RE: [PATCH 3/3] target/nios2: Use gen_io_start around wrctl instruction

[Wu, Wentong]

Hi,
I think we can get this patch series merged first in order to get qemu_nios2 
working with icount, actually we are blocked by it for some time. 
BTW if maintainers(Chris Wulff and Marek Vasut) don't have time for the 
re-work, I'd like to take it.

Thanks
> -----Original Message-----
> From: Peter Maydell <peter.maydell@linaro.org> 
> Sent: Monday, July 6, 2020 1:10 AM
> To: Wu, Wentong <wentong.wu@intel.com>
> Cc: QEMU Developers <qemu-devel@nongnu.org>; QEMU Trivial 
> <qemu-trivial@nongnu.org>; Chris Wulff <crwulff@gmail.com>; Marek Vasut 
> <marex@denx.de>
> Subject: Re: [PATCH 3/3] target/nios2: Use gen_io_start around wrctl 
> instruction
>
> On Mon, 29 Jun 2020 at 09:17, Wentong Wu <wentong.wu@intel.com> wrote:
> >
> > wrctl instruction on nios2 target will cause checking cpu interrupt 
> > but tcg_handle_interrupt() will call cpu_abort() if the CPU gets an 
> > interrupt while it's not in 'can do IO'
> > state, so add gen_io_start around wrctl instruction. Also at the same 
> > time, end the onging TB with DISAS_UPDATE.
> >
> > Signed-off-by: Wentong Wu <wentong.wu@intel.com>
> > ---
> >  target/nios2/translate.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> >
> > diff --git a/target/nios2/translate.c b/target/nios2/translate.c index 
> > 83c10eb2..51347ada 100644
> > --- a/target/nios2/translate.c
> > +++ b/target/nios2/translate.c
> > @@ -32,6 +32,7 @@
> >  #include "exec/cpu_ldst.h"
> >  #include "exec/translator.h"
> >  #include "qemu/qemu-print.h"
> > +#include "exec/gen-icount.h"
> >
> >  /* is_jmp field values */
> >  #define DISAS_JUMP    DISAS_TARGET_0 /* only pc was modified dynamically */
> > @@ -518,7 +519,11 @@ static void wrctl(DisasContext *dc, uint32_t code, 
> > uint32_t flags)
> >      /* If interrupts were enabled using WRCTL, trigger them. */  #if 
> > !defined(CONFIG_USER_ONLY)
> >      if ((instr.imm5 + CR_BASE) == CR_STATUS) {
> > +        if (tb_cflags(dc->tb) & CF_USE_ICOUNT) {
> > +            gen_io_start();
> > +        }
> >          gen_helper_check_interrupts(dc->cpu_env);
> > +        dc->is_jmp = DISAS_UPDATE;
> >      }
> >  #endif
> >  }
> 
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
>
> though as Richard notes ideally the interrupt handling code here should be 
> rewritten because the check_interrupts helper is a very weird way to 
> implement things.
>
> thanks
> -- PMM