Re: [RFC PATCH 1/3] target/riscv: add support for svnapot extension

[Alistair Francis]

On Sun, Nov 28, 2021 at 11:54 PM liweiwei <liweiwei@iscas.ac.cn> wrote:
>

Can you add a commit message that describes what you are changing?

Alistair

> Signed-off-by: liweiwei <liweiwei@iscas.ac.cn>
> Signed-off-by: wangjunqiang <wangjunqiang@iscas.ac.cn>
> ---
>  target/riscv/cpu_bits.h   |  1 +
>  target/riscv/cpu_helper.c | 18 ++++++++++++------
>  2 files changed, 13 insertions(+), 6 deletions(-)
>
> diff --git a/target/riscv/cpu_bits.h b/target/riscv/cpu_bits.h
> index 9913fa9f77..70391424b0 100644
> --- a/target/riscv/cpu_bits.h
> +++ b/target/riscv/cpu_bits.h
> @@ -473,6 +473,7 @@ typedef enum {
>  #define PTE_A               0x040 /* Accessed */
>  #define PTE_D               0x080 /* Dirty */
>  #define PTE_SOFT            0x300 /* Reserved for Software */
> +#define PTE_N               0x8000000000000000
>
>  /* 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 9eeed38c7e..e68db3e119 100644
> --- a/target/riscv/cpu_helper.c
> +++ b/target/riscv/cpu_helper.c
> @@ -588,7 +588,7 @@ restart:
>              return TRANSLATE_FAIL;
>          }
>
> -        hwaddr ppn = pte >> PTE_PPN_SHIFT;
> +        hwaddr ppn = (pte & ~(target_ulong)PTE_N) >> PTE_PPN_SHIFT;
>
>          if (!(pte & PTE_V)) {
>              /* Invalid PTE */
> @@ -668,8 +668,17 @@ restart:
>              /* for superpage mappings, make a fake leaf PTE for the TLB's
>                 benefit. */
>              target_ulong vpn = addr >> PGSHIFT;
> -            *physical = ((ppn | (vpn & ((1L << ptshift) - 1))) << PGSHIFT) |
> -                        (addr & ~TARGET_PAGE_MASK);
> +
> +            int napot_bits = ((pte & PTE_N) ? (ctzl(ppn) + 1) : 0);
> +            if (((pte & PTE_N) && ((ppn == 0) || (i != (levels - 1)))) ||
> +                (napot_bits != 0 && napot_bits != 4)) {
> +                return TRANSLATE_FAIL;
> +            }
> +
> +            *physical = (((ppn & ~(((target_ulong)1 << napot_bits) - 1)) |
> +                          (vpn & (((target_ulong)1 << napot_bits) - 1)) |
> +                          (vpn & (((target_ulong)1 << ptshift) - 1))
> +                        ) << PGSHIFT) | (addr & ~TARGET_PAGE_MASK);
>
>              /* set permissions on the TLB entry */
>              if ((pte & PTE_R) || ((pte & PTE_X) && mxr)) {
> @@ -856,7 +865,6 @@ bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address, int 
> size,
>          ret = get_physical_address(env, &pa, &prot, address,
>                                     &env->guest_phys_fault_addr, access_type,
>                                     mmu_idx, true, true, false);
> -
>          /*
>           * A G-stage exception may be triggered during two state lookup.
>           * And the env->guest_phys_fault_addr has already been set in
> @@ -879,7 +887,6 @@ bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address, int 
> size,
>              ret = get_physical_address(env, &pa, &prot2, im_address, NULL,
>                                         access_type, mmu_idx, false, true,
>                                         false);
> -
>              qemu_log_mask(CPU_LOG_MMU,
>                      "%s 2nd-stage address=%" VADDR_PRIx " ret %d physical "
>                      TARGET_FMT_plx " prot %d\n",
> @@ -914,7 +921,6 @@ bool riscv_cpu_tlb_fill(CPUState *cs, vaddr address, int 
> size,
>          /* Single stage lookup */
>          ret = get_physical_address(env, &pa, &prot, address, NULL,
>                                     access_type, mmu_idx, true, false, false);
> -
>          qemu_log_mask(CPU_LOG_MMU,
>                        "%s address=%" VADDR_PRIx " ret %d physical "
>                        TARGET_FMT_plx " prot %d\n",
> --
> 2.17.1
>
>