On Tue, Dec 07, 2021 at 05:47:14AM -0800, Jacob Pan wrote:
In-kernel DMA should be managed by DMA mapping API. The existing kernelEr, shouldn't this be adding dma_map/etc type calls?
PASID support is based on the SVA machinery in SVA lib that is intended
for user process SVA. The binding between a kernel PASID and kernel
mapping has many flaws. See discussions in the link below.
This patch utilizes iommu_enable_pasid_dma() to enable DSA to perform DMA
requests with PASID under the same mapping managed by DMA mapping API.
In addition, SVA-related bits for kernel DMA are removed. As a result,
DSA users shall use DMA mapping API to obtain DMA handles instead of
using kernel virtual addresses.
You can't really say a driver is using the DMA API without actually
calling the DMA API..
+ /*Huh? How can the driver keep going if PASID isn't supported? I thought
+ * Try to enable both in-kernel and user DMA request with PASID.
+ * PASID is supported unless both user and kernel PASID are
+ * supported. Do not fail probe here in that idxd can still be
+ * used w/o PASID or IOMMU.
+ */
+ if (iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_SVA) ||
+ idxd_enable_system_pasid(idxd)) {
+ dev_warn(dev, "Failed to enable PASID\n");
+ } else {
+ set_bit(IDXD_FLAG_PASID_ENABLED, &idxd->flags);
}
the whole point of this was because the device cannot do DMA without
PASID at all?
Jason