Re: [PATCH v2 1/8] target/riscv: Fix csr number based privilege checking

[Atish Patra]

On Wed, May 11, 2022 at 7:46 AM Anup Patel <apatel@ventanamicro.com> wrote:
>
> When hypervisor and VS CSRs are accessed from VS-mode or VU-mode,
> the riscv_csrrw_check() function should generate virtual instruction
> trap instead illegal instruction trap.
>
> Fixes: 0a42f4c44088 (" target/riscv: Fix CSR perm checking for HS mode")
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
> Reviewed-by: Frank Chang <frank.chang@sifive.com>
> ---
>  target/riscv/csr.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/target/riscv/csr.c b/target/riscv/csr.c
> index 3500e07f92..2bf0a97196 100644
> --- a/target/riscv/csr.c
> +++ b/target/riscv/csr.c
> @@ -3139,7 +3139,7 @@ static inline RISCVException 
> riscv_csrrw_check(CPURISCVState *env,
>      int read_only = get_field(csrno, 0xC00) == 3;
>      int csr_min_priv = csr_ops[csrno].min_priv_ver;
>  #if !defined(CONFIG_USER_ONLY)
> -    int effective_priv = env->priv;
> +    int csr_priv, effective_priv = env->priv;
>
>      if (riscv_has_ext(env, RVH) &&
>          env->priv == PRV_S &&
> @@ -3152,7 +3152,11 @@ static inline RISCVException 
> riscv_csrrw_check(CPURISCVState *env,
>          effective_priv++;
>      }
>
> -    if (!env->debugger && (effective_priv < get_field(csrno, 0x300))) {
> +    csr_priv = get_field(csrno, 0x300);
> +    if (!env->debugger && (effective_priv < csr_priv)) {
> +        if (csr_priv == (PRV_S + 1) && riscv_cpu_virt_enabled(env)) {
> +            return RISCV_EXCP_VIRT_INSTRUCTION_FAULT;
> +        }
>          return RISCV_EXCP_ILLEGAL_INST;
>      }
>  #endif
> --
> 2.34.1
>

It seems Alistair has already queued a similar fix
https://www.mail-archive.com/qemu-devel@nongnu.org/msg886861.html

-- 
Regards,
Atish