Re: [PATCH 10/10] xen: arm: Use a direct mapping of RAM on arm64

[Julien Grall <julien.grall@citrix.com>]

On 06/18/2013 02:26 PM, Ian Campbell wrote:

> We have plenty of virtual address space so we can avoid needing to map and
> unmap pages all the time.
> 
> A totally arbitrarily chosen 32GB frame table leads to support for 5TB of RAM.
> I haven't tested with anything near that amount of RAM though. There is plenty
> of room to expand further when that becomes necessary.
> 
> Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
> ---
>  xen/arch/arm/mm.c            |  155 ++++++++++++++++++++++++++++++++++--------
>  xen/arch/arm/setup.c         |   92 +++++++++++++++++++++++++
>  xen/include/asm-arm/config.h |   96 +++++++++++++++++++-------
>  xen/include/asm-arm/mm.h     |   16 ++++
>  4 files changed, 307 insertions(+), 52 deletions(-)
> 
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index 5ad687f..35ef56d 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -37,6 +37,7 @@
>  #include <public/memory.h>
>  #include <xen/sched.h>
>  #include <xen/vmap.h>
> +#include <asm/early_printk.h>
>  #include <xsm/xsm.h>
>  #include <xen/pfn.h>
>  
> @@ -48,6 +49,14 @@ struct domain *dom_xen, *dom_io, *dom_cow;
>  lpae_t boot_pgtable[LPAE_ENTRIES] __attribute__((__aligned__(4096)));
>  #ifdef CONFIG_ARM_64
>  lpae_t boot_first[LPAE_ENTRIES] __attribute__((__aligned__(4096)));
> +/* The first page of the first level mapping of the xenheap. The
> + * subsequent xenheap first level pages are dynamically allocated, but
> + * we need this one to bootstrap ourselves. */
> +lpae_t xenheap_first_first[LPAE_ENTRIES] __attribute__((__aligned__(4096)));
> +/* The zeroeth level slot which uses xenheap_first_first. Used because
> + * setup_xenheap_mappings otherwise relies on mfn_to_virt which isn't
> + * valid for a non-xenheap mapping. */
> +static __initdata int xenheap_first_first_slot = -1;
>  #endif
>  
>  /*
> @@ -57,6 +66,9 @@ lpae_t boot_first[LPAE_ENTRIES] __attribute__((__aligned__(4096)));
>   * xen_second, xen_fixmap and xen_xenmap are shared between all PCPUs.
>   */
>  
> +#ifdef CONFIG_ARM_64
> +#define THIS_CPU_PGTABLE boot_pgtable
> +#else
>  /* Per-CPU pagetable pages */
>  /* xen_pgtable == root of the trie (zeroeth level on 64-bit, first on 32-bit) */
>  static DEFINE_PER_CPU(lpae_t *, xen_pgtable);
> @@ -65,6 +77,7 @@ static DEFINE_PER_CPU(lpae_t *, xen_pgtable);
>   * the second level pagetables which mapp the domheap region
>   * DOMHEAP_VIRT_START...DOMHEAP_VIRT_END in 2MB chunks. */
>  static DEFINE_PER_CPU(lpae_t *, xen_dommap);
> +#endif
>  
>  /* Common pagetable leaves */
>  /* Second level page tables.
> @@ -73,10 +86,16 @@ static DEFINE_PER_CPU(lpae_t *, xen_dommap);
>   * addresses from 0 to 0x7fffffff. Offsets into it are calculated
>   * with second_linear_offset(), not second_table_offset().
>   *
> - * Addresses 0x80000000 to 0xffffffff are covered by the per-cpu
> - * xen_domheap mappings described above. However we allocate 4 pages
> + * On 32bit addresses 0x80000000 to 0xffffffff are covered by the
> + * per-cpu xen_domheap mappings described above. We allocate 4 pages
>   * here for use in the boot page tables and the second two pages
>   * become the boot CPUs xen_dommap pages.
