From 3a232277c1ac6df70552129a9722abc6ab250128 Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Fri, 27 May 2022 14:01:17 +0800 Subject: virtio-ccw: implement synchronize_cbs() This patch tries to implement the synchronize_cbs() for ccw. For the vring_interrupt() that is called via virtio_airq_handler(), the synchronization is simply done via the airq_info's lock. For the vring_interrupt() that is called via virtio_ccw_int_handler(), a per device rwlock is introduced and used in the synchronization method. Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: "Paul E. McKenney" Cc: Marc Zyngier Cc: Halil Pasic Cc: Cornelia Huck Cc: Vineeth Vijayan Cc: Peter Oberparleiter Cc: linux-s390@vger.kernel.org Reviewed-by: Halil Pasic Signed-off-by: Jason Wang Message-Id: <20220527060120.20964-7-jasowang@redhat.com> Signed-off-by: Michael S. Tsirkin --- drivers/s390/virtio/virtio_ccw.c | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) (limited to 'drivers/s390') diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c index d35e7a3f7067..c188e4f20ca3 100644 --- a/drivers/s390/virtio/virtio_ccw.c +++ b/drivers/s390/virtio/virtio_ccw.c @@ -62,6 +62,7 @@ struct virtio_ccw_device { unsigned int revision; /* Transport revision */ wait_queue_head_t wait_q; spinlock_t lock; + rwlock_t irq_lock; struct mutex io_lock; /* Serializes I/O requests */ struct list_head virtqueues; bool is_thinint; @@ -984,6 +985,30 @@ static const char *virtio_ccw_bus_name(struct virtio_device *vdev) return dev_name(&vcdev->cdev->dev); } +static void virtio_ccw_synchronize_cbs(struct virtio_device *vdev) +{ + struct virtio_ccw_device *vcdev = to_vc_device(vdev); + struct airq_info *info = vcdev->airq_info; + + if (info) { + /* + * This device uses adapter interrupts: synchronize with + * vring_interrupt() called by virtio_airq_handler() + * via the indicator area lock. + */ + write_lock_irq(&info->lock); + write_unlock_irq(&info->lock); + } else { + /* This device uses classic interrupts: synchronize + * with vring_interrupt() called by + * virtio_ccw_int_handler() via the per-device + * irq_lock + */ + write_lock_irq(&vcdev->irq_lock); + write_unlock_irq(&vcdev->irq_lock); + } +} + static const struct virtio_config_ops virtio_ccw_config_ops = { .get_features = virtio_ccw_get_features, .finalize_features = virtio_ccw_finalize_features, @@ -995,6 +1020,7 @@ static const struct virtio_config_ops virtio_ccw_config_ops = { .find_vqs = virtio_ccw_find_vqs, .del_vqs = virtio_ccw_del_vqs, .bus_name = virtio_ccw_bus_name, + .synchronize_cbs = virtio_ccw_synchronize_cbs, }; @@ -1106,6 +1132,8 @@ static void virtio_ccw_int_handler(struct ccw_device *cdev, vcdev->err = -EIO; } virtio_ccw_check_activity(vcdev, activity); + /* Interrupts are disabled here */ + read_lock(&vcdev->irq_lock); for_each_set_bit(i, indicators(vcdev), sizeof(*indicators(vcdev)) * BITS_PER_BYTE) { /* The bit clear must happen before the vring kick. */ @@ -1114,6 +1142,7 @@ static void virtio_ccw_int_handler(struct ccw_device *cdev, vq = virtio_ccw_vq_by_ind(vcdev, i); vring_interrupt(0, vq); } + read_unlock(&vcdev->irq_lock); if (test_bit(0, indicators2(vcdev))) { virtio_config_changed(&vcdev->vdev); clear_bit(0, indicators2(vcdev)); @@ -1284,6 +1313,7 @@ static int virtio_ccw_online(struct ccw_device *cdev) init_waitqueue_head(&vcdev->wait_q); INIT_LIST_HEAD(&vcdev->virtqueues); spin_lock_init(&vcdev->lock); + rwlock_init(&vcdev->irq_lock); mutex_init(&vcdev->io_lock); spin_lock_irqsave(get_ccwdev_lock(cdev), flags); -- cgit v1.2.3 From 8b4ec69d7e098a7ddf832e1e7840de53ed474c77 Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Fri, 27 May 2022 14:01:19 +0800 Subject: virtio: harden vring IRQ This is a rework on the previous IRQ hardening that is done for virtio-pci where several drawbacks were found and were reverted: 1) try to use IRQF_NO_AUTOEN which is not friendly to affinity managed IRQ that is used by some device such as virtio-blk 2) done only for PCI transport The vq->broken is re-used in this patch for implementing the IRQ hardening. The vq->broken is set to true during both initialization and reset. And the vq->broken is set to false in virtio_device_ready(). Then vring_interrupt() can check and return when vq->broken is true. And in this case, switch to return IRQ_NONE to let the interrupt core aware of such invalid interrupt to prevent IRQ storm. The reason of using a per queue variable instead of a per device one is that we may need it for per queue reset hardening in the future. Note that the hardening is only done for vring interrupt since the config interrupt hardening is already done in commit 22b7050a024d7 ("virtio: defer config changed notifications"). But the method that is used by config interrupt can't be reused by the vring interrupt handler because it uses spinlock to do the synchronization which is expensive. Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: "Paul E. McKenney" Cc: Marc Zyngier Cc: Halil Pasic Cc: Cornelia Huck Cc: Vineeth Vijayan Cc: Peter Oberparleiter Cc: linux-s390@vger.kernel.org Signed-off-by: Jason Wang Message-Id: <20220527060120.20964-9-jasowang@redhat.com> Signed-off-by: Michael S. Tsirkin Reviewed-by: Xuan Zhuo --- drivers/s390/virtio/virtio_ccw.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'drivers/s390') diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c index c188e4f20ca3..97e51c34e6cf 100644 --- a/drivers/s390/virtio/virtio_ccw.c +++ b/drivers/s390/virtio/virtio_ccw.c @@ -971,6 +971,10 @@ static void virtio_ccw_set_status(struct virtio_device *vdev, u8 status) ccw->flags = 0; ccw->count = sizeof(status); ccw->cda = (__u32)(unsigned long)&vcdev->dma_area->status; + /* We use ssch for setting the status which is a serializing + * instruction that guarantees the memory writes have + * completed before ssch. + */ ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_WRITE_STATUS); /* Write failed? We assume status is unchanged. */ if (ret) -- cgit v1.2.3