[ Upstream commit fe9a7082684eb059b925c535682e68c34d487d43 ]
Currently for devices requiring masking at the irqchip for INTx, ie. devices without DisINTx support, the IRQ is enabled in request_irq() and subsequently disabled as necessary to align with the masked status flag. This presents a window where the interrupt could fire between these events, resulting in the IRQ incrementing the disable depth twice. This would be unrecoverable for a user since the masked flag prevents nested enables through vfio.
Instead, invert the logic using IRQF_NO_AUTOEN such that exclusive INTx is never auto-enabled, then unmask as required.
Cc: stable@vger.kernel.org Fixes: 89e1f7d4c66d ("vfio: Add PCI device driver") Reviewed-by: Kevin Tian kevin.tian@intel.com Reviewed-by: Eric Auger eric.auger@redhat.com Link: https://lore.kernel.org/r/20240308230557.805580-2-alex.williamson@redhat.com Signed-off-by: Alex Williamson alex.williamson@redhat.com --- drivers/vfio/pci/vfio_pci_intrs.c | 17 ++++++++++------- 1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c index 6069a11fb51a..0f2739e113b2 100644 --- a/drivers/vfio/pci/vfio_pci_intrs.c +++ b/drivers/vfio/pci/vfio_pci_intrs.c @@ -199,8 +199,15 @@ static int vfio_intx_set_signal(struct vfio_pci_core_device *vdev, int fd)
vdev->ctx[0].trigger = trigger;
+ /* + * Devices without DisINTx support require an exclusive interrupt, + * IRQ masking is performed at the IRQ chip. The masked status is + * protected by vdev->irqlock. Setup the IRQ without auto-enable and + * unmask as necessary below under lock. DisINTx is unmodified by + * the IRQ configuration and may therefore use auto-enable. + */ if (!vdev->pci_2_3) - irqflags = 0; + irqflags = IRQF_NO_AUTOEN;
ret = request_irq(pdev->irq, vfio_intx_handler, irqflags, vdev->ctx[0].name, vdev); @@ -211,13 +218,9 @@ static int vfio_intx_set_signal(struct vfio_pci_core_device *vdev, int fd) return ret; }
- /* - * INTx disable will stick across the new irq setup, - * disable_irq won't. - */ spin_lock_irqsave(&vdev->irqlock, flags); - if (!vdev->pci_2_3 && vdev->ctx[0].masked) - disable_irq_nosync(pdev->irq); + if (!vdev->pci_2_3 && !vdev->ctx[0].masked) + enable_irq(pdev->irq); spin_unlock_irqrestore(&vdev->irqlock, flags);
return 0;