches *caches;
> >> +    hwaddr pa;
> >>  
> >> +    if (unlikely(!vq->vring.avail)) {
> >> +        return 0;
> >> +    }
> >> +
> >> +    caches = vring_get_region_caches(vq);
> >>      if (!caches) {
> >>          return 0;
> >>      }
> >>  
> >> +    pa = offsetof(VRingAvail, flags);
> >>      return virtio_lduw_phys_cached(vq->vdev, &caches->avail, pa);
> >>  }
> >>  
> >>  /* Called within rcu_read_lock().  */
> >>  static inline uint16_t vring_avail_idx(VirtQueue *vq)
> >>  {
> >> -    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
> >> -    hwaddr pa = offsetof(VRingAvail, idx);
> >> +    VRingMemoryRegionCaches *caches;
> >> +    hwaddr pa;
> >>  
> >> +    if (unlikely(!vq->vring.avail)) {
> >> +        return 0;
> >> +    }
> >> +
> >> +    caches = vring_get_region_caches(vq);
> >>      if (!caches) {
> >>          return 0;
> >>      }
> >>  
> >> +    pa = offsetof(VRingAvail, idx);
> >>      vq->shadow_avail_idx = virtio_lduw_phys_cached(vq->vdev, &caches->avail, pa);
> >>      return vq->shadow_avail_idx;
> >>  }
> >> @@ -316,13 +328,19 @@ static inline uint16_t vring_avail_idx(VirtQueue *vq)
> >>  /* Called within rcu_read_lock().  */
> >>  static inline uint16_t vring_avail_ring(VirtQueue *vq, int i)
> >>  {
> >> -    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
> >> -    hwaddr pa = offsetof(VRingAvail, ring[i]);
> >> +    VRingMemoryRegionCaches *caches;
> >> +    hwaddr pa;
> >>  
> >> +    if (unlikely(!vq->vring.avail)) {
> >> +        return 0;
> >> +    }
> >> +
> >> +    caches = vring_get_region_caches(vq);
> >>      if (!caches) {
> >>          return 0;
> >>      }
> >>  
> >> +    pa = offsetof(VRingAvail, ring[i]);
> >>      return virtio_lduw_phys_cached(vq->vdev, &caches->avail, pa);
> >>  }
> > 
> > Self-NAck.
> > 
> > While the previous part could be OK, what follows is crap (checking
> > avail instead of used) so please disregard this patch.
> 
> Previous part is also crap :/

The topic reminds me of:

  commit abdd16f4681cc4d6bf84990227b5c9b98e869ccd
  Author: Stefan Hajnoczi <stefanha@redhat.com>
  Date:   Fri Feb 7 10:46:19 2020 +0000

      virtio: gracefully handle invalid region caches

Stefan
diff mbox series

Patch

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 874377f37a7..be1ec9e05ef 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -289,26 +289,38 @@  static VRingMemoryRegionCaches *vring_get_region_caches(struct VirtQueue *vq)
 /* Called within rcu_read_lock().  */
 static inline uint16_t vring_avail_flags(VirtQueue *vq)
 {
-    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
-    hwaddr pa = offsetof(VRingAvail, flags);
+    VRingMemoryRegionCaches *caches;
+    hwaddr pa;
 
+    if (unlikely(!vq->vring.avail)) {
+        return 0;
+    }
+
+    caches = vring_get_region_caches(vq);
     if (!caches) {
         return 0;
     }
 
+    pa = offsetof(VRingAvail, flags);
     return virtio_lduw_phys_cached(vq->vdev, &caches->avail, pa);
 }
 
 /* Called within rcu_read_lock().  */
 static inline uint16_t vring_avail_idx(VirtQueue *vq)
 {
-    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
-    hwaddr pa = offsetof(VRingAvail, idx);
+    VRingMemoryRegionCaches *caches;
+    hwaddr pa;
 
+    if (unlikely(!vq->vring.avail)) {
+        return 0;
+    }
+
+    caches = vring_get_region_caches(vq);
     if (!caches) {
         return 0;
     }
 
+    pa = offsetof(VRingAvail, idx);
     vq->shadow_avail_idx = virtio_lduw_phys_cached(vq->vdev, &caches->avail, pa);
     return vq->shadow_avail_idx;
 }
@@ -316,13 +328,19 @@  static inline uint16_t vring_avail_idx(VirtQueue *vq)
 /* Called within rcu_read_lock().  */
 static inline uint16_t vring_avail_ring(VirtQueue *vq, int i)
 {
-    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
-    hwaddr pa = offsetof(VRingAvail, ring[i]);
+    VRingMemoryRegionCaches *caches;
+    hwaddr pa;
 
