Re: [PATCH] target/riscv: Fix the bug of HLVX/HLV/HSV

[Alistair Francis <alistair23@gmail.com>]

On Sun, Nov 29, 2020 at 5:37 PM Yifei Jiang <jiangyifei@huawei.com> wrote:
>
> We found that the hypervisor virtual-machine load and store instructions,
> included HLVX/HLV/HSV, couldn't access guest userspace memory.
>
> In the riscv-privileged spec, HLVX/HLV/HSV is defined as follow:
> "As usual when V=1, two-stage address translation is applied, and
> the HS-level sstatus.SUM is ignored."
>
> But get_physical_address() doesn't ignore sstatus.SUM, when HLVX/HLV/HSV
> accesses guest userspace memory. So this patch fixes it.
>
> Signed-off-by: Yifei Jiang <jiangyifei@huawei.com>
> Signed-off-by: Yipeng Yin <yinyipeng1@huawei.com>

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

Alistair

> ---
>  target/riscv/cpu_helper.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
> index a2787b1d48..7274f971a4 100644
> --- a/target/riscv/cpu_helper.c
> +++ b/target/riscv/cpu_helper.c
> @@ -367,7 +367,8 @@ static int get_physical_address(CPURISCVState *env, hwaddr *physical,
>          vm = get_field(env->hgatp, HGATP_MODE);
>          widened = 2;
>      }
> -    sum = get_field(env->mstatus, MSTATUS_SUM);
> +    /* status.SUM will be ignored if execute on background */
> +    sum = get_field(env->mstatus, MSTATUS_SUM) || use_background;
>      switch (vm) {
>      case VM_1_10_SV32:
>        levels = 2; ptidxbits = 10; ptesize = 4; break;
> --
> 2.19.1
>
>