s390/pci_dma: make lazy flush independent from the tlb_refresh bit

We have 2 strategies to reduce the number of RPCIT instructions:
* A HW feature indicated via the tlb_refresh bit allows us to omit RPCIT for
  invalid -> valid translation-table entry updates.
* With "lazy flush" we omit RPCIT for valid -> invalid updates until we run
  out of dma addresses. When we have to reuse dma addresses we issue a global
  tlb flush using only one RPCIT instruction.

Currently lazy flushing depends on tlb_refresh. Since there is no technical
reason for this remove this dependency.

Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 11 insertions, 8 deletions

diff --git a/arch/s390/pci/pci_dma.c b/arch/s390/pci/pci_dma.c
index 47f4afbff0a5..0c626c1303cb 100644
--- a/arch/s390/pci/pci_dma.c
+++ b/arch/s390/pci/pci_dma.c
@@ -181,14 +181,17 @@ static int __dma_purge_tlb(struct zpci_dev *zdev, dma_addr_t dma_addr,
 	/*
 	 * With zdev->tlb_refresh == 0, rpcit is not required to establish new
 	 * translations when previously invalid translation-table entries are
-	 * validated. With lazy unmap, it also is skipped for previously valid
+	 * validated. With lazy unmap, rpcit is skipped for previously valid
 	 * entries, but a global rpcit is then required before any address can
 	 * be re-used, i.e. after each iommu bitmap wrap-around.
 	 */
-	if (!zdev->tlb_refresh &&
-			(!s390_iommu_strict ||
-			((flags & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_VALID)))
-		return 0;
+	if ((flags & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_VALID) {
+		if (!zdev->tlb_refresh)
+			return 0;
+	} else {
+		if (!s390_iommu_strict)
+			return 0;
+	}
 
 	return zpci_refresh_trans((u64) zdev->fh << 32, dma_addr,
 				  PAGE_ALIGN(size));
@@ -257,7 +260,7 @@ static dma_addr_t dma_alloc_address(struct device *dev, int size)
 	spin_lock_irqsave(&zdev->iommu_bitmap_lock, flags);
 	offset = __dma_alloc_iommu(dev, zdev->next_bit, size);
 	if (offset == -1) {
-		if (!zdev->tlb_refresh && !s390_iommu_strict) {
+		if (!s390_iommu_strict) {
 			/* global flush before DMA addresses are reused */
 			if (zpci_refresh_global(zdev))
 				goto out_error;
@@ -292,7 +295,7 @@ static void dma_free_address(struct device *dev, dma_addr_t dma_addr, int size)
 	if (!zdev->iommu_bitmap)
 		goto out;
 
-	if (zdev->tlb_refresh || s390_iommu_strict)
+	if (s390_iommu_strict)
 		bitmap_clear(zdev->iommu_bitmap, offset, size);
 	else
 		bitmap_set(zdev->lazy_bitmap, offset, size);
@@ -565,7 +568,7 @@ int zpci_dma_init_device(struct zpci_dev *zdev)
 		rc = -ENOMEM;
 		goto free_dma_table;
 	}
-	if (!zdev->tlb_refresh && !s390_iommu_strict) {
+	if (!s390_iommu_strict) {
 		zdev->lazy_bitmap = vzalloc(zdev->iommu_pages / 8);
 		if (!zdev->lazy_bitmap) {
 			rc = -ENOMEM;