Re: [Qemu-devel] [PATCH v1 09/12] target-arm: powerctl: Enable HVC when starting CPUs to EL2

["Edgar E. Iglesias" <edgar.iglesias@xilinx.com>]

On Mon, Oct 08, 2018 at 01:41:36PM +0100, Peter Maydell wrote:
> On 3 October 2018 at 16:07, Edgar E. Iglesias <edgar.iglesias@gmail.com> wrote:
> > From: "Edgar E. Iglesias" <edgar.iglesias@xilinx.com>
> >
> > When QEMU provides the equivalent of the EL3 firmware, we
> > need to enable HVCs in scr_el3 when turning on CPUs that
> > target EL2.
> >
> > Signed-off-by: Edgar E. Iglesias <edgar.iglesias@xilinx.com>
> > ---
> >  target/arm/arm-powerctl.c | 11 +++++++++++
> >  1 file changed, 11 insertions(+)
> >
> > diff --git a/target/arm/arm-powerctl.c b/target/arm/arm-powerctl.c
> > index ce55eeb..54f2974 100644
> > --- a/target/arm/arm-powerctl.c
> > +++ b/target/arm/arm-powerctl.c
> > @@ -63,6 +63,7 @@ static void arm_set_cpu_on_async_work(CPUState *target_cpu_state,
> >      struct CpuOnInfo *info = (struct CpuOnInfo *) data.host_ptr;
> >
> >      /* Initialize the cpu we are turning on */
> > +    qemu_log("CPU%d reset\n", target_cpu_state->cpu_index);
> 
> qemu_log logging should always be masked to a particular
> log kind (either via qemu_log_mask() or by explicit check on
> the log level). If this was accidentally left-in debug, you could
> just drop it :-)

Hah, yes this is an accidental leftover...


> 
> >      cpu_reset(target_cpu_state);
> >      target_cpu_state->halted = 0;
> >
> > @@ -103,6 +104,16 @@ static void arm_set_cpu_on_async_work(CPUState *target_cpu_state,
> >      } else {
> >          /* Processor is not in secure mode */
> >          target_cpu->env.cp15.scr_el3 |= SCR_NS;
> > +
> > +        /*
> > +         * If QEMU is providing the equivalent of EL3 firmware, then we need
> > +         * to make sure a CPU targeting EL2 comes out of reset with a
> > +         * functional HVC insn.
> > +         */
> > +        if (arm_feature(&target_cpu->env, ARM_FEATURE_EL3)
> > +            && info->target_el == 2) {
> > +            target_cpu->env.cp15.scr_el3 |= SCR_HCE;
> > +        }
> >      }
> 
> Otherwise
> Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
> This is definitely required for PSCI and I think it makes sense
> in other cases that end up in this powerctl code with EL3 set.

Thanks,
Edgar