Re: [PATCH v3] x86-64/Xen: fix stack switching

[Juergen Gross]

On 15/01/2019 17:58, Jan Beulich wrote:
> While in the native case entry into the kernel happens on the trampoline
> stack, PV Xen kernels get entered with the current thread stack right
> away. Hence source and destination stacks are identical in that case,
> and special care is needed.
> 
> Other than in sync_regs() the copying done on the INT80 path isn't
> NMI / #MC safe, as either of these events occurring in the middle of the
> stack copying would clobber data on the (source) stack.
> 
> I'm not altering the similar code in interrupt_entry() and nmi(), as
> those code paths are unreachable afaict when running PV Xen guests.
> 
> Fixes: 7f2590a110b837af5679d08fc25c6227c5a8c497
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> Cc: stable@xxxxxxxxxx 

Reviewed-by: Juergen Gross <jgross@xxxxxxxx>


Juergen