[Xen-devel] Re: [PATCH 01/04] Kexec / Kdump: Generic code

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 18/10/06 2:00 am, "Horms" <horms@xxxxxxxxxxxx> wrote:

>> Yes please. This isn't performance critical. Folding will make the interface
>> better match other hypercalls.
> 
> The main thing that I am concerned about is, that in the
> case that dom0 panics, and we are asking the hypercall to take a dump
> for us, do we really want a copy_from guest in that path?
> It seems to me that its best to have that path as simple as possible.
> But I do argree that it comes at the expense of making the interface
> a bit unclean.

We need to assume that kernel address space hasn't been too badly
compromised, or we couldn't execute as far as making the hypercall. A failed
copy_from_guest() in the crash hypercall could simply cause you to use the
guest_cpu_user_regs() instead. So you still crash, but the crash site is now
the hypercall call site.

 -- Keir



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