Re: [PATCH v3 1/2] efi: Fix allocation problems if ExitBootServices() fails

[Ian Campbell <ian.campbell@citrix.com>]

On Mon, 2015-06-01 at 12:10 +0100, Jan Beulich wrote:
> >>> On 01.06.15 at 12:17, <ross.lagerwall@citrix.com> wrote:
> > If calling ExitBootServices() fails, the required memory map size may
> > have increased. When initially allocating the memory map, allocate a
> > slightly larger buffer (by an arbitrary 8 entries) to fix this.
> > 
> > The ARM code path was already allocating a larger buffer than required,
> > so this moves the code to be common for all architectures.
> > 
> > This was seen on the following machine when using the iscsidxe UEFI
> > driver. The machine would consistently fail the first call to
> > ExitBootServices().
> > System Information
> >         Manufacturer: Supermicro
> >         Product Name: X10SLE-F/HF
> > BIOS Information
> >         Vendor: American Megatrends Inc.
> >         Version: 2.00
> >         Release Date: 04/24/2014
> > 
> > Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
> 
> Provided ARM folks are happy with the reduced increase,

Hi Roy,

This patch[0] turns a +PAGE_SIZE in efi_arch_allocate_mmap_buffer into a
"8 * efi_mdesc_size" in the common code.

The +PAGE_SIZE came from [1] so I think it is as arbitrary as the
+8*sizeof here.

IOW this change looks ok to me, what do you think?

Thanks,
Ian.

[0] http://lists.xen.org/archives/html/xen-devel/2015-06/msg00067.html
[1] http://xenbits.xen.org/gitweb/?p=xen.git;a=commit;h=932881d953476444ed934c94dbc098c0fefb4d77

> Acked-by: Jan Beulich <jbeulich@suse.com>
>