[PATCH] dmaengine: idxd: don't load pasid config until needed

[Dave Jiang <dave.jiang@xxxxxxxxx>]

The driver currently programs the system pasid to the WQ preemptively when
system pasid is enabled. Given that a dwq will reprogram the pasid and
possibly a different pasid, the programming is not necessary. The pasid_en
bit can be set for swq as it does not need pasid pasid programming but
needs the pasid_en bit. Remove system pasid programming on device config
write. Add pasid programming for kernel wq type on wq driver enable. The
char dev driver already reprograms the dwq on ->open() call so there's no
change.

Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
---
 drivers/dma/idxd/device.c    |   46 ++++++++++++++++++++++++++++++++++--------
 drivers/dma/idxd/registers.h |    1 +
 2 files changed, 38 insertions(+), 9 deletions(-)

diff --git a/drivers/dma/idxd/device.c b/drivers/dma/idxd/device.c
index 573ad8b86804..b2aaf4b64a8b 100644
--- a/drivers/dma/idxd/device.c
+++ b/drivers/dma/idxd/device.c
@@ -299,16 +299,25 @@ void idxd_wqs_unmap_portal(struct idxd_device *idxd)
 	}
 }
 
-int idxd_wq_set_pasid(struct idxd_wq *wq, int pasid)
+static void __idxd_wq_set_priv_locked(struct idxd_wq *wq)
 {
 	struct idxd_device *idxd = wq->idxd;
-	int rc;
 	union wqcfg wqcfg;
 	unsigned int offset;
 
-	rc = idxd_wq_disable(wq, false);
-	if (rc < 0)
-		return rc;
+	offset = WQCFG_OFFSET(idxd, wq->id, WQCFG_PRIVL_IDX);
+	spin_lock(&idxd->dev_lock);
+	wqcfg.bits[WQCFG_PRIVL_IDX] = ioread32(idxd->reg_base + offset);
+	wqcfg.priv = 1;
+	iowrite32(wqcfg.bits[WQCFG_PRIVL_IDX], idxd->reg_base + offset);
+	spin_unlock(&idxd->dev_lock);
+}
+
+static void __idxd_wq_set_pasid_locked(struct idxd_wq *wq, int pasid)
+{
+	struct idxd_device *idxd = wq->idxd;
+	union wqcfg wqcfg;
+	unsigned int offset;
 
 	offset = WQCFG_OFFSET(idxd, wq->id, WQCFG_PASID_IDX);
 	spin_lock(&idxd->dev_lock);
@@ -317,6 +326,17 @@ int idxd_wq_set_pasid(struct idxd_wq *wq, int pasid)
 	wqcfg.pasid = pasid;
 	iowrite32(wqcfg.bits[WQCFG_PASID_IDX], idxd->reg_base + offset);
 	spin_unlock(&idxd->dev_lock);
+}
+
+int idxd_wq_set_pasid(struct idxd_wq *wq, int pasid)
+{
+	int rc;
+
+	rc = idxd_wq_disable(wq, false);
+	if (rc < 0)
+		return rc;
+
+	__idxd_wq_set_pasid_locked(wq, pasid);
 
 	rc = idxd_wq_enable(wq);
 	if (rc < 0)
@@ -808,11 +828,13 @@ static int idxd_wq_config_write(struct idxd_wq *wq)
 	if (wq_dedicated(wq))
 		wq->wqcfg->mode = 1;
 
-	if (device_pasid_enabled(idxd)) {
+	/*
+	 * Enable this for shared WQ. swq does not need to program the pasid field,
+	 * but pasid_en needs to be set. Programming here prevents swq needing to
+	 * be disabled and re-enabled for reprogramming, which is something to avoid.
+	 */
+	if (device_pasid_enabled(idxd))
 		wq->wqcfg->pasid_en = 1;
-		if (wq->type == IDXD_WQT_KERNEL && wq_dedicated(wq))
-			wq->wqcfg->pasid = idxd->pasid;
-	}
 
 	/*
 	 * Here the priv bit is set depending on the WQ type. priv = 1 if the
@@ -1258,6 +1280,12 @@ int __drv_enable_wq(struct idxd_wq *wq)
 		}
 	}
 
+	if (is_idxd_wq_kernel(wq)) {
+		if (device_pasid_enabled(idxd) && wq_dedicated(wq))
+			__idxd_wq_set_pasid_locked(wq, idxd->pasid);
+		__idxd_wq_set_priv_locked(wq);
+	}
+
 	rc = 0;
 	spin_lock(&idxd->dev_lock);
 	if (test_bit(IDXD_FLAG_CONFIGURABLE, &idxd->flags))
diff --git a/drivers/dma/idxd/registers.h b/drivers/dma/idxd/registers.h
index aa642aecdc0b..02449aa9c454 100644
--- a/drivers/dma/idxd/registers.h
+++ b/drivers/dma/idxd/registers.h
@@ -353,6 +353,7 @@ union wqcfg {
 } __packed;
 
 #define WQCFG_PASID_IDX                2
+#define WQCFG_PRIVL_IDX		2
 #define WQCFG_OCCUP_IDX		6
 
 #define WQCFG_OCCUP_MASK	0xffff