> + *
> + * On 64bit addresses 0x80000000 to 0xffffffff are unused. However we
> + * allocate 4 pages here for use while relocating Xen, which currently
> + * expects a second level page to exist for all addresses in the first
> + * 4GB. We need to keep these extra mappings in place for seconary CPU
> + * bring up too. For now we just leave them forever.
>   */
>  lpae_t xen_second[LPAE_ENTRIES*4] __attribute__((__aligned__(4096*4)));
>  /* First level page table used for fixmap */
> @@ -92,7 +111,7 @@ uint64_t boot_ttbr;
>  static paddr_t phys_offset;
>  
>  /* Limits of the Xen heap */
> -unsigned long xenheap_mfn_start __read_mostly;
> +unsigned long xenheap_mfn_start __read_mostly = ~0UL;
>  unsigned long xenheap_mfn_end __read_mostly;
>  unsigned long xenheap_virt_end __read_mostly;
>  
> @@ -112,7 +131,9 @@ static inline void check_memory_layout_alignment_constraints(void) {
>      BUILD_BUG_ON(BOOT_MISC_VIRT_START & ~SECOND_MASK);
>      /* 1GB aligned regions */
>      BUILD_BUG_ON(XENHEAP_VIRT_START & ~FIRST_MASK);
> +#ifdef CONFIG_DOMAIN_PAGE
>      BUILD_BUG_ON(DOMHEAP_VIRT_START & ~FIRST_MASK);
> +#endif
>  }
>  
>  void dump_pt_walk(lpae_t *first, paddr_t addr)
> @@ -180,6 +201,7 @@ void clear_fixmap(unsigned map)
>      flush_xen_data_tlb_range_va(FIXMAP_ADDR(map), PAGE_SIZE);
>  }
>  
> +#ifdef CONFIG_DOMAIN_PAGE
>  void *map_domain_page_global(unsigned long mfn)
>  {
>      return vmap(&mfn, 1);
> @@ -284,6 +306,7 @@ unsigned long domain_page_map_to_mfn(const void *va)
>  
>      return map[slot].pt.base + offset;
>  }
> +#endif
>  
>  void __init arch_init_memory(void)
>  {
> @@ -431,6 +454,7 @@ void __init setup_pagetables(unsigned long boot_phys_offset, paddr_t xen_paddr)
>      /* Flush everything after setting WXN bit. */
>      flush_xen_text_tlb();
>  
> +#ifdef CONFIG_ARM_32
>      per_cpu(xen_pgtable, 0) = boot_pgtable;
>      per_cpu(xen_dommap, 0) = xen_second +
>          second_linear_offset(DOMHEAP_VIRT_START);
> @@ -440,43 +464,31 @@ void __init setup_pagetables(unsigned long boot_phys_offset, paddr_t xen_paddr)
>      memset(this_cpu(xen_dommap), 0, DOMHEAP_SECOND_PAGES*PAGE_SIZE);
>      flush_xen_dcache_va_range(this_cpu(xen_dommap),
>                                DOMHEAP_SECOND_PAGES*PAGE_SIZE);
> +#endif
>  }
>  
>  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();
> +    /* All CPUs share a single page table on 64 bit */
> +    return 0;
>  #else
> -    first = root; /* root == first level on 32-bit 3-level trie */
> -#endif
> +    lpae_t *first, *domheap, pte;
> +    int i;
> +
> +    first = alloc_xenheap_page(); /* root == first level on 32-bit 3-level trie */
