Re: [PATCH v5 5/5] target/riscv: add support for svpbmt extension

[Anup Patel]

On Tue, Jan 18, 2022 at 2:40 PM Weiwei Li <liweiwei@iscas.ac.cn> wrote:
>
>
> 在 2022/1/18 上午11:35, Anup Patel 写道:
> > On Tue, Jan 18, 2022 at 6:47 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>
> >> Cc: Heiko Stuebner <heiko@sntech.de>
> >> Cc: Anup Patel <anup@brainfault.org>
> >> ---
> >>   target/riscv/cpu.c        | 1 +
> >>   target/riscv/cpu.h        | 1 +
> >>   target/riscv/cpu_bits.h   | 2 ++
> >>   target/riscv/cpu_helper.c | 4 +++-
> >>   4 files changed, 7 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> >> index 45ac98e06b..4f82bd00a3 100644
> >> --- a/target/riscv/cpu.c
> >> +++ b/target/riscv/cpu.c
> >> @@ -670,6 +670,7 @@ 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.h b/target/riscv/cpu.h
> >> index c3d1845ca1..53f314c752 100644
> >> --- a/target/riscv/cpu.h
> >> +++ b/target/riscv/cpu.h
> >> @@ -329,6 +329,7 @@ struct RISCVCPU {
> >>           bool ext_icsr;
> >>           bool ext_svinval;
> >>           bool ext_svnapot;
> >> +        bool ext_svpbmt;
> >>           bool ext_zfh;
> >>           bool ext_zfhmin;
> >>
> >> diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
> >> index 5501e9698b..24b7eb2b1f 100644
> >> --- a/target/riscv/cpu_bits.h
> >> +++ b/target/riscv/cpu_bits.h
> >> @@ -486,7 +486,9 @@ typedef enum {
> >>   #define PTE_A               0x040 /* Accessed */
> >>   #define PTE_D               0x080 /* Dirty */
> >>   #define PTE_SOFT            0x300 /* Reserved for Software */
> >> +#define PTE_PBMT            0x6000000000000000 /* Page-based memory types 
> >> */
> >>   #define PTE_N               0x8000000000000000 /* 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 c276760c7f..9fffaccffb 100644
> >> --- a/target/riscv/cpu_helper.c
> >> +++ b/target/riscv/cpu_helper.c
> >> @@ -625,9 +625,11 @@ restart:
> >>           if (!(pte & PTE_V)) {
> >>               /* Invalid PTE */
> >>               return TRANSLATE_FAIL;
> >> +        } else if (!cpu->cfg.ext_svpbmt && (pte & 
> >> (target_ulong)PTE_PBMT)) {
> > Rather than, type-casting defines here you can simply define
> > ULL constants. E.g.
> > #define PTE_PBMT            0x6000000000000000ULL
>
> Sorry, I'm wonder why add ULL can replace the function of type-casting.
>
> The type-casting here is to compatible with RV32 for possible strict
> type check warnings since pte is 32 bits and PTE_PBMT is 64 bits in RV32.

If adding ULL does not help for RV32 target then no need to change.

>
> If I add ULL in PTE_PBMT, it seems have no change to PTE_PBMT. It's
> still 64 bits in RV32.

Reviewed-by: Anup Patel <anup@brainfault.org>

Regards,
Anup

>
> Regards,
>
> Weiwei Li
>
> >
> >> +            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
> >>
> > Regards,
> > Anup
>
>