Re: [PATCH v8 5/5] target/riscv: add support for svpbmt extension

[Alistair Francis]

On Wed, Feb 2, 2022 at 2:13 AM Weiwei Li <liweiwei@iscas.ac.cn> wrote:
>
> - add PTE_PBMT bits: It uses two PTE bits, but otherwise has no effect on 
> QEMU, since QEMU is sequentially consistent and doesn't model PMAs currently
> - add PTE_PBMT bit check for inner PTE
>
> Signed-off-by: Weiwei Li <liweiwei@iscas.ac.cn>
> Signed-off-by: Junqiang Wang <wangjunqiang@iscas.ac.cn>
> Reviewed-by: Anup Patel <anup@brainfault.org>
> ---
>  target/riscv/cpu.c        | 1 +
>  target/riscv/cpu_bits.h   | 2 ++
>  target/riscv/cpu_helper.c | 4 +++-
>  3 files changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index 4442c4b81d..e231708ffb 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -731,6 +731,7 @@ static Property riscv_cpu_properties[] = {
>
>      DEFINE_PROP_BOOL("svinval", RISCVCPU, cfg.ext_svinval, false),
>      DEFINE_PROP_BOOL("svnapot", RISCVCPU, cfg.ext_svnapot, false),
> +    DEFINE_PROP_BOOL("svpbmt", RISCVCPU, cfg.ext_svpbmt, false),
>
>      DEFINE_PROP_BOOL("zba", RISCVCPU, cfg.ext_zba, true),
>      DEFINE_PROP_BOOL("zbb", RISCVCPU, cfg.ext_zbb, true),
> diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
> index 7abe9607ff..20ab4f4a0d 100644
> --- a/target/riscv/cpu_bits.h
> +++ b/target/riscv/cpu_bits.h
> @@ -489,7 +489,9 @@ typedef enum {
>  #define PTE_A               0x040 /* Accessed */
>  #define PTE_D               0x080 /* Dirty */
>  #define PTE_SOFT            0x300 /* Reserved for Software */
> +#define PTE_PBMT            0x6000000000000000ULL /* Page-based memory types 
> */
>  #define PTE_N               0x8000000000000000ULL /* NAPOT translation */
> +#define PTE_ATTR            (PTE_N | PTE_PBMT) /* All attributes bits */
>
>  /* Page table PPN shift amount */
>  #define PTE_PPN_SHIFT       10
> diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
> index 77b263c37e..f975de8213 100644
> --- a/target/riscv/cpu_helper.c
> +++ b/target/riscv/cpu_helper.c
> @@ -640,9 +640,11 @@ restart:
>          if (!(pte & PTE_V)) {
>              /* Invalid PTE */
>              return TRANSLATE_FAIL;
> +        } else if (!cpu->cfg.ext_svpbmt && (pte & (target_ulong)PTE_PBMT)) {

Same comment about the casts, I don't think they are required.

Otherwise:

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

Alistair

> +            return TRANSLATE_FAIL;
>          } else if (!(pte & (PTE_R | PTE_W | PTE_X))) {
>              /* Inner PTE, continue walking */
> -            if (pte & (target_ulong)(PTE_D | PTE_A | PTE_U | PTE_N)) {
> +            if (pte & (target_ulong)(PTE_D | PTE_A | PTE_U | PTE_ATTR)) {
>                  return TRANSLATE_FAIL;
>              }
>              base = ppn << PGSHIFT;
> --
> 2.17.1
>
>