On Tue, Sep 26 2023, Halil Pasic <pasic@xxxxxxxxxxxxx> wrote:
> [..]
>> --- a/drivers/crypto/virtio/virtio_crypto_akcipher_algs.c
>> +++ b/drivers/crypto/virtio/virtio_crypto_akcipher_algs.c
>> @@ -61,8 +61,9 @@ static void virtio_crypto_akcipher_finalize_req(
>> vc_akcipher_req->src_buf = NULL;
>> vc_akcipher_req->dst_buf = NULL;
>> virtcrypto_clear_request(&vc_akcipher_req->base);
>> -
>> + local_bh_disable();
>> crypto_finalize_akcipher_request(vc_akcipher_req->base.dataq->engine, req, err);
>> + local_bh_enable();
>
> Thanks Gonglei!
>
> I did this a quick spin, and it does not seem to be sufficient on s390x.
> Which does not come as a surprise to me, because
>
> #define lockdep_assert_in_softirq() \
> do { \
> WARN_ON_ONCE(__lockdep_enabled && \
> (!in_softirq() || in_irq() || in_nmi())); \
> } while (0)
>
> will still warn because in_irq() still evaluates to true (your patch
> addresses the !in_softirq() part).
>
> I don't have any results on x86 yet. My current understanding is that the
> virtio-pci transport code disables interrupts locally somewhere in the
> call chain (actually in vp_vring_interrupt() via spin_lock_irqsave())
> and then x86 would be fine. But I will get that verified.
>
> On the other hand virtio_airq_handler() calls vring_interrupt() with
> interrupts enabled. (While vring_interrupt() is called in a (read)
> critical section in virtio_airq_handler() we use read_lock() and
> not read_lock_irqsave() to grab the lock. Whether that is correct in
> it self (i.e. disregarding the crypto problem) or not I'm not sure right
> now. Will think some more about it tomorrow.) If the way to go forward
> is disabling interrupts in virtio-ccw before vring_interrupt() is
> called, I would be glad to spin a patch for that.
virtio_airq_handler() is supposed to be an interrupt handler for an
adapter interrupt -- as such I would expect it to always run with
interrupts disabled (and I'd expect vring_interrupt() to be called
with interrupts disabled as well; if that's not the case, I think it
would need to run asynchronously.) At least that was my understanding at
the time I wrote the code.
>
> Copying Conny, as she may have an opinion on this (if I'm not wrong she
> authored that code).
>
> Regards,
> Halil
