Re: [Xen-devel] [PATCH] xen/x86: Increase xen_e820_map to E820_X_MAX possible entries

[Alex Thorlton <athorlton@xxxxxxx>]

On Wed, Nov 16, 2016 at 07:09:01AM +0100, Juergen Gross wrote:
> On 15/11/16 01:11, Alex Thorlton wrote:
> > On systems with sufficiently large e820 tables, and several IOAPICs, it
> > is possible for the XENMEM_machine_memory_map callback (and its
> > counterpart, XENMEM_memory_map) to attempt to return an e820 table with
> > more than 128 entries.  This callback adds entries to the BIOS-provided
> > e820 table to account for IOAPIC registers, which, on sufficiently large
> > systems, can result in an e820 table that is too large to copy back into
> > xen_e820_map.
> > 
> > This change simply increases the size of xen_e820_map to E820_X_MAX to
> > ensure that there is enough room to store the entire e820 map returned
> > from this callback.
> > 
> > Signed-off-by: Alex Thorlton <athorlton@xxxxxxx>
> > Suggested-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> > Cc: Russ Anderson <rja@xxxxxxx>
> > Cc: David Vrabel <david.vrabel@xxxxxxxxxx>
> > Cc: Juergen Gross <jgross@xxxxxxxx>
> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> > Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> > Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
> > Cc: x86@xxxxxxxxxx
> > Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
> > ---
> >  arch/x86/xen/setup.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
> > index f8960fc..5e1ecc7 100644
> > --- a/arch/x86/xen/setup.c
> > +++ b/arch/x86/xen/setup.c
> > @@ -41,7 +41,7 @@
> >  unsigned long xen_released_pages;
> >  
> >  /* E820 map used during setting up memory. */
> > -static struct e820entry xen_e820_map[E820MAX] __initdata;
> > +static struct e820entry xen_e820_map[E820_X_MAX] __initdata;
> >  static u32 xen_e820_map_entries __initdata;
> >  
> >  /*
> > @@ -750,7 +750,7 @@ char * __init xen_memory_setup(void)
> >     max_pfn = min(max_pfn, xen_start_info->nr_pages);
> >     mem_end = PFN_PHYS(max_pfn);
> >  
> > -   memmap.nr_entries = E820MAX;
> > +   memmap.nr_entries = E820_X_MAX;
> 
> Please use ARRAY_SIZE(xen_e820_map) here and ...
> 
> >     set_xen_guest_handle(memmap.buffer, xen_e820_map);
> >  
> >     op = xen_initial_domain() ?
> > @@ -923,7 +923,7 @@ char * __init xen_auto_xlated_memory_setup(void)
> >     int i;
> >     int rc;
> >  
> > -   memmap.nr_entries = E820MAX;
> > +   memmap.nr_entries = E820_X_MAX;
> 
> ... here.

Got it.  Thanks, Juergen!

- Alex

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