Re: [Xen-devel] [PATCH V2 3/4] arm: allocate per-PCPU domheap pagetable pages

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Tue, 23 Apr 2013, Ian Campbell wrote:
> +int init_secondary_pagetables(int cpu)
> +{
> +    lpae_t *root, *first, *domheap, pte;
> +    int i;
> +
> +    root = alloc_xenheap_page();
> +#ifdef CONFIG_ARM_64
> +    first = alloc_xenheap_page();
> +#else
> +    first = root; /* root == first level on 32-bit 3-level trie */
> +#endif
> +    domheap = 
> alloc_xenheap_pages(get_order_from_pages(DOMHEAP_SECOND_PAGES), 0);
> +
> +    if ( root == NULL || domheap == NULL || first == NULL )
> +    {
> +        printk("Not enough free memory for secondary CPU%d pagetables\n", 
> cpu);
> +        free_xenheap_pages(domheap, 
> get_order_from_pages(DOMHEAP_SECOND_PAGES));
> +#ifdef CONFIG_ARM_64
> +        free_xenheap_page(first);
> +#endif
> +        free_xenheap_page(root);
> +        return -ENOMEM;
> +    }
> +
> +    /* Initialise root pagetable from root of boot tables */
> +    memcpy(root, boot_pgtable, PAGE_SIZE);
> +
> +#ifdef CONFIG_ARM_64
> +    /* Initialise first pagetable from first level of boot tables, and
> +     * hook into the new root. */
> +    memcpy(first, boot_first, PAGE_SIZE);
> +    pte = mfn_to_xen_entry(virt_to_mfn(first));
> +    pte.pt.table = 1;
> +    write_pte(root, pte);
> +#endif
> +
> +    /* Ensure the domheap has no stray mappings */
> +    memset(domheap, 0, DOMHEAP_SECOND_PAGES*PAGE_SIZE);
> +
> +    /* Update the first level mapping to reference the local CPUs
> +     * domheap mapping pages. */
> +    for ( i = 0; i < DOMHEAP_SECOND_PAGES; i++ )
> +    {
> +        pte = mfn_to_xen_entry(virt_to_mfn(domheap+i*LPAE_ENTRIES));
> +        pte.pt.table = 1;
> +        
> write_pte(&first[first_table_offset(DOMHEAP_VIRT_START+i*FIRST_SIZE)], pte);
> +    }
> +
> +    flush_xen_dcache_va_range(root, PAGE_SIZE);
> +    flush_xen_dcache_va_range(domheap, DOMHEAP_SECOND_PAGES*PAGE_SIZE);

Don't we need to flush first too (on ARMv8)?


> +    per_cpu(xen_pgtable, cpu) = root;
> +    per_cpu(xen_dommap, cpu) = domheap;

I think we should flush the two per_cpu variables here


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