linux-kernel - [PATCH v2 10/66] KVM: x86: Clean up CPUID 0x7 sub-leaf loop

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Date:   Mon,  2 Mar 2020 15:56:13 -0800
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Xiaoyao Li <xiaoyao.li@...el.com>
Subject: [PATCH v2 10/66] KVM: x86: Clean up CPUID 0x7 sub-leaf loop

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.

Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.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;
 	}
-- 
2.24.1