BUG: virtcrypto_dataq_callback calls crypto_finalize_request() from irq context

[Halil Pasic]

Hi Gonglei!

Our CI has found that virtio-crypto does not honor the requirement of 
crypto_finalize_request() being called in softirq context which is
asserted in that function via lockdep_assert_in_softirq() since commit
4058cf08945c ("crypto: engine - check if BH is disabled during
completion").

The problem was originally found on s390x but Marc Hartmayer was so kind
to reproduce it on amd64. Please find the corresponding kernel messages
at the end of this email.

The call chain looks like this. 
interrupt handler for queue notification
 --> virtcrypto_dataq_callback()
 --> via vc_req->alg_cb either virtio_crypto_skcipher_finalize_req()
     or virtio_crypto_akcipher_finalize_req()
 --> crypto_finalize_skcipher_request()
     or crypto_finalize_akcipher_request()
 --> crypto_finalize_request()

Everything above is happening in the interrupt handler (and in "hard" irq
context).

I'm not really familiar with the implementation of virtio_crypto or with
the crypto_engine interfaces. I assume the problem is on the side of
virtio-crypto so I would like to kindly ask you as the maintainer of
virtio-crypt to have a look at it. But if you think it is rather in the
crypto_engine, please clarify that with Herbert. I have no strong opinion
on this issue.

Regards,
Halil

[ 31.033415][ C0] WARNING: CPU: 0 PID: 136 at crypto/crypto_engine.c:58 crypto_finalize_request (crypto/crypto_engine.c:58 (discriminator 23)) crypto_engine
[   31.034131][    C0] Modules linked in: virtio_crypto(+) vmw_vsock_virtio_transport_common(+) crypto_engine vsock
[   31.035326][    C0] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-1.fc38 04/01/2014
[ 31.035917][ C0] RIP: 0010:crypto_finalize_request (crypto/crypto_engine.c:58 (discriminator 23)) crypto_engine
[ 31.036398][ C0] Code: 08 5b 5d 41 5c 41 5d e9 bf 88 1c c1 65 8b 05 b0 36 01 40 f6 c4 ff 74 12 a9 00 00 0f 00 75 0b a9 00 00 f0 00 0f 84 54 ff ff ff <0f> 0b e9 4d ff ff ff 4c 8d 6b 38 4c 89 ef e8 8e 47 1b c4 48 8d bb
All code
========
   0:	08 5b 5d             	or     %bl,0x5d(%rbx)
   3:	41 5c                	pop    %r12
   5:	41 5d                	pop    %r13
   7:	e9 bf 88 1c c1       	jmp    0xffffffffc11c88cb
   c:	65 8b 05 b0 36 01 40 	mov    %gs:0x400136b0(%rip),%eax        # 0x400136c3
  13:	f6 c4 ff             	test   $0xff,%ah
  16:	74 12                	je     0x2a
  18:	a9 00 00 0f 00       	test   $0xf0000,%eax
  1d:	75 0b                	jne    0x2a
  1f:	a9 00 00 f0 00       	test   $0xf00000,%eax
  24:	0f 84 54 ff ff ff    	je     0xffffffffffffff7e
  2a:*	0f 0b                	ud2		<-- trapping instruction
  2c:	e9 4d ff ff ff       	jmp    0xffffffffffffff7e
  31:	4c 8d 6b 38          	lea    0x38(%rbx),%r13
  35:	4c 89 ef             	mov    %r13,%rdi
  38:	e8 8e 47 1b c4       	call   0xffffffffc41b47cb
  3d:	48                   	rex.W
  3e:	8d                   	.byte 0x8d
  3f:	bb                   	.byte 0xbb

