From b68e60e6f0d2865e961a800fb8db96a7fc6494c4 Mon Sep 17 00:00:00 2001 From: Benjamin Herrenschmidt Date: Tue, 3 May 2016 18:03:33 +0200 Subject: [PATCH] ppc: Get out of emulation on SMT "OR" ops Otherwise tight loops at smt_low for example, which OPAL does, eat so much CPU that we can't boot a kernel anymore. With that, I can boot 8 CPUs just fine with powernv. Signed-off-by: Benjamin Herrenschmidt Reviewed-by: David Gibson Signed-off-by: David Gibson --- target-ppc/translate.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) diff --git a/target-ppc/translate.c b/target-ppc/translate.c index 51f6eb11c6..fe10bf8774 100644 --- a/target-ppc/translate.c +++ b/target-ppc/translate.c @@ -1392,6 +1392,19 @@ GEN_LOGICAL2(nand, tcg_gen_nand_tl, 0x0E, PPC_INTEGER); /* nor & nor. */ GEN_LOGICAL2(nor, tcg_gen_nor_tl, 0x03, PPC_INTEGER); +#if defined(TARGET_PPC64) +static void gen_pause(DisasContext *ctx) +{ + TCGv_i32 t0 = tcg_const_i32(0); + tcg_gen_st_i32(t0, cpu_env, + -offsetof(PowerPCCPU, env) + offsetof(CPUState, halted)); + tcg_temp_free_i32(t0); + + /* Stop translation, this gives other CPUs a chance to run */ + gen_exception_err(ctx, EXCP_HLT, 1); +} +#endif /* defined(TARGET_PPC64) */ + /* or & or. */ static void gen_or(DisasContext *ctx) { @@ -1447,7 +1460,7 @@ static void gen_or(DisasContext *ctx) } break; case 7: - if (ctx->hv) { + if (ctx->hv && !ctx->pr) { /* Set process priority to very high */ prio = 7; } @@ -1464,6 +1477,10 @@ 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 + */ + gen_pause(ctx); } #endif } @@ -1489,8 +1506,6 @@ static void gen_ori(DisasContext *ctx) target_ulong uimm = UIMM(ctx->opcode); if (rS(ctx->opcode) == rA(ctx->opcode) && uimm == 0) { - /* NOP */ - /* XXX: should handle special NOPs for POWER series */ return; } tcg_gen_ori_tl(cpu_gpr[rA(ctx->opcode)], cpu_gpr[rS(ctx->opcode)], uimm); -- 2.11.0