>      domheap = alloc_xenheap_pages(get_order_from_pages(DOMHEAP_SECOND_PAGES), 0);
>  
> -    if ( root == NULL || domheap == NULL || first == NULL )
> +    if ( 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
> +    memcpy(first, boot_pgtable, PAGE_SIZE);
>  
>      /* Ensure the domheap has no stray mappings */
>      memset(domheap, 0, DOMHEAP_SECOND_PAGES*PAGE_SIZE);
> @@ -490,16 +502,14 @@ int init_secondary_pagetables(int cpu)
>          write_pte(&first[first_table_offset(DOMHEAP_VIRT_START+i*FIRST_SIZE)], pte);
>      }
>  
> -    flush_xen_dcache_va_range(root, PAGE_SIZE);
> -#ifdef CONFIG_ARM_64
>      flush_xen_dcache_va_range(first, PAGE_SIZE);
> -#endif
>      flush_xen_dcache_va_range(domheap, DOMHEAP_SECOND_PAGES*PAGE_SIZE);
>  
> -    per_cpu(xen_pgtable, cpu) = root;
> +    per_cpu(xen_pgtable, cpu) = first;
>      per_cpu(xen_dommap, cpu) = domheap;
>  
>      return 0;
> +#endif
>  }
>  
>  /* MMU setup for secondary CPUS (which already have paging enabled) */
> @@ -544,6 +554,7 @@ static void __init create_32mb_mappings(lpae_t *second,
>      flush_xen_data_tlb();
>  }
>  
> +#ifdef CONFIG_ARM_32
>  /* Set up the xenheap: up to 1GB of contiguous, always-mapped memory. */
>  void __init setup_xenheap_mappings(unsigned long base_mfn,
>                                     unsigned long nr_mfns)
> @@ -556,19 +567,107 @@ void __init setup_xenheap_mappings(unsigned long base_mfn,
>      xenheap_mfn_end = base_mfn + nr_mfns;
>  }
>  
> +#else /* CONFIG_ARM_64 */
> +
> +void __init setup_xenheap_mappings(unsigned long base_mfn,
> +                                   unsigned long nr_mfns)
> +{
> +    lpae_t *first, pte;
> +    unsigned long offset, end_mfn;
> +    vaddr_t vaddr;
> +
> +    /* First call sets the xenheap physical offset. */
> +    if ( xenheap_mfn_start == ~0UL )
> +        xenheap_mfn_start = base_mfn;
> +
> +    if ( base_mfn < xenheap_mfn_start )
> +        early_panic("cannot add xenheap mapping at %lx below heap start %lx\n",
> +                    base_mfn, xenheap_mfn_start);
> +
> +    end_mfn = base_mfn + nr_mfns;
> +
> +    /* Align to previous 1GB boundary */
> +    base_mfn &= ~FIRST_MASK;
> +
> +    offset = base_mfn - xenheap_mfn_start;
> +    vaddr = DIRECTMAP_VIRT_START + offset*PAGE_SIZE;
> +
> +    while ( base_mfn < end_mfn )
> +    {
> +        int slot = zeroeth_table_offset(vaddr);
> +        lpae_t *p = &boot_pgtable[slot];
> +
> +        if ( p->pt.valid )
> +        {
> +            /* mfn_to_virt is not valid on the 1st 1st mfn, since it
> +             * is not within the xenheap. */
> +            first = slot == xenheap_first_first_slot ?
