amd_iommu: Fix truncation of oldval in amdvi_writeq

The variable `oldval` was incorrectly declared as a 32-bit `uint32_t`.
This could lead to truncation and incorrect behavior where the upper
read-only 32 bits are significant.

Fix the type of `oldval` to match the return type of `ldq_le_p()`.

Cc: [email protected]
Fixes: d29a09c ("hw/i386: Introduce AMD IOMMU")
Signed-off-by: Ethan Milon <[email protected]>
Message-Id: <[email protected]>
Reviewed-by: Vasant Hegde <[email protected]>
Reviewed-by: Michael S. Tsirkin <[email protected]>
Signed-off-by: Michael S. Tsirkin <[email protected]>
(cherry picked from commit 5788929e05e18ed5f76dc8ade4210f022c9ba5a1)
Signed-off-by: Michael Tokarev <[email protected]>

Author: Ethsan

hw/i386/amd_iommu.c

@@ -140,7 +140,7 @@ static void amdvi_writeq(AMDVIState *s, hwaddr addr, uint64_t val)
 {
     uint64_t romask = ldq_le_p(&s->romask[addr]);
     uint64_t w1cmask = ldq_le_p(&s->w1cmask[addr]);
-    uint32_t oldval = ldq_le_p(&s->mmior[addr]);
+    uint64_t oldval = ldq_le_p(&s->mmior[addr]);
     stq_le_p(&s->mmior[addr],
             ((oldval & romask) | (val & ~romask)) & ~(val & w1cmask));
 }