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

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Message-Id: <20231009085123.463179-2-yi.l.liu@intel.com>
Date:   Mon,  9 Oct 2023 01:51:17 -0700
From:   Yi Liu <yi.l.liu@...el.com>
To:     joro@...tes.org, alex.williamson@...hat.com, jgg@...dia.com,
        kevin.tian@...el.com, robin.murphy@....com,
        baolu.lu@...ux.intel.com
Cc:     cohuck@...hat.com, eric.auger@...hat.com, nicolinc@...dia.com,
        kvm@...r.kernel.org, mjrosato@...ux.ibm.com,
        chao.p.peng@...ux.intel.com, yi.l.liu@...el.com,
        yi.y.sun@...ux.intel.com, peterx@...hat.com, jasowang@...hat.com,
        shameerali.kolothum.thodi@...wei.com, lulu@...hat.com,
        suravee.suthikulpanit@....com, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        zhenzhong.duan@...el.com, joao.m.martins@...cle.com
Subject: [RFC 1/7] iommufd: Handle unsafe interrupts in a separate function

From: Kevin Tian <kevin.tian@...el.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@...el.com>
Signed-off-by: Yi Liu <yi.l.liu@...el.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