[v4,06/11] hvf: Simplify post reset/init/loadvm hooks

The hooks we have that call us after reset, init and loadvm really all
just want to say "The reference of all register state is in the QEMU
vcpu struct, please push it".

We already have a working pushing mechanism though called cpu->vcpu_dirty,
so we can just reuse that for all of the above, syncing state properly the
next time we actually execute a vCPU.

This fixes PSCI resets on ARM, as they modify CPU state even after the
post init call has completed, but before we execute the vCPU again.

To also make the scheme work for x86, we have to make sure we don't
move stale eflags into our env when the vcpu state is dirty.

Signed-off-by: Alexander Graf <agraf@csgraf.de>
---
 accel/hvf/hvf-cpus.c     | 27 +++++++--------------------
 target/i386/hvf/x86hvf.c |  5 ++++-
 2 files changed, 11 insertions(+), 21 deletions(-)

On Fri, Dec 04, 2020 at 12:48:52AM +0100, Alexander Graf wrote:
> The hooks we have that call us after reset, init and loadvm really all
> just want to say "The reference of all register state is in the QEMU
> vcpu struct, please push it".
> 
> We already have a working pushing mechanism though called cpu->vcpu_dirty,
> so we can just reuse that for all of the above, syncing state properly the
> next time we actually execute a vCPU.
> 
> This fixes PSCI resets on ARM, as they modify CPU state even after the
> post init call has completed, but before we execute the vCPU again.
> 
> To also make the scheme work for x86, we have to make sure we don't
> move stale eflags into our env when the vcpu state is dirty.
> 
> Signed-off-by: Alexander Graf <agraf@csgraf.de>
> ---
>  accel/hvf/hvf-cpus.c     | 27 +++++++--------------------
>  target/i386/hvf/x86hvf.c |  5 ++++-
>  2 files changed, 11 insertions(+), 21 deletions(-)
> 
> diff --git a/accel/hvf/hvf-cpus.c b/accel/hvf/hvf-cpus.c
> index 1b0c868944..71721e17de 100644
> --- a/accel/hvf/hvf-cpus.c
> +++ b/accel/hvf/hvf-cpus.c
> @@ -275,39 +275,26 @@ static void hvf_cpu_synchronize_state(CPUState *cpu)
>      }
>  }
>  
> -static void do_hvf_cpu_synchronize_post_reset(CPUState *cpu,
> -                                              run_on_cpu_data arg)
> +static void do_hvf_cpu_synchronize_set_dirty(CPUState *cpu,
> +                                             run_on_cpu_data arg)
>  {
> -    hvf_put_registers(cpu);
> -    cpu->vcpu_dirty = false;
> +    /* QEMU state is the reference, push it to HVF now and on next entry */

It's only signalling now. The actual push is delayed until the next
entry.

It'd be good if Paolo or Eduardo would also peek at this change because
it makes HVF a bit different from other accels.

HVF's post_reset, post_init and pre_loadvm no longer result into QEMU
state being pushed to HVF. I'm not sure I can fully grasp if there're
undesired side-effects of this so it's something worth broader review.

If nobody raises objections:

Reviewed-by: Roman Bolshakov <r.bolshakov@yadro.com>
Tested-by: Roman Bolshakov <r.bolshakov@yadro.com>

Thanks,
Roman

> +    cpu->vcpu_dirty = true;
>  }
>  
>  static void hvf_cpu_synchronize_post_reset(CPUState *cpu)
>  {
> -    run_on_cpu(cpu, do_hvf_cpu_synchronize_post_reset, RUN_ON_CPU_NULL);
> -}
> -
> -static void do_hvf_cpu_synchronize_post_init(CPUState *cpu,
> -                                             run_on_cpu_data arg)
> -{
> -    hvf_put_registers(cpu);
> -    cpu->vcpu_dirty = false;
> +    run_on_cpu(cpu, do_hvf_cpu_synchronize_set_dirty, RUN_ON_CPU_NULL);
>  }
>  
>  static void hvf_cpu_synchronize_post_init(CPUState *cpu)
>  {
> -    run_on_cpu(cpu, do_hvf_cpu_synchronize_post_init, RUN_ON_CPU_NULL);
> -}
> -
> -static void do_hvf_cpu_synchronize_pre_loadvm(CPUState *cpu,
> -                                              run_on_cpu_data arg)
> -{
> -    cpu->vcpu_dirty = true;
> +    run_on_cpu(cpu, do_hvf_cpu_synchronize_set_dirty, RUN_ON_CPU_NULL);
>  }
>  
>  static void hvf_cpu_synchronize_pre_loadvm(CPUState *cpu)
>  {
> -    run_on_cpu(cpu, do_hvf_cpu_synchronize_pre_loadvm, RUN_ON_CPU_NULL);
> +    run_on_cpu(cpu, do_hvf_cpu_synchronize_set_dirty, RUN_ON_CPU_NULL);
>  }
>  
>  static void hvf_vcpu_destroy(CPUState *cpu)
> diff --git a/target/i386/hvf/x86hvf.c b/target/i386/hvf/x86hvf.c
> index 0f2aeb1cf8..3111c0be4c 100644
> --- a/target/i386/hvf/x86hvf.c
> +++ b/target/i386/hvf/x86hvf.c
> @@ -435,7 +435,10 @@ int hvf_process_events(CPUState *cpu_state)
>      X86CPU *cpu = X86_CPU(cpu_state);
>      CPUX86State *env = &cpu->env;
>  
> -    env->eflags = rreg(cpu_state->hvf->fd, HV_X86_RFLAGS);
> +    if (!cpu_state->vcpu_dirty) {
> +        /* light weight sync for CPU_INTERRUPT_HARD and IF_MASK */
> +        env->eflags = rreg(cpu_state->hvf->fd, HV_X86_RFLAGS);
> +    }
>  
>      if (cpu_state->interrupt_request & CPU_INTERRUPT_INIT) {
>          cpu_synchronize_state(cpu_state);
> -- 
> 2.24.3 (Apple Git-128)
>