vfio/fsl-mc: Block calling interrupt handler without trigger

[ Upstream commit 7447d911af699a15f8d050dfcb7c680a86f87012 ]

The eventfd_ctx trigger pointer of the vfio_fsl_mc_irq object is
initially NULL and may become NULL if the user sets the trigger
eventfd to -1.  The interrupt handler itself is guaranteed that
trigger is always valid between request_irq() and free_irq(), but
the loopback testing mechanisms to invoke the handler function
need to test the trigger.  The triggering and setting ioctl paths
both make use of igate and are therefore mutually exclusive.

The vfio-fsl-mc driver does not make use of irqfds, nor does it
support any sort of masking operations, therefore unlike vfio-pci
and vfio-platform, the flow can remain essentially unchanged.

Cc: Diana Craciun <diana.craciun@oss.nxp.com>
Cc:  <stable@vger.kernel.org>
Fixes: cc0ee20bd969 ("vfio/fsl-mc: trigger an interrupt via eventfd")
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Link: https://lore.kernel.org/r/20240308230557.805580-8-alex.williamson@redhat.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc_intr.c b/drivers/vfio/fsl-mc/vfio_fsl_mc_intr.c
index 77e584093a233d995a033f54776c68f81e4492bb..50c2f82f2b68aef155a6a11a7f7278c0b54d59cb 100644 (file)
--- a/drivers/vfio/fsl-mc/vfio_fsl_mc_intr.c
+++ b/drivers/vfio/fsl-mc/vfio_fsl_mc_intr.c
@@ -142,13 +142,14 @@ static int vfio_fsl_mc_set_irq_trigger(struct vfio_fsl_mc_device *vdev,
        irq = &vdev->mc_irqs[index];
 
        if (flags & VFIO_IRQ_SET_DATA_NONE) {
-               vfio_fsl_mc_irq_handler(hwirq, irq);
+               if (irq->trigger)
+                       eventfd_signal(irq->trigger, 1);
 
        } else if (flags & VFIO_IRQ_SET_DATA_BOOL) {
                u8 trigger = *(u8 *)data;
 
-               if (trigger)
-                       vfio_fsl_mc_irq_handler(hwirq, irq);
+               if (trigger && irq->trigger)
+                       eventfd_signal(irq->trigger, 1);
        }
 
        return 0;