Code starting with the faulting instruction
===========================================
   0:	0f 0b                	ud2
   2:	e9 4d ff ff ff       	jmp    0xffffffffffffff54
   7:	4c 8d 6b 38          	lea    0x38(%rbx),%r13
   b:	4c 89 ef             	mov    %r13,%rdi
   e:	e8 8e 47 1b c4       	call   0xffffffffc41b47a1
  13:	48                   	rex.W
  14:	8d                   	.byte 0x8d
  15:	bb                   	.byte 0xbb
[   31.037591][    C0] RSP: 0018:ffffc90000007da0 EFLAGS: 00010046
[   31.037976][    C0] RAX: 0000000080010002 RBX: ffff888006c87428 RCX: 1ffffffff0c0e523
[   31.038471][    C0] RDX: 0000000000000000 RSI: ffff88810d0819e8 RDI: ffff888006c87449
[   31.038967][    C0] RBP: ffff88810d0819e8 R08: 0000000000000000 R09: fffffbfff0b04f04
[   31.039463][    C0] R10: ffffffff85827823 R11: ffffffff842013e6 R12: 0000000000000000
[   31.039963][    C0] R13: 0000000000000001 R14: ffff88810d081a18 R15: dffffc0000000000
[   31.040475][    C0] FS:  00007f80c0cc6800(0000) GS:ffff88811ae00000(0000) knlGS:0000000000000000
[   31.041058][    C0] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   31.041473][    C0] CR2: 00007f22ad455270 CR3: 0000000106b22000 CR4: 00000000000006f0
[   31.042024][    C0] Call Trace:
[   31.042250][    C0]  <IRQ>
[ 31.042433][ C0] ? __warn (kernel/panic.c:673) 
[ 31.042710][ C0] ? crypto_finalize_request (crypto/crypto_engine.c:58 (discriminator 23)) crypto_engine
[ 31.043161][ C0] ? report_bug (lib/bug.c:180 lib/bug.c:219) 
[ 31.043451][ C0] ? handle_bug (arch/x86/kernel/traps.c:237 (discriminator 1)) 
[ 31.043728][ C0] ? exc_invalid_op (arch/x86/kernel/traps.c:258 (discriminator 1)) 
[ 31.044039][ C0] ? asm_exc_invalid_op (./arch/x86/include/asm/idtentry.h:568) 
[ 31.044385][ C0] ? asm_common_interrupt (./arch/x86/include/asm/idtentry.h:636) 
[ 31.044746][ C0] ? crypto_finalize_request (crypto/crypto_engine.c:58 (discriminator 23)) crypto_engine
[ 31.045202][ C0] virtcrypto_dataq_callback (drivers/crypto/virtio/virtio_crypto_core.c:91) virtio_crypto
[ 31.045661][ C0] ? __pfx_virtcrypto_dataq_callback (drivers/crypto/virtio/virtio_crypto_core.c:76) virtio_crypto
[ 31.046148][ C0] ? __pfx_do_raw_spin_lock (kernel/locking/spinlock_debug.c:113) 
[ 31.046499][ C0] vring_interrupt (drivers/virtio/virtio_ring.c:2598) 
[ 31.046806][ C0] vp_vring_interrupt (drivers/virtio/virtio_pci_common.c:67 (discriminator 2)) 
[ 31.047125][ C0] ? __pfx_vp_vring_interrupt (drivers/virtio/virtio_pci_common.c:60) 
[ 31.047477][ C0] __handle_irq_event_percpu (kernel/irq/handle.c:158) 
[ 31.047845][ C0] handle_irq_event (kernel/irq/handle.c:195 kernel/irq/handle.c:210) 
[ 31.048147][ C0] handle_edge_irq (kernel/irq/chip.c:833) 
[ 31.048454][ C0] __common_interrupt (arch/x86/kernel/irq.c:271) 
[ 31.048767][ C0] common_interrupt (arch/x86/kernel/irq.c:247 (discriminator 47)) 
[   31.049071][    C0]  </IRQ>
[   31.049273][    C0]  <TASK>
[ 31.049468][ C0] asm_common_interrupt (./arch/x86/include/asm/idtentry.h:636) 
[ 31.049805][ C0] RIP: 0010:unwind_next_frame (arch/x86/kernel/unwind_orc.c:494)