[PATCH] dmaengine: idxd: Only call idxd_enable_system_pasid if succeeded in enabling SVA feature

Jerry Snitselaar
2022-06-25T22:13:48Z

iommu_sva_bind_device requires that iommu_dev_enable_feature has been
previously called with IOMMU_DEV_FEAT_SVA, and succeeded. Without this
it is possible to run into a situation where you will dereference a
null pointer if the intel_iommu driver is not enabled.

Note: checkpatch didn't like the suggested addition of braces for the
first arm of the "if (idxd_enable_system_pasid)" block.

Fixes: 42a1b73852c4 ("dmaengine: idxd: Separate user and kernel pasid enabling")
Cc: Vinod Koul <vkoul@kernel.org>
Cc: linux-kernel@vger.kernel.org
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>
---
drivers/dma/idxd/init.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
index 355fb3ef4cbf..5b49fd5c1e25 100644
--- a/drivers/dma/idxd/init.c
+++ b/drivers/dma/idxd/init.c
@@ -514,13 +514,14 @@ static int idxd_probe(struct idxd_device *idxd)
if (IS_ENABLED(CONFIG_INTEL_IDXD_SVM) && sva) {
if (iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_SVA))
dev_warn(dev, "Unable to turn on user SVA feature.\n");
- else
+ else {
set_bit(IDXD_FLAG_USER_PASID_ENABLED, &idxd->flags);

- if (idxd_enable_system_pasid(idxd))
- dev_warn(dev, "No in-kernel DMA with PASID.\n");
- else
- set_bit(IDXD_FLAG_PASID_ENABLED, &idxd->flags);
+ if (idxd_enable_system_pasid(idxd))
+ dev_warn(dev, "No in-kernel DMA with PASID.\n");
+ else
+ set_bit(IDXD_FLAG_PASID_ENABLED, &idxd->flags);
+ }
} else if (!sva) {
dev_warn(dev, "User forced SVA off via module param.\n");
}
--
2.36.1