[Xen-devel] Re: [PATCH] txt: 1/6 - "fix" xen_phys_start for 32b builds

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

Yeah, I would point out in any case that Xen has always allocated plenty of
'domheap' memory and depends on the consistency of that too (e.g., VT-d
tables, shadow page tables) so checking only Xen + Xen heap is insufficient
anyway.

Could you not just check all of memory, minus a few bits you expect can
change? I don't think any other approach will be robust.

 -- Keir

On 20/01/2009 09:04, "Wang, Shane" <shane.wang@xxxxxxxxx> wrote:

> We are using xen_phys_start ~ xenheap_phys_end to check its integrity (for the
> purpose of memory integrity protection) before and after Sx by MACing this
> range.
> It looks like xen heap is not continuous any more.
> 
> Shane
> ________________________________
> 
> From: Keir Fraser [mailto:keir.fraser@xxxxxxxxxxxxx]
> Sent: 2009年1月20日 17:00
> To: Cihula, Joseph; xen-devel@xxxxxxxxxxxxxxxxxxx;
> xense-devel@xxxxxxxxxxxxxxxxxxx
> Cc: Wang, Shane
> Subject: Re: [PATCH] txt: 1/6 - "fix" xen_phys_start for 32b builds
> 
> 
> Xen_phys/xenheap_phys has changed a bit since removing Xen heap for x86/64. It
> sounds like you’ll be re-sending these patches later once fixed up for
> xen-unstable tip. Perhaps this won’t be needed any more. I’m not sure what
> you’re using xen_phys_start for, but it does sound dubious.
> 
>  -- Keir
> 
> On 20/01/2009 05:48, "Cihula, Joseph" <joseph.cihula@xxxxxxxxx> wrote:
> 
> 
> 
> On IA32 (32b/32b PAE) builds, set xen_phys_start (and by extension
> xenheap_phys_start) to be the start of hypervisor code (instead of 0).  This
> reflects the actual trust/protection boundary of the hypervisor.
> 
> Signed-off-by: Joseph Cihula <joseph.cihula@xxxxxxxxx>
> 
> diff -r 8df3c145923f -r f96073a97f5c xen/arch/x86/setup.c
> --- a/xen/arch/x86/setup.c      Mon Jan 19 17:40:28 2009 +0000
> +++ b/xen/arch/x86/setup.c      Mon Jan 19 20:22:24 2009 -0800
> @@ -843,7 +843,7 @@ void __init __start_xen(unsigned long mb
>     /* Initialise the Xen heap. */
>     init_xenheap_pages(xenheap_phys_start, xenheap_phys_end);
>     nr_pages = (xenheap_phys_end - xenheap_phys_start) >> PAGE_SHIFT;
> -    xenheap_phys_start = xen_phys_start;
> +    xenheap_phys_start = xen_phys_start = __pa(&_start);
>     printk("Xen heap: %luMB (%lukB)\n",
>            nr_pages >> (20 - PAGE_SHIFT),
>            nr_pages << (PAGE_SHIFT - 10));
> 
> 
> 



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