[RFC 1/7] iommufd: Handle unsafe interrupts in a separate function

Yi Liu
2023-10-09T08:51:46Z

From: Kevin Tian <kevin.tian@intel.com>

This wraps the unsafe interrupts handling into helper as same check is also
required when supporting iommufd_device_bind_pasid() later.

Signed-off-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
drivers/iommu/iommufd/device.c | 36 ++++++++++++++++++++--------------
1 file changed, 21 insertions(+), 15 deletions(-)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 6a6145b4a25e..ca3919fecc89 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -145,6 +145,25 @@ void iommufd_device_destroy(struct iommufd_object *obj)
iommufd_ctx_put(idev->ictx);
}

+/*
+ * For historical compat with VFIO the insecure interrupt path is
+ * allowed if the module parameter is set. Insecure means that a MemWr
+ * operation from the device (eg a simple DMA) cannot trigger an
+ * interrupt outside this iommufd context.
+ */
+static int iommufd_allow_unsafe_interrupts(struct device *dev)
+{
+ if (!allow_unsafe_interrupts)
+ return -EPERM;
+
+ dev_warn(
+ dev,
+ "MSI interrupts are not secure, they cannot be isolated by the platform. "
+ "Check that platform features like interrupt remapping are enabled. "
+ "Use the \"allow_unsafe_interrupts\" module parameter to override\n");
+ return 0;
+}
+
/**
* iommufd_device_bind - Bind a physical device to an iommu fd
* @ictx: iommufd file descriptor
@@ -179,24 +198,11 @@ struct iommufd_device *iommufd_device_bind(struct iommufd_ctx *ictx,
if (IS_ERR(igroup))
return ERR_CAST(igroup);

- /*
- * For historical compat with VFIO the insecure interrupt path is
- * allowed if the module parameter is set. Secure/Isolated means that a
- * MemWr operation from the device (eg a simple DMA) cannot trigger an
- * interrupt outside this iommufd context.
- */
if (!iommufd_selftest_is_mock_dev(dev) &&
!iommu_group_has_isolated_msi(igroup->group)) {
- if (!allow_unsafe_interrupts) {
- rc = -EPERM;
+ rc = iommufd_allow_unsafe_interrupts(dev);
+ if (rc)
goto out_group_put;
- }
-
- dev_warn(
- dev,
- "MSI interrupts are not secure, they cannot be isolated by the platform. "
- "Check that platform features like interrupt remapping are enabled. "
- "Use the \"allow_unsafe_interrupts\" module parameter to override\n");
}

rc = iommu_device_claim_dma_owner(dev, ictx);
--
2.34.1