Re: [PATCH] x86/pv: Fix breakpoint reporting

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Mon, May 26, 2025 at 09:53:02PM +0100, Andrew Cooper wrote:
> x86_merge_dr6() is not a no-op when 0 is passed in; it will discard the
> previously latched breakpoint bits.
> 
> The combination of do_debug()'s manual call to x86_merge_dr6() for external
> debuggers, and pv_inject_DB() calling pv_inject_event(), results in two
> x86_merge_dr6() calls.
> 
> Feed the same pending_dbg in the second time.  This makes pv_inject_event()'s
> update of dr6 effectively a no-op, retaining the correct breakpoint bits.
> 
> Fixes: db39fa4b27ea ("x86/pv: Fix merging of new status bits into %dr6")
> Reported-by: Manuel Bouyer <bouyer@xxxxxxxxxxxxxxx>
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Thanks, Roger.