Re: [RFC v2 2/6] xen/arm: implement support for XENMEM_maximum_gpfn hypercall

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

Hello Wei,

Thank you for the patch.

On 15/04/14 22:05, Wei Huang wrote:
> From: Jaeyong Yoo <jaeyong.yoo@samsung.com>
>
> This patch implements ddomain_get_maximum_gpfn by using max_mapped_gfn
> field of P2M struct. A support function to retrieve guest VM pfn range
> is also added.
>
> Signed-off-by: Evgeny Fedotov <e.fedotov@samsung.com>
> Signed-off-by: Wei Huang <w1.huang@samsung.com>
> ---
>   xen/arch/arm/mm.c        |   21 ++++++++++++++++++++-
>   xen/include/asm-arm/mm.h |    1 +
>   2 files changed, 21 insertions(+), 1 deletion(-)
>
> diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c
> index 362bc8d..473ad04 100644
> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -947,7 +947,11 @@ int page_is_ram_type(unsigned long mfn, unsigned long mem_type)
>
>   unsigned long domain_get_maximum_gpfn(struct domain *d)
>   {
> -    return -ENOSYS;
> +    paddr_t end;
> +
> +    domain_get_gpfn_range(d, NULL, &end);
> +
> +    return (unsigned long)end;
>   }
>
>   void share_xen_page_with_guest(struct page_info *page,
> @@ -1235,6 +1239,21 @@ int is_iomem_page(unsigned long mfn)
>           return 1;
>       return 0;
>   }
> +
> +/*
> + * Return start and end addresses of guest VM
> + */
> +void domain_get_gpfn_range(struct domain *d, paddr_t *start, paddr_t *end)

The content of the function doesn't match the name.

This function should return a PFN not an address.
Actually, libxc (i.e the return of domain_get_maximum_gpfn) expect a pfn.

> +{
> +    struct p2m_domain *p2m = &d->arch.p2m;
> +
> +    if ( start )
> +        *start = GUEST_RAM_BASE;

You can use  p2m->lowest_mapped_gfn here.

> +    if ( end )
> +        *end = GUEST_RAM_BASE + ((paddr_t) p2m->max_mapped_gfn);

This is wrong, max_mapped_gpfn contains a guest frame number, not a 
number of frames.

The code should be smth like:

*end = pfn_to_paddr(p2m->max_mapped_gfn);

Regards,

-- 
Julien Grall