s390/pci_dma: handle dma table failures

We use lazy allocation for translation table entries but don't handle
allocation (and other) failures during translation table updates.

Handle these failures and undo translation table updates when it's
meaningful.
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>

arch/s390/include/asm/pci_dma.h

@@ -195,5 +195,7 @@ void zpci_dma_exit_device(struct zpci_dev *);
 void dma_free_seg_table(unsigned long);
 unsigned long *dma_alloc_cpu_table(void);
 void dma_cleanup_tables(unsigned long *);
-void dma_update_cpu_trans(unsigned long *, void *, dma_addr_t, int);
+unsigned long *dma_walk_cpu_trans(unsigned long *rto, dma_addr_t dma_addr);
+void dma_update_cpu_trans(unsigned long *entry, void *page_addr, int flags);
+
 #endif

arch/s390/pci/pci_dma.c

@@ -95,7 +95,7 @@ static unsigned long *dma_get_page_table_origin(unsigned long *entry)
 	return pto;
 }
 
-static unsigned long *dma_walk_cpu_trans(unsigned long *rto, dma_addr_t dma_addr)
+unsigned long *dma_walk_cpu_trans(unsigned long *rto, dma_addr_t dma_addr)
 {
 	unsigned long *sto, *pto;
 	unsigned int rtx, sx, px;
@@ -114,17 +114,8 @@ static unsigned long *dma_walk_cpu_trans(unsigned long *rto, dma_addr_t dma_addr
 	return &pto[px];
 }
 
-void dma_update_cpu_trans(unsigned long *dma_table, void *page_addr,
-			  dma_addr_t dma_addr, int flags)
+void dma_update_cpu_trans(unsigned long *entry, void *page_addr, int flags)
 {
-	unsigned long *entry;
-
-	entry = dma_walk_cpu_trans(dma_table, dma_addr);
-	if (!entry) {
-		WARN_ON_ONCE(1);
-		return;
-	}
-
 	if (flags & ZPCI_PTE_INVALID) {
 		invalidate_pt_entry(entry);
 	} else {
@@ -145,18 +136,25 @@ static int dma_update_trans(struct zpci_dev *zdev, unsigned long pa,
 	u8 *page_addr = (u8 *) (pa & PAGE_MASK);
 	dma_addr_t start_dma_addr = dma_addr;
 	unsigned long irq_flags;
+	unsigned long *entry;
 	int i, rc = 0;
 
 	if (!nr_pages)
 		return -EINVAL;
 
 	spin_lock_irqsave(&zdev->dma_table_lock, irq_flags);
-	if (!zdev->dma_table)
+	if (!zdev->dma_table) {
+		rc = -EINVAL;
 		goto no_refresh;
+	}
 
 	for (i = 0; i < nr_pages; i++) {
-		dma_update_cpu_trans(zdev->dma_table, page_addr, dma_addr,
-				     flags);
+		entry = dma_walk_cpu_trans(zdev->dma_table, dma_addr);
+		if (!entry) {
+			rc = -ENOMEM;
+			goto undo_cpu_trans;
+		}
+		dma_update_cpu_trans(entry, page_addr, flags);
 		page_addr += PAGE_SIZE;
 		dma_addr += PAGE_SIZE;
 	}
@@ -175,6 +173,18 @@ static int dma_update_trans(struct zpci_dev *zdev, unsigned long pa,
 
 	rc = zpci_refresh_trans((u64) zdev->fh << 32, start_dma_addr,
 				nr_pages * PAGE_SIZE);
+undo_cpu_trans:
+	if (rc && ((flags & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_VALID)) {
+		flags = ZPCI_PTE_INVALID;
+		while (i-- > 0) {
+			page_addr -= PAGE_SIZE;
+			dma_addr -= PAGE_SIZE;
+			entry = dma_walk_cpu_trans(zdev->dma_table, dma_addr);
+			if (!entry)
+				break;
+			dma_update_cpu_trans(entry, page_addr, flags);
+		}
+	}
 
 no_refresh:
 	spin_unlock_irqrestore(&zdev->dma_table_lock, irq_flags);

drivers/iommu/s390-iommu.c

@@ -216,6 +216,7 @@ static int s390_iommu_update_trans(struct s390_domain *s390_domain,
 	u8 *page_addr = (u8 *) (pa & PAGE_MASK);
 	dma_addr_t start_dma_addr = dma_addr;
 	unsigned long irq_flags, nr_pages, i;
+	unsigned long *entry;
 	int rc = 0;
 
 	if (dma_addr < s390_domain->domain.geometry.aperture_start ||
@@ -228,8 +229,12 @@ static int s390_iommu_update_trans(struct s390_domain *s390_domain,
 
 	spin_lock_irqsave(&s390_domain->dma_table_lock, irq_flags);
 	for (i = 0; i < nr_pages; i++) {
-		dma_update_cpu_trans(s390_domain->dma_table, page_addr,
-				     dma_addr, flags);
+		entry = dma_walk_cpu_trans(s390_domain->dma_table, dma_addr);
+		if (!entry) {
+			rc = -ENOMEM;
+			goto undo_cpu_trans;
+		}
+		dma_update_cpu_trans(entry, page_addr, flags);
 		page_addr += PAGE_SIZE;
 		dma_addr += PAGE_SIZE;
 	}
@@ -242,6 +247,20 @@ static int s390_iommu_update_trans(struct s390_domain *s390_domain,
 			break;
 	}
 	spin_unlock(&s390_domain->list_lock);
+
+undo_cpu_trans:
+	if (rc && ((flags & ZPCI_PTE_VALID_MASK) == ZPCI_PTE_VALID)) {
+		flags = ZPCI_PTE_INVALID;
+		while (i-- > 0) {
+			page_addr -= PAGE_SIZE;
+			dma_addr -= PAGE_SIZE;
+			entry = dma_walk_cpu_trans(s390_domain->dma_table,
+						   dma_addr);
+			if (!entry)
+				break;
+			dma_update_cpu_trans(entry, page_addr, flags);
+		}
+	}
 	spin_unlock_irqrestore(&s390_domain->dma_table_lock, irq_flags);
 
 	return rc;