Re: [PATCH v4 7/9] target/i386/kvm: Clean up return values of MSR filter related functions

["Chen, Zide" <zide.chen@intel.com>]

On 7/16/2024 9:10 AM, Zhao Liu wrote:
> At present, the error code of MSR filter enablement attempts to print in
> error_report().
> 
> Unfortunately, this behavior doesn't work because the MSR filter-related
> functions return the boolean and current error_report() use the wrong
> return value.
> 
> So fix this by making MSR filter related functions return int type and
> printing such returned value in error_report().
> 
> Signed-off-by: Zhao Liu <zhao1.liu@intel.com>

 Reviewed-by: Zide Chen <zide.chen@intel.com>

> ---
> v4: Returned kvm_vm_ioctl() directly. (Zide)
> v3: new commit.
> ---
>  target/i386/kvm/kvm.c      | 34 ++++++++++++++--------------------
>  target/i386/kvm/kvm_i386.h |  4 ++--
>  2 files changed, 16 insertions(+), 22 deletions(-)
> 
> diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
> index 4aae4ffc9ccd..f68be68eb411 100644
> --- a/target/i386/kvm/kvm.c
> +++ b/target/i386/kvm/kvm.c
> @@ -2780,8 +2780,6 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
>              }
>      }
>      if (kvm_vm_check_extension(s, KVM_CAP_X86_USER_SPACE_MSR)) {
> -        bool r;
> -
>          ret = kvm_vm_enable_cap(s, KVM_CAP_X86_USER_SPACE_MSR, 0,
>                                  KVM_MSR_EXIT_REASON_FILTER);
>          if (ret) {
> @@ -2790,9 +2788,9 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
>              exit(1);
>          }
>  
> -        r = kvm_filter_msr(s, MSR_CORE_THREAD_COUNT,
> -                           kvm_rdmsr_core_thread_count, NULL);
> -        if (!r) {
> +        ret = kvm_filter_msr(s, MSR_CORE_THREAD_COUNT,
> +                             kvm_rdmsr_core_thread_count, NULL);
> +        if (ret) {
>              error_report("Could not install MSR_CORE_THREAD_COUNT handler: %s",
>                           strerror(-ret));
>              exit(1);
> @@ -5274,13 +5272,13 @@ void kvm_arch_update_guest_debug(CPUState *cpu, struct kvm_guest_debug *dbg)
>      }
>  }
>  
> -static bool kvm_install_msr_filters(KVMState *s)
> +static int kvm_install_msr_filters(KVMState *s)
>  {
>      uint64_t zero = 0;
>      struct kvm_msr_filter filter = {
>          .flags = KVM_MSR_FILTER_DEFAULT_ALLOW,
>      };
> -    int r, i, j = 0;
> +    int i, j = 0;
>  
>      for (i = 0; i < KVM_MSR_FILTER_MAX_RANGES; i++) {
>          KVMMSRHandlers *handler = &msr_handlers[i];
> @@ -5304,18 +5302,13 @@ static bool kvm_install_msr_filters(KVMState *s)
>          }
>      }
>  
> -    r = kvm_vm_ioctl(s, KVM_X86_SET_MSR_FILTER, &filter);
> -    if (r) {
> -        return false;
> -    }
> -
> -    return true;
> +    return kvm_vm_ioctl(s, KVM_X86_SET_MSR_FILTER, &filter);
>  }
>  
> -bool kvm_filter_msr(KVMState *s, uint32_t msr, QEMURDMSRHandler *rdmsr,
> -                    QEMUWRMSRHandler *wrmsr)
> +int kvm_filter_msr(KVMState *s, uint32_t msr, QEMURDMSRHandler *rdmsr,
> +                   QEMUWRMSRHandler *wrmsr)
>  {
> -    int i;
> +    int i, ret;
>  
>      for (i = 0; i < ARRAY_SIZE(msr_handlers); i++) {
>          if (!msr_handlers[i].msr) {
> @@ -5325,16 +5318,17 @@ bool kvm_filter_msr(KVMState *s, uint32_t msr, QEMURDMSRHandler *rdmsr,
>                  .wrmsr = wrmsr,
>              };
>  
> -            if (!kvm_install_msr_filters(s)) {
> +            ret = kvm_install_msr_filters(s);
> +            if (ret) {
>                  msr_handlers[i] = (KVMMSRHandlers) { };
> -                return false;
> +                return ret;
>              }
>  
> -            return true;
> +            return 0;
>          }
>      }
>  
> -    return false;
> +    return 0;
>  }
>  
>  static int kvm_handle_rdmsr(X86CPU *cpu, struct kvm_run *run)
> diff --git a/target/i386/kvm/kvm_i386.h b/target/i386/kvm/kvm_i386.h
> index 34fc60774b86..91c2d6e69163 100644
> --- a/target/i386/kvm/kvm_i386.h
> +++ b/target/i386/kvm/kvm_i386.h
> @@ -74,8 +74,8 @@ typedef struct kvm_msr_handlers {
>      QEMUWRMSRHandler *wrmsr;
>  } KVMMSRHandlers;
>  
> -bool kvm_filter_msr(KVMState *s, uint32_t msr, QEMURDMSRHandler *rdmsr,
> -                    QEMUWRMSRHandler *wrmsr);
> +int kvm_filter_msr(KVMState *s, uint32_t msr, QEMURDMSRHandler *rdmsr,
> +                   QEMUWRMSRHandler *wrmsr);
>  
>  #endif /* CONFIG_KVM */
>