Re: [PATCH 1/2] x86/Xen/32: make xen_iret_crit_fixup independent of frame layout

[JÃrgen GroÃ]

On 11.11.19 15:32, Jan Beulich wrote:
> Now that SS:ESP always get saved by SAVE_ALL, this also needs to be
> accounted for in xen_iret_crit_fixup. Otherwise the old_ax value gets
> interpreted as EFLAGS, and hence VM86 mode appears to be active all
> the time, leading to random "vm86_32: no user_vm86: BAD" log messages
> alongside processes randomly crashing.
>
> Since following the previous model (sitting after SAVE_ALL) would
> further complicate the code _and_ retain the dependency of
> xen_iret_crit_fixup on frame manipulations done by entry_32.S, switch
> things around and do the adjustment ahead of SAVE_ALL.
>
> Fixes: 3c88c692c287 ("x86/stackframe/32: Provide consistent pt_regs")
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Reviewed-by: Juergen Gross <jgross@xxxxxxxx>


Juergen