From: Christoph Muellner <cmuellner@linux.com>
Date: Fri, 24 Feb 2023 13:25:36 +0000 (-0300)
Subject: target/riscv: add Zicbop cbo.prefetch{i, r, m} placeholder
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=59cb29d6a5;p=qemu.git

target/riscv: add Zicbop cbo.prefetch{i, r, m} placeholder

The cmo.prefetch instructions are nops for QEMU (no emulation of the
memory hierarchy, no illegal instructions, no permission faults, no
traps).

Add a comment noting where they would be decoded in case cbo.prefetch
instructions become relevant in the future.

Co-developed-by: Philipp Tomsich <philipp.tomsich@vrull.eu>
Signed-off-by: Christoph Muellner <cmuellner@linux.com>
Signed-off-by: Daniel Henrique Barboza <dbarboza@ventanamicro.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Weiwei Li <liweiwei@iscas.ac.cn>
Message-ID: <20230224132536.552293-5-dbarboza@ventanamicro.com>
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
---

diff --git a/target/riscv/insn32.decode b/target/riscv/insn32.decode
index 282e41aa3e..73d5d1b045 100644
--- a/target/riscv/insn32.decode
+++ b/target/riscv/insn32.decode
@@ -134,6 +134,7 @@ addi     ............     ..... 000 ..... 0010011 @i
 slti     ............     ..... 010 ..... 0010011 @i
 sltiu    ............     ..... 011 ..... 0010011 @i
 xori     ............     ..... 100 ..... 0010011 @i
+# cbo.prefetch_{i,r,m} instructions are ori with rd=x0 and not decoded.
 ori      ............     ..... 110 ..... 0010011 @i
 andi     ............     ..... 111 ..... 0010011 @i
 slli     00000. ......    ..... 001 ..... 0010011 @sh