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Re: [Xen-devel] [PATCH 20/27] xen/arm: page: Use ARMv8 naming to improve readability



Hi,

On 14/08/17 15:24, Julien Grall wrote:
> This is based on the Linux ARMv8 naming scheme (see arch/arm64/mm/proc.S). 
> Each
> type will contain "NORMAL" or "DEVICE" to make clear whether each attribute
> targets device or normal memory.

Yes, that makes sense and improves readability as the naming matches the
spec and is more intuitive. Also it looks correct to me.

However I feel it would be more helpful is this patches comes before the
previous one which reworks the MAIR construction.

However for this patch:

> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>

Reviewed-by: Andre Przywara <andre.przywara@xxxxxxx>

Cheers,
Andre.

> ---
>  xen/arch/arm/kernel.c             |  2 +-
>  xen/arch/arm/mm.c                 | 28 +++++++++++++-------------
>  xen/arch/arm/platforms/vexpress.c |  2 +-
>  xen/drivers/video/arm_hdlcd.c     |  2 +-
>  xen/include/asm-arm/page.h        | 42 
> +++++++++++++++++++--------------------
>  5 files changed, 38 insertions(+), 38 deletions(-)
> 
> diff --git a/xen/arch/arm/kernel.c b/xen/arch/arm/kernel.c
> index 9c183f96da..a12baa86e7 100644
> --- a/xen/arch/arm/kernel.c
> +++ b/xen/arch/arm/kernel.c
> @@ -54,7 +54,7 @@ void copy_from_paddr(void *dst, paddr_t paddr, unsigned 
> long len)
>          s = paddr & (PAGE_SIZE-1);
>          l = min(PAGE_SIZE - s, len);
>  
> -        set_fixmap(FIXMAP_MISC, maddr_to_mfn(paddr), MT_BUFFERABLE);
> +        set_fixmap(FIXMAP_MISC, maddr_to_mfn(paddr), MT_NORMAL_NC);
>          memcpy(dst, src + s, l);
>          clean_dcache_va_range(dst, l);
>  
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index 45974846a9..ce1858fbf3 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -290,7 +290,7 @@ static inline lpae_t mfn_to_xen_entry(mfn_t mfn, unsigned 
> attr)
>  
>      switch ( attr )
>      {
> -    case MT_BUFFERABLE:
> +    case MT_NORMAL_NC:
>          /*
>           * ARM ARM: Overlaying the shareability attribute (DDI
>           * 0406C.b B3-1376 to 1377)
> @@ -305,8 +305,8 @@ static inline lpae_t mfn_to_xen_entry(mfn_t mfn, unsigned 
> attr)
>           */
>          e.pt.sh = LPAE_SH_OUTER;
>          break;
> -    case MT_UNCACHED:
> -    case MT_DEV_SHARED:
> +    case MT_DEVICE_nGnRnE:
> +    case MT_DEVICE_nGnRE:
>          /*
>           * Shareability is ignored for non-Normal memory, Outer is as
>           * good as anything.
> @@ -369,7 +369,7 @@ static void __init create_mappings(lpae_t *second,
>  
>      count = nr_mfns / LPAE_ENTRIES;
>      p = second + second_linear_offset(virt_offset);
> -    pte = mfn_to_xen_entry(_mfn(base_mfn), MT_WRITEALLOC);
> +    pte = mfn_to_xen_entry(_mfn(base_mfn), MT_NORMAL);
>      if ( granularity == 16 * LPAE_ENTRIES )
>          pte.pt.contig = 1;  /* These maps are in 16-entry contiguous chunks. 
> */
>      for ( i = 0; i < count; i++ )
> @@ -422,7 +422,7 @@ void *map_domain_page(mfn_t mfn)
>          else if ( map[slot].pt.avail == 0 )
>          {
>              /* Commandeer this 2MB slot */
> -            pte = mfn_to_xen_entry(_mfn(slot_mfn), MT_WRITEALLOC);
> +            pte = mfn_to_xen_entry(_mfn(slot_mfn), MT_NORMAL);
>              pte.pt.avail = 1;
>              write_pte(map + slot, pte);
>              break;
> @@ -543,7 +543,7 @@ static inline lpae_t pte_of_xenaddr(vaddr_t va)
>  {
>      paddr_t ma = va + phys_offset;
>  
> -    return mfn_to_xen_entry(maddr_to_mfn(ma), MT_WRITEALLOC);
> +    return mfn_to_xen_entry(maddr_to_mfn(ma), MT_NORMAL);
>  }
>  
>  /* Map the FDT in the early boot page table */
