[10/61] KVM: x86: Clean up CPUID 0x7 sub-leaf loop
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Message ID 20200201185218.24473-11-sean.j.christopherson@intel.com
State New
Headers show
Series
  • KVM: x86: Introduce KVM cpu caps
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Commit Message

Sean Christopherson Feb. 1, 2020, 6:51 p.m. UTC
Refactor the sub-leaf loop for CPUID 0x7 to move the main leaf out of
said loop.  The emitted code savings is basically a mirage, as the
handling of the main leaf can easily be split to its own helper to avoid
code bloat.

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 arch/x86/kvm/cpuid.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

Comments

Vitaly Kuznetsov Feb. 21, 2020, 2:20 p.m. UTC | #1
Sean Christopherson <sean.j.christopherson@intel.com> writes:

> Refactor the sub-leaf loop for CPUID 0x7 to move the main leaf out of
> said loop.  The emitted code savings is basically a mirage, as the
> handling of the main leaf can easily be split to its own helper to avoid
> code bloat.
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
>  arch/x86/kvm/cpuid.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 6e1685a16cca..b626893a11d5 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -573,16 +573,16 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
>  	case 7: {
>  		int i;
>  
> -		for (i = 0; ; ) {
> +		do_cpuid_7_mask(entry, 0);
> +
> +		for (i = 1; i <= entry->eax; i++) {
> +			if (*nent >= maxnent)
> +				goto out;
> +
> +			do_host_cpuid(&entry[i], function, i);
> +			++*nent;
> +
>  			do_cpuid_7_mask(&entry[i], i);
> -			if (i == entry->eax)
> -				break;
> -			if (*nent >= maxnent)
> -				goto out;
> -
> -			++i;
> -			do_host_cpuid(&entry[i], function, i);
> -			++*nent;
>  		}
>  		break;
>  	}

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>

Patch
diff mbox series

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 6e1685a16cca..b626893a11d5 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -573,16 +573,16 @@  static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, u32 function,
 	case 7: {
 		int i;
 
-		for (i = 0; ; ) {
+		do_cpuid_7_mask(entry, 0);
+
+		for (i = 1; i <= entry->eax; i++) {
+			if (*nent >= maxnent)
+				goto out;
+
+			do_host_cpuid(&entry[i], function, i);
+			++*nent;
+
 			do_cpuid_7_mask(&entry[i], i);
-			if (i == entry->eax)
-				break;
-			if (*nent >= maxnent)
-				goto out;
-
-			++i;
-			do_host_cpuid(&entry[i], function, i);
-			++*nent;
 		}
 		break;
 	}