[RFC PATCH v3 3/3] target/ppc: Fix gen_priv_exception error value in mfspr/mtspr

[matheus . ferst]

From: Matheus Ferst <matheus.ferst@eldorado.org.br>

The code in linux-user/ppc/cpu_loop.c expects POWERPC_EXCP_PRIV
exception with error POWERPC_EXCP_PRIV_OPC or POWERPC_EXCP_PRIV_REG,
while POWERPC_EXCP_INVAL_SPR is expected in POWERPC_EXCP_INVAL
exceptions. This mismatch caused an EXCP_DUMP with the message "Unknown
privilege violation (03)", as seen in [1].

Fixes: 9b2fadda3e01 ("ppc: Rework generation of priv and inval interrupts")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/588

[1] https://gitlab.com/qemu-project/qemu/-/issues/588

Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
---
Is there any case where throwing a PRIV/INVAL exception with a
INVAL/PRIV error makes sense? It seems wrong, but maybe I'm missing
something... especially with the HV_EMU to program check conversion.

Also, if this patch is correct, it seems that all invalid SPR access
would be nop or privilege exceptions. In this case, is
POWERPC_EXCP_INVAL_SPR still needed?
---
 target/ppc/translate.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/target/ppc/translate.c b/target/ppc/translate.c
index 40232201bb..abbc3a5bb9 100644
--- a/target/ppc/translate.c
+++ b/target/ppc/translate.c
@@ -4827,11 +4827,11 @@ static inline void gen_op_mfspr(DisasContext *ctx)
          */
         if (sprn & 0x10) {
             if (ctx->pr) {
-                gen_priv_exception(ctx, POWERPC_EXCP_INVAL_SPR);
+                gen_priv_exception(ctx, POWERPC_EXCP_PRIV_REG);
             }
         } else {
             if (ctx->pr || sprn == 0 || sprn == 4 || sprn == 5 || sprn == 6) {
-                gen_hvpriv_exception(ctx, POWERPC_EXCP_INVAL_SPR);
+                gen_hvpriv_exception(ctx, POWERPC_EXCP_PRIV_REG);
             }
         }
     }
@@ -5014,11 +5014,11 @@ static void gen_mtspr(DisasContext *ctx)
          */
         if (sprn & 0x10) {
             if (ctx->pr) {
-                gen_priv_exception(ctx, POWERPC_EXCP_INVAL_SPR);
+                gen_priv_exception(ctx, POWERPC_EXCP_PRIV_REG);
             }
         } else {
             if (ctx->pr || sprn == 0) {
-                gen_hvpriv_exception(ctx, POWERPC_EXCP_INVAL_SPR);
+                gen_hvpriv_exception(ctx, POWERPC_EXCP_PRIV_REG);
             }
         }
     }
-- 
2.25.1