Re: [Xen-devel] dom0 PVH: Over-allocation for domain 0: 393217 > 393216

[Sander Eikelenboom <linux@xxxxxxxxxxxxxx>]

Wednesday, June 4, 2014, 12:48:49 PM, you wrote:

> On 04/06/14 01:49, Mukesh Rathor wrote:
>> On Tue, 3 Jun 2014 12:28:27 -0700
>> Mukesh Rathor <mukesh.rathor@xxxxxxxxxx> wrote:
>> 
>>> On Tue, 3 Jun 2014 14:11:17 +0200
>>> Sander Eikelenboom <linux@xxxxxxxxxxxxxx> wrote:
>>>
>>>> Hi,
>>>>
>>>> I just tried booting with "dom0pvh" and found the following warnings
>>>> (complete combined xl-dmesg/dmesg attached) which don't show up when
>>>> booting without dom0pvh:
>>>
>>> Yeah, I see. I'm able to reproduce. Something about
>>> dom0_mem=1536M,max:1536M ie, specifying max in there. Without it,
>>> dom0_mem=1536M, its fine. You can do that to play around more while I
>>> take a look.
>> 
>> Ok, I know whats going on. Basically, we are trying to populate the
>> pfns removed due to punched holes in the e820, but because max is
>> specified (same as initial ram), guest_physmap_add_page can't add.
>> 
>> This will be fixed by the e820 work that Roger and David Vrabel are 
>> doing. Please keep an eye on the thread:
>> 
>> http://www.gossamer-threads.com/lists/xen/devel/332603

> Hello,

> I've been looking into this, and commented on David's patch:

> http://lists.xenproject.org/archives/html/xen-devel/2014-06/msg00293.html

> I'm also appending a modified version of patch 1, so you can apply it 
> directly. It seems to work fine in all my test cases (no dom0_mem, 
> dom0_mem=<mem> and dom0_mem=<mem>,max:<mem>).

> ---
> commit f503c114f86d92036e1af4e4246550f15e85c4bb
> Author: David Vrabel <david.vrabel@xxxxxxxxxx>
> Date:   Tue Jun 3 09:13:43 2014 +0200

>     x86/xen: fix memory setup for PVH dom0
>     
>     Since af06d66ee32b (x86: fix setup of PVH Dom0 memory map) in Xen, PVH
>     dom0 need only use the memory memory provided by Xen which has already
>     setup all the correct holes.
>     
>     xen_memory_setup() then ends up being trivial for a PVH guest so
>     introduce a new function (xen_auto_xlated_memory_setup()).
>     
>     Signed-off-by: David Vrabel <david.vrabel@xxxxxxxxxx>
>     Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index 201d09a..4e7d2b7 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -1536,7 +1536,10 @@ asmlinkage void __init xen_start_kernel(void)
>         if (!xen_pvh_domain())
>                 pv_cpu_ops = xen_cpu_ops;
>  
> -       x86_init.resources.memory_setup = xen_memory_setup;
> +       if (xen_feature(XENFEAT_auto_translated_physmap))
> +               x86_init.resources.memory_setup = 
> xen_auto_xlated_memory_setup;
> +       else
> +               x86_init.resources.memory_setup = xen_memory_setup;
>         x86_init.oem.arch_setup = xen_arch_setup;
>         x86_init.oem.banner = xen_banner;
>  
> diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
> index 0982233..e6e9df8 100644
> --- a/arch/x86/xen/setup.c
> +++ b/arch/x86/xen/setup.c
> @@ -509,6 +509,34 @@ char * __init xen_memory_setup(void)
>  }
>  
>  /*
> + * Machine specific memory setup for auto-translated guests.
> + */
> +char * __init xen_auto_xlated_memory_setup(void)
> +{
> +       static struct e820entry map[E820MAX] __initdata;
> +
> +       struct xen_memory_map memmap;
> +       int i;
> +       int rc;
> +
> +       memmap.nr_entries = E820MAX;
> +       set_xen_guest_handle(memmap.buffer, map);
> +
> +       rc = HYPERVISOR_memory_op(XENMEM_memory_map, &memmap);
> +       BUG_ON(rc);
> +
> +       sanitize_e820_map(map, ARRAY_SIZE(map), &memmap.nr_entries);
> +
> +       for (i = 0; i < memmap.nr_entries; i++)
> +               e820_add_region(map[i].addr, map[i].size, map[i].type);
> +
> +       memblock_reserve(__pa(xen_start_info->mfn_list),
> +               xen_start_info->pt_base - xen_start_info->mfn_list);
> +
> +       return "Xen";
> +}
> +
> +/*
>   * Set the bit indicating "nosegneg" library variants should be used.
>   * We only need to bother in pure 32-bit mode; compat 32-bit processes
>   * can have un-truncated segments, so wrapping around is allowed.
> diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
> index 1cb6f4c..b371d18 100644
> --- a/arch/x86/xen/xen-ops.h
> +++ b/arch/x86/xen/xen-ops.h
> @@ -34,6 +34,7 @@ extern unsigned long xen_max_p2m_pfn;
>  void xen_set_pat(u64);
>  
>  char * __init xen_memory_setup(void);
> +char * xen_auto_xlated_memory_setup(void);
>  void __init xen_arch_setup(void);
>  void xen_enable_sysenter(void);
>  void xen_enable_syscall(void);

Hi Roger,

Applied and it works for me as well !
Time to play some more :-)

Thx,

Sander


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