> +                xenheap_first_first : mfn_to_virt(p->pt.base);
> +        }
> +        else if ( xenheap_first_first_slot == -1)
> +        {
> +            /* Use xenheap_first_first to bootstrap the mappings */
> +            first = xenheap_first_first;
> +
> +            pte = pte_of_xenaddr((vaddr_t)xenheap_first_first);
> +            pte.pt.table = 1;
> +            write_pte(p, pte);
> +
> +            xenheap_first_first_slot = slot;
> +        }
> +        else
> +        {
> +            unsigned long first_mfn = alloc_boot_pages(1, 1);
> +            pte = mfn_to_xen_entry(first_mfn);
> +            pte.pt.table = 1;
> +            write_pte(p, pte);
> +            first = mfn_to_virt(first_mfn);
> +        }
> +
> +        pte = mfn_to_xen_entry(base_mfn);
> +        //pte.pt.contig = /* XXX need to think about the logic */
> +        write_pte(&first[first_table_offset(vaddr)], pte);
> +
> +        base_mfn += FIRST_SIZE>>PAGE_SHIFT;
> +        vaddr += FIRST_SIZE;
> +    }
> +
> +    flush_xen_data_tlb();
> +}
> +#endif
> +
>  /* Map a frame table to cover physical addresses ps through pe */
>  void __init setup_frametable_mappings(paddr_t ps, paddr_t pe)
>  {
>      unsigned long nr_pages = (pe - ps) >> PAGE_SHIFT;
>      unsigned long frametable_size = nr_pages * sizeof(struct page_info);
>      unsigned long base_mfn;
> +#ifdef CONFIG_ARM_64
> +    lpae_t *second, pte;
> +    unsigned long nr_second, second_base;
> +    int i;
> +#endif
>  
>      frametable_base_mfn = ps >> PAGE_SHIFT;
>  
>      /* Round up to 32M boundary */
>      frametable_size = (frametable_size + 0x1ffffff) & ~0x1ffffff;
>      base_mfn = alloc_boot_pages(frametable_size >> PAGE_SHIFT, 32<<(20-12));
> +
> +#ifdef CONFIG_ARM_64
> +    nr_second = frametable_size >> SECOND_SHIFT;
> +    second_base = alloc_boot_pages(nr_second, 1);
> +    second = mfn_to_virt(second_base);
> +    for ( i = 0; i < nr_second; i++ )
> +    {
> +        pte = mfn_to_xen_entry(second_base + i);
> +        pte.pt.table = 1;
> +        write_pte(&boot_first[first_table_offset(FRAMETABLE_VIRT_START)+i], pte);
> +    }
> +    create_32mb_mappings(second, 0, base_mfn, frametable_size >> PAGE_SHIFT);
> +#else
>      create_32mb_mappings(xen_second, FRAMETABLE_VIRT_START, base_mfn, frametable_size >> PAGE_SHIFT);
> +#endif
>  
>      memset(&frame_table[0], 0, nr_pages * sizeof(struct page_info));
>      memset(&frame_table[nr_pages], -1,
> diff --git a/xen/arch/arm/setup.c b/xen/arch/arm/setup.c
> index da2a734..3efa063 100644
> --- a/xen/arch/arm/setup.c
> +++ b/xen/arch/arm/setup.c
> @@ -279,6 +279,7 @@ static paddr_t __init get_xen_paddr(void)
>      return paddr;
>  }
>  
> +#ifdef CONFIG_ARM_32
>  static void __init setup_mm(unsigned long dtb_paddr, size_t dtb_size)
>  {
>      paddr_t ram_start;
> @@ -392,6 +393,97 @@ static void __init setup_mm(unsigned long dtb_paddr, size_t dtb_size)
>  
>      end_boot_allocator();
>  }
> +#else /* CONFIG_ARM_64 */
> +static void __init setup_mm(unsigned long dtb_paddr, size_t dtb_size)
> +{
> +    paddr_t ram_start = ~0;
> +    paddr_t ram_end = 0;
> +    int bank;
> +    unsigned long  xenheap_pages = 0;
> +    unsigned long dtb_pages;
> +
> +    /*
> +     * TODO: only using the first RAM bank for now.  The heaps and the
> +     * frame table assume RAM is physically contiguous.
> +     */
> +    total_pages = 0;
> +    for ( bank = 0 ; bank < early_info.mem.nr_banks; bank++ )
> +    {
> +        paddr_t bank_start = early_info.mem.bank[bank].start;
> +        paddr_t bank_size  = early_info.mem.bank[bank].size;
> +        paddr_t  bank_end = bank_start + bank_size;
> +        unsigned long bank_pages = bank_size >> PAGE_SHIFT;
> +        paddr_t s, e;
> +
> +        total_pages += bank_pages;
> +
> +        if ( bank_start < ram_start )
> +            ram_start = bank_start;
> +        if ( bank_end > ram_end )
> +            ram_end = bank_end;
> +
> +        /*
> +         * Locate the xenheap using these constraints:
> +         *
> +         *  - must be 32 MiB aligned
> +         *  - must not include Xen itself or the boot modules
> +         *  - must be at most 1 GiB
> +         *  - must be at least 128M
> +         *
> +         * We try to allocate the largest xenheap possible within these
> +         * constraints.
