Re: [PATCH v4 9/9] target/i386/kvm: Replace ARRAY_SIZE(msr_handlers) with KVM_MSR_FILTER_MAX_RANGES

[Chen, Zide]

On 7/16/2024 9:10 AM, Zhao Liu wrote:
> kvm_install_msr_filters() uses KVM_MSR_FILTER_MAX_RANGES as the bound
> when traversing msr_handlers[], while other places still compute the
> size by ARRAY_SIZE(msr_handlers).
> 
> In fact, msr_handlers[] is an array with the fixed size
> KVM_MSR_FILTER_MAX_RANGES, so there is no difference between the two
> ways.
> 
> For the code consistency and to avoid additional computational overhead,
> use KVM_MSR_FILTER_MAX_RANGES instead of ARRAY_SIZE(msr_handlers).
> 
> Suggested-by: Zide Chen <zide.chen@intel.com>
> Signed-off-by: Zhao Liu <zhao1.liu@intel.com>

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


> ---
> v4: new commit.
> ---
>  target/i386/kvm/kvm.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
> index d47476e96813..43b2ea63d584 100644
> --- a/target/i386/kvm/kvm.c
> +++ b/target/i386/kvm/kvm.c
> @@ -5314,7 +5314,7 @@ int kvm_filter_msr(KVMState *s, uint32_t msr, 
> QEMURDMSRHandler *rdmsr,
>  {
>      int i, ret;
>  
> -    for (i = 0; i < ARRAY_SIZE(msr_handlers); i++) {
> +    for (i = 0; i < KVM_MSR_FILTER_MAX_RANGES; i++) {
>          if (!msr_handlers[i].msr) {
>              msr_handlers[i] = (KVMMSRHandlers) {
>                  .msr = msr,
> @@ -5340,7 +5340,7 @@ static int kvm_handle_rdmsr(X86CPU *cpu, struct kvm_run 
> *run)
>      int i;
>      bool r;
>  
> -    for (i = 0; i < ARRAY_SIZE(msr_handlers); i++) {
> +    for (i = 0; i < KVM_MSR_FILTER_MAX_RANGES; i++) {
>          KVMMSRHandlers *handler = &msr_handlers[i];
>          if (run->msr.index == handler->msr) {
>              if (handler->rdmsr) {
> @@ -5360,7 +5360,7 @@ static int kvm_handle_wrmsr(X86CPU *cpu, struct kvm_run 
> *run)
>      int i;
>      bool r;
>  
> -    for (i = 0; i < ARRAY_SIZE(msr_handlers); i++) {
> +    for (i = 0; i < KVM_MSR_FILTER_MAX_RANGES; i++) {
>          KVMMSRHandlers *handler = &msr_handlers[i];
>          if (run->msr.index == handler->msr) {
>              if (handler->wrmsr) {