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    SubjectRe: [PATCH V2 06/12] virtio_pci: harden MSI-X interrupts
    On Tue, Oct 12, 2021 at 02:52:21PM +0800, Jason Wang wrote:
    > We used to synchronize pending MSI-X irq handlers via
    > synchronize_irq(), this may not work for the untrusted device which
    > may keep sending interrupts after reset which may lead unexpected
    > results. Similarly, we should not enable MSI-X interrupt until the
    > device is ready.

    You mean until the driver is ready.

    > So this patch fixes those two issues by:
    >
    > 1) switching to use disable_irq() to prevent the virtio interrupt
    > handlers to be called after the device is reset.
    > 2) using IRQF_NO_AUTOEN and enable the MSI-X irq during .ready()
    >
    > This can make sure the virtio interrupt handler won't be called before
    > virtio_device_ready() and after reset.
    >
    > Cc: Thomas Gleixner <tglx@linutronix.de>
    > Cc: Peter Zijlstra <peterz@infradead.org>
    > Cc: Paul E. McKenney <paulmck@kernel.org>
    > Signed-off-by: Jason Wang <jasowang@redhat.com>
    > ---
    > drivers/virtio/virtio_pci_common.c | 27 +++++++++++++++++++++------
    > drivers/virtio/virtio_pci_common.h | 6 ++++--
    > drivers/virtio/virtio_pci_legacy.c | 5 +++--
    > drivers/virtio/virtio_pci_modern.c | 6 ++++--
    > 4 files changed, 32 insertions(+), 12 deletions(-)
    >
    > diff --git a/drivers/virtio/virtio_pci_common.c b/drivers/virtio/virtio_pci_common.c
    > index b35bb2d57f62..0b9523e6dd39 100644
    > --- a/drivers/virtio/virtio_pci_common.c
    > +++ b/drivers/virtio/virtio_pci_common.c
    > @@ -24,8 +24,8 @@ MODULE_PARM_DESC(force_legacy,
    > "Force legacy mode for transitional virtio 1 devices");
    > #endif
    >
    > -/* wait for pending irq handlers */
    > -void vp_synchronize_vectors(struct virtio_device *vdev)
    > +/* disable irq handlers */
    > +void vp_disable_vectors(struct virtio_device *vdev)
    > {
    > struct virtio_pci_device *vp_dev = to_vp_device(vdev);
    > int i;
    > @@ -34,7 +34,20 @@ void vp_synchronize_vectors(struct virtio_device *vdev)
    > synchronize_irq(vp_dev->pci_dev->irq);
    >
    > for (i = 0; i < vp_dev->msix_vectors; ++i)
    > - synchronize_irq(pci_irq_vector(vp_dev->pci_dev, i));
    > + disable_irq(pci_irq_vector(vp_dev->pci_dev, i));
    > +}
    > +
    > +/* enable irq handlers */
    > +void vp_enable_vectors(struct virtio_device *vdev)
    > +{
    > + struct virtio_pci_device *vp_dev = to_vp_device(vdev);
    > + int i;
    > +
    > + if (vp_dev->intx_enabled)
    > + return;
    > +
    > + for (i = 0; i < vp_dev->msix_vectors; ++i)
    > + enable_irq(pci_irq_vector(vp_dev->pci_dev, i));
    > }
    >
    > /* the notify function used when creating a virt queue */
    > @@ -141,7 +154,8 @@ static int vp_request_msix_vectors(struct virtio_device *vdev, int nvectors,
    > snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
    > "%s-config", name);
    > err = request_irq(pci_irq_vector(vp_dev->pci_dev, v),
    > - vp_config_changed, 0, vp_dev->msix_names[v],
    > + vp_config_changed, IRQF_NO_AUTOEN,
    > + vp_dev->msix_names[v],
    > vp_dev);
    > if (err)
    > goto error;
    > @@ -160,7 +174,8 @@ static int vp_request_msix_vectors(struct virtio_device *vdev, int nvectors,
    > snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
    > "%s-virtqueues", name);
    > err = request_irq(pci_irq_vector(vp_dev->pci_dev, v),
    > - vp_vring_interrupt, 0, vp_dev->msix_names[v],
    > + vp_vring_interrupt, IRQF_NO_AUTOEN,