> +         */
> +        xenheap_pages += (bank_size >> PAGE_SHIFT);
> +
> +        /* XXX we assume that the ram regions are ordered */
> +        s = bank_start;
> +        while ( s < bank_end )
> +        {
> +            paddr_t n = bank_end;
> +
> +            e = next_module(s, &n);
> +
> +            if ( e == ~(paddr_t)0 )
> +            {
> +                e = n = bank_end;
> +            }
> +
> +            setup_xenheap_mappings(s>>PAGE_SHIFT, (e-s)>>PAGE_SHIFT);
> +
> +            xenheap_mfn_end = e;
> +
> +            init_boot_pages(s, e);
> +            s = n;
> +        }
> +    }
> +
> +    xenheap_virt_end = XENHEAP_VIRT_START + ram_end - ram_start;
> +    xenheap_mfn_start = ram_start >> PAGE_SHIFT;
> +    xenheap_mfn_end = ram_end >> PAGE_SHIFT;
> +    xenheap_max_mfn(xenheap_mfn_end);
> +
> +    /*
> +     * Need enough mapped pages for copying the DTB.
> +     *
> +     * TODO: The DTB (and other payloads) are assumed to be towards
> +     * the start of RAM.
> +     */
> +    dtb_pages = (dtb_size + PAGE_SIZE-1) >> PAGE_SHIFT;
> +
> +    /*
> +     * Copy the DTB.
> +     *
> +     * TODO: handle other payloads too.
> +     */
> +    device_tree_flattened = mfn_to_virt(alloc_boot_pages(dtb_pages, 1));
> +    copy_from_paddr(device_tree_flattened, dtb_paddr, dtb_size, BUFFERABLE);
> +
> +    setup_frametable_mappings(ram_start, ram_end);
> +    max_page = PFN_DOWN(ram_end);
> +
> +    end_boot_allocator();
> +}
> +#endif
>  
>  size_t __read_mostly cacheline_bytes;
>  
> diff --git a/xen/include/asm-arm/config.h b/xen/include/asm-arm/config.h
> index fb9e93c..259d4c6 100644
> --- a/xen/include/asm-arm/config.h
> +++ b/xen/include/asm-arm/config.h
> @@ -35,9 +35,6 @@
>  
>  #define CONFIG_SMP 1
>  
> -#define CONFIG_DOMAIN_PAGE 1
> -#define CONFIG_SEPARATE_XENHEAP 1
> -
>  #define CONFIG_VIDEO 1
>  
>  #define OPT_CONSOLE_STR "dtuart"
> @@ -76,38 +73,89 @@
>  #include <xen/const.h>
>  
>  /*
> - * Memory layout:
> - *  0  -   2M   Unmapped
> - *  2M -   4M   Xen text, data, bss
> - *  4M -   6M   Fixmap: special-purpose 4K mapping slots
> - *  6M  -  8M   Early boot misc (see below)
> - *
> - * 32M - 128M   Frametable: 24 bytes per page for 16GB of RAM
> - * 256M -  1G   VMAP: ioremap and early_ioremap use this virtual address
> - *                    space
> - *
> - *  1G -   2G   Xenheap: always-mapped memory
> - *  2G -   4G   Domheap: on-demand-mapped
> + * Common ARM32 and ARM64 layout:
> + *   0  -   2M   Unmapped
> + *   2M -   4M   Xen text, data, bss
> + *   4M -   6M   Fixmap: special-purpose 4K mapping slots
> + *   6M -   8M   Early boot misc (see below)
>   *
>   * The early boot misc area is used:
>   *   - in head.S for the DTB for device_tree_early_init().
