[Qemu-devel] [PATCH2] ppc64: fix mtmsr behavior on 64-bit targets

[Nathan Whitehorn <nwhitehorn@freebsd.org>]

The mtmsr instruction is required not to modify the upper 32-bits of the 
machine state register, but checks the current value of MSR[SF] to 
decide whether to do this. This has the effect of zeroing the upper 32 
bits of the MSR whenever mtmsr is executed in 64-bit mode. 
Unconditionally preserve the upper 32-bits in mtmsr for TARGET_PPC64.

Signed-off-by: Nathan Whitehorn <nwhitehorn@freebsd.org>
---
  target-ppc/translate.c |    5 ++---
  1 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/target-ppc/translate.c b/target-ppc/translate.c
index 59aef85..38d2e2e 100644
--- a/target-ppc/translate.c
+++ b/target-ppc/translate.c
@@ -3884,18 +3884,17 @@ static void gen_mtmsr(DisasContext *ctx)
           */
          gen_update_nip(ctx, ctx->nip);
  #if defined(TARGET_PPC64)
-        if (!ctx->sf_mode) {
-            TCGv t0 = tcg_temp_new();
-            TCGv t1 = tcg_temp_new();
-            tcg_gen_andi_tl(t0, cpu_msr, 0xFFFFFFFF00000000ULL);
-            tcg_gen_ext32u_tl(t1, cpu_gpr[rS(ctx->opcode)]);
-            tcg_gen_or_tl(t0, t0, t1);
-            tcg_temp_free(t1);
-            gen_helper_store_msr(t0);
-            tcg_temp_free(t0);
-        } else
+        TCGv t0 = tcg_temp_new();
+        TCGv t1 = tcg_temp_new();
+        tcg_gen_andi_tl(t0, cpu_msr, 0xFFFFFFFF00000000ULL);
+        tcg_gen_ext32u_tl(t1, cpu_gpr[rS(ctx->opcode)]);
+        tcg_gen_or_tl(t0, t0, t1);
+        tcg_temp_free(t1);
+        gen_helper_store_msr(t0);
+        tcg_temp_free(t0);
+#else
+        gen_helper_store_msr(cpu_gpr[rS(ctx->opcode)]);
  #endif
-            gen_helper_store_msr(cpu_gpr[rS(ctx->opcode)]);
          /* Must stop the translation as machine state (may have) 
changed */
          /* Note that mtmsr is not always defined as 
context-synchronizing */
          gen_stop_exception(ctx);