dmaengine: idxd: Add shared workqueue support

Add shared workqueue support that includes the support of Shared Virtual
memory (SVM) or in similar terms On Demand Paging (ODP). The shared
workqueue uses the enqcmds command in kernel and will respond with retry if
the workqueue is full. Shared workqueue only works when there is PASID
support from the IOMMU.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/160382007499.3911367.26043087963708134.stgit@djiang5-desk3.ch.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 30 insertions, 5 deletions

diff --git a/drivers/dma/idxd/submit.c b/drivers/dma/idxd/submit.c
index 156a1ee233aa..efca5d8468a6 100644
--- a/drivers/dma/idxd/submit.c
+++ b/drivers/dma/idxd/submit.c
@@ -11,11 +11,22 @@
 static struct idxd_desc *__get_desc(struct idxd_wq *wq, int idx, int cpu)
 {
 	struct idxd_desc *desc;
+	struct idxd_device *idxd = wq->idxd;
 
 	desc = wq->descs[idx];
 	memset(desc->hw, 0, sizeof(struct dsa_hw_desc));
 	memset(desc->completion, 0, sizeof(struct dsa_completion_record));
 	desc->cpu = cpu;
+
+	if (device_pasid_enabled(idxd))
+		desc->hw->pasid = idxd->pasid;
+
+	/*
+	 * Descriptor completion vectors are 1-8 for MSIX. We will round
+	 * robin through the 8 vectors.
+	 */
+	wq->vec_ptr = (wq->vec_ptr % idxd->num_wq_irqs) + 1;
+	desc->hw->int_handle = wq->vec_ptr;
 	return desc;
 }
 
@@ -70,18 +81,32 @@ int idxd_submit_desc(struct idxd_wq *wq, struct idxd_desc *desc)
 	struct idxd_device *idxd = wq->idxd;
 	int vec = desc->hw->int_handle;
 	void __iomem *portal;
+	int rc;
 
 	if (idxd->state != IDXD_DEV_ENABLED)
 		return -EIO;
 
-	portal = wq->dportal + idxd_get_wq_portal_offset(IDXD_PORTAL_UNLIMITED);
+	portal = wq->portal + idxd_get_wq_portal_offset(IDXD_PORTAL_LIMITED);
+
 	/*
-	 * The wmb() flushes writes to coherent DMA data before possibly
-	 * triggering a DMA read. The wmb() is necessary even on UP because
-	 * the recipient is a device.
+	 * The wmb() flushes writes to coherent DMA data before
+	 * possibly triggering a DMA read. The wmb() is necessary
+	 * even on UP because the recipient is a device.
 	 */
 	wmb();
-	iosubmit_cmds512(portal, desc->hw, 1);
+	if (wq_dedicated(wq)) {
+		iosubmit_cmds512(portal, desc->hw, 1);
+	} else {
+		/*
+		 * It's not likely that we would receive queue full rejection
+		 * since the descriptor allocation gates at wq size. If we
+		 * receive a -EAGAIN, that means something went wrong such as the
+		 * device is not accepting descriptor at all.
+		 */
+		rc = enqcmds(portal, desc->hw);
+		if (rc < 0)
+			return rc;
+	}
 
 	/*
 	 * Pending the descriptor to the lockless list for the irq_entry