Re: [patch 01/60] x86/entry/64/paravirt: Use paravirt-safe macro to access eflags

[Juergen Gross]

On 04/12/17 15:07, Thomas Gleixner wrote:
> From: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> 
> Commit 1d3e53e8624a ("x86/entry/64: Refactor IRQ stacks and make them
> NMI-safe") added DEBUG_ENTRY_ASSERT_IRQS_OFF macro that acceses eflags
> using 'pushfq' instruction when testing for IF bit. On PV Xen guests
> looking at IF flag directly will always see it set, resulting in 'ud2'.
> 
> Introduce SAVE_FLAGS() macro that will use appropriate save_fl pv op when
> running paravirt.
> 
> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: jgross@xxxxxxxx
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
> Cc: luto@xxxxxxxxxx
> Link: https://lkml.kernel.org/r/1512159805-6314-1-git-send-email-boris.ostrovsky@xxxxxxxxxx

Reviewed-by: Juergen Gross <jgross@xxxxxxxx>


Juergen