linux-kernel - [PATCH 22/42] KVM: selftests: Add helpers to get and modify a vCPU's CPUID entries

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Message-Id: <20220604012058.1972195-23-seanjc@google.com>
Date:   Sat,  4 Jun 2022 01:20:38 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     kvm@...r.kernel.org, Vitaly Kuznetsov <vkuznets@...hat.com>,
        David Matlack <dmatlack@...gle.com>,
        Jim Mattson <jmattson@...gle.com>, linux-kernel@...r.kernel.org
Subject: [PATCH 22/42] KVM: selftests: Add helpers to get and modify a vCPU's
 CPUID entries

Add helpers to get a specific CPUID entry for a given vCPU, and to toggle
a specific CPUID-based feature for a vCPU.  The helpers will reduce the
amount of boilerplate code needed to tweak a vCPU's CPUID model, improve
code clarity, and most importantly move tests away from modifying the
static "cpuid" returned by kvm_get_supported_cpuid().

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 .../selftests/kvm/include/x86_64/processor.h  | 30 +++++++++++++++++++
 .../selftests/kvm/lib/x86_64/processor.c      | 18 +++++++++++
 2 files changed, 48 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index e43a1d2fd112..61b8047243e0 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -620,6 +620,19 @@ struct kvm_cpuid_entry2 *get_cpuid_entry(struct kvm_cpuid2 *cpuid,
 					 uint32_t function, uint32_t index);
 void vcpu_init_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid);
 
+static inline struct kvm_cpuid_entry2 *__vcpu_get_cpuid_entry(struct kvm_vcpu *vcpu,
+							      uint32_t function,
+							      uint32_t index)
+{
+	return get_cpuid_entry(vcpu->cpuid, function, index);
+}
+
+static inline struct kvm_cpuid_entry2 *vcpu_get_cpuid_entry(struct kvm_vcpu *vcpu,
+							    uint32_t function)
+{
+	return __vcpu_get_cpuid_entry(vcpu, function, 0);
+}
+
 static inline int __vcpu_set_cpuid(struct kvm_vcpu *vcpu)
 {
 	int r;
@@ -643,6 +656,23 @@ static inline void vcpu_set_cpuid(struct kvm_vcpu *vcpu)
 	vcpu_ioctl(vcpu, KVM_GET_CPUID2, vcpu->cpuid);
 }
 
+void vcpu_set_or_clear_cpuid_feature(struct kvm_vcpu *vcpu,
+				     struct kvm_x86_cpu_feature feature,
+				     bool set);
+
+static inline void vcpu_set_cpuid_feature(struct kvm_vcpu *vcpu,
+					  struct kvm_x86_cpu_feature feature)
+{
+	vcpu_set_or_clear_cpuid_feature(vcpu, feature, true);
+
+}
+
+static inline void vcpu_clear_cpuid_feature(struct kvm_vcpu *vcpu,
+					    struct kvm_x86_cpu_feature feature)
+{
+	vcpu_set_or_clear_cpuid_feature(vcpu, feature, false);
+}
+
 static inline struct kvm_cpuid_entry2 *kvm_get_supported_cpuid_index(uint32_t function,
 								     uint32_t index)
 {
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index a835a63a6924..6c21893f5038 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -767,6 +767,24 @@ void vcpu_init_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid)
 	vcpu_set_cpuid(vcpu);
 }
 
+void vcpu_set_or_clear_cpuid_feature(struct kvm_vcpu *vcpu,
+				     struct kvm_x86_cpu_feature feature,
+				     bool set)
+{
+	struct kvm_cpuid_entry2 *entry;
+	u32 *reg;
+
+	entry = __vcpu_get_cpuid_entry(vcpu, feature.function, feature.index);
+	reg = (&entry->eax) + feature.reg;
+
+	if (set)
+		*reg |= BIT(feature.bit);
+	else
+		*reg &= ~BIT(feature.bit);
+
+	vcpu_set_cpuid(vcpu);
+}
+
 uint64_t vcpu_get_msr(struct kvm_vcpu *vcpu, uint64_t msr_index)
 {
 	struct {
-- 
2.36.1.255.ge46751e96f-goog