Re: [Xen-devel] xl create failure on arm64 with XEN 4.9rc6

[Feng Kan <fkan@xxxxxxx>]

Yap, worked like a charm. Much thanks.

Tested on Centos 7 arm64 system with 4.12rc2 64K page size kernel
(dom0 and domU) & Xen 4.9rc6
Tested-by: Feng Kan <fkan@xxxxxxx>

On Sun, May 28, 2017 at 10:12 AM, Julien Grall <julien.grall@xxxxxxx> wrote:
> Hi,
>
> On 05/26/2017 11:22 PM, Feng Kan wrote:
>> On Fri, May 26, 2017 at 5:40 AM, Julien Grall <julien.grall@xxxxxxx> wrote:
>>>
>>>
>>> On 26/05/17 01:37, Feng Kan wrote:
>>>>
>>>> On Thu, May 25, 2017 at 12:56 PM, Julien Grall <julien.grall@xxxxxxx>
>>>> wrote:
>>>>>
>>>>> (CC toolstack maintainers)
>>>>>
>>>>> On 25/05/2017 19:58, Feng Kan wrote:
>>>>>>
>>>>>>
>>>>>> Hi All:
>>>>>
>>>>>
>>>>>
>>>>> Hello,
>>>>>
>>>>>> This is not specifically against the XEN 4.9. I am using 4.12rc2
>>>>>> kernel on arm64 platform. Started dom0 fine with ACPI enabled, but
>>>>>> failed when creating the domU guest. Xen is built natively on the
>>>>>> arm64 platform. Using the same kernel and ramdisk as dom0. Any idea as
>>>>>> why it is stuck here
>>>>>> would be greatly appreciated?
>>>>>
>>>>>
>>>>>
>>>>> The first step would to try a stable release if you can. Also, it would
>>>>> be
>>>>> useful if you provide information about the guest (i.e the configuration)
>>>>> and your .config for the kernel.
>>>>
>>>> I am using the default xen_defconfig in the arm64 directory.
>>>
>>>
>>> I am confused. There are no xen_defconfig in the arm64 directory of the
>>> kernel. So which one are you talking about?
>> Sorry, my mistake.
>>>
>>>> This is
>>>> very early on
>>>> in building the domain, would the guest configuration matter?
>>>
>>>
>>> The configuration of DOM0 kernel matters when you want to build the guest.
>>> That's why I wanted to know what options you enabled.
>> I see. I am using the default centos 7.2 kernel config plus enabling
>> the XEN option. (Attached below)
>
> Looking at the .config, Linux is using 64KB page granularity.
>
> I managed to reproduce the failure (though different error) by using
> an initramfs > 32MB (smaller works). The patch below should fix the
> error, can you give it a try?
>
> commit c4684b425552a8330f00d7703f3175d721992ab0
> Author: Julien Grall <julien.grall@xxxxxxx>
> Date:   Sun May 28 17:50:07 2017 +0100
>
>     xen/privcmd: Support correctly 64KB page granularity when mapping memory
>
>     Commit 5995a68 "xen/privcmd: Add support for Linux 64KB page granularity" 
> did
>     not go far enough to support 64KB in mmap_batch_fn.
>
>     The variable 'nr' is the number of 4KB chunk to map. However, when Linux
>     is using 64KB page granularity the array of pages (vma->vm_private_data)
>     contain one page per 64KB. Fix it by incrementing st->index correctly.
>
>     Furthermore, st->va is not correctly incremented as PAGE_SIZE !=
>     XEN_PAGE_SIZE.
>
>     Fixes: 5995a68 ("xen/privcmd: Add support for Linux 64KB page 
> granularity")
>     CC: stable@xxxxxxxxxxxxxxx
>     Reported-by: Feng Kan <fkan@xxxxxxx>
>     Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
>
> diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
> index 7a92a5e..38d9a43 100644
> --- a/drivers/xen/privcmd.c
> +++ b/drivers/xen/privcmd.c
> @@ -345,7 +345,7 @@ static int mmap_batch_fn(void *data, int nr, void *state)
>         int ret;
>
>         if (xen_feature(XENFEAT_auto_translated_physmap))
> -               cur_pages = &pages[st->index];
> +               cur_pages = &pages[st->index / XEN_PFN_PER_PAGE];
>
>         BUG_ON(nr < 0);
>         ret = xen_remap_domain_gfn_array(st->vma, st->va & PAGE_MASK, gfnp, 
> nr,
> @@ -362,7 +362,7 @@ static int mmap_batch_fn(void *data, int nr, void *state)
>                                 st->global_error = 1;
>                 }
>         }
> -       st->va += PAGE_SIZE * nr;
> +       st->va += XEN_PAGE_SIZE * nr;
>         st->index += nr;
>
>         return 0;
>
> Cheers,
>
> --
> Julien Grall

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