> @@ -652,7 +652,7 @@ void __init setup_pagetables(unsigned long 
> boot_phys_offset, paddr_t xen_paddr)
>      /* Initialise xen second level entries ... */
>      /* ... Xen's text etc */
>  
> -    pte = mfn_to_xen_entry(maddr_to_mfn(xen_paddr), MT_WRITEALLOC);
> +    pte = mfn_to_xen_entry(maddr_to_mfn(xen_paddr), MT_NORMAL);
>      pte.pt.xn = 0;/* Contains our text mapping! */
>      xen_second[second_table_offset(XEN_VIRT_START)] = pte;
>  
> @@ -669,7 +669,7 @@ void __init setup_pagetables(unsigned long 
> boot_phys_offset, paddr_t xen_paddr)
>  
>      /* ... Boot Misc area for xen relocation */
>      dest_va = BOOT_RELOC_VIRT_START;
> -    pte = mfn_to_xen_entry(maddr_to_mfn(xen_paddr), MT_WRITEALLOC);
> +    pte = mfn_to_xen_entry(maddr_to_mfn(xen_paddr), MT_NORMAL);
>      /* Map the destination in xen_second. */
>      xen_second[second_table_offset(dest_va)] = pte;
>      /* Map the destination in boot_second. */
> @@ -700,7 +700,7 @@ void __init setup_pagetables(unsigned long 
> boot_phys_offset, paddr_t xen_paddr)
>          unsigned long va = XEN_VIRT_START + (i << PAGE_SHIFT);
>          if ( !is_kernel(va) )
>              break;
> -        pte = mfn_to_xen_entry(mfn, MT_WRITEALLOC);
> +        pte = mfn_to_xen_entry(mfn, MT_NORMAL);
>          pte.pt.table = 1; /* 4k mappings always have this bit set */
>          if ( is_kernel_text(va) || is_kernel_inittext(va) )
>          {
> @@ -771,7 +771,7 @@ int init_secondary_pagetables(int cpu)
>      for ( i = 0; i < DOMHEAP_SECOND_PAGES; i++ )
>      {
>          pte = mfn_to_xen_entry(virt_to_mfn(domheap+i*LPAE_ENTRIES),
> -                               MT_WRITEALLOC);
> +                               MT_NORMAL);
>          pte.pt.table = 1;
>          
> write_pte(&first[first_table_offset(DOMHEAP_VIRT_START+i*FIRST_SIZE)], pte);
>      }
> @@ -869,13 +869,13 @@ void __init setup_xenheap_mappings(unsigned long 
> base_mfn,
>              mfn_t first_mfn = alloc_boot_pages(1, 1);
>  
>              clear_page(mfn_to_virt(first_mfn));
> -            pte = mfn_to_xen_entry(first_mfn, MT_WRITEALLOC);
> +            pte = mfn_to_xen_entry(first_mfn, MT_NORMAL);
>              pte.pt.table = 1;
>              write_pte(p, pte);
>              first = mfn_to_virt(first_mfn);
>          }
>  
> -        pte = mfn_to_xen_entry(_mfn(mfn), MT_WRITEALLOC);
> +        pte = mfn_to_xen_entry(_mfn(mfn), MT_NORMAL);
>          /* TODO: Set pte.pt.contig when appropriate. */
>          write_pte(&first[first_table_offset(vaddr)], pte);
>  
> @@ -915,7 +915,7 @@ void __init setup_frametable_mappings(paddr_t ps, paddr_t 
> pe)
>      for ( i = 0; i < nr_second; i++ )
>      {
>          clear_page(mfn_to_virt(mfn_add(second_base, i)));
> -        pte = mfn_to_xen_entry(mfn_add(second_base, i), MT_WRITEALLOC);
> +        pte = mfn_to_xen_entry(mfn_add(second_base, i), MT_NORMAL);
>          pte.pt.table = 1;
>          write_pte(&xen_first[first_table_offset(FRAMETABLE_VIRT_START)+i], 
> pte);
>      }
> @@ -969,7 +969,7 @@ static int create_xen_table(lpae_t *entry)
>      if ( p == NULL )
>          return -ENOMEM;
>      clear_page(p);
> -    pte = mfn_to_xen_entry(virt_to_mfn(p), MT_WRITEALLOC);
> +    pte = mfn_to_xen_entry(virt_to_mfn(p), MT_NORMAL);
>      pte.pt.table = 1;
>      write_pte(entry, pte);
>      return 0;
> diff --git a/xen/arch/arm/platforms/vexpress.c 
> b/xen/arch/arm/platforms/vexpress.c
> index 9badbc079d..df2c4b5bec 100644
> --- a/xen/arch/arm/platforms/vexpress.c
> +++ b/xen/arch/arm/platforms/vexpress.c
> @@ -65,7 +65,7 @@ int vexpress_syscfg(int write, int function, int device, 
> uint32_t *data)
>      uint32_t *syscfg = (uint32_t *) FIXMAP_ADDR(FIXMAP_MISC);
>      int ret = -1;
