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 <[e-mail]>
Reviewed-by: Gerald Schaefer <[e-mail]>
Signed-off-by: Martin Schwidefsky <[e-mail]>

arch/s390/include/asm/pci_dma.h

···
 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

···
 	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;
···
 	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 {
···
 	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;
 	}
···
 
 	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

···
 	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 ||
···
 
 	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;
 	}
···
 			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;