On 9/13/21 6:37 PM, frank.chang@sifive.com wrote:
> From: Frank Chang <frank.chang@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.chang@sifive.com>
> Reviewed-by: Vincent Chen <vincent.chen@sifive.com>
> Tested-by: Vincent Chen <vincent.chen@sifive.com>
> ---
> target/riscv/translate.c | 19 ++++++++++---------
> 1 file changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/target/riscv/translate.c b/target/riscv/translate.c
> index e356fc6c46c..0096b098738 100644
> --- a/target/riscv/translate.c
> +++ b/target/riscv/translate.c
> @@ -280,26 +280,27 @@ 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->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);
> + }
>
> if (ctx->mstatus_fs == MSTATUS_FS) {
> return;
> }
You should introduce a ctx->mstatus_hs field to track the code that you moved. Otherwise
you'll be setting this dirty bit for every fp insn.
Thanks, Richard, I was struggling with whether to introduce a new field in DisasContext.
I will update my patch.
Regards,
Frank Chang
r~