Re: [PATCH v3 1/6] Add an "info pg" command that prints the current page tables

[Richard Henderson <richard.henderson@linaro.org>]

On 6/6/24 07:02, Don Porter wrote:
> +/**
> + * get_pte - Copy the contents of the page table entry at node[i] into pt_entry.
> + *           Optionally, add the relevant bits to the virtual address in
> + *           vaddr_pte.
> + *
> + * @cs - CPU state
> + * @node - physical address of the current page table node
> + * @i - index (in page table entries, not bytes) of the page table
> + *      entry, within node
> + * @height - height of node within the tree (leaves are 1, not 0)
> + * @pt_entry - Poiter to a PTE_t, stores the contents of the page table entry
> + * @vaddr_parent - The virtual address bits already translated in walking the
> + *                 page table to node.  Optional: only used if vaddr_pte is set.
> + * @vaddr_pte - Optional pointer to a variable storing the virtual address bits
> + *              translated by node[i].
> + * @pte_paddr - Pointer to the physical address of the PTE within node.
> + *              Optional parameter.
> + */
> +void
> +x86_get_pte(CPUState *cs, hwaddr node, int i, int height,
> +            PTE_t *pt_entry, vaddr vaddr_parent, vaddr *vaddr_pte,
> +            hwaddr *pte_paddr)
> +
> +{
> +    X86CPU *cpu = X86_CPU(cs);
> +    CPUX86State *env = &cpu->env;
> +    int32_t a20_mask = x86_get_a20_mask(env);
> +    hwaddr pte;
> +
> +    if (env->hflags & HF_LMA_MASK) {
> +        /* 64 bit */
> +        int pte_width = 8;
> +        pte = (node + (i * pte_width)) & a20_mask;
> +        pt_entry->pte64_t = address_space_ldq(cs->as, pte,
> +                                              MEMTXATTRS_UNSPECIFIED, NULL);
> +    } else {
> +        /* 32 bit */
> +        int pte_width = 4;
> +        pte = (node + (i * pte_width)) & a20_mask;
> +        pt_entry->pte32_t = address_space_ldl(cs->as, pte,
> +                                              MEMTXATTRS_UNSPECIFIED, NULL);
> +    }
> +
> +    if (vaddr_pte) {
> +        int shift = 0;
> +        _mmu_decode_va_parameters(cs, height, &shift, NULL);
> +        *vaddr_pte = vaddr_parent | ((i & 0x1ffULL) << shift);
> +    }
> +
> +    if (pte_paddr) {
> +        *pte_paddr = pte;
> +    }
> +}

This fails to recurse with nested page tables, which definitely breaks the TCG walker.


r~