dmaengine/idxd: Re-enable kernel workqueue under DMA API

Kernel workqueues were disabled due to flawed use of kernel VA and SVA
API. Now that we have the support for attaching PASID to the device's
default domain and the ability to reserve global PASIDs from SVA APIs,
we can re-enable the kernel work queues and use them under DMA API.

We also use non-privileged access for in-kernel DMA to be consistent
with the IOMMU settings. Consequently, interrupt for user privilege is
enabled for work completion IRQs.

Link: https://lore.kernel.org/linux-iommu/20210511194726.GP1002214@nvidia.com/
Tested-by: Tony Zhu <tony.zhu@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Fenghua Yu <fenghua.yu@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Acked-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Link: https://lore.kernel.org/r/20230802212427.1497170-9-jacob.jun.pan@linux.intel.com
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 9 insertions, 0 deletions

diff --git a/drivers/dma/idxd/idxd.h b/drivers/dma/idxd/idxd.h
index 5428a2e1b1ec..502be9db63f4 100644
--- a/drivers/dma/idxd/idxd.h
+++ b/drivers/dma/idxd/idxd.h
@@ -473,6 +473,15 @@ static inline struct idxd_device *ie_to_idxd(struct idxd_irq_entry *ie)
 	return container_of(ie, struct idxd_device, ie);
 }
 
+static inline void idxd_set_user_intr(struct idxd_device *idxd, bool enable)
+{
+	union gencfg_reg reg;
+
+	reg.bits = ioread32(idxd->reg_base + IDXD_GENCFG_OFFSET);
+	reg.user_int_en = enable;
+	iowrite32(reg.bits, idxd->reg_base + IDXD_GENCFG_OFFSET);
+}
+
 extern struct bus_type dsa_bus_type;
 
 extern bool support_enqcmd;