Merge tag 'kvm-x86-pvunhalt-6.9' of https://github.com/kvm-x86/linux into HEAD

Fix a bug in KVM_SET_CPUID{2,} where KVM looks at the wrong CPUID entries (old
vs. new) and ultimately neglects to clear PV_UNHALT from vCPUs with HLT-exiting
disabled.

2 files changed, 50 insertions, 0 deletions

diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 3bd03b088dda..81ce37ec407d 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -1037,8 +1037,19 @@ static inline void vcpu_set_cpuid(struct kvm_vcpu *vcpu)
 void vcpu_set_cpuid_property(struct kvm_vcpu *vcpu,
 			     struct kvm_x86_cpu_property property,
 			     uint32_t value);
+void vcpu_set_cpuid_maxphyaddr(struct kvm_vcpu *vcpu, uint8_t maxphyaddr);
 
 void vcpu_clear_cpuid_entry(struct kvm_vcpu *vcpu, uint32_t function);
+
+static inline bool vcpu_cpuid_has(struct kvm_vcpu *vcpu,
+				  struct kvm_x86_cpu_feature feature)
+{
+	struct kvm_cpuid_entry2 *entry;
+
+	entry = __vcpu_get_cpuid_entry(vcpu, feature.function, feature.index);
+	return *((&entry->eax) + feature.reg) & BIT(feature.bit);
+}
+
 void vcpu_set_or_clear_cpuid_feature(struct kvm_vcpu *vcpu,
 				     struct kvm_x86_cpu_feature feature,
 				     bool set);
diff --git a/tools/testing/selftests/kvm/x86_64/kvm_pv_test.c b/tools/testing/selftests/kvm/x86_64/kvm_pv_test.c
index 9e2879af7c20..40cc59f4e650 100644
--- a/tools/testing/selftests/kvm/x86_64/kvm_pv_test.c
+++ b/tools/testing/selftests/kvm/x86_64/kvm_pv_test.c
@@ -133,6 +133,43 @@ static void enter_guest(struct kvm_vcpu *vcpu)
 	}
 }
 
+static void test_pv_unhalt(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+	struct kvm_cpuid_entry2 *ent;
+	u32 kvm_sig_old;
+
+	pr_info("testing KVM_FEATURE_PV_UNHALT\n");
+
+	TEST_REQUIRE(KVM_CAP_X86_DISABLE_EXITS);
+
+	/* KVM_PV_UNHALT test */
+	vm = vm_create_with_one_vcpu(&vcpu, guest_main);
+	vcpu_set_cpuid_feature(vcpu, X86_FEATURE_KVM_PV_UNHALT);
+
+	TEST_ASSERT(vcpu_cpuid_has(vcpu, X86_FEATURE_KVM_PV_UNHALT),
+		    "Enabling X86_FEATURE_KVM_PV_UNHALT had no effect");
+
+	/* Make sure KVM clears vcpu->arch.kvm_cpuid */
+	ent = vcpu_get_cpuid_entry(vcpu, KVM_CPUID_SIGNATURE);
+	kvm_sig_old = ent->ebx;
+	ent->ebx = 0xdeadbeef;
+	vcpu_set_cpuid(vcpu);
+
+	vm_enable_cap(vm, KVM_CAP_X86_DISABLE_EXITS, KVM_X86_DISABLE_EXITS_HLT);
+	ent = vcpu_get_cpuid_entry(vcpu, KVM_CPUID_SIGNATURE);
+	ent->ebx = kvm_sig_old;
+	vcpu_set_cpuid(vcpu);
+
+	TEST_ASSERT(!vcpu_cpuid_has(vcpu, X86_FEATURE_KVM_PV_UNHALT),
+		    "KVM_FEATURE_PV_UNHALT is set with KVM_CAP_X86_DISABLE_EXITS");
+
+	/* FIXME: actually test KVM_FEATURE_PV_UNHALT feature */
+
+	kvm_vm_free(vm);
+}
+
 int main(void)
 {
 	struct kvm_vcpu *vcpu;
@@ -151,4 +188,6 @@ int main(void)
 
 	enter_guest(vcpu);
 	kvm_vm_free(vm);
+
+	test_pv_unhalt();
 }