Re: [PATCH v3 4/4] target/riscv: Ensure opcode is saved for all relevant instructions

[Alistair Francis]

On Fri, Jan 20, 2023 at 11:01 PM Anup Patel <apatel@ventanamicro.com> wrote:
>
> We should call decode_save_opc() for all relevant instructions which
> can potentially generate a virtual instruction fault or a guest page
> fault because generating transformed instruction upon guest page fault
> expects opcode to be available. Without this, hypervisor will see
> transformed instruction as zero in htinst CSR for guest MMIO emulation
> which makes MMIO emulation in hypervisor slow and also breaks nested
> virtualization.
>
> Fixes: a9814e3e08d2 ("target/riscv: Minimize the calls to decode_save_opc")
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>

Reviewed-by: Alistair Francis <alistair.francis@wdc.com>

Alistair

> ---
>  target/riscv/insn_trans/trans_rva.c.inc     | 10 +++++++---
>  target/riscv/insn_trans/trans_rvd.c.inc     |  2 ++
>  target/riscv/insn_trans/trans_rvf.c.inc     |  2 ++
>  target/riscv/insn_trans/trans_rvh.c.inc     |  3 +++
>  target/riscv/insn_trans/trans_rvi.c.inc     |  2 ++
>  target/riscv/insn_trans/trans_rvzfh.c.inc   |  2 ++
>  target/riscv/insn_trans/trans_svinval.c.inc |  3 +++
>  7 files changed, 21 insertions(+), 3 deletions(-)
>
> diff --git a/target/riscv/insn_trans/trans_rva.c.inc 
> b/target/riscv/insn_trans/trans_rva.c.inc
> index 45db82c9be..5f194a447b 100644
> --- a/target/riscv/insn_trans/trans_rva.c.inc
> +++ b/target/riscv/insn_trans/trans_rva.c.inc
> @@ -20,8 +20,10 @@
>
>  static bool gen_lr(DisasContext *ctx, arg_atomic *a, MemOp mop)
>  {
> -    TCGv src1 = get_address(ctx, a->rs1, 0);
> +    TCGv src1;
>
> +    decode_save_opc(ctx);
> +    src1 = get_address(ctx, a->rs1, 0);
>      if (a->rl) {
>          tcg_gen_mb(TCG_MO_ALL | TCG_BAR_STRL);
>      }
> @@ -43,6 +45,7 @@ static bool gen_sc(DisasContext *ctx, arg_atomic *a, MemOp 
> mop)
>      TCGLabel *l1 = gen_new_label();
>      TCGLabel *l2 = gen_new_label();
>
> +    decode_save_opc(ctx);
>      src1 = get_address(ctx, a->rs1, 0);
>      tcg_gen_brcond_tl(TCG_COND_NE, load_res, src1, l1);
>
> @@ -81,9 +84,10 @@ static bool gen_amo(DisasContext *ctx, arg_atomic *a,
>                      MemOp mop)
>  {
>      TCGv dest = dest_gpr(ctx, a->rd);
> -    TCGv src1 = get_address(ctx, a->rs1, 0);
> -    TCGv src2 = get_gpr(ctx, a->rs2, EXT_NONE);
> +    TCGv src1, src2 = get_gpr(ctx, a->rs2, EXT_NONE);
>
> +    decode_save_opc(ctx);
> +    src1 = get_address(ctx, a->rs1, 0);
>      func(dest, src1, src2, ctx->mem_idx, mop);
>
>      gen_set_gpr(ctx, a->rd, dest);
> diff --git a/target/riscv/insn_trans/trans_rvd.c.inc 
> b/target/riscv/insn_trans/trans_rvd.c.inc
> index 1397c1ce1c..6e3159b797 100644