>   *   - in setup_pagetables() when relocating Xen.
> + *
> + * ARM32 layout:
> + *   0  -   8M   <COMMON>
> + *
> + *  32M - 128M   Frametable: 24 bytes per page for 16GB of RAM
> + * 256M -   1G   VMAP: ioremap and early_ioremap use this virtual address
> + *                    space
> + *
> + *   1G -   2G   Xenheap: always-mapped memory
> + *   2G -   4G   Domheap: on-demand-mapped
> + *
> + * ARM64 layout:
> + * 0x0000000000000000 - 0x0000007fffffffff (512GB, L0 slot [0])
> + *   0  -   8M   <COMMON>
> + *
> + *   1G -   2G   VMAP: ioremap and early_ioremap
> + *
> + *  32G -  64G   Frametable: 24 bytes per page for 5.3TB of RAM
> + *
> + * 0x0000008000000000 - 0x00007fffffffffff (127.5TB, L0 slots [1..255])
> + *  Unused
> + *
> + * 0x0000800000000000 - 0x000084ffffffffff (5TB, L0 slots [256..265])
> + *  1:1 mapping of RAM
> + *
> + * 0x0000850000000000 - 0x0000ffffffffffff (123TB, L0 slots [266..511])
> + *  Unused
>   */
>  
> -#define XEN_VIRT_START         _AC(0x00200000,UL)
> -#define FIXMAP_ADDR(n)        (_AC(0x00400000,UL) + (n) * PAGE_SIZE)
> -#define BOOT_MISC_VIRT_START   _AC(0x00600000,UL)
> -#define FRAMETABLE_VIRT_START  _AC(0x02000000,UL)
> -#define VMAP_VIRT_START        _AC(0x10000000,UL)
> -#define XENHEAP_VIRT_START     _AC(0x40000000,UL)
> -#define DOMHEAP_VIRT_START     _AC(0x80000000,UL)
> -#define DOMHEAP_VIRT_END       _AC(0xffffffff,UL)
> +#define XEN_VIRT_START         _AT(vaddr_t,0x00200000)
> +#define FIXMAP_ADDR(n)        (_AT(vaddr_t,0x00400000) + (n) * PAGE_SIZE)
> +#define BOOT_MISC_VIRT_START   _AT(vaddr_t,0x00600000)
>  
> -#define VMAP_VIRT_END          XENHEAP_VIRT_START
>  #define HYPERVISOR_VIRT_START  XEN_VIRT_START
>  
> +#ifdef CONFIG_ARM_32
> +
> +#define CONFIG_DOMAIN_PAGE 1
> +#define CONFIG_SEPARATE_XENHEAP 1
> +
> +#define FRAMETABLE_VIRT_START  _AT(vaddr_t,0x02000000)
> +#define VMAP_VIRT_START  _AT(vaddr_t,0x10000000)
> +#define XENHEAP_VIRT_START     _AT(vaddr_t,0x40000000)
> +#define XENHEAP_VIRT_END       _AT(vaddr_t,0x7fffffff)
> +#define DOMHEAP_VIRT_START     _AT(vaddr_t,0x80000000)
> +#define DOMHEAP_VIRT_END       _AT(vaddr_t,0xffffffff)
> +
> +#define VMAP_VIRT_END    XENHEAP_VIRT_START
> +
>  #define DOMHEAP_ENTRIES        1024  /* 1024 2MB mapping slots */
>  
> +#else /* ARM_64 */
> +
> +#define SLOT0_ENTRY_BITS  39
> +#define SLOT0(slot) (_AT(vaddr_t,slot) << SLOT0_ENTRY_BITS)
> +#define SLOT0_ENTRY_SIZE  SLOT0(1)
> +#define GB(_gb)     (_AC(_gb, UL) << 30)
> +
> +#define VMAP_VIRT_START  GB(1)
> +#define VMAP_VIRT_END    (VMAP_VIRT_START + GB(1) - 1)
