[PATCH v1 06/13] hw/usb/hcd-ehci: Reject CTRLDSSEGMENT writes without 64-bit capability

[Jamin Lin <jamin_lin@aspeedtech.com>]

The EHCI CTRLDSSEGMENT register provides the upper 32 bits [63:32] used to
form 64-bit addresses for EHCI control data structures. Per EHCI 1.0
spec section 2.3.5, when the HCCPARAMS 64-bit Addressing Capability bit
is zero, CTRLDSSEGMENT is not used: software cannot write it and reads
must return zero.

Add a capability check in the operational register write handler and
reject guest writes to CTRLDSSEGMENT when 64-bit addressing is
not enabled.

Signed-off-by: Jamin Lin <jamin_lin@aspeedtech.com>
---
 hw/usb/hcd-ehci.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c
index 9e82328116..d7a0917caf 100644
--- a/hw/usb/hcd-ehci.c
+++ b/hw/usb/hcd-ehci.c
@@ -1106,7 +1106,14 @@ static void ehci_opreg_write(void *ptr, hwaddr addr,
               "      is enabled and HC is enabled\n");
         }
         break;
-
+    case CTRLDSSEGMENT:
+        if (!s->caps_64bit_addr) {
+            fprintf(stderr,
+                    "ehci: write to CTRLDSSEGMENT while "
+                    "64-bit addressing capability is disabled\n");
+            return;
+        }
+        break;
     case ASYNCLISTADDR:
         if (ehci_async_enabled(s)) {
             fprintf(stderr,
-- 
2.43.0