> --- a/target/riscv/insn_trans/trans_rvd.c.inc
> +++ b/target/riscv/insn_trans/trans_rvd.c.inc
> @@ -38,6 +38,7 @@ static bool trans_fld(DisasContext *ctx, arg_fld *a)
>      REQUIRE_FPU;
>      REQUIRE_EXT(ctx, RVD);
>
> +    decode_save_opc(ctx);
>      addr = get_address(ctx, a->rs1, a->imm);
>      tcg_gen_qemu_ld_i64(cpu_fpr[a->rd], addr, ctx->mem_idx, MO_TEUQ);
>
> @@ -52,6 +53,7 @@ static bool trans_fsd(DisasContext *ctx, arg_fsd *a)
>      REQUIRE_FPU;
>      REQUIRE_EXT(ctx, RVD);
>
> +    decode_save_opc(ctx);
>      addr = get_address(ctx, a->rs1, a->imm);
>      tcg_gen_qemu_st_i64(cpu_fpr[a->rs2], addr, ctx->mem_idx, MO_TEUQ);
>      return true;
> diff --git a/target/riscv/insn_trans/trans_rvf.c.inc 
> b/target/riscv/insn_trans/trans_rvf.c.inc
> index a1d3eb52ad..965e1f8d11 100644
> --- a/target/riscv/insn_trans/trans_rvf.c.inc
> +++ b/target/riscv/insn_trans/trans_rvf.c.inc
> @@ -38,6 +38,7 @@ static bool trans_flw(DisasContext *ctx, arg_flw *a)
>      REQUIRE_FPU;
>      REQUIRE_EXT(ctx, RVF);
>
> +    decode_save_opc(ctx);
>      addr = get_address(ctx, a->rs1, a->imm);
>      dest = cpu_fpr[a->rd];
>      tcg_gen_qemu_ld_i64(dest, addr, ctx->mem_idx, MO_TEUL);
> @@ -54,6 +55,7 @@ static bool trans_fsw(DisasContext *ctx, arg_fsw *a)
>      REQUIRE_FPU;
>      REQUIRE_EXT(ctx, RVF);
>
> +    decode_save_opc(ctx);
>      addr = get_address(ctx, a->rs1, a->imm);
>      tcg_gen_qemu_st_i64(cpu_fpr[a->rs2], addr, ctx->mem_idx, MO_TEUL);
>      return true;
> diff --git a/target/riscv/insn_trans/trans_rvh.c.inc 
> b/target/riscv/insn_trans/trans_rvh.c.inc
> index 4f8aecddc7..9248b48c36 100644
> --- a/target/riscv/insn_trans/trans_rvh.c.inc
> +++ b/target/riscv/insn_trans/trans_rvh.c.inc
> @@ -36,6 +36,7 @@ static bool do_hlv(DisasContext *ctx, arg_r2 *a, MemOp mop)
>  #ifdef CONFIG_USER_ONLY
>      return false;
>  #else
> +    decode_save_opc(ctx);
>      if (check_access(ctx)) {
>          TCGv dest = dest_gpr(ctx, a->rd);
>          TCGv addr = get_gpr(ctx, a->rs1, EXT_NONE);
> @@ -82,6 +83,7 @@ static bool do_hsv(DisasContext *ctx, arg_r2_s *a, MemOp 
> mop)
>  #ifdef CONFIG_USER_ONLY
>      return false;
>  #else
> +    decode_save_opc(ctx);
>      if (check_access(ctx)) {
>          TCGv addr = get_gpr(ctx, a->rs1, EXT_NONE);
>          TCGv data = get_gpr(ctx, a->rs2, EXT_NONE);
> @@ -135,6 +137,7 @@ static bool trans_hsv_d(DisasContext *ctx, arg_hsv_d *a)
>  static bool do_hlvx(DisasContext *ctx, arg_r2 *a,
>                      void (*func)(TCGv, TCGv_env, TCGv))
>  {
> +    decode_save_opc(ctx);
>      if (check_access(ctx)) {
>          TCGv dest = dest_gpr(ctx, a->rd);
>          TCGv addr = get_gpr(ctx, a->rs1, EXT_NONE);
> diff --git a/target/riscv/insn_trans/trans_rvi.c.inc 
