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[Qemu-devel] [PATCH] target-ppc: gen_pause for instructions: yield, mdoi
From: |
Aaron Larson |
Subject: |
[Qemu-devel] [PATCH] target-ppc: gen_pause for instructions: yield, mdoio, mdoom, miso |
Date: |
Fri, 24 Jun 2016 13:18:28 -0700 |
Call gen_pause for all "or rx,rx,rx" encodings other nop. This
provides a reasonable implementation for yield, and a better
approximation for mdoio, mdoom, and miso. The choice to pause for all
encodings !=0 leverages the PowerISA admonition that the reserved
encodings might change program priority, providing a slight "future
proofing".
Signed-off-by: Aaron Larson <address@hidden>
---
target-ppc/translate.c | 15 ++++++++-------
1 file changed, 8 insertions(+), 7 deletions(-)
diff --git a/target-ppc/translate.c b/target-ppc/translate.c
index 2f1c591..c4559b6 100644
--- a/target-ppc/translate.c
+++ b/target-ppc/translate.c
@@ -1471,7 +1471,7 @@ static void gen_or(DisasContext *ctx)
} else if (unlikely(Rc(ctx->opcode) != 0)) {
gen_set_Rc0(ctx, cpu_gpr[rs]);
#if defined(TARGET_PPC64)
- } else {
+ } else if (rs != 0) { /* 0 is nop */
int prio = 0;
switch (rs) {
@@ -1514,7 +1514,6 @@ static void gen_or(DisasContext *ctx)
break;
#endif
default:
- /* nop */
break;
}
if (prio) {
@@ -1524,13 +1523,15 @@ static void gen_or(DisasContext *ctx)
tcg_gen_ori_tl(t0, t0, ((uint64_t)prio) << 50);
gen_store_spr(SPR_PPR, t0);
tcg_temp_free(t0);
- /* Pause us out of TCG otherwise spin loops with smt_low
- * eat too much CPU and the kernel hangs
- */
+ }
#if !defined(CONFIG_USER_ONLY)
- gen_pause(ctx);
+ /* Pause out of TCG otherwise spin loops with smt_low eat too much
+ * CPU and the kernel hangs. This applies to all encodings other
+ * than no-op, e.g., miso(rs=26), yield(27), mdoio(29), mdoom(30),
+ * and all currently undefined.
+ */
+ gen_pause(ctx);
#endif
- }
#endif
}
}
--
2.7.4
- [Qemu-devel] [PATCH] target-ppc: gen_pause for instructions: yield, mdoio, mdoom, miso,
Aaron Larson <=
- Re: [Qemu-devel] [PATCH] target-ppc: gen_pause for instructions: yield, mdoio, mdoom, miso, David Gibson, 2016/06/26
- Re: [Qemu-devel] [Qemu-ppc] [PATCH] target-ppc: gen_pause for instructions: yield, mdoio, mdoom, miso, Benjamin Herrenschmidt, 2016/06/29