Re: [Xen-devel] [PATCH V2 2/2] xen/arm: mm: clean up code in setup_pagetables

[Julien Grall <julien.grall@xxxxxxx>]

Hi Peng,

Hi Peng,

On 12/05/16 03:01, Peng Fan wrote:
> In setup_pagetables, need to map BOOT_RELOC_VIRT_START
> in xen_second and boot_second, so we can merge the two
> pieces code into one code block.
There is a missing subject for "need". I would say:

"The base of address for the relocated xen needs to be mapped at the 
same virtual address (BOOT_RELOC_VIRT_START) in both the boot and 
runtime page tables. So we can merge the two pieces of code into on code 
block."
> Also no need to use write_pte when map BOOT_RELOC_VIRT_START
> in xen_second, because CPU0 is using boot page tables now.
>
> Signed-off-by: Peng Fan <van.freenix@xxxxxxxxx>
> Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
> Cc: Julien Grall <julien.grall@xxxxxxx>
> ---
>
> V2:
>   Follow Julien's comments:
>     split the V1 patch into two patches, this patch is the code movement part.
>
>   xen/arch/arm/mm.c | 10 ++++------
>   1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index addd699..0a4f845 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -443,11 +443,6 @@ void __init setup_pagetables(unsigned long 
> boot_phys_offset, paddr_t xen_paddr)
>       lpae_t pte, *p;
>       int i;
>
> -    /* Map the destination in the boot misc area. */
> -    dest_va = BOOT_RELOC_VIRT_START;
> -    pte = mfn_to_xen_entry(xen_paddr >> PAGE_SHIFT, WRITEALLOC);
> -    write_pte(xen_second + second_table_offset(dest_va), pte);
> -
>       /* Calculate virt-to-phys offset for the new location */
>       phys_offset = xen_paddr - (unsigned long) _start;
>
> @@ -494,9 +489,12 @@ void __init setup_pagetables(unsigned long 
> boot_phys_offset, paddr_t xen_paddr)
>       pte = boot_second[second_table_offset(BOOT_FDT_VIRT_START)];
>       xen_second[second_table_offset(BOOT_FDT_VIRT_START)] = pte;
>
> -    /* Map the destination in the boot misc area. */
> +    /* ... Boot Misc area for xen relocation */
>       dest_va = BOOT_RELOC_VIRT_START;
>       pte = mfn_to_xen_entry(xen_paddr >> PAGE_SHIFT, WRITEALLOC);
> +    /* Map the destination in xen_second. */
> +    xen_second[second_table_offset(dest_va)] = pte;
> +    /* Map the destination in boot_second. */
>       write_pte(boot_second + second_table_offset(dest_va), pte);
>       flush_xen_data_tlb_range_va_local(dest_va, SECOND_SIZE);
>   #ifdef CONFIG_ARM_64
Regards,

--
Julien Grall

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