Re: [PATCH 3/3] Revert "xen/arm: Allocate memory for dom0 from the bottom with the 1:1 Workaround"

[Julien Grall <julien.grall@linaro.org>]

Hi Ian,

On 04/04/2014 01:56 PM, Ian Campbell wrote:
> This reverts commit 6c21cb36e263de2db8716b477157a5b6cd531e1e.
> 
> The Linux = issue which this works around was fixed in v3.13 via f52bb722547f
> "ARM: mm: Correct virt_to_phys patching for 64 bit physical addresses".
> 
> This is the second attempt to revert this. Now that we have fixed
> allocate_memory_11 to allocate accessible memory on 32-bit this is safe to do.
> This is not quite a straight revert since we need to ensure that for 32-bit
> domain 0 we do not allocate dom0's memory above 4GB where the domain cannot
> access it without paging (which is disabled at start of day) and LPAE (which
> the kernel may not support) enabled.

When multiple banks will be supported, I guess it will be safe to
allocate above 32bits (if dom0 has more than 4G) of RAM.

Anyway, it's not the goal of this patch :).

>  xen/arch/arm/domain_build.c |   16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
> index 4d6b26b..e7cc2c9 100644
> --- a/xen/arch/arm/domain_build.c
> +++ b/xen/arch/arm/domain_build.c
> @@ -69,19 +69,21 @@ static void allocate_memory_11(struct domain *d, struct kernel_info *kinfo)
>  {
>      paddr_t start;
>      paddr_t size;
> -    struct page_info *pg = NULL;
> +    struct page_info *pg;
>      unsigned int order = get_order_from_bytes(dom0_mem);
>      int res;
>      paddr_t spfn;
> -    unsigned int bits;
>  
> -    for ( bits = PAGE_SHIFT + 1; bits < PADDR_BITS; bits++ )
> +    if ( is_32bit_domain(d) )
>      {
> -        pg = alloc_domheap_pages(d, order, MEMF_bits(bits));
> -        if ( pg != NULL )
> -            break;
> +        printk("32 bit domain\n");

[..]

> +        printk("64 bit domain\n");

Can you be more explicit on both of theses messages? Nothing specify we
are allocate memory before them.

Regards,

-- 
Julien Grall