include/exec/memattrs: Add two bits of space to MemTxAttrs

We will need 2 bits to represent ARMSecurityState.

Do not attempt to replace or widen secure, even though it
logically overlaps the new field -- there are uses within
e.g. hw/block/pflash_cfi01.c, which don't know anything
specific about ARM.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230620124418.805717-7-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

include/exec/memattrs.h

@@ -29,10 +29,17 @@ typedef struct MemTxAttrs {
      * "didn't specify" if necessary.
      */
     unsigned int unspecified:1;
-    /* ARM/AMBA: TrustZone Secure access
+    /*
+     * ARM/AMBA: TrustZone Secure access
      * x86: System Management Mode access
      */
     unsigned int secure:1;
+    /*
+     * ARM: ArmSecuritySpace.  This partially overlaps secure, but it is
+     * easier to have both fields to assist code that does not understand
+     * ARMv9 RME, or no specific knowledge of ARM at all (e.g. pflash).
+     */
+    unsigned int space:2;
     /* Memory access is usermode (unprivileged) */
     unsigned int user:1;
     /*