Re: [Xen-devel] [PATCH v3 10/15] xen: arm: handle traps from 64-bit guests

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Wed, 2013-07-24 at 12:30 +0100, Stefano Stabellini wrote:
> On Fri, 19 Jul 2013, Ian Campbell wrote:
> > While there observe that we weren't ever restoring the outer stack frame, 
> > even
> > for 32-bit guests when running a 64-bit hypervisor! The outer stack frame
> > "only" contains most of the SPSR registers for 32-bit...
> > 
> > We can also remove the logic at "return_to_new_vcpu" which detects returns 
> > to
> > hypervisor mode -- seemingly trying to handle hypervisor threads which 
> > aren't
> > an thing which we have. The idle VCPUs do not take this path. This 
> > simplifies
> > the return_to_new_vcpu code, we also split it into 32- and 64-bit VCPU 
> > paths.
> > 
> > There is no need to export return_to_hypervisor (now renamed 
> > return_from_trap
> > on arm64) and likewise stop doing so on 32-bit as well.
> > 
> > Also tweak the case of some system registers for consistency.
> > 
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > ---
> > v3: actually restore the outer stack frame! Due to this change I have 
> > dropped
> > the previous Acks.
> 
> It looks OK. However the code refactoring, the naming changes, and the
> new code to save the outer stack frame are difficult to follow together.
> Maybe separate out the latter?

Right, I'll see what I can do.

Ian



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