> b/target/riscv/insn_trans/trans_rvi.c.inc
> index 5c69b88d1e..4496f21266 100644
> --- a/target/riscv/insn_trans/trans_rvi.c.inc
> +++ b/target/riscv/insn_trans/trans_rvi.c.inc
> @@ -261,6 +261,7 @@ static bool gen_load_i128(DisasContext *ctx, arg_lb *a, 
> MemOp memop)
>
>  static bool gen_load(DisasContext *ctx, arg_lb *a, MemOp memop)
>  {
> +    decode_save_opc(ctx);
>      if (get_xl(ctx) == MXL_RV128) {
>          return gen_load_i128(ctx, a, memop);
>      } else {
> @@ -350,6 +351,7 @@ static bool gen_store_i128(DisasContext *ctx, arg_sb *a, 
> MemOp memop)
>
>  static bool gen_store(DisasContext *ctx, arg_sb *a, MemOp memop)
>  {
> +    decode_save_opc(ctx);
>      if (get_xl(ctx) == MXL_RV128) {
>          return gen_store_i128(ctx, a, memop);
>      } else {
> diff --git a/target/riscv/insn_trans/trans_rvzfh.c.inc 
> b/target/riscv/insn_trans/trans_rvzfh.c.inc
> index 5d07150cd0..2ad5716312 100644
> --- a/target/riscv/insn_trans/trans_rvzfh.c.inc
> +++ b/target/riscv/insn_trans/trans_rvzfh.c.inc
> @@ -49,6 +49,7 @@ static bool trans_flh(DisasContext *ctx, arg_flh *a)
>      REQUIRE_FPU;
>      REQUIRE_ZFH_OR_ZFHMIN(ctx);
>
> +    decode_save_opc(ctx);
>      t0 = get_gpr(ctx, a->rs1, EXT_NONE);
>      if (a->imm) {
>          TCGv temp = temp_new(ctx);
> @@ -71,6 +72,7 @@ static bool trans_fsh(DisasContext *ctx, arg_fsh *a)
>      REQUIRE_FPU;
>      REQUIRE_ZFH_OR_ZFHMIN(ctx);
>
> +    decode_save_opc(ctx);
>      t0 = get_gpr(ctx, a->rs1, EXT_NONE);
>      if (a->imm) {
>          TCGv temp = tcg_temp_new();
> diff --git a/target/riscv/insn_trans/trans_svinval.c.inc 
> b/target/riscv/insn_trans/trans_svinval.c.inc
> index 2682bd969f..f3cd7d5c0b 100644
> --- a/target/riscv/insn_trans/trans_svinval.c.inc
> +++ b/target/riscv/insn_trans/trans_svinval.c.inc
> @@ -28,6 +28,7 @@ static bool trans_sinval_vma(DisasContext *ctx, 
> arg_sinval_vma *a)
>      /* Do the same as sfence.vma currently */
>      REQUIRE_EXT(ctx, RVS);
>  #ifndef CONFIG_USER_ONLY
> +    decode_save_opc(ctx);
>      gen_helper_tlb_flush(cpu_env);
>      return true;
>  #endif
> @@ -56,6 +57,7 @@ static bool trans_hinval_vvma(DisasContext *ctx, 
> arg_hinval_vvma *a)
>      /* Do the same as hfence.vvma currently */
>      REQUIRE_EXT(ctx, RVH);
>  #ifndef CONFIG_USER_ONLY
> +    decode_save_opc(ctx);
>      gen_helper_hyp_tlb_flush(cpu_env);
>      return true;
>  #endif
> @@ -68,6 +70,7 @@ static bool trans_hinval_gvma(DisasContext *ctx, 
> arg_hinval_gvma *a)
>      /* Do the same as hfence.gvma currently */
>      REQUIRE_EXT(ctx, RVH);
>  #ifndef CONFIG_USER_ONLY
> +    decode_save_opc(ctx);
>      gen_helper_hyp_gvma_tlb_flush(cpu_env);
>      return true;
>  #endif
> --
> 2.34.1
>
>