Re: [PATCH v3 11/13] x86/xen: use lazy_mmu_state when context-switching

[David Woodhouse <dwmw2@xxxxxxxxxxxxx>]

On Fri, 2025-10-24 at 16:51 +0200, David Hildenbrand wrote:
> On 24.10.25 16:47, David Woodhouse wrote:
> > On Thu, 2025-10-23 at 22:06 +0200, David Hildenbrand wrote:
> > > On 15.10.25 10:27, Kevin Brodsky wrote:
> > > > We currently set a TIF flag when scheduling out a task that is in
> > > > lazy MMU mode, in order to restore it when the task is scheduled
> > > > again.
> > > > 
> > > > The generic lazy_mmu layer now tracks whether a task is in lazy MMU
> > > > mode in task_struct::lazy_mmu_state. We can therefore check that
> > > > state when switching to the new task, instead of using a separate
> > > > TIF flag.
> > > > 
> > > > Signed-off-by: Kevin Brodsky <kevin.brodsky@xxxxxxx>
> > > > ---
> > > 
> > > 
> > > Looks ok to me, but I hope we get some confirmation from x86 / xen
> > > folks.
> > 
> > 
> > I know tglx has shouted at me in the past for precisely this reminder,
> > but you know you can test Xen guests under QEMU/KVM now and don't need
> > to actually run Xen? Has this been boot tested?
> 
> And after that, boot-testing sparc as well? :D

Also not that hard in QEMU, I believe. Although I do have some SPARC
boxes in the shed...

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