+    if (unlikely(!vq->vring.avail)) {
+        return 0;
+    }
+
+    caches = vring_get_region_caches(vq);
     if (!caches) {
         return 0;
     }
 
+    pa = offsetof(VRingAvail, ring[i]);
     return virtio_lduw_phys_cached(vq->vdev, &caches->avail, pa);
 }
 
@@ -336,13 +354,19 @@  static inline uint16_t vring_get_used_event(VirtQueue *vq)
 static inline void vring_used_write(VirtQueue *vq, VRingUsedElem *uelem,
                                     int i)
 {
-    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
-    hwaddr pa = offsetof(VRingUsed, ring[i]);
+    VRingMemoryRegionCaches *caches;
+    hwaddr pa;
 
+    if (unlikely(!vq->vring.avail)) {
+        return;
+    }
+
+    caches = vring_get_region_caches(vq);
     if (!caches) {
         return;
     }
 
+    pa = offsetof(VRingUsed, ring[i]);
     virtio_tswap32s(vq->vdev, &uelem->id);
     virtio_tswap32s(vq->vdev, &uelem->len);
     address_space_write_cached(&caches->used, pa, uelem, sizeof(VRingUsedElem));
@@ -352,23 +376,35 @@  static inline void vring_used_write(VirtQueue *vq, VRingUsedElem *uelem,
 /* Called within rcu_read_lock().  */
 static uint16_t vring_used_idx(VirtQueue *vq)
 {
-    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
-    hwaddr pa = offsetof(VRingUsed, idx);
+    VRingMemoryRegionCaches *caches;
+    hwaddr pa;
 
+    if (unlikely(!vq->vring.avail)) {
+        return 0;
+    }
+
+    caches = vring_get_region_caches(vq);
     if (!caches) {
         return 0;
     }
 
+    pa = offsetof(VRingUsed, idx);
     return virtio_lduw_phys_cached(vq->vdev, &caches->used, pa);
 }
 
 /* Called within rcu_read_lock().  */
 static inline void vring_used_idx_set(VirtQueue *vq, uint16_t val)
 {
-    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
-    hwaddr pa = offsetof(VRingUsed, idx);
+    VRingMemoryRegionCaches *caches;
 
+    if (unlikely(!vq->vring.avail)) {
+        return;
+    }
+
+    caches = vring_get_region_caches(vq);
     if (caches) {
+        hwaddr pa = offsetof(VRingUsed, idx);
+
         virtio_stw_phys_cached(vq->vdev, &caches->used, pa, val);
         address_space_cache_invalidate(&caches->used, pa, sizeof(val));
     }
@@ -379,17 +415,22 @@  static inline void vring_used_idx_set(VirtQueue *vq, uint16_t val)
 /* Called within rcu_read_lock().  */
 static inline void vring_used_flags_set_bit(VirtQueue *vq, int mask)
 {
-    VRingMemoryRegionCaches *caches = vring_get_region_caches(vq);
-    VirtIODevice *vdev = vq->vdev;
-    hwaddr pa = offsetof(VRingUsed, flags);
+    VRingMemoryRegionCaches *caches;
+    hwaddr pa;
     uint16_t flags;
 
+    if (unlikely(!vq->vring.avail)) {
+        return;
+    }
+
+    caches = vring_get_region_caches(vq);
     if (!caches) {
         return;
     }
 
+    pa = offsetof(VRingUsed, flags);
     flags = virtio_lduw_phys_cached(vq->vdev, &caches->used, pa);
-    virtio_stw_phys_cached(vdev, &caches->used, pa, flags | mask);
+    virtio_stw_phys_cached(vq->vdev, &caches->used, pa, flags | mask);
     address_space_cache_invalidate(&caches->used, pa, sizeof(flags));
 }
 
@@ -401,6 +442,10 @@  static inline void vring_used_flags_unset_bit(VirtQueue *vq, int mask)
     hwaddr pa = offsetof(VRingUsed, flags);
     uint16_t flags;
 
+    if (unlikely(!vq->vring.avail)) {
+        return;
+    }
+
     if (!caches) {
         return;
     }
@@ -415,10 +460,15 @@  static inline void vring_set_avail_event(VirtQueue *vq, uint16_t val)
 {
     VRingMemoryRegionCaches *caches;
     hwaddr pa;
+
     if (!vq->notification) {
         return;
     }
 
+    if (unlikely(!vq->vring.avail)) {
+        return;
+    }
+
     caches = vring_get_region_caches(vq);
     if (!caches) {
         return;