Re: [Xen-devel] [PATCH v4 23/24] xen/arm: Add a hypercall for device mmio mapping

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 28.02.16 at 12:19, <zhaoshenglong@xxxxxxxxxx> wrote:
> It needs to map platform or amba device mmio to Dom0 on ARM. But when
> booting with ACPI, it can't get the mmio region in Xen due to lack of
> AML interpreter to parse DSDT table. Therefore, let Dom0 call a
> hypercall to map mmio region when it adds the devices.

Leaving aside the fact that XEN_DOMCTL_memory_mapping is not
meant to be called by other than the tools - is there anything here
which that hypercall wouldn't provide? If not, I think the commit
message should reference that hypercall too while rationalizing
the need for this new map space.

> ---
>  xen/arch/arm/mm.c           |  4 ++++
>  xen/arch/arm/p2m.c          | 23 +++++++++++++++++++++++
>  xen/common/memory.c         | 14 ++++++++++++++
>  xen/include/asm-arm/p2m.h   |  5 +++++
>  xen/include/public/memory.h |  1 +
>  5 files changed, 47 insertions(+)

This touches code with no maintainers Cc-ed.

> --- a/xen/arch/arm/mm.c
> +++ b/xen/arch/arm/mm.c
> @@ -1138,6 +1138,10 @@ int xenmem_add_to_physmap_one(
>          rcu_unlock_domain(od);
>          break;
>      }
> +    case XENMAPSPACE_dev_mmio:
> +        rc = map_dev_mmio_region(d, gpfn, 1, idx);
> +        return rc;
> +        break;

Dead code.

> --- a/xen/common/memory.c
> +++ b/xen/common/memory.c
> @@ -980,6 +980,13 @@ long do_memory_op(unsigned long cmd, 
> XEN_GUEST_HANDLE_PARAM(void) arg)
>          if ( d == NULL )
>              return -ESRCH;
>  
> +        /* XENMAPSPACE_dev_mmio mapping is only supported for hardware Domain
> +         * to map this kind of space to itself.
> +         */

Coding style.

> +        if ( (xatp.space == XENMAPSPACE_dev_mmio) &&
> +             (!is_hardware_domain(current->domain) || (d != 
> current->domain)) )
> +            return -EOPNOTSUPP;

More like -EPERM or -EACCES.

Jan


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