On Thu, Oct 29, 2020 at 03:39:24PM +0800, Jason Wang wrote:
>
> On 2020/10/29 下午3:37, Eli Cohen wrote:
> > On Thu, Oct 29, 2020 at 03:03:24PM +0800, Jason Wang wrote:
> > > On 2020/10/28 下午10:20, Eli Cohen wrote:
> > > > Both irq_bypass_register_producer() and irq_bypass_unregister_producer()
> > > > require process context to run. Change the call context lock from
> > > > spinlock to mutex to protect the setup process to avoid deadlocks.
> > > >
> > > > Fixes: 265a0ad8731d ("vhost: introduce vhost_vring_call")
> > > > Signed-off-by: Eli Cohen <e...@nvidia.com>
> > >
> > > Hi Eli:
> > >
> > > During review we spot that the spinlock is not necessary. And it was
> > > already
> > > protected by vq mutex. So it was removed in this commit:
> > >
> > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=86e182fe12ee5869022614457037097c70fe2ed1
> > >
> > > Thanks
> > >
> > I see, thanks.
> >
> > BTW, while testing irq bypassing, I noticed that qemu started crashing
> > and I fail to boot the VM? Is that a known issue. I checked using
> > updated master branch of qemu updated yesterday.
>
>
> Not known yet.
>
>
> >
> > Any ideas how to check this further?
>
>
> I would be helpful if you can paste the calltrace here.
>
I am not too familiar with qemu. Assuming I am using virsh start to boot
the VM, how can I get the call trace?
>
> > Did anyone actually check that irq bypassing works?
>
>
> Yes, Ling Shan tested it via IFCVF driver.
>
> Thanks
>
>
> >
> > > > ---
> > > > drivers/vhost/vdpa.c | 10 +++++-----
> > > > drivers/vhost/vhost.c | 6 +++---
> > > > drivers/vhost/vhost.h | 3 ++-
> > > > 3 files changed, 10 insertions(+), 9 deletions(-)
> > > >
> > > > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
> > > > index be783592fe58..0a744f2b6e76 100644
> > > > --- a/drivers/vhost/vdpa.c
> > > > +++ b/drivers/vhost/vdpa.c
> > > > @@ -98,26 +98,26 @@ static void vhost_vdpa_setup_vq_irq(struct
> > > > vhost_vdpa *v, u16 qid)
> > > > return;
> > > > irq = ops->get_vq_irq(vdpa, qid);
> > > > - spin_lock(&vq->call_ctx.ctx_lock);
> > > > + mutex_lock(&vq->call_ctx.ctx_lock);
> > > > irq_bypass_unregister_producer(&vq->call_ctx.producer);
> > > > if (!vq->call_ctx.ctx || irq < 0) {
> > > > - spin_unlock(&vq->call_ctx.ctx_lock);
> > > > + mutex_unlock(&vq->call_ctx.ctx_lock);
> > > > return;
> > > > }
> > > > vq->call_ctx.producer.token = vq->call_ctx.ctx;
> > > > vq->call_ctx.producer.irq = irq;
> > > > ret = irq_bypass_register_producer(&vq->call_ctx.producer);
> > > > - spin_unlock(&vq->call_ctx.ctx_lock);
> > > > + mutex_unlock(&vq->call_ctx.ctx_lock);
> > > > }
> > > > static void vhost_vdpa_unsetup_vq_irq(struct vhost_vdpa *v, u16 qid)
> > > > {
> > > > struct vhost_virtqueue *vq = &v->vqs[qid];
> > > > - spin_lock(&vq->call_ctx.ctx_lock);
> > > > + mutex_lock(&vq->call_ctx.ctx_lock);
> > > > irq_bypass_unregister_producer(&vq->call_ctx.producer);
> > > > - spin_unlock(&vq->call_ctx.ctx_lock);
> > > > + mutex_unlock(&vq->call_ctx.ctx_lock);
> > > > }
> > > > static void vhost_vdpa_reset(struct vhost_vdpa *v)
> > > > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> > > > index 9ad45e1d27f0..938239e11455 100644
> > > > --- a/drivers/vhost/vhost.c
> > > > +++ b/drivers/vhost/vhost.c
> > > > @@ -302,7 +302,7 @@ static void vhost_vring_call_reset(struct
> > > > vhost_vring_call *call_ctx)
> > > > {
> > > > call_ctx->ctx = NULL;
> > > > memset(&call_ctx->producer, 0x0, sizeof(struct
> > > > irq_bypass_producer));
> > > > - spin_lock_init(&call_ctx->ctx_lock);
> > > > + mutex_init(&call_ctx->ctx_lock);
> > > > }
> > > > static void vhost_vq_reset(struct vhost_dev *dev,
> > > > @@ -1650,9 +1650,9 @@ long vhost_vring_ioctl(struct vhost_dev *d,
> > > > unsigned int ioctl, void __user *arg
> > > > break;
> > > > }
> > > > - spin_lock(&vq->call_ctx.ctx_lock);
> > > > + mutex_lock(&vq->call_ctx.ctx_lock);
> > > > swap(ctx, vq->call_ctx.ctx);
> > > > - spin_unlock(&vq->call_ctx.ctx_lock);
> > > > + mutex_unlock(&vq->call_ctx.ctx_lock);
> > > > break;
> > > > case VHOST_SET_VRING_ERR:
> > > > if (copy_from_user(&f, argp, sizeof f)) {
> > > > diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
> > > > index 9032d3c2a9f4..e8855ea04205 100644
> > > > --- a/drivers/vhost/vhost.h
> > > > +++ b/drivers/vhost/vhost.h
> > > > @@ -64,7 +64,8 @@ enum vhost_uaddr_type {
> > > > struct vhost_vring_call {
> > > > struct eventfd_ctx *ctx;
> > > > struct irq_bypass_producer producer;
> > > > - spinlock_t ctx_lock;
> > > > + /* protect vq irq setup */
> > > > + struct mutex ctx_lock;
> > > > };
> > > > /* The virtqueue structure describes a queue attached to a device. */
>
