Re: [Xen-devel] [PATCH v9 3/3] tools/libxc: use superpages during restore of HVM guest

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 01/09/17 17:08, Olaf Hering wrote:
> +    /* No superpage in 1st 2MB due to VGA hole */
> +    xc_sr_set_bit(0, &ctx->x86_hvm.restore.attempted_1g);
> +    xc_sr_set_bit(0, &ctx->x86_hvm.restore.attempted_2m);

This is false for PVH guests.

I still fail to understand why you need the bitmaps at all?  You can
calculate everything you need from the pfn list alone, which will also
let you spot the presence or absence of the VGA hole.

You need to track which pfns you've see so far in the stream, and which
pfns have been populated.  When you find holes in the pfns in the
stream, you need to undo the prospective superpage allocation.  Unless
I've missed something?

Also, please take care to use 2M decrease reservations wherever
possible, or you will end up shattering the host superpage as part of
trying to remove the memory.

~Andrew

> +
>      return 0;
> +
> +out:
> +    ERROR("Unable to allocate memory for pfn bitmaps");
> +    return -1;
>  }
>  
>  /*
>


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