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From:   Jason Wang <jasowang@redhat.com>
To:     jasowang@redhat.com, mst@redhat.com,
        virtualization@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org
Cc:     tglx@linutronix.de, peterz@infradead.org, paulmck@kernel.org,
        maz@kernel.org, pasic@linux.ibm.com, cohuck@redhat.com,
        eperezma@redhat.com, lulu@redhat.com, sgarzare@redhat.com,
        xuanzhuo@linux.alibaba.com
Subject: [PATCH V4 0/9] rework on the IRQ hardening of virtio
Date:   Sat,  7 May 2022 15:19:45 +0800
Message-Id: <20220507071954.14455-1-jasowang@redhat.com>
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Hi All:

This is a rework on the IRQ hardening for virtio which is done
previously by the following commits are reverted:

9e35276a5344 ("virtio_pci: harden MSI-X interrupts")
080cd7c3ac87 ("virtio-pci: harden INTX interrupts")

The reason is that it depends on the IRQF_NO_AUTOEN which may conflict
with the assumption of the affinity managed IRQ that is used by some
virtio drivers. And what's more, it is only done for virtio-pci but
not other transports.

In this rework, I try to implement a general virtio solution which
borrows the idea of the INTX hardening by re-using per virtqueue
boolean vq->broken and toggle it in virtio_device_ready() and
virtio_reset_device(). Then we can simply reuse the existing checks in
the vring_interrupt() and return early if the driver is not ready.

Note that, I only did compile test on ccw and MMIO transport.

Please review.

Changes since v1:

- Use transport specific irq synchronization method when possible
- Drop the module parameter and enable the hardening unconditonally
- Tweak the barrier/ordering facilities used in the code
- Reanme irq_soft_enabled to driver_ready
- Avoid unnecssary IRQ synchornization (e.g during boot)

Changes since V2:

- add ccw and MMIO support
- rename synchronize_vqs() to synchronize_cbs()
- switch to re-use vq->broken instead of introducing new device
  attributes for the future virtqueue reset support
- remove unnecssary READ_ONCE()/WRITE_ONCE()
- a new patch to remove device triggerable BUG_ON()
- more tweaks on the comments

Changes since V3:

- Rename synchornize_vqs() to synchronize_cbs()
- tweak the comment for synchronize_cbs()
- switch to use a dedicated helper __virtio_unbreak_device() and
  document it should be only used for probing
- switch to use rwlick to synchornize the non airq for ccw

Jason Wang (8):
  virtio: use virtio_reset_device() when possible
  virtio: introduce config op to synchronize vring callbacks
  virtio-pci: implement synchronize_cbs()
  virtio-mmio: implement synchronize_cbs()
  virtio-ccw: implement synchronize_cbs()
  virtio: allow to unbreak virtqueue
  virtio: harden vring IRQ
  virtio: use WARN_ON() to warning illegal status value

Stefano Garzarella (1):
  virtio: use virtio_device_ready() in virtio_device_restore()

 drivers/s390/virtio/virtio_ccw.c   | 27 +++++++++++++++++++++
 drivers/virtio/virtio.c            | 24 ++++++++++++------
 drivers/virtio/virtio_mmio.c       |  9 +++++++
 drivers/virtio/virtio_pci_legacy.c |  1 +
 drivers/virtio/virtio_pci_modern.c |  2 ++
 drivers/virtio/virtio_ring.c       | 32 +++++++++++++++++++++---
 include/linux/virtio.h             |  1 +
 include/linux/virtio_config.h      | 39 +++++++++++++++++++++++++++++-
 8 files changed, 123 insertions(+), 12 deletions(-)

-- 
2.25.1