>  
> -    set_fixmap(FIXMAP_MISC, maddr_to_mfn(V2M_SYS_MMIO_BASE), MT_DEV_SHARED);
> +    set_fixmap(FIXMAP_MISC, maddr_to_mfn(V2M_SYS_MMIO_BASE), 
> MT_DEVICE_nGnRE);
>  
>      if ( syscfg[V2M_SYS_CFGCTRL/4] & V2M_SYS_CFG_START )
>          goto out;
> diff --git a/xen/drivers/video/arm_hdlcd.c b/xen/drivers/video/arm_hdlcd.c
> index 5fa7f518b1..1175399dbc 100644
> --- a/xen/drivers/video/arm_hdlcd.c
> +++ b/xen/drivers/video/arm_hdlcd.c
> @@ -227,7 +227,7 @@ void __init video_init(void)
>      /* uses FIXMAP_MISC */
>      set_pixclock(videomode->pixclock);
>  
> -    set_fixmap(FIXMAP_MISC, maddr_to_mfn(hdlcd_start), MT_DEV_SHARED);
> +    set_fixmap(FIXMAP_MISC, maddr_to_mfn(hdlcd_start), MT_DEVICE_nGnRE);
>      HDLCD[HDLCD_COMMAND] = 0;
>  
>      HDLCD[HDLCD_LINELENGTH] = videomode->xres * bytes_per_pixel;
> diff --git a/xen/include/asm-arm/page.h b/xen/include/asm-arm/page.h
> index 86b227c291..d9dac92e73 100644
> --- a/xen/include/asm-arm/page.h
> +++ b/xen/include/asm-arm/page.h
> @@ -29,43 +29,43 @@
>   * registers, as defined above.
>   *
>   */
> -#define MT_UNCACHED      0x0
> -#define MT_BUFFERABLE    0x1
> -#define MT_WRITETHROUGH  0x2
> -#define MT_WRITEBACK     0x3
> -#define MT_DEV_SHARED    0x4
> -#define MT_WRITEALLOC    0x7
> +#define MT_DEVICE_nGnRnE 0x0
> +#define MT_NORMAL_NC     0x1
> +#define MT_NORMAL_WT     0x2
> +#define MT_NORMAL_WB     0x3
> +#define MT_DEVICE_nGnRE  0x4
> +#define MT_NORMAL        0x7
>  
>  /*
>   * LPAE Memory region attributes. Indexed by the AttrIndex bits of a
>   * LPAE entry; the 8-bit fields are packed little-endian into MAIR0 and 
> MAIR1.
>   *
>   *                    ai    encoding
> - *   MT_UNCACHED      000   0000 0000  -- Strongly Ordered
> - *   MT_BUFFERABLE    001   0100 0100  -- Non-Cacheable
> - *   MT_WRITETHROUGH  010   1010 1010  -- Write-through
> - *   MT_WRITEBACK     011   1110 1110  -- Write-back
> - *   MT_DEV_SHARED    100   0000 0100  -- Device
> + *   MT_DEVICE_nGnRE  000   0000 0000  -- Strongly Ordered/Device nGnRnE
> + *   MT_NORMAL_NC     001   0100 0100  -- Non-Cacheable
> + *   MT_NORMAL_WT     010   1010 1010  -- Write-through
> + *   MT_NORMAL_WB     011   1110 1110  -- Write-back
> + *   MT_DEVICE_nGnRE  100   0000 0100  -- Device nGnRE
>   *   ??               101
>   *   reserved         110
> - *   MT_WRITEALLOC    111   1111 1111  -- Write-back write-allocate
> + *   MT_NORMAL        111   1111 1111  -- Write-back write-allocate
>   *
>   */
>  #define MAIR(attr, mt) (_AC(attr, ULL) << ((mt) * 8))
>  
> -#define MAIRVAL (MAIR(0x00, MT_UNCACHED)     | \
> -                 MAIR(0x44, MT_BUFFERABLE)   | \
> -                 MAIR(0xaa, MT_WRITETHROUGH) | \
> -                 MAIR(0xee, MT_WRITEBACK)    | \
> -                 MAIR(0x04, MT_DEV_SHARED)   | \
> -                 MAIR(0xff, MT_WRITEALLOC))
> +#define MAIRVAL (MAIR(0x00, MT_DEVICE_nGnRnE)| \
> +                 MAIR(0x44, MT_NORMAL_NC)    | \
> +                 MAIR(0xaa, MT_NORMAL_WT)    | \
> +                 MAIR(0xee, MT_NORMAL_WB)    | \
> +                 MAIR(0x04, MT_DEVICE_nGnRE) | \
> +                 MAIR(0xff, MT_NORMAL))
>  
>  #define MAIR0VAL (MAIRVAL & 0xffffffff)
>  #define MAIR1VAL (MAIRVAL >> 32)
>  
> -#define PAGE_HYPERVISOR         (MT_WRITEALLOC)
> -#define PAGE_HYPERVISOR_NOCACHE (MT_DEV_SHARED)
> -#define PAGE_HYPERVISOR_WC      (MT_BUFFERABLE)
> +#define PAGE_HYPERVISOR         (MT_NORMAL)
> +#define PAGE_HYPERVISOR_NOCACHE (MT_DEVICE_nGnRE)
> +#define PAGE_HYPERVISOR_WC      (MT_NORMAL_NC)
>  
>  /*
>   * Defines for changing the hypervisor PTE .ro and .nx bits. This is only to 
> be
> 

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