[PATCH 1/2] ppc/pnv: initialize 'taddr' in pnv_phb3_translate_tve()

[Daniel Henrique Barboza <danielhb413@gmail.com>]

The 'taddr' variable is left unintialized, being set only inside the
"while ((lev--) >= 0)" loop where we get the TCE address. The 'lev' var
is an int32_t that is being initiliazed by the GETFIELD() macro, which
returns an uint64_t.

For a human reader this means that 'lev' will always be positive or zero.
But some compilers may beg to differ. 'lev' being an int32_t can in theory
be set as negative, and the "while ((lev--) >= 0)" loop might never be
reached, and 'taddr' will be left unitialized. This can cause phb3_error()
to use 'taddr' uninitialized down below:

if ((is_write & !(tce & 2)) || ((!is_write) && !(tce & 1))) {
    phb3_error(phb, "TCE access fault at 0x%"PRIx64, taddr);

Setting 'taddr' to the top level base address will make compilers happy.

Resolves: https://gitlab.com/qemu-project/qemu/-/issues/573
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
---
 hw/pci-host/pnv_phb3.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/hw/pci-host/pnv_phb3.c b/hw/pci-host/pnv_phb3.c
index 7fb35dc031..617d42c5a0 100644
--- a/hw/pci-host/pnv_phb3.c
+++ b/hw/pci-host/pnv_phb3.c
@@ -788,6 +788,17 @@ static void pnv_phb3_translate_tve(PnvPhb3DMASpace *ds, hwaddr addr,
         /* Top level table base address */
         base = tta << 12;
 
+        /*
+         * Some compilers will complain that the "TCE access fault"
+         * phb3_error() down below will use 'taddr' uninitialized
+         * because, in theory, the loop that sets 'taddr' is skippable
+         * due to 'lev' being an signed int.
+         *
+         * Setting 'taddr 'to the base address will bring piece of mind
+         * to such compilers.
+         */
+        taddr = base;
+
         /* Total shift to first level */
         sh = tbl_shift * lev + tce_shift;
 
-- 
2.34.1