[PATCH v3] target/riscv: Set mstatus_hs.[SD|FS] bits if Clean and V=1 in mark_fs_dirty()

[frank . chang]

From: Frank Chang <frank.ch...@sifive.com>

When V=1, both vsstauts.FS and HS-level sstatus.FS are in effect.
Modifying the floating-point state when V=1 causes both fields to
be set to 3 (Dirty).

However, it's possible that HS-level sstatus.FS is Clean and VS-level
vsstatus.FS is Dirty at the time mark_fs_dirty() is called when V=1.
We can't early return for this case because we still need to set
sstatus.FS to Dirty according to spec.

Signed-off-by: Frank Chang <frank.ch...@sifive.com>
Reviewed-by: Vincent Chen <vincent.c...@sifive.com>
Tested-by: Vincent Chen <vincent.c...@sifive.com>
Reviewed-by: Richard Henderson <richard.hender...@linaro.org>
---
 target/riscv/cpu.h       |  4 ++++
 target/riscv/translate.c | 30 +++++++++++++++++-------------
 2 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
index e735e53e26c..bef7c551646 100644
--- a/target/riscv/cpu.h
+++ b/target/riscv/cpu.h
@@ -394,6 +394,7 @@ FIELD(TB_FLAGS, SEW, 5, 3)
 FIELD(TB_FLAGS, VILL, 8, 1)
 /* Is a Hypervisor instruction load/store allowed? */
 FIELD(TB_FLAGS, HLSX, 9, 1)
+FIELD(TB_FLAGS, MSTATUS_HS_FS, 10, 2)
 
 bool riscv_cpu_is_32bit(CPURISCVState *env);
 
@@ -450,6 +451,9 @@ static inline void cpu_get_tb_cpu_state(CPURISCVState *env, 
target_ulong *pc,
                 get_field(env->hstatus, HSTATUS_HU))) {
             flags = FIELD_DP32(flags, TB_FLAGS, HLSX, 1);
         }
+
+        flags = FIELD_DP32(flags, TB_FLAGS, MSTATUS_HS_FS,
+                           get_field(env->mstatus_hs, MSTATUS_FS));
     }
 #endif
 
diff --git a/target/riscv/translate.c b/target/riscv/translate.c
index 74b33fa3c90..6be22347426 100644
--- a/target/riscv/translate.c
+++ b/target/riscv/translate.c
@@ -58,6 +58,7 @@ typedef struct DisasContext {
     target_ulong misa;
     uint32_t opcode;
     uint32_t mstatus_fs;
+    uint32_t mstatus_hs_fs;
     uint32_t mem_idx;
     /* Remember the rounding mode encoded in the previous fp instruction,
        which we have already installed into env->fp_status.  Or -1 for
@@ -280,27 +281,29 @@ static void gen_jal(DisasContext *ctx, int rd, 
target_ulong imm)
 static void mark_fs_dirty(DisasContext *ctx)
 {
     TCGv tmp;
-    target_ulong sd;
+    target_ulong sd = is_32bit(ctx) ? MSTATUS32_SD : MSTATUS64_SD;
 
-    if (ctx->mstatus_fs == MSTATUS_FS) {
-        return;
-    }
-    /* Remember the state change for the rest of the TB.  */
-    ctx->mstatus_fs = MSTATUS_FS;
+    if (ctx->mstatus_fs != MSTATUS_FS) {
+        /* Remember the state change for the rest of the TB. */
+        ctx->mstatus_fs = MSTATUS_FS;
 
-    tmp = tcg_temp_new();
-    sd = is_32bit(ctx) ? MSTATUS32_SD : MSTATUS64_SD;
+        tmp = tcg_temp_new();
+        tcg_gen_ld_tl(tmp, cpu_env, offsetof(CPURISCVState, mstatus));
+        tcg_gen_ori_tl(tmp, tmp, MSTATUS_FS | sd);
+        tcg_gen_st_tl(tmp, cpu_env, offsetof(CPURISCVState, mstatus));
+        tcg_temp_free(tmp);
+    }
 
-    tcg_gen_ld_tl(tmp, cpu_env, offsetof(CPURISCVState, mstatus));
-    tcg_gen_ori_tl(tmp, tmp, MSTATUS_FS | sd);
-    tcg_gen_st_tl(tmp, cpu_env, offsetof(CPURISCVState, mstatus));
+    if (ctx->virt_enabled && ctx->mstatus_hs_fs != MSTATUS_FS) {
+        /* Remember the stage change for the rest of the TB. */
+        ctx->mstatus_hs_fs = MSTATUS_FS;
 
-    if (ctx->virt_enabled) {
+        tmp = tcg_temp_new();
         tcg_gen_ld_tl(tmp, cpu_env, offsetof(CPURISCVState, mstatus_hs));
         tcg_gen_ori_tl(tmp, tmp, MSTATUS_FS | sd);
         tcg_gen_st_tl(tmp, cpu_env, offsetof(CPURISCVState, mstatus_hs));
+        tcg_temp_free(tmp);
     }
-    tcg_temp_free(tmp);
 }
 #else
 static inline void mark_fs_dirty(DisasContext *ctx) { }
@@ -533,6 +536,7 @@ static void riscv_tr_init_disas_context(DisasContextBase 
*dcbase, CPUState *cs)
     ctx->frm = -1;  /* unknown rounding mode */
     ctx->ext_ifencei = cpu->cfg.ext_ifencei;
     ctx->vlen = cpu->cfg.vlen;
+    ctx->mstatus_hs_fs = FIELD_EX32(tb_flags, TB_FLAGS, MSTATUS_HS_FS);
     ctx->hlsx = FIELD_EX32(tb_flags, TB_FLAGS, HLSX);
     ctx->vill = FIELD_EX32(tb_flags, TB_FLAGS, VILL);
     ctx->sew = FIELD_EX32(tb_flags, TB_FLAGS, SEW);
-- 
2.25.1