linux-kernel - [PATCH 3/5] iommu/vt-d: Multiple descriptors per qi_submit

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Date:   Tue, 17 Mar 2020 15:02:27 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Joerg Roedel <joro@...tes.org>
Cc:     ashok.raj@...el.com, jacob.jun.pan@...ux.intel.com,
        Liu Yi L <yi.l.liu@...el.com>, kevin.tian@...el.com,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Lu Baolu <baolu.lu@...ux.intel.com>
Subject: [PATCH 3/5] iommu/vt-d: Multiple descriptors per qi_submit_sync()

Extend qi_submit_sync() function to support multiple descriptors.

Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/iommu/dmar.c        | 30 +++++++++++++++++++-----------
 include/linux/intel-iommu.h |  1 +
 2 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c
index dc9f9449907c..37910283022b 100644
--- a/drivers/iommu/dmar.c
+++ b/drivers/iommu/dmar.c
@@ -1156,12 +1156,11 @@ static inline void reclaim_free_desc(struct q_inval *qi)
 	}
 }
 
-static int qi_check_fault(struct intel_iommu *iommu, int index)
+static int qi_check_fault(struct intel_iommu *iommu, int index, int wait_index)
 {
 	u32 fault;
 	int head, tail;
 	struct q_inval *qi = iommu->qi;
-	int wait_index = (index + 1) % QI_LENGTH;
 	int shift = qi_shift(iommu);
 
 	if (qi->desc_status[wait_index] == QI_ABORT)
@@ -1233,12 +1232,12 @@ static int qi_check_fault(struct intel_iommu *iommu, int index)
 int qi_submit_sync(struct intel_iommu *iommu, struct qi_desc *desc,
 		   unsigned int count, unsigned long options)
 {
-	int rc;
 	struct q_inval *qi = iommu->qi;
 	int offset, shift, length;
 	struct qi_desc wait_desc;
 	int wait_index, index;
 	unsigned long flags;
+	int rc, i;
 
 	if (!qi)
 		return 0;
@@ -1247,32 +1246,41 @@ int qi_submit_sync(struct intel_iommu *iommu, struct qi_desc *desc,
 	rc = 0;
 
 	raw_spin_lock_irqsave(&qi->q_lock, flags);
-	while (qi->free_cnt < 3) {
+	/*
+	 * Check if we have enough empty slots in the queue to submit,
+	 * the calculation is based on:
+	 * # of desc + 1 wait desc + 1 space between head and tail
+	 */
+	while (qi->free_cnt < count + 2) {
 		raw_spin_unlock_irqrestore(&qi->q_lock, flags);
 		cpu_relax();
 		raw_spin_lock_irqsave(&qi->q_lock, flags);
 	}
 
 	index = qi->free_head;
-	wait_index = (index + 1) % QI_LENGTH;
+	wait_index = (index + count) % QI_LENGTH;
 	shift = qi_shift(iommu);
-	length = 1 << shift;
+	length = count << shift;
 
-	qi->desc_status[index] = qi->desc_status[wait_index] = QI_IN_USE;
+	/* Mark all desc and wait desc status in use */
+	for (i = 0; i < count + 1; i++)
+		qi->desc_status[(index + i) % QI_LENGTH] = QI_IN_USE;
 
 	offset = index << shift;
 	memcpy(qi->desc + offset, desc, length);
 	wait_desc.qw0 = QI_IWD_STATUS_DATA(QI_DONE) |
 			QI_IWD_STATUS_WRITE | QI_IWD_TYPE;
+	if (options & QI_OPT_WAIT_DRAIN)
+		wait_desc.qw0 |= QI_IWD_PRQ_DRAIN;
 	wait_desc.qw1 = virt_to_phys(&qi->desc_status[wait_index]);
 	wait_desc.qw2 = 0;
 	wait_desc.qw3 = 0;
 
 	offset = wait_index << shift;
-	memcpy(qi->desc + offset, &wait_desc, length);
+	memcpy(qi->desc + offset, &wait_desc, 1 << shift);
 
-	qi->free_head = (qi->free_head + 2) % QI_LENGTH;
-	qi->free_cnt -= 2;
+	qi->free_head = (qi->free_head + count + 1) % QI_LENGTH;
+	qi->free_cnt -= count + 1;
 
 	/*
 	 * update the HW tail register indicating the presence of
@@ -1288,7 +1296,7 @@ int qi_submit_sync(struct intel_iommu *iommu, struct qi_desc *desc,
 		 * a deadlock where the interrupt context can wait indefinitely
 		 * for free slots in the queue.
 		 */
-		rc = qi_check_fault(iommu, index);
+		rc = qi_check_fault(iommu, index, wait_index);
 		if (rc)
 			break;
 
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index e9190ffbd013..255b23f59a78 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -324,6 +324,7 @@ enum {
 
 #define QI_IWD_STATUS_DATA(d)	(((u64)d) << 32)
 #define QI_IWD_STATUS_WRITE	(((u64)1) << 5)
+#define QI_IWD_PRQ_DRAIN	(((u64)1) << 7)
 
 #define QI_IOTLB_DID(did) 	(((u64)did) << 16)
 #define QI_IOTLB_DR(dr) 	(((u64)dr) << 7)
-- 
2.17.1