diff mbox

[PULL,1/4] xhci: Avoid DMA when ERSTBA is set to zero

Message ID 20170913093215.10043-2-kraxel@redhat.com (mailing list archive)
State New, archived
Headers show

Commit Message

Gerd Hoffmann Sept. 13, 2017, 9:32 a.m. UTC 
From: Alexey Kardashevskiy <aik@ozlabs.ru>

The existing XHCI code reads the Event Ring Segment Table Base Address
Register (ERSTBA) every time when it is changed. However zero is its
default state so one would think that zero there means it is not in use.

This adds a check for ERSTBA in addition to the existing check for
the Event Ring Segment Table Size Register (ERSTSZ).

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Message-id: 20170911065606.40600-1-aik@ozlabs.ru
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
---
 hw/usb/hcd-xhci.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff mbox

Patch

diff --git a/hw/usb/hcd-xhci.c b/hw/usb/hcd-xhci.c
index 204ea69d3f..d75c085d94 100644
--- a/hw/usb/hcd-xhci.c
+++ b/hw/usb/hcd-xhci.c
@@ -811,8 +811,9 @@  static void xhci_er_reset(XHCIState *xhci, int v)
 {
     XHCIInterrupter *intr = &xhci->intr[v];
     XHCIEvRingSeg seg;
+    dma_addr_t erstba = xhci_addr64(intr->erstba_low, intr->erstba_high);
 
-    if (intr->erstsz == 0) {
+    if (intr->erstsz == 0 || erstba == 0) {
         /* disabled */
         intr->er_start = 0;
         intr->er_size = 0;
@@ -824,7 +825,6 @@  static void xhci_er_reset(XHCIState *xhci, int v)
         xhci_die(xhci);
         return;
     }
-    dma_addr_t erstba = xhci_addr64(intr->erstba_low, intr->erstba_high);
     pci_dma_read(PCI_DEVICE(xhci), erstba, &seg, sizeof(seg));
     le32_to_cpus(&seg.addr_low);
     le32_to_cpus(&seg.addr_high);