Re: [Qemu-devel] [RFC PATCH v2 2/3] kvm-all: Introduce kvm_set_singlestep

[David Gibson]

On Wed, Nov 21, 2018 at 04:13:46PM -0200, Fabiano Rosas wrote:
> This will be used in a future patch to implement an
> architecture-specific single step mechanism for POWER.
> 
> Signed-off-by: Fabiano Rosas <address@hidden>
> ---
>  accel/kvm/kvm-all.c  | 10 ++++++++++
>  exec.c               |  1 +
>  include/sysemu/kvm.h |  4 ++++
>  target/arm/kvm.c     |  4 ++++
>  target/i386/kvm.c    |  4 ++++
>  target/mips/kvm.c    |  4 ++++
>  target/ppc/kvm.c     |  4 ++++
>  target/s390x/kvm.c   |  4 ++++
>  8 files changed, 35 insertions(+)
> 
> diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
> index 4880a05399..4fb7199a15 100644
> --- a/accel/kvm/kvm-all.c
> +++ b/accel/kvm/kvm-all.c
> @@ -2313,6 +2313,11 @@ int kvm_update_guest_debug(CPUState *cpu, unsigned 
> long reinject_trap)
>      return data.err;
>  }
>  
> +void kvm_set_singlestep(CPUState *cs, int enabled)
> +{
> +    kvm_arch_set_singlestep(cs, enabled);
> +}
> +
>  int kvm_insert_breakpoint(CPUState *cpu, target_ulong addr,
>                            target_ulong len, int type)
>  {
> @@ -2439,6 +2444,11 @@ int kvm_remove_breakpoint(CPUState *cpu, target_ulong 
> addr,
>  void kvm_remove_all_breakpoints(CPUState *cpu)
>  {
>  }
> +
> +void kvm_set_singlestep(CPUState *cs, int enabled)
> +{
> +}

You could use stubs to avoid having to put this empty implementation
in every arch.

It also seems like it might be a good idea to report an error here,
rather than having set single step silently do nothing on arches which
don't support it yet.

>  #endif /* !KVM_CAP_SET_GUEST_DEBUG */
>  
>  static int kvm_set_signal_mask(CPUState *cpu, const sigset_t *sigset)
> diff --git a/exec.c b/exec.c
> index bb6170dbff..55614822c3 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -1233,6 +1233,7 @@ void cpu_single_step(CPUState *cpu, int enabled)
>      if (cpu->singlestep_enabled != enabled) {
>          cpu->singlestep_enabled = enabled;
>          if (kvm_enabled()) {
> +            kvm_set_singlestep(cpu, enabled);
>              kvm_update_guest_debug(cpu, 0);
>          } else {
>              /* must flush all the translated code to avoid inconsistencies */
> diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
> index 97d8d9d0d5..a01a8d58dd 100644
> --- a/include/sysemu/kvm.h
> +++ b/include/sysemu/kvm.h
> @@ -259,6 +259,8 @@ int kvm_remove_breakpoint(CPUState *cpu, target_ulong 
> addr,
>  void kvm_remove_all_breakpoints(CPUState *cpu);
>  int kvm_update_guest_debug(CPUState *cpu, unsigned long reinject_trap);
>  
> +void kvm_set_singlestep(CPUState *cpu, int enabled);
> +
>  int kvm_on_sigbus_vcpu(CPUState *cpu, int code, void *addr);
>  int kvm_on_sigbus(int code, void *addr);
>  
> @@ -431,6 +433,8 @@ void kvm_arch_remove_all_hw_breakpoints(void);
>  
>  void kvm_arch_update_guest_debug(CPUState *cpu, struct kvm_guest_debug *dbg);
>  
> +void kvm_arch_set_singlestep(CPUState *cpu, int enabled);
> +
>  bool kvm_arch_stop_on_emulation_error(CPUState *cpu);
>  
>  int kvm_check_extension(KVMState *s, unsigned int extension);
> diff --git a/target/arm/kvm.c b/target/arm/kvm.c
> index 44dd0ce6ce..dd8e43ab7e 100644
> --- a/target/arm/kvm.c
> +++ b/target/arm/kvm.c
> @@ -670,6 +670,10 @@ int kvm_arch_process_async_events(CPUState *cs)
>      return 0;
>  }
>  
> +void kvm_arch_set_singlestep(CPUState *cs, int enabled)
> +{
> +}
> +
>  /* The #ifdef protections are until 32bit headers are imported and can
>   * be removed once both 32 and 64 bit reach feature parity.
>   */
> diff --git a/target/i386/kvm.c b/target/i386/kvm.c
> index f524e7d929..ba56f2ee1f 100644
> --- a/target/i386/kvm.c
> +++ b/target/i386/kvm.c
> @@ -3521,6 +3521,10 @@ static int kvm_handle_debug(X86CPU *cpu,
>      return ret;
>  }
>  
> +void kvm_arch_set_singlestep(CPUState *cs, int enabled)
> +{
> +}
> +
>  void kvm_arch_update_guest_debug(CPUState *cpu, struct kvm_guest_debug *dbg)
>  {
>      const uint8_t type_code[] = {
> diff --git a/target/mips/kvm.c b/target/mips/kvm.c
> index 8e72850962..8035262131 100644
> --- a/target/mips/kvm.c
> +++ b/target/mips/kvm.c
> @@ -119,6 +119,10 @@ int kvm_arch_remove_sw_breakpoint(CPUState *cs, struct 
> kvm_sw_breakpoint *bp)
>      return 0;
>  }
>  
> +void kvm_arch_set_singlestep(CPUState *cs, int enabled)
> +{
> +}
> +
>  static inline int cpu_mips_io_interrupts_pending(MIPSCPU *cpu)
>  {
>      CPUMIPSState *env = &cpu->env;
> diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
> index f81327d6cd..9d0b4f1f3f 100644
> --- a/target/ppc/kvm.c
> +++ b/target/ppc/kvm.c
> @@ -1551,6 +1551,10 @@ void kvm_arch_remove_all_hw_breakpoints(void)
>      nb_hw_breakpoint = nb_hw_watchpoint = 0;
>  }
>  
> +void kvm_arch_set_singlestep(CPUState *cs, int enabled)
> +{
> +}
> +
>  void kvm_arch_update_guest_debug(CPUState *cs, struct kvm_guest_debug *dbg)
>  {
>      int n;
> diff --git a/target/s390x/kvm.c b/target/s390x/kvm.c
> index 2ebf26adfe..4bde183458 100644
> --- a/target/s390x/kvm.c
> +++ b/target/s390x/kvm.c
> @@ -975,6 +975,10 @@ void kvm_arch_remove_all_hw_breakpoints(void)
>      hw_breakpoints = NULL;
>  }
>  
> +void kvm_arch_set_singlestep(CPUState *cs, int enabled)
> +{
> +}
> +
>  void kvm_arch_update_guest_debug(CPUState *cpu, struct kvm_guest_debug *dbg)
>  {
>      int i;

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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