[Qemu-devel] [PATCH] PPC: Only set lower 32bits with mtmsr

[Qemu-devel] [PATCH] PPC: Only set lower 32bits with mtmsr

[Alexander Graf]

As Nathan pointed out correctly, the mtmsr instruction does not modify
the high 32 bits of MSR. It also doesn't matter if SF is set or not,
the instruction always behaves the same.

This patch moves it a bit closer to the spec.

Reported-by: Nathan Whitehorn <nwhitehorn@freebsd.org>
Signed-off-by: Alexander Graf <agraf@suse.de>
---
 target-ppc/translate.c |   17 ++++++-----------
 1 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/target-ppc/translate.c b/target-ppc/translate.c
index 59aef85..7e318e3 100644
--- a/target-ppc/translate.c
+++ b/target-ppc/translate.c
@@ -3878,24 +3878,19 @@ static void gen_mtmsr(DisasContext *ctx)
         tcg_gen_or_tl(cpu_msr, cpu_msr, t0);
         tcg_temp_free(t0);
     } else {
+        TCGv msr = tcg_temp_new();
+
         /* XXX: we need to update nip before the store
          *      if we enter power saving mode, we will exit the loop
          *      directly from ppc_store_msr
          */
         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
+        tcg_gen_deposit_tl(msr, cpu_msr, cpu_gpr[rS(ctx->opcode)], 0, 32);
+#else
+        tcg_gen_mov_tl(msr, cpu_gpr[rS(ctx->opcode)]);
 #endif
-            gen_helper_store_msr(cpu_gpr[rS(ctx->opcode)]);
+        gen_helper_store_msr(msr);
         /* Must stop the translation as machine state (may have) changed */
         /* Note that mtmsr is not always defined as context-synchronizing */
         gen_stop_exception(ctx);
-- 
1.6.0.2