    > + vp_dev->msix_names[v],
    > vp_dev);
    > if (err)
    > goto error;
    > @@ -337,7 +352,7 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
    > "%s-%s",
    > dev_name(&vp_dev->vdev.dev), names[i]);
    > err = request_irq(pci_irq_vector(vp_dev->pci_dev, msix_vec),
    > - vring_interrupt, 0,
    > + vring_interrupt, IRQF_NO_AUTOEN,
    > vp_dev->msix_names[msix_vec],
    > vqs[i]);
    > if (err)
    > diff --git a/drivers/virtio/virtio_pci_common.h b/drivers/virtio/virtio_pci_common.h
    > index beec047a8f8d..a235ce9ff6a5 100644
    > --- a/drivers/virtio/virtio_pci_common.h
    > +++ b/drivers/virtio/virtio_pci_common.h
    > @@ -102,8 +102,10 @@ static struct virtio_pci_device *to_vp_device(struct virtio_device *vdev)
    > return container_of(vdev, struct virtio_pci_device, vdev);
    > }
    >
    > -/* wait for pending irq handlers */
    > -void vp_synchronize_vectors(struct virtio_device *vdev);
    > +/* disable irq handlers */
    > +void vp_disable_vectors(struct virtio_device *vdev);
    > +/* enable irq handlers */
    > +void vp_enable_vectors(struct virtio_device *vdev);
    > /* the notify function used when creating a virt queue */
    > bool vp_notify(struct virtqueue *vq);
    > /* the config->del_vqs() implementation */
    > diff --git a/drivers/virtio/virtio_pci_legacy.c b/drivers/virtio/virtio_pci_legacy.c
    > index d62e9835aeec..bdf6bc667ab5 100644
    > --- a/drivers/virtio/virtio_pci_legacy.c
    > +++ b/drivers/virtio/virtio_pci_legacy.c
    > @@ -97,8 +97,8 @@ static void vp_reset(struct virtio_device *vdev)
    > /* Flush out the status write, and flush in device writes,
    > * including MSi-X interrupts, if any. */
    > ioread8(vp_dev->ioaddr + VIRTIO_PCI_STATUS);
    > - /* Flush pending VQ/configuration callbacks. */
    > - vp_synchronize_vectors(vdev);
    > + /* Disable VQ/configuration callbacks. */
    > + vp_disable_vectors(vdev);
    > }
    >
    > static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
    > @@ -194,6 +194,7 @@ static void del_vq(struct virtio_pci_vq_info *info)
    > }
    >
    > static const struct virtio_config_ops virtio_pci_config_ops = {
    > + .ready = vp_enable_vectors,
    > .get = vp_get,
    > .set = vp_set,
    > .get_status = vp_get_status,
    > diff --git a/drivers/virtio/virtio_pci_modern.c b/drivers/virtio/virtio_pci_modern.c
    > index 30654d3a0b41..acf0f6b6381d 100644
    > --- a/drivers/virtio/virtio_pci_modern.c
    > +++ b/drivers/virtio/virtio_pci_modern.c
    > @@ -172,8 +172,8 @@ static void vp_reset(struct virtio_device *vdev)
    > */
    > while (vp_modern_get_status(mdev))
    > msleep(1);
    > - /* Flush pending VQ/configuration callbacks. */
    > - vp_synchronize_vectors(vdev);
    > + /* Disable VQ/configuration callbacks. */
    > + vp_disable_vectors(vdev);
    > }
    >
    > static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
    > @@ -380,6 +380,7 @@ static bool vp_get_shm_region(struct virtio_device *vdev,
    > }
    >
    > static const struct virtio_config_ops virtio_pci_config_nodev_ops = {
    > + .ready = vp_enable_vectors,
    > .get = NULL,
    > .set = NULL,
    > .generation = vp_generation,
    > @@ -397,6 +398,7 @@ static const struct virtio_config_ops virtio_pci_config_nodev_ops = {
    > };
    >
    > static const struct virtio_config_ops virtio_pci_config_ops = {
    > + .ready = vp_enable_vectors,
    > .get = vp_get,
    > .set = vp_set,
    > .generation = vp_generation,
    > --
    > 2.25.1

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