Devices/Security/DevTpm: Allow unaligned reads, Windows loves to access the FIFO status register unaligned, bugref:10075

git-svn-id: https://www.virtualbox.org/svn/vbox/trunk@90904 cfe28804-0f27-0410-a406-dd0f0b0b656f

1 files changed, 7 insertions, 6 deletions

diff --git a/src/VBox/Devices/Security/DevTpm.cpp b/src/VBox/Devices/Security/DevTpm.cpp
index e52cde9a9e3..160b8dfa9c6 100644
--- a/src/VBox/Devices/Security/DevTpm.cpp
+++ b/src/VBox/Devices/Security/DevTpm.cpp
@@ -1128,11 +1128,12 @@ static DECLCALLBACK(VBOXSTRICTRC) tpmMmioRead(PPDMDEVINS pDevIns, void *pvUser,
     PDEVTPM pThis  = PDMDEVINS_2_DATA(pDevIns, PDEVTPM);
     RT_NOREF(pvUser);
 
-    Assert(!(off & (cb - 1)));
+    RTGCPHYS offAligned = off & ~UINT64_C(0x3);
+    uint8_t cBitsShift  = (off & 0x3) * 8;
 
     VBOXSTRICTRC rc = VINF_SUCCESS;
-    uint32_t uReg = tpmGetRegisterFromOffset(off);
-    uint8_t bLoc = tpmGetLocalityFromOffset(off);
+    uint32_t uReg = tpmGetRegisterFromOffset(offAligned);
+    uint8_t bLoc = tpmGetLocalityFromOffset(offAligned);
     PDEVTPMLOCALITY pLoc = &pThis->aLoc[bLoc];
 
     uint64_t u64;
@@ -1147,9 +1148,9 @@ static DECLCALLBACK(VBOXSTRICTRC) tpmMmioRead(PPDMDEVINS pDevIns, void *pvUser,
     {
         switch (cb)
         {
-            case 1: *(uint8_t *)pv = (uint8_t)u64; break;
-            case 2: *(uint16_t *)pv = (uint16_t)u64; break;
-            case 4: *(uint32_t *)pv = (uint32_t)u64; break;
+            case 1: *(uint8_t *)pv = (uint8_t)(u64 >> cBitsShift); break;
+            case 2: *(uint16_t *)pv = (uint16_t)(u64 >> cBitsShift); break;
+            case 4: *(uint32_t *)pv = (uint32_t)(u64 >> cBitsShift); break;
             case 8: *(uint64_t *)pv = u64; break;
             default: AssertFailedBreakStmt(rc = VERR_INTERNAL_ERROR);
         }