> +
> +#define FRAMETABLE_VIRT_START  GB(32)
> +#define FRAMETABLE_VIRT_END    (FRAMETABLE_VIRT_START + GB(32) - 1)
> +
> +#define DIRECTMAP_VIRT_START   SLOT0(256)
> +#define DIRECTMAP_SIZE         (SLOT0_ENTRY_SIZE * (265-256))
> +#define DIRECTMAP_VIRT_END     (DIRECTMAP_VIRT_START + DIRECTMAP_SIZE - 1)
> +
> +#define XENHEAP_VIRT_START     DIRECTMAP_VIRT_START
> +
> +#define HYPERVISOR_VIRT_END    DIRECTMAP_VIRT_END
> +
> +#endif
> +
>  /* Number of domheap pagetable pages required at the second level (2MB mappings) */
>  #define DOMHEAP_SECOND_PAGES ((DOMHEAP_VIRT_END - DOMHEAP_VIRT_START + 1) >> FIRST_SHIFT)
>  
> diff --git a/xen/include/asm-arm/mm.h b/xen/include/asm-arm/mm.h
> index 7aca836..27284d0 100644
> --- a/xen/include/asm-arm/mm.h
> +++ b/xen/include/asm-arm/mm.h
> @@ -118,11 +118,18 @@ struct page_info
>  extern unsigned long xenheap_mfn_start, xenheap_mfn_end;
>  extern unsigned long xenheap_virt_end;
>  
> +#ifdef CONFIG_ARM_32
>  #define is_xen_heap_page(page) is_xen_heap_mfn(page_to_mfn(page))
>  #define is_xen_heap_mfn(mfn) ({                                 \
>      unsigned long _mfn = (mfn);                                 \
>      (_mfn >= xenheap_mfn_start && _mfn < xenheap_mfn_end);      \
>  })
> +#else
> +#define is_xen_heap_page(page) ((page)->count_info & PGC_xen_heap)
> +#define is_xen_heap_mfn(mfn) \
> +    (mfn_valid(mfn) && is_xen_heap_page(__mfn_to_page(mfn)))
> +#endif
> +
>  #define is_xen_fixed_mfn(mfn)                                   \
>      ((((mfn) << PAGE_SHIFT) >= virt_to_maddr(&_start)) &&       \
>       (((mfn) << PAGE_SHIFT) <= virt_to_maddr(&_end)))
> @@ -215,12 +222,21 @@ static inline paddr_t __virt_to_maddr(vaddr_t va)
>  }
>  #define virt_to_maddr(va)   __virt_to_maddr((vaddr_t)(va))
>  
> +#ifdef CONFIG_ARM_32
>  static inline void *maddr_to_virt(paddr_t ma)
>  {
>      ASSERT(is_xen_heap_mfn(ma >> PAGE_SHIFT));
>      ma -= pfn_to_paddr(xenheap_mfn_start);
>      return (void *)(unsigned long) ma + XENHEAP_VIRT_START;
>  }
> +#else
> +static inline void *maddr_to_virt(paddr_t ma)
> +{
> +    ASSERT((ma >> PAGE_SHIFT) < (DIRECTMAP_SIZE >> PAGE_SHIFT));
> +    ma -= pfn_to_paddr(xenheap_mfn_start);
> +    return (void *)(unsigned long) ma + DIRECTMAP_VIRT_START;
> +}
> +#endif


I'm curious, this is not specific to this patch, why don't you split the
file in 3 parts (common, arm32, arm64)?

>From what I've seen, we use the both way on Xen. I think it's clearer to
divide the code in different headers/sources files. Sometimes defines
are hard to follow.

-- 
Julien