Re: [PATCH 05/16] xen/arm: mm: Re-implement early_fdt_map() using map_pages_to_xen()

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Fri, 20 May 2022, Julien Grall wrote:
> From: Julien Grall <julien.grall@xxxxxxx>
> 
> Now that map_pages_to_xen() has been extended to support 2MB mappings,
> we can replace the create_mappings() calls by map_pages_to_xen() calls.
> 
> The mapping can also be marked read-only as Xen should not modify
> the host Device Tree during boot.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
> Reviewed-by: Hongda Deng <Hongda.Heng@xxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
>     Changes in v4:
>         - Fix typo in the commit message
>         - Add Hongda's reviewed-by
> 
>     Changes in v2:
>         - Add my AWS signed-off-by
>         - Fix typo in the commit message
> ---
>  xen/arch/arm/mm.c | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index 64a79d45b38c..03f970e4d10b 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -574,6 +574,7 @@ void * __init early_fdt_map(paddr_t fdt_paddr)
>      paddr_t offset;
>      void *fdt_virt;
>      uint32_t size;
> +    int rc;
>  
>      /*
>       * Check whether the physical FDT address is set and meets the minimum
> @@ -589,8 +590,12 @@ void * __init early_fdt_map(paddr_t fdt_paddr)
>      /* The FDT is mapped using 2MB superpage */
>      BUILD_BUG_ON(BOOT_FDT_VIRT_START % SZ_2M);
>  
> -    create_mappings(xen_second, BOOT_FDT_VIRT_START, 
> paddr_to_pfn(base_paddr),
> -                    SZ_2M >> PAGE_SHIFT, SZ_2M);
> +    rc = map_pages_to_xen(BOOT_FDT_VIRT_START, maddr_to_mfn(base_paddr),
> +                          SZ_2M >> PAGE_SHIFT,
> +                          PAGE_HYPERVISOR_RO | _PAGE_BLOCK);
> +    if ( rc )
> +        panic("Unable to map the device-tree.\n");
> +
>  
>      offset = fdt_paddr % SECOND_SIZE;
>      fdt_virt = (void *)BOOT_FDT_VIRT_START + offset;
> @@ -604,9 +609,12 @@ void * __init early_fdt_map(paddr_t fdt_paddr)
>  
>      if ( (offset + size) > SZ_2M )
>      {
> -        create_mappings(xen_second, BOOT_FDT_VIRT_START + SZ_2M,
> -                        paddr_to_pfn(base_paddr + SZ_2M),
> -                        SZ_2M >> PAGE_SHIFT, SZ_2M);
> +        rc = map_pages_to_xen(BOOT_FDT_VIRT_START + SZ_2M,
> +                              maddr_to_mfn(base_paddr + SZ_2M),
> +                              SZ_2M >> PAGE_SHIFT,
> +                              PAGE_HYPERVISOR_RO | _PAGE_BLOCK);
> +        if ( rc )
> +            panic("Unable to map the device-tree\n");
>      }
>  
>      return fdt_virt;
> -- 
> 2.32.0
>