[PATCH v3 1/3] hw/usb/hcd-ehci: Check for DMA errors in get_dwords()/put_dwords()

[Jamin Lin <jamin_lin@aspeedtech.com>]

get_dwords() and put_dwords() return -1 when ehci->as is NULL, but that
can no longer happen. The sysbus variants set it in instance_init
(ehci_sysbus_init()), the PCI variant sets it in realize
(usb_ehci_pci_realize()), and usb_ehci_pci_write_config() only switches
between the bus master address space and address_space_memory.

Meanwhile the results of dma_memory_read() and dma_memory_write() are
ignored, so a failed guest memory access is silently treated as success.

Drop the dead NULL test and check the MemTxResult of each access
instead, so that the existing -1 error path reports real DMA errors:
raise USBSTS_HSE, clear USBCMD_RUNSTOP and stop processing the
descriptor, as the NULL path used to do. All 11 get_dwords() callers
already check the return value.

put_dwords() now returns void: none of its four callers (ehci_flush_qh(),
ehci_state_fetchitd() and twice in ehci_state_writeback()) looks at the
status.

Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Jamin Lin <jamin_lin@aspeedtech.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@oss.qualcomm.com>
---
 hw/usb/hcd-ehci.c | 38 ++++++++++++++++----------------------
 1 file changed, 16 insertions(+), 22 deletions(-)

diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c
index 451a918e9f..ecf98c4e19 100644
--- a/hw/usb/hcd-ehci.c
+++ b/hw/usb/hcd-ehci.c
@@ -421,16 +421,14 @@ static inline int get_dwords(EHCIState *ehci, uint64_t addr,
 {
     int i;
 
-    if (!ehci->as) {
-        ehci_raise_irq(ehci, USBSTS_HSE);
-        ehci->usbcmd &= ~USBCMD_RUNSTOP;
-        trace_usb_ehci_dma_error();
-        return -1;
-    }
-
     for (i = 0; i < num; i++, buf++, addr += sizeof(*buf)) {
-        dma_memory_read(ehci->as, addr, buf, sizeof(*buf),
-                        MEMTXATTRS_UNSPECIFIED);
+        if (dma_memory_read(ehci->as, addr, buf, sizeof(*buf),
+                            MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+            ehci_raise_irq(ehci, USBSTS_HSE);
+            ehci->usbcmd &= ~USBCMD_RUNSTOP;
+            trace_usb_ehci_dma_error();
+            return -1;
+        }
         *buf = le32_to_cpu(*buf);
     }
 
@@ -438,25 +436,21 @@ static inline int get_dwords(EHCIState *ehci, uint64_t addr,
 }
 
 /* Put an array of dwords in to main memory */
-static inline int put_dwords(EHCIState *ehci, uint64_t addr,
-                             uint32_t *buf, int num)
+static inline void put_dwords(EHCIState *ehci, uint64_t addr,
+                              uint32_t *buf, int num)
 {
     int i;
 
-    if (!ehci->as) {
-        ehci_raise_irq(ehci, USBSTS_HSE);
-        ehci->usbcmd &= ~USBCMD_RUNSTOP;
-        trace_usb_ehci_dma_error();
-        return -1;
-    }
-
     for (i = 0; i < num; i++, buf++, addr += sizeof(*buf)) {
         uint32_t tmp = cpu_to_le32(*buf);
-        dma_memory_write(ehci->as, addr, &tmp, sizeof(tmp),
-                         MEMTXATTRS_UNSPECIFIED);
+        if (dma_memory_write(ehci->as, addr, &tmp, sizeof(tmp),
+                             MEMTXATTRS_UNSPECIFIED) != MEMTX_OK) {
+            ehci_raise_irq(ehci, USBSTS_HSE);
+            ehci->usbcmd &= ~USBCMD_RUNSTOP;
+            trace_usb_ehci_dma_error();
+            return;
+        }
     }
-
-    return num;
 }
 
 static int ehci_get_pid(EHCIqtd *qtd)
-- 
2.53.0