On 2023/6/12 11:10, Weiwei Li wrote:
On 2023/6/12 10:45, LIU Zhiwei wrote:
On 2023/5/29 20:17, Weiwei Li wrote:
Upon MRET or explicit memory access with MPRV=1, MPV should be ignored
when MPP=PRV_M.
Does MPP==PRV_M always indicate the MPV==0?
No, I think . The spec doesn't restrict this. When MPP=PRV_M, MPV wll
be 0 in normal case.
But users can set MPV=1 by write to mstatus CSR directly.
Make sense. The fields specification(WARL and others) of mstatus and
other CSR always not clear on the specification. Maybe I missed
something. But I think this field could be written by the mode software.
Reviewed-by: LIU Zhiwei <zhiwei_...@linux.alibaba.com>
Zhiwei
As described in spec, "When an MRET instruction is executed, the
virtualization mode V is set to MPV, unless
MPP=3, in which case V remains 0."
MPV is just ignored if MPP = 3. This also can be seen in "table 9.5
Effect of MPRV on the translation and protection of explicit memory
accesses".
Regards,
Weiwei Li
Zhiwei
Signed-off-by: Weiwei Li <liwei...@iscas.ac.cn>
Signed-off-by: Junqiang Wang <wangjunqi...@iscas.ac.cn>
---
target/riscv/cpu_helper.c | 3 ++-
target/riscv/op_helper.c | 3 ++-
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
index 09ea227ceb..bd892c05d4 100644
--- a/target/riscv/cpu_helper.c
+++ b/target/riscv/cpu_helper.c
@@ -46,7 +46,8 @@ int riscv_cpu_mmu_index(CPURISCVState *env, bool
ifetch)
if (mode == PRV_M && get_field(status, MSTATUS_MPRV)) {
mode = get_field(env->mstatus, MSTATUS_MPP);
- virt = get_field(env->mstatus, MSTATUS_MPV);
+ virt = get_field(env->mstatus, MSTATUS_MPV) &&
+ (mode != PRV_M);
if (virt) {
status = env->vsstatus;
}
diff --git a/target/riscv/op_helper.c b/target/riscv/op_helper.c
index f563dc3981..9cdb9cdd06 100644
--- a/target/riscv/op_helper.c
+++ b/target/riscv/op_helper.c
@@ -335,7 +335,8 @@ target_ulong helper_mret(CPURISCVState *env)
riscv_raise_exception(env, RISCV_EXCP_INST_ACCESS_FAULT,
GETPC());
}
- target_ulong prev_virt = get_field(env->mstatus, MSTATUS_MPV);
+ target_ulong prev_virt = get_field(env->mstatus, MSTATUS_MPV) &&
+ (prev_priv != PRV_M);
mstatus = set_field(mstatus, MSTATUS_MIE,
get_field(mstatus, MSTATUS_MPIE));
mstatus = set_field(mstatus, MSTATUS_MPIE, 1);
