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Re: [PATCH v2 2/7] xen: introduce generic helper checking for memory map conflicts


  • To: Juergen Gross <jgross@xxxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Tue, 20 Aug 2024 10:35:48 +0200
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  • Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>, Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxxx, Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, x86@xxxxxxxxxx
  • Delivery-date: Tue, 20 Aug 2024 08:36:01 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 20.08.2024 10:20, Juergen Gross wrote:
> When booting as a Xen PV dom0 the memory layout of the dom0 is
> modified to match that of the host, as this requires less changes in
> the kernel for supporting Xen.
> 
> There are some cases, though, which are problematic, as it is the Xen
> hypervisor selecting the kernel's load address plus some other data,
> which might conflict with the host's memory map.
> 
> These conflicts are detected at boot time and result in a boot error.
> In order to support handling at least some of these conflicts in
> future, introduce a generic helper function which will later gain the
> ability to adapt the memory layout when possible.
> 
> Add the missing check for the xen_start_info area.
> 
> Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> Tested-by: Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

However, since you mention the start_info area it may be worth adding half
a sentence to the description also mentioning why the hypervisor allocated
stack page doesn't need checking. In fact this may want to extend to
initrd and phys-mach map as well, to cover everything Xen sets up on behalf
of the kernel.

Jan



 


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