linux-kernel - [PATCH v2 39/49] KVM: x86: Extract code for generating per-entry emulated CPUID information

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Date: Fri, 17 May 2024 10:39:16 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>, Sean Christopherson <seanjc@...gle.com>, 
	Vitaly Kuznetsov <vkuznets@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Hou Wenlong <houwenlong.hwl@...group.com>, Kechen Lu <kechenl@...dia.com>, 
	Oliver Upton <oliver.upton@...ux.dev>, Maxim Levitsky <mlevitsk@...hat.com>, 
	Binbin Wu <binbin.wu@...ux.intel.com>, Yang Weijiang <weijiang.yang@...el.com>, 
	Robert Hoo <robert.hoo.linux@...il.com>
Subject: [PATCH v2 39/49] KVM: x86: Extract code for generating per-entry
 emulated CPUID information

Extract the meat of __do_cpuid_func_emulated() into a separate helper,
cpuid_func_emulated(), so that cpuid_func_emulated() can be used with a
single CPUID entry.  This will allow marking emulated features as fully
supported in the guest cpu_caps without needing to hardcode the set of
emulated features in multiple locations.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/cpuid.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index fd725cbbcce5..d1849fe874ab 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -1007,14 +1007,10 @@ static struct kvm_cpuid_entry2 *do_host_cpuid(struct kvm_cpuid_array *array,
 	return entry;
 }
 
-static int __do_cpuid_func_emulated(struct kvm_cpuid_array *array, u32 func)
+static int cpuid_func_emulated(struct kvm_cpuid_entry2 *entry, u32 func)
 {
-	struct kvm_cpuid_entry2 *entry;
+	memset(entry, 0, sizeof(*entry));
 
-	if (array->nent >= array->maxnent)
-		return -E2BIG;
-
-	entry = &array->entries[array->nent];
 	entry->function = func;
 	entry->index = 0;
 	entry->flags = 0;
@@ -1022,23 +1018,27 @@ static int __do_cpuid_func_emulated(struct kvm_cpuid_array *array, u32 func)
 	switch (func) {
 	case 0:
 		entry->eax = 7;
-		++array->nent;
-		break;
+		return 1;
 	case 1:
 		entry->ecx = F(MOVBE);
-		++array->nent;
-		break;
+		return 1;
 	case 7:
 		entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
 		entry->eax = 0;
 		if (kvm_cpu_cap_has(X86_FEATURE_RDTSCP))
 			entry->ecx = F(RDPID);
-		++array->nent;
-		break;
+		return 1;
 	default:
-		break;
+		return 0;
 	}
+}
 
+static int __do_cpuid_func_emulated(struct kvm_cpuid_array *array, u32 func)
+{
+	if (array->nent >= array->maxnent)
+		return -E2BIG;
+
+	array->nent += cpuid_func_emulated(&array->entries[array->nent], func);
 	return 0;
 }
 
-- 
2.45.0.215.